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THE AUSTRALIAN NATIONAL UNIVERSITY. Pressure Changes and Airflow during Breathing Christian Stricker Associate Professor for Systems Physiology ANUMS/JCSMR - ANU [email protected] http:/ /stricker.jcsmr.anu.edu.au/Airflow.pptx. Respiratory Part in Block 2. Week 8 Airflow - PowerPoint PPT Presentation
Citation preview
CS 2015
Pressure Changes and Airflow during Breathing
Christian StrickerAssociate Professor for Systems Physiology
ANUMSJCSMR - ANU
ChristianStrickeranueduauhttpstrickerjcsmranueduauAirflowpptx
THE AUSTRALIAN NATIONAL UNIVERSITY
CS 2015
CS 2015
Respiratory Part in Block 2bull Week 8
1 Airflow
bull Week 9
2 Mechanical properties of lung thorax
ndash Spirometry practical
3 Pulmonary ventilation
4 Pulmonary perfusion and matching of perfusion with ventilation
bull Week 10
5 Respiratory control and regulation
ndash Respiratory regulation practical
bull Week 12
6 Wrap-up of Block 2
CS 2015
Aims
At the end of this lecture students should be able to
bull discuss different types of spirometers
bull outline how flows volumes amp pressures are measured
bull illustrate the phases of the respiratory cycle and what
determines them
bull define forced volumes and peak flows
bull recognise some important features in a flow-volume loop
and
bull explain the P-V work during respiration
CS 2015
Contents
bull Measuring techniques
bull How to measure RV
bull Repetition of volumespressures
bull Respiratory cycle
bull Forced volumes and peak flows
bull Flow-volume curves
bull P-V (V-P) work and its optimisation
CS 2015
Static Lung Volumes
bull Measured with a spirometer
bull Static volumes (no flow) only maximal
values relevant
bull Volumes = cannot be broken down
any further
bull Capacities ge 2 volumes
bull TLC reached with maximal inspiration
bull RV reached with maximal expiration
bull FRC reached when in- and expiratory
muscles are ldquorelaxedrdquo (training)
bull Coaching required to achieve
maxima
Modified from Boron amp Boulpaep 2003
CS 2015
Bell Spirometersbull Bell dome filled with air and
immersed in water (separation)
bull Oldest spirometer type still used
bull Different makes and variants
bull Prosndash Direct volume measurement
ndash Very precise when well adjusted
ndash Allows for measurements of O2
uptake (metabolic studies)
bull Consndash Poor dynamics due to inertia no flow
measurements possible
ndash Expensive (several K AU$)Wintrich 1854
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
CS 2015
Respiratory Part in Block 2bull Week 8
1 Airflow
bull Week 9
2 Mechanical properties of lung thorax
ndash Spirometry practical
3 Pulmonary ventilation
4 Pulmonary perfusion and matching of perfusion with ventilation
bull Week 10
5 Respiratory control and regulation
ndash Respiratory regulation practical
bull Week 12
6 Wrap-up of Block 2
CS 2015
Aims
At the end of this lecture students should be able to
bull discuss different types of spirometers
bull outline how flows volumes amp pressures are measured
bull illustrate the phases of the respiratory cycle and what
determines them
bull define forced volumes and peak flows
bull recognise some important features in a flow-volume loop
and
bull explain the P-V work during respiration
CS 2015
Contents
bull Measuring techniques
bull How to measure RV
bull Repetition of volumespressures
bull Respiratory cycle
bull Forced volumes and peak flows
bull Flow-volume curves
bull P-V (V-P) work and its optimisation
CS 2015
Static Lung Volumes
bull Measured with a spirometer
bull Static volumes (no flow) only maximal
values relevant
bull Volumes = cannot be broken down
any further
bull Capacities ge 2 volumes
bull TLC reached with maximal inspiration
bull RV reached with maximal expiration
bull FRC reached when in- and expiratory
muscles are ldquorelaxedrdquo (training)
bull Coaching required to achieve
maxima
Modified from Boron amp Boulpaep 2003
CS 2015
Bell Spirometersbull Bell dome filled with air and
immersed in water (separation)
bull Oldest spirometer type still used
bull Different makes and variants
bull Prosndash Direct volume measurement
ndash Very precise when well adjusted
ndash Allows for measurements of O2
uptake (metabolic studies)
bull Consndash Poor dynamics due to inertia no flow
measurements possible
ndash Expensive (several K AU$)Wintrich 1854
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Respiratory Part in Block 2bull Week 8
1 Airflow
bull Week 9
2 Mechanical properties of lung thorax
ndash Spirometry practical
3 Pulmonary ventilation
4 Pulmonary perfusion and matching of perfusion with ventilation
bull Week 10
5 Respiratory control and regulation
ndash Respiratory regulation practical
bull Week 12
6 Wrap-up of Block 2
CS 2015
Aims
At the end of this lecture students should be able to
bull discuss different types of spirometers
bull outline how flows volumes amp pressures are measured
bull illustrate the phases of the respiratory cycle and what
determines them
bull define forced volumes and peak flows
bull recognise some important features in a flow-volume loop
and
bull explain the P-V work during respiration
CS 2015
Contents
bull Measuring techniques
bull How to measure RV
bull Repetition of volumespressures
bull Respiratory cycle
bull Forced volumes and peak flows
bull Flow-volume curves
bull P-V (V-P) work and its optimisation
CS 2015
Static Lung Volumes
bull Measured with a spirometer
bull Static volumes (no flow) only maximal
values relevant
bull Volumes = cannot be broken down
any further
bull Capacities ge 2 volumes
bull TLC reached with maximal inspiration
bull RV reached with maximal expiration
bull FRC reached when in- and expiratory
muscles are ldquorelaxedrdquo (training)
bull Coaching required to achieve
maxima
Modified from Boron amp Boulpaep 2003
CS 2015
Bell Spirometersbull Bell dome filled with air and
immersed in water (separation)
bull Oldest spirometer type still used
bull Different makes and variants
bull Prosndash Direct volume measurement
ndash Very precise when well adjusted
ndash Allows for measurements of O2
uptake (metabolic studies)
bull Consndash Poor dynamics due to inertia no flow
measurements possible
ndash Expensive (several K AU$)Wintrich 1854
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Aims
At the end of this lecture students should be able to
bull discuss different types of spirometers
bull outline how flows volumes amp pressures are measured
bull illustrate the phases of the respiratory cycle and what
determines them
bull define forced volumes and peak flows
bull recognise some important features in a flow-volume loop
and
bull explain the P-V work during respiration
CS 2015
Contents
bull Measuring techniques
bull How to measure RV
bull Repetition of volumespressures
bull Respiratory cycle
bull Forced volumes and peak flows
bull Flow-volume curves
bull P-V (V-P) work and its optimisation
CS 2015
Static Lung Volumes
bull Measured with a spirometer
bull Static volumes (no flow) only maximal
values relevant
bull Volumes = cannot be broken down
any further
bull Capacities ge 2 volumes
bull TLC reached with maximal inspiration
bull RV reached with maximal expiration
bull FRC reached when in- and expiratory
muscles are ldquorelaxedrdquo (training)
bull Coaching required to achieve
maxima
Modified from Boron amp Boulpaep 2003
CS 2015
Bell Spirometersbull Bell dome filled with air and
immersed in water (separation)
bull Oldest spirometer type still used
bull Different makes and variants
bull Prosndash Direct volume measurement
ndash Very precise when well adjusted
ndash Allows for measurements of O2
uptake (metabolic studies)
bull Consndash Poor dynamics due to inertia no flow
measurements possible
ndash Expensive (several K AU$)Wintrich 1854
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Contents
bull Measuring techniques
bull How to measure RV
bull Repetition of volumespressures
bull Respiratory cycle
bull Forced volumes and peak flows
bull Flow-volume curves
bull P-V (V-P) work and its optimisation
CS 2015
Static Lung Volumes
bull Measured with a spirometer
bull Static volumes (no flow) only maximal
values relevant
bull Volumes = cannot be broken down
any further
bull Capacities ge 2 volumes
bull TLC reached with maximal inspiration
bull RV reached with maximal expiration
bull FRC reached when in- and expiratory
muscles are ldquorelaxedrdquo (training)
bull Coaching required to achieve
maxima
Modified from Boron amp Boulpaep 2003
CS 2015
Bell Spirometersbull Bell dome filled with air and
immersed in water (separation)
bull Oldest spirometer type still used
bull Different makes and variants
bull Prosndash Direct volume measurement
ndash Very precise when well adjusted
ndash Allows for measurements of O2
uptake (metabolic studies)
bull Consndash Poor dynamics due to inertia no flow
measurements possible
ndash Expensive (several K AU$)Wintrich 1854
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Static Lung Volumes
bull Measured with a spirometer
bull Static volumes (no flow) only maximal
values relevant
bull Volumes = cannot be broken down
any further
bull Capacities ge 2 volumes
bull TLC reached with maximal inspiration
bull RV reached with maximal expiration
bull FRC reached when in- and expiratory
muscles are ldquorelaxedrdquo (training)
bull Coaching required to achieve
maxima
Modified from Boron amp Boulpaep 2003
CS 2015
Bell Spirometersbull Bell dome filled with air and
immersed in water (separation)
bull Oldest spirometer type still used
bull Different makes and variants
bull Prosndash Direct volume measurement
ndash Very precise when well adjusted
ndash Allows for measurements of O2
uptake (metabolic studies)
bull Consndash Poor dynamics due to inertia no flow
measurements possible
ndash Expensive (several K AU$)Wintrich 1854
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Bell Spirometersbull Bell dome filled with air and
immersed in water (separation)
bull Oldest spirometer type still used
bull Different makes and variants
bull Prosndash Direct volume measurement
ndash Very precise when well adjusted
ndash Allows for measurements of O2
uptake (metabolic studies)
bull Consndash Poor dynamics due to inertia no flow
measurements possible
ndash Expensive (several K AU$)Wintrich 1854
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Pneumotachographsbull Modern spirometers (Lilly used in
practical) measure flow
bull Based on Ohmrsquos lawndash ΔP = R I (I = flow = V Δt)
ndash Volume obtained by integration
bull Prosndash Excellent dynamic response
ndash Cheap (few 100rsquos AU$)
bull Consndash ldquoFiddlyrdquo - small pressure changes can
cause ldquodriftsrdquo (Temperature)
ndash Need repeated calibrations
ndash Need a computerhttpwwwspirxpertcomtechnical3htm
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
How to Measure RV (TLC)
bull Body plethysmograph
bull Insp rarr air flow rarr ΔV rarr ΔP
bull From ΔPBox PA and FRC are
determined
bull If Ppl measured (oesoph)
all respiratory pressures known
bull Allows RAW estimationModified from Boron amp Boulpaep 2003
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Another Method for RV
bull Helium dilution technique
bull Requires [He] to be measured
bull TLV can be estimated if initial [He]
and that after equilibration are
known
bull Simple and effective method
bull Problem Small amount of He is
dissolved in plasma rarr over-
estimates of true volume (correction
required)
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Important Pressuresbull (always take ldquoinside viewrdquo)
bull Pb = barometric pressure
bull Ppl = intrapleural pressure
bull PA (alveolar pressure) = 0 at
beginningend of in-expiration
(FRecoil = FThorax)
ndash Volume corresponds to FRC (when all
muscles are relaxed)
bull PL = translung pressure
bull Pw = transthoracic pressure
bull Prs = resp system pressureModified from Boron amp Boulpaep 2003
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Respiratory Cycle within TV
A FRC Ppl = -PL (no muscle force)
(PA = Ppl + PL PA = 0)
B Inspiration muscles contract (-25 cm
H2O) rarr Ppldarr and -PLdarr lags (due to RAW
amp CL) PA lt 0 rarr air flow into alveoli
C End of I start of E Ppl = -PL but at
a larger magnitude (PL = 75 cm H2O)
D Expiration muscles relax rarr recoil of
system rarr Ppluarr with lagging -PLuarr
PA gt 0 rarr air flow out of alveoli
bull 2 parts of Ppl (Ppl = PA - PL)
ndash PA tracks air flow
ndash PL tracks lung volume (integrated
flow)
Modified from Boron amp Boulpaep 2003
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Reasons Why -PL Lags Ppl
bull There are two major
factorsndash Airway resistance (RAW)
ndash Total compliance (CT)
bull Characteristic time (τ) is
product τ = RAWCT
bull For influence of each
factor see next lecture
bull See also influence on
ventilation (later)
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
ForcedLarge Respiratory Cycle
bull Pmus = 27 cm H2O causes
inspiration to ~90 TLC
bull Similar story as before
bull Muscles build-up considerable
recoil energy not only in elastic
lungthorax tissue but also in
muscles
bull At gt60 TLC considerable
pressures generated by
muscles which can render
thorax recoil inward at end of
inspirationModified from Hlastala amp Berger 2001
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Forced Volumes amp Peak Flowbull Dynamic volumes important in
evaluating RAW
bull Training required
bull Best out of 3 trials E for 10 s
(count down)
bull Peak flows PEF and PIFndash PEF more sensitive to RAW
ndash PIF is normally gt PEF (airway
distension - next)
bull FEV1 and FVC (more dynamic)
ndash FEV1 good test of RAW
ndash FVC gt VC (acceleration)
Mod
ified
from
Bor
on amp
Bou
lpae
p 2
003
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Flow-Volume Diagrambull Air flow plotted against volume change
from maximal filling (TLC) 0 TLC
maximum = RV span = FVC
bull Maximal efforts required to have
indicative curves (training)
bull Positive flow inspiration negative
expiration
bull PEF reached le 20 volume
bull Expiratory flow rates at lt 2 L are
effort-dependent muscle
bull Expiratory flow rates at gt 2 L are
effort-independent limited by
lungthorax recoil amp RAWBerne et al 2008
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
TV and Different Efforts
bull TV in ldquomiddlerdquo of graph
bull Inspiratory part of loop
unimportant
bull Detailed interpretation
given later
bull Make sure that person puts
in best effort (judge ithellip)
bull Effort-independent region
flow determined by RAW and
recoil CTBerne et al 2008
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
bull Inspiration Winsp + Wela (ldquoloading of recoilrdquo)
bull Expiration Wexp - Wela (recoil at TV is sufficient)
bull For volumes gt TV Wmus(exp) becomes more important
Respiratory Work - V-P Loop
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Optimisation of Respiration
bull Resistive workuarr with respiratory rate as flowuarr (transitional flow)
bull Elastic workdarr with respiratory rate (time constant of recoil)ndash Elastic work (Wela) at
mimimum ~ 30 bpm (ldquoresonancerdquo of elastic system)
bull Minimum of total work at ~ eupnoea (12 ndash 20 bpm)
Berne et al 2004
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Take-Home Messagesbull Several methods to measure volumes and
pressure all have their place in clinical practice
bull Pneumotachography and He-dilution allow measurement of RV and TLC
bull Intrapleural pressure (Ppl) has 2 components
ndash PA determining flow and
ndash PL determining volume
bull PL lags behind -Ppl during respiratory cycle
bull Air flow into lung is determined by RAW and CT
bull V-P loop indicates external work during respiration
ndash at TV expiration is passive inspiration via muscle force
bull Flow-volume loop reveals most dynamic aspects
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
Thatrsquos it folkshellip
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
CS 2015
MCQA 17 year-old woman presents to emergency with an acute asthma
exacerbation of moderate severity Which of the following sets of lung
function tests best describes her current condition
A Decreased FVC FEV1 FEV1FVC PEF and increased RV
B Decreased FVC FEV1 PEF and normal FEV1FVC RV
C Decreased FVC FEV1 FEV1FVC and increased PEF RV
D Decreased FVC FEV1 PEF and increased FEV1FVC RV
E Decreased FVC FEV1 FEV1FVC and normal PEF RV
