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8/3/2019 Week 3 Ventilation of the Critically Ill Transfer Simon Giles
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Simon Giles
Ventilation of the Critically ill
Simon GilesConsultant Nurse in Critical CareHeart of England NHS Trust
8/3/2019 Week 3 Ventilation of the Critically Ill Transfer Simon Giles
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Simon Giles
8/3/2019 Week 3 Ventilation of the Critically Ill Transfer Simon Giles
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Simon Giles
Objectives
Review the Basic Anatomy & Physiology of Respiratory System
Understand reasons Artificial Ventilation
Review modes & specific strategies usedin ventilating the Critically Ill
Discuss specific conditions in the CriticallyIll patient
Be aware of possible complications
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Simon Giles
Basic Anatomy
Upper Airway
humidifies inhaled gases
site of most resistance to airflow
Lower Airway
conducting airways (anatomic dead space)
respiratory bronchioles and alveoli (gasexchange)
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Simon Giles
8/3/2019 Week 3 Ventilation of the Critically Ill Transfer Simon Giles
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Basic Physiology
http://www.biology.eku.edu/RITCHISO/301notes6.htm
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8/3/2019 Week 3 Ventilation of the Critically Ill Transfer Simon Giles
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Physiology of Respiration
Ventilation
Movement of air between the alveoli andatmosphere
Diffusion
Movement of CO2 and O2 between alveoli andcapillaries
Transport
Movement of O2 from the alveoli to the cells
Movement of CO2 from the cells to the alveoli
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Simon Giles
Abnormal Gas
Exchange Hypoxemia can bedue to:
hypoventilation
V/Q mismatch
shunt
diffusion
impairments
Hypercarbia can bedue to:
hypoventilation
V/Q mismatch
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Simon Giles
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VOELAR
GALILEO
RAPHAEL
HAMILTON G5
ventiPAC 200D
TRANSFER VENTILATOR
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Simon Giles
Mechanical Ventilation
Ventilators deliver gas to the lungsusing positive pressure at a
certain rate . The amount of gasdelivered can be limited by time,pressure or volume. The duration
can be cycled by time, pressureor flow.
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Surgical: Post-operative support, supporting other organs failure.
Respiratory centre depression:• Head injury raised intracranial pressure.• Hypercapnia.• Drug toxicity.• Meningitis, tumours, epilepsy.
Lung Disease:
• ARDS (acute respiratory distress syndrome), pneumonia, acute asthma, COPD (chronicobstructive pulmonary disease).• Aspiration, drowning, smoke inhalation, chemical attack e.g. anthrax, biological e.g. bird
flu, legionella.
Circulatory: Cardiac arrest, pulmonary oedema, shock, sepsis.
Trauma: Cervical cord trauma above C4, neck fractures, facial injury, major blood loss.
Neuromuscular disorders: Guillian-Barre, myasthenia gravis, poliomyelitis.
Chest wall disorders: traumatic flail segment, mesothelioma.
Other factors:• Poor nutrition leading to muscle weakness.• Abdominal distension/pain which squashes the diaphragm .• Low GCS ( Glasgow Coma Scale).
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• The most commonly used in the ITU setting an ET (Endo-Tracheal) tube.
• For patient on a ventilator for longer than 7-10 days a tracheotomy is performed, as thishelps with the patients weaning, its more comfortable for the patient and less dead spacereducing the work of breathing for the patient, and easier for the patient to communicate
(Orlando, 2007c).
• For short term ventilation for an operation or in an emergency, LMA (Laryngeal MaskAirway) may be used. (Leach,et al, 2004).
• For non invasive ventilation a tight fitting face mask is used (Leach,et al, 2004).
Video on Endotracheal Ventilation , (Bmedinago, May 2007) <http://uk.youtube.com/watch?v=cLL6XwhFEFQ>
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PRESSURE BASED
• “In a pressure-cycled ventilator, once a pre-setpressure is reached within the ventilator, thebreath is terminated and positive pressure cyclecompleted.” (Cited from Wikimedia, 2008)
VOLUME BASED
• “In a volume-cycled ventilator the ventilator delivers a pre-setvolume of gas with each breath to the patient as soon as thespecified volume of breath is delivered, the positive pressurecycle is completed.” (Cited from Wikimedia, 2008)
P-CMV (Pressure Controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t
support any spontaneous efforts(Wikimedia, 2008).(S) CMV (Synchronised volume controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t support any
spontaneous efforts (Hamilton, 2007).
P-SIMV (Pressure controlled SynchronisedIntermittent Mandatory Ventilation).• Allows the patient to breathe synchronising with
them providing some support l imiting thepressure(Wikimedia, 2008).
SIMV (Synchronised Intermittent Mandatory Ventilation)• Allows the patient to breathe providing some support but
delivers a set volume (Wikimedia, 2008)
PSV/SPONT(Pressure Support Ventilation).• No Set Rate used with PEEP and a set pressure ,
supporting the patients own respiratory pattern(Orlando, 2007c).
ADAPTIVE INTELIGENT MODES
• These modes provide the advantages of both pressure based
modes whilst still offering a volume guarantee• Allows spontaneous breathing adjusting the support required to
reach the targeted volume(Hamilton, 2007).
BI-PHASIC MODES
• These modes allow the patient to breathspontaneously at any time, even when the ventilatoris delivering a mandatory breath. (Hamilton, 2007).
APV (cmv) (Adaptive Pressure Ventilation with pressurecontrolled mandatory ventilation).• Targets a specified volume to be delivered.• Automatic regulation in inspired pressure and flow (Hamilton,
2007).
Duo PAP (Dual Positive Airway Pressure).
• You have to set the Rate and high airway pressure.• All other advantages same as APRV (Hamilton,
2007).
APV (simv) (Adaptive Pressure Ventilation with synchronised
intermittent mandatory ventilation).• Same as above.
APRV(Airway Pressure Release Ventilation).• The ventilator cycles from high CPAP to low CPAP
(high lung pressure/volume to low lungpressure/volume).
• Allows the patient to breathe supported or unsupported .
• Used usually for patients with severe ARDS
(Neligan, 2006)
ASV (Adaptive Support Ventilation).• Closed loop control ventilation system• ASV responds to and adapt to the patients own spontaneous
breathing pattern.• Reduces the work of breathing.• Patients height measured to calculate ideal body weight.• Reduces weaning time (Hamilton, 2006a).
PRESSURE BASED
• “In a pressure-cycled ventilator, once a pre-setpressure is reached within the ventilator, thebreath is terminated and positive pressure cyclecompleted.” (Cited from Wikimedia, 2008)
VOLUME BASED
• “In a volume-cycled ventilator the ventilator delivers a pre-setvolume of gas with each breath to the patient as soon as thespecified volume of breath is delivered, the positive pressurecycle is completed.” (Cited from Wikimedia, 2008)
P-CMV (Pressure Controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t
support any spontaneous efforts(Wikimedia, 2008).
(S) CMV (Synchronised volume controlled Mandatory Ventilation).• Does Not allow the patient to breath and doesn’t support any
spontaneous efforts (Hamilton, 2007).
P-SIMV (Pressure controlled SynchronisedIntermittent Mandatory Ventilation).• Allows the patient to breathe synchronising with
them providing some support l imiting thepressure(Wikimedia, 2008).
SIMV (Synchronised Intermittent Mandatory Ventilation)• Allows the patient to breathe providing some support but
delivers a set volume (Wikimedia, 2008)
PSV/SPONT(Pressure Support Ventilation).• No Set Rate used with PEEP and a set pressure ,
supporting the patients own respiratory pattern(Orlando, 2007c).
ADAPTIVE INTELIGENT MODES
• These modes provide the advantages of both pressure based
modes whilst still offering a volume guarantee• Allows spontaneous breathing adjusting the support required to
reach the targeted volume(Hamilton, 2007).
BI-PHASIC MODES
• These modes allow the patient to breathspontaneously at any time, even when the ventilatoris delivering a mandatory breath. (Hamilton, 2007).
APV (cmv) (Adaptive Pressure Ventilation with pressurecontrolled mandatory ventilation).• Targets a specified volume to be delivered.• Automatic regulation in inspired pressure and flow (Hamilton,
2007).
Duo PAP (Dual Positive Airway Pressure).
• You have to set the Rate and high airway pressure.• All other advantages same as APRV (Hamilton,
2007).
APV (simv) (Adaptive Pressure Ventilation with synchronised
intermittent mandatory ventilation).• Same as above.
APRV(Airway Pressure Release Ventilation).• The ventilator cycles from high CPAP to low CPAP
(high lung pressure/volume to low lungpressure/volume).
• Allows the patient to breathe supported or unsupported .
• Used usually for patients with severe ARDS
(Neligan, 2006)
ASV (Adaptive Support Ventilation).• Closed loop control ventilation system• ASV responds to and adapt to the patients own spontaneous
breathing pattern.• Reduces the work of breathing.• Patients height measured to calculate ideal body weight.• Reduces weaning time (Hamilton, 2006a).
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Simon Giles
SIMV, volume-limited
Ingento EP & Drazen J: Mechanical Ventilators, in Hall JB,
Scmidt GA, & Wood LDH(eds.): Principles of Critical Care
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Simon Giles
Pressure vs. Volume
Pressure Limited
Control FiO2 and MAP(oxygenation)
Still can influenceventilation somewhat(respiratory rate, PAP)
Decelerating flow
pattern (lower PIP forsame TV)
Volume Limited
Control minuteventilation
Still can influenceoxygenationsomewhat (FiO2,
PEEP, I-time) Square wave flow
pattern
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Simon Giles
Pressure vs. Volume
Pressure Pitfalls tidal volume by change
suddenly as patient’s
compliance changes this can lead to
hypoventilation oroverexpansion of thelung
if ETT is obstructedacutely, delivered tidalvolume will decrease
Volume Vitriol
no limit per se on PIP(usually vent will haveupper pressure limit)
square wave(constant)flow pattern results inhigher PIP for same tidal
volume as compared toPressure modes
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Simon Giles
Trigger
How does the vent know when to give abreath? - “Trigger”
patient effort
elapsed time
The patient’s effort can be “sensed” as
a change in pressure or a change in
flow (in the circuit)
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Simon Giles
Need a hand??
Pressure Support
“Triggering” vent requires certain amount of work by patient
Can decrease work of breathing by providingflow during inspiration for patient triggeredbreaths
Can be given with spontaneous breaths inIMV modes or as stand alone mode withoutset rate
Flow-cycled
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TERMINOLOGY OFVENTILATION
FREQUENCY : BREATH RATE
TV : TIDAL VOLUME IN SINGLE BREATH
MV : MINUTE VOLUME (TV x BR)
I:E RATIO : INSPIRATORY/EXPIRATORY RATIO PEAK PRESSURE : HIGHEST PRESSURE ON
INSPIRATION
PEEP : POSITVE END EXPIRATORY PRESSURE
CPAP : CONTIUOUS POSITIVE AIRWAY PRESSURE FIO2 : FRACTIONAL INSPIRED OXYGEN
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Simon Giles
Initial Settings
Pressure Limited
FiO2
Rate I-time or I:E ratio
PEEP
PIP or PAP
Volume Limited
FiO2
Rate I-time or I:E ratio
PEEP
Tidal VolumeThese choices are with time - cycled ventilators.
Flow cycled vents are available but not commonly
used in pediatrics.
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TROUBLE SHOOTING : LOWOXYGENATION
INCREASE FIO2
CHECK TV
SUCTION PATIENT IF NEEDED INCREASE PEEP
CHANGE I:E RATIO
CHECK SEDATION
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TROUBLE SHOOTING : LOWOXYGENATION
INCREASE FIO2
CHECK TV
SUCTION PATIENT IF NEEDED INCREASE PEEP
CHANGE I:E RATIO
CHECK SEDATION
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TROUBLE SHOOTING: HIGHCARBON DIOXIDE
INCREASE RESPIRATORY RATE
CHANGE I:E RATIO
CHECK SEDATION CHECK TIDAL VOLUMES
CHECK MINUTE VOLUMES
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Simon Giles
Except...
Is it really that simple ?
Increasing PEEP can increase dead
space, decrease cardiac output, increase V/Q mismatch
Increasing the respiratory rate can leadto dynamic hyperinflation (aka auto-PEEP), resulting in worseningoxygenation and ventilation
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Simon Giles
Troubleshooting
Is it working ?
Look at the patient !!
Listen to the patient !! Pulse Ox, ABG, EtCO2
Chest X ray Look at the vent (PIP; expired TV;
alarms)
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Simon Giles
Troubleshooting
When in doubt, DISCONNECT THEPATIENT FROM THE VENT, and begin bagventilation.
Ensure you are bagging with 100% O2.
This eliminates the vent circuit as thesource of the problem.
Bagging by hand can also help you gaugepatient’s compliance
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Simon Giles
Troubleshooting Airway first: is the tube still in? (may need
DL/EtCO2 to confirm) Is it patent? Is it in theright position?
Breathing next: is the chest rising? Breathsounds present and equal? Changes in exam?
Atelectasis, bronchospasm, pneumothorax,
pneumonia? (Consider needle thoracentesis) Circulation: shock? Sepsis?
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Simon Giles
Troubleshooting
Well, it isn’t working….. Right settings ? Right Mode ?
Does the vent need to do more work ?
Patient unable to do so
Underlying process worsening (or new problem?)
Air leaks?
Does the patient need to be more sedated ? Does the patient need to be extubated ?
Vent is only human…..(is it working ?)
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Simon Giles
Troubleshooting
Patient - Ventilator Interaction
Vent must recognize patient’s
respiratory efforts (trigger) Vent must be able to meet patient’s
demands (response)
Vent must not interfere with patient’s
efforts (synchrony)
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Simon Giles
Troubleshooting
Improving Ventilation and/or Oxygenation can increase respiratory rate (or decrease rate
if air trapping is an issue)
can increase tidal volume/PAP to increasetidal volume
can increase PEEP to help recruit collapsedareas
can increase pressure support and/ordecrease sedation to improve patient’sspontaneous effort
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Difficult Clinical conditions to
Ventilate
ARDS
Rule of 1/3
Thoracic Surgical BPF
One lung
Complex Pneumonia
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• The three pictures of the alveoli show the differentphases they go through in an ARDS patient.
• It is beyond the scope of this teaching tool to go intoin-depth anatomy and physiology, but it is hoped thatthis gives the reader a brief glimpse, leading tofurther reading, improving knowledge.
• The author found these very useful in Understanding
ARDS.
FIBROTIC/RECOVERY PHASE.
HEALTHY ALVEOLI.
INJUREDALVEOLI OF
ARDSPATIENT DURING
ACUTE PHASE.
Pictures from Module 2 ARDS lectureGiven by: Nurse Consultant, Simon Gi les.(October, 2007).
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Simon Giles
Lowered Expectations
Permissive Hypercapnia accept higher PaCO2s in exchange for limiting
peak airway pressures
can titrate pH as desired with sodiumbicarbonate or other buffer
Permissive Hypoxemia accept PaO2 of 55-65; SaO2 88-90% in
exchange for limiting FiO2 (<.60) and PEEP can maintain oxygen content by keeping
hematocrit > 30%
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Simon Giles
Complications
Ventilator Induced Lung Injury
Oxygen toxicity
Barotrauma / VolutraumaPeak Pressure
Plateau Pressure
Shear Injury (tidal volume)
PEEP
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Simon Giles
Complications
Cardiovascular Complications Impaired venous return to RH
Bowing of the Interventricular Septum Decreased left sided afterload (good)
Altered right sided afterload
Sum Effect…..decreased cardiac output(usually, not always and often we don’t evennotice)
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Simon Giles
Complications
Other Complications
Ventilator Associated Pneumonia
Sinusitis
Sedation
Risks from associated devices (CVLs, A-lines)
Unplanned Extubation
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Long Term Complications
Airway Stenosis – ETT Cuff / Tracheostomy
Mouth / lips - erosions
Lung Fibrosis (ARDS)
General Critical Illness ( neuropathy )
Simon Giles
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To ‘Wind’ Up
Whistle top tour of A&P
Ventilation of the Critically Ill is OftenComplex
Modern Machines have many differentmodes for difficult ventilation
Positive Pressure Ventilation is harmful tolung tissue and does not cure patient