CAPNOGRAPHYCAPNOGRAPHYIn Emergency CareIn Emergency Care
EDUCATIONAL SERIESEDUCATIONAL SERIES
Part 2:Part 2:IntroductionIntroduction
Part 2: Introduction to CapnographyPart 2: Introduction to Capnography
CAPNOGRAPHYCAPNOGRAPHYIn Emergency CareIn Emergency Care
Part 2: Introduction to Capnography Part 2: Introduction to Capnography Learning ObjectivesLearning Objectives
• Differentiate between oxygenation Differentiate between oxygenation and ventilationand ventilation
• Define end-tidal CODefine end-tidal CO22
• Identify phases of a normal capnogramIdentify phases of a normal capnogram• Recognize patterns of hypoventilation, Recognize patterns of hypoventilation,
hyperventilation and bronchospasmhyperventilation and bronchospasm
Oxygenation and VentilationOxygenation and Ventilation
What is the difference?What is the difference?
Oxygenation and VentilationOxygenation and Ventilation
• Two completely different and Two completely different and separate functionsseparate functions– Oxygenation is the transport of OOxygenation is the transport of O22 via the via the
bloodstream to the cellsbloodstream to the cells• Oxygen is required for metabolismOxygen is required for metabolism
– Ventilation is the exhaling of COVentilation is the exhaling of CO22 via the via the respiratory tractrespiratory tract• Carbon dioxide is a byproduct Carbon dioxide is a byproduct
of metabolismof metabolism
Oxygenation and VentilationOxygenation and Ventilation
OxygenationOxygenation(oximetry(oximetry))
CellularCellularMetabolismMetabolism
VentilationVentilation(capnography)(capnography)
COCO22
OO22
OxygenationOxygenation
• Measured by pulse oximetry (SpOMeasured by pulse oximetry (SpO22) ) – Noninvasive measurementNoninvasive measurement– Percentage of oxygen in red blood cells Percentage of oxygen in red blood cells – Changes in ventilation take minutes Changes in ventilation take minutes
to be detected to be detected – Affected by motion artifact, poor perfusion Affected by motion artifact, poor perfusion
and some dysrhythmiasand some dysrhythmias
OxygenationOxygenation
Pulse OximetryPulse Oximetry SensorsSensors
Pulse Oximetry WaveformPulse Oximetry Waveform
VentilationVentilation
• Measured by the end-tidal COMeasured by the end-tidal CO22
– Partial pressure (mmHg) or volume (% vol) of Partial pressure (mmHg) or volume (% vol) of COCO22 in the airway at the end of exhalation in the airway at the end of exhalation
– Breath-to-breath measurement provides Breath-to-breath measurement provides information within secondsinformation within seconds
– Not affected by motion artifact, poor perfusion Not affected by motion artifact, poor perfusion or dysrhythmiasor dysrhythmias
VentilationVentilation
Capnography waveformCapnography waveform
Capnography Capnography LinesLines
Oxygenation versus VentilationOxygenation versus Ventilation
• Monitor your own Monitor your own SpOSpO22 and EtCO and EtCO22
• SpOSpO22 waveform is in waveform is in the second channelthe second channel
• EtCOEtCO22 waveform is waveform is in the third channelin the third channel
OxygenationOxygenation versusversus VentilationVentilation
• Now hold your breathNow hold your breath• Note what happens to Note what happens to
the two waveforms the two waveforms
How long did it take the How long did it take the EtCOEtCO22 waveform to go flat line? waveform to go flat line?
How long did it take the How long did it take the SpOSpO22 to drop below 90%? to drop below 90%?
SpOSpO22
EtCOEtCO22
Oxygenation and VentilationOxygenation and Ventilation
• OxygenationOxygenation– Oxygen for Oxygen for
metabolismmetabolism
– SpOSpO22 measures measures
% of O% of O22 in RBC in RBC
– Reflects change in Reflects change in oxygenation within oxygenation within 5 minutes5 minutes
• VentilationVentilation– Carbon dioxide Carbon dioxide
from metabolismfrom metabolism
– EtCOEtCO22 measures measures
exhaled COexhaled CO22 at at
point of exitpoint of exit– Reflects change in Reflects change in
ventilation within ventilation within 10 seconds10 seconds
Why Measure VentilationWhy Measure Ventilation——Intubated PatientsIntubated Patients
• Verify and document ET tube placementVerify and document ET tube placement• Immediately detect changes in ET tube positionImmediately detect changes in ET tube position• Assess effectiveness of chest compressionsAssess effectiveness of chest compressions• Earliest indication of ROSCEarliest indication of ROSC• Indicator of probability of successful Indicator of probability of successful
resuscitationresuscitation• Optimally adjust manual ventilations in patients Optimally adjust manual ventilations in patients
sensitive to changes in COsensitive to changes in CO22
Why Measure VentilationWhy Measure Ventilation——Non-Intubated PatientsNon-Intubated Patients
• Objectively assess acute Objectively assess acute respiratory disorders respiratory disorders – Asthma Asthma – COPDCOPD
• Possibly gauge response to treatmentPossibly gauge response to treatment
Why Measure Ventilation—Why Measure Ventilation—Non-intubated PatientsNon-intubated Patients
• Gauge severity of hypoventilation statesGauge severity of hypoventilation states– Drug and ETOH intoxicationDrug and ETOH intoxication– Congestive heart failureCongestive heart failure– Sedation and analgesiaSedation and analgesia– Stroke Stroke – Head injury Head injury
• Assess perfusion statusAssess perfusion status• Noninvasive monitoring of patients in DKANoninvasive monitoring of patients in DKA
Interpreting EtCOInterpreting EtCO22 and the and the Capnography WaveformCapnography Waveform
• Interpreting EtCOInterpreting EtCO22 – MeasuringMeasuring– PhysiologyPhysiology
• Capnography waveformCapnography waveform
End-tidal COEnd-tidal CO2 2 (EtCO(EtCO22))
r r Oxygen
O2
CO2O
2
VeinA te y
VentilationVentilation
PerfusionPerfusion
Pulmonary Blood Flow
Right Ventricle
LeftAtrium
End-tidal COEnd-tidal CO22 (EtCO (EtCO22))
• Carbon dioxide can be measured Carbon dioxide can be measured
• Arterial blood gas is PaCOArterial blood gas is PaCO22 – Normal range: 35-45mmHgNormal range: 35-45mmHg
• Mixed venous blood gas PeCOMixed venous blood gas PeCO22
– Normal range: 46-48mmHgNormal range: 46-48mmHg
• Exhaled carbon dioxide is EtCOExhaled carbon dioxide is EtCO22 – Normal range: 35-45mmHgNormal range: 35-45mmHg
a-A Gradienta-A Gradient
r r Alveolus
PaCO2
VeinA te y
VentilationVentilation
PerfusionPerfusion
Arterial to Alveolar Difference for CO2
Right Ventricle
LeftAtrium
EtCO2
End-tidal COEnd-tidal CO22 (EtCO (EtCO22))
• Normal a-A gradientNormal a-A gradient– 2-5mmHg difference between the EtCO2-5mmHg difference between the EtCO22
and PaCOand PaCO22 in a patient with healthy lungs in a patient with healthy lungs
– Wider differences found Wider differences found • In abnormal perfusion and ventilation In abnormal perfusion and ventilation • Incomplete alveolar emptyingIncomplete alveolar emptying• Poor samplingPoor sampling
End-tidal COEnd-tidal CO2 2 (EtCO(EtCO22))
• Reflects changes inReflects changes in – VentilationVentilation - movement of air in and - movement of air in and
out of the lungsout of the lungs– DiffusionDiffusion - exchange of gases between - exchange of gases between
the air-filled alveoli and the pulmonary the air-filled alveoli and the pulmonary circulationcirculation
– Perfusion Perfusion - circulation of blood- circulation of blood
End-tidal COEnd-tidal CO2 2 (EtCO(EtCO22))
• Monitors changes in Monitors changes in – VentilationVentilation - asthma, COPD, airway - asthma, COPD, airway
edema, foreign body, strokeedema, foreign body, stroke– Diffusion Diffusion - pulmonary edema, - pulmonary edema,
alveolar damage, CO poisoning, alveolar damage, CO poisoning, smoke inhalationsmoke inhalation
– PerfusionPerfusion - shock, pulmonary - shock, pulmonary embolus, cardiac arrest, embolus, cardiac arrest, severe dysrhythmiassevere dysrhythmias
Capnographic WaveformCapnographic Waveform
• Normal waveform of one respiratory cycleNormal waveform of one respiratory cycle• Similar to ECGSimilar to ECG
– Height shows amount of COHeight shows amount of CO22
– Length depicts timeLength depicts time
Capnographic WaveformCapnographic Waveform
• Waveforms on screen and printout Waveforms on screen and printout may differ in durationmay differ in duration– On-screen capnography waveform is On-screen capnography waveform is
condensed to provide adequate information condensed to provide adequate information the in 4-second viewthe in 4-second view
– Printouts are in real-timePrintouts are in real-time– Observe RR on deviceObserve RR on device
Capnographic WaveformCapnographic Waveform
• Capnograph detects only COCapnograph detects only CO22 from ventilationfrom ventilation
• No CONo CO22 present during inspiration present during inspiration– Baseline is normally zeroBaseline is normally zero
A B
C D
E
BaselineBaseline
Capnogram Phase ICapnogram Phase IDead Space VentilationDead Space Ventilation
• Beginning of exhalationBeginning of exhalation
• No CONo CO22 present present
• Air from trachea, Air from trachea, posterior pharynx, posterior pharynx, mouth and nosemouth and nose– No gas exchange No gas exchange
occurs thereoccurs there– Called “dead space”Called “dead space”
Capnogram Phase I Capnogram Phase I BaselineBaseline
Beginning of exhalationBeginning of exhalation
A B
I BaselineBaseline
Capnogram Phase IICapnogram Phase IIAscending PhaseAscending Phase
• COCO22 from the alveoli from the alveoli
begins to reach the upper begins to reach the upper airway and mix with the airway and mix with the dead space air dead space air – Causes a rapid rise in the Causes a rapid rise in the
amount of COamount of CO22
• COCO22 now present and now present and
detected in exhaled airdetected in exhaled air
Alveoli
Capnogram Phase IICapnogram Phase IIAscending PhaseAscending Phase
COCO22 present and increasing in exhaled air present and increasing in exhaled air
II
A B
C
Ascending PhaseAscending PhaseEarly ExhalationEarly Exhalation
Capnogram Phase IIICapnogram Phase IIIAlveolar PlateauAlveolar Plateau
• COCO22 rich alveolar gas rich alveolar gas now constitutes the now constitutes the majority of the majority of the exhaled air exhaled air
• Uniform concentration Uniform concentration of COof CO22 from alveoli to from alveoli to
nose/mouthnose/mouth
Capnogram Phase IIICapnogram Phase IIIAlveolar PlateauAlveolar Plateau
COCO22 exhalation wave plateaus exhalation wave plateaus
A B
C D
III
Alveolar PlateauAlveolar Plateau
Capnogram Phase IIICapnogram Phase IIIEnd-TidalEnd-Tidal
• End of exhalation contains the highest End of exhalation contains the highest concentration of COconcentration of CO22 – The “end-tidal COThe “end-tidal CO22””
– The number seen on your monitorThe number seen on your monitor
• Normal EtCONormal EtCO2 2 is 35-45mmHgis 35-45mmHg
Capnogram Phase IIICapnogram Phase IIIEnd-TidalEnd-Tidal
End of the the wave of exhalationEnd of the the wave of exhalation
A B
C D End-tidal
Capnogram Phase IVCapnogram Phase IVDescending PhaseDescending Phase
• Inhalation beginsInhalation begins• Oxygen fills airwayOxygen fills airway
• COCO22 level quickly level quickly
drops to zerodrops to zero
Alveoli
Capnogram Phase IVCapnogram Phase IVDescending PhaseDescending Phase
Inspiratory downstroke returns to baselineInspiratory downstroke returns to baseline
A B
C D
EIV
Descending Phase Descending Phase InhalationInhalation
Capnography WaveformCapnography Waveform
Normal range is 35-45mm Hg (5% vol)Normal range is 35-45mm Hg (5% vol)
Normal WaveformNormal Waveform
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0
Capnography Waveform QuestionCapnography Waveform Question
• How would your capnogram change How would your capnogram change if you intentionally started to breathe if you intentionally started to breathe at a rate of 30?at a rate of 30?– FrequencyFrequency– DurationDuration– HeightHeight– ShapeShape
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0
HyperventilationHyperventilation
RR : EtCORR : EtCO22
45
0
NormalNormal
HyperventilationHyperventilation
Capnography Waveform QuestionCapnography Waveform Question
• How would your capnogram change How would your capnogram change if you intentionally decreased your if you intentionally decreased your respiratory rate to 8?respiratory rate to 8?– FrequencyFrequency– DurationDuration– HeightHeight– ShapeShape
HypoventilationHypoventilation
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0
45
0
RR : EtCORR : EtCO22
NormalNormal
HypoventilationHypoventilation
Capnography Waveform PatternsCapnography Waveform Patterns
0
45
HypoventilationHypoventilation
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HyperventilationHyperventilation
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0
NormalNormal
Capnography Waveform QuestionCapnography Waveform Question
How would the waveform How would the waveform shape change during an shape change during an asthma attack?asthma attack?
Bronchospasm Waveform PatternBronchospasm Waveform Pattern
• Bronchospasm hampers ventilationBronchospasm hampers ventilation– Alveoli unevenly filled on inspiration Alveoli unevenly filled on inspiration
– Empty asynchronously during expirationEmpty asynchronously during expiration
– Asynchronous air flow on exhalation dilutes exhaled Asynchronous air flow on exhalation dilutes exhaled COCO22
• AltersAlters the ascending phase and plateauthe ascending phase and plateau– Slower rise inSlower rise in COCO2 2 concentration concentration
– Characteristic pattern for bronchospasmCharacteristic pattern for bronchospasm
– ““Shark Fin” shape to waveformShark Fin” shape to waveform
Capnography Waveform Patterns Capnography Waveform Patterns
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NormaNormall
BronchospasmBronchospasm45
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Part 2: Part 2: Introduction to Capnography SummaryIntroduction to Capnography Summary
• Oxygenation and ventilation Oxygenation and ventilation • Pulse oximetry Pulse oximetry
– Measures OMeasures O22 saturation in blood saturation in blood
– Slow to indicate change in ventilationSlow to indicate change in ventilation
• Capnography Capnography – Measures COMeasures CO22 in the the airway in the the airway
– Provides a breath-to-breath Provides a breath-to-breath status of ventilationstatus of ventilation
Part 2: Part 2: Introduction to Capnography SummaryIntroduction to Capnography Summary
• Capnographic waveform has four phases Capnographic waveform has four phases
• The highest COThe highest CO22 concentration is at the concentration is at the end of alveolar plateauend of alveolar plateau– End-tidal COEnd-tidal CO22
– Normal EtCONormal EtCO22 range is 35-45mmHg range is 35-45mmHg
• Several conditions can be immediately Several conditions can be immediately detected with capnographydetected with capnography
Capnography Waveform PatternsCapnography Waveform Patterns
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HypoventilationHypoventilation
NormalNormal
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BronchospasmBronchospasm
HyperventilationHyperventilation
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Part 2: Introduction to CapnographyPart 2: Introduction to Capnography
We’re off to a running start!We’re off to a running start!