Capnography

Adam Thompson, EMT-P, AS

ObjectivesObjectives

Review respiratory systemLearn the terms of capnographyLearn the uses of capnographyReview confirmation of intubationReview ventilatory usesReview circulatory usesReview metabolism usesPractice scenarios

Review respiratory systemLearn the terms of capnographyLearn the uses of capnographyReview confirmation of intubationReview ventilatory usesReview circulatory usesReview metabolism usesPractice scenarios

Respiratory SystemRespiratory System

Exchange O2 for CO2Air enters nose &

mouthO2 is exchanged for

CO2 in alveoliO2 is transported to

the body and exchanged for CO2 again

Exchange O2 for CO2Air enters nose &

mouthO2 is exchanged for

CO2 in alveoliO2 is transported to

the body and exchanged for CO2 again

Nasal Passages

Roof of the Mouth

Epiglottis

Trachea (windpipe)

Esophagus (food tube)

Alveoli

BronchiPulmonary VeinBronchiole

Nasal Passages

Roof of the Mouth

Epiglottis

Trachea (windpipe)

Esophagus (food tube)

Alveoli

BronchiPulmonary VeinBronchiole

The heart pumps the freshly oxygenated blood throughout the body to the cells where oxygen is consumed (metabolism), and carbon dioxide, produced as a byproduct, diffuses out of the cells into the vascular system.


Carbon dioxide rich blood is then pumped through the pulmonary capillary bed where the carbon dioxidediffuses across the alveolar capillary membrane and is exhaled via the nose or mouth.

Carbon dioxide rich blood is then pumped through the pulmonary capillary bed where the carbon dioxidediffuses across the alveolar capillary membrane and is exhaled via the nose or mouth.


TerminologyTerminology

Capnometry The numeric value


45mmHg




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CO2: 38


Capnogram The waveform

Capnogram The waveform

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A

B C

D


The capnogram measures expired CO2. The plateau signifies expiration

The capnogram measures expired CO2. The plateau signifies expiration

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A

B C

D


ETCO2 (PeCO2) = End-Tidal CO2

CO2 = Carbon Dioxide Carbon dioxide is the by-product of all

metabolism, and is eliminated by exhaling.

ETCO2 (PeCO2) = End-Tidal CO2

CO2 = Carbon Dioxide Carbon dioxide is the by-product of all

metabolism, and is eliminated by exhaling.

O2Body

TissuesCellular

Metabolism

Carbon DioxideLungs


ETCO2 = C on the image below End-tidal CO2 is measured at the end of

expiration. The highest level of expired CO2 is ETCO2

ETCO2 = C on the image below End-tidal CO2 is measured at the end of

expiration. The highest level of expired CO2 is ETCO2

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A

B C

D

CapnographyCapnography

CO2 detected with infra Red sensorSide-stream & Main-stream ETCO2

CO2 detected with infra Red sensorSide-stream & Main-stream ETCO2

Use of CapnographyUse of Capnography

Confirm ET-Tube PlacementMeasure of VentilationMeasure of Cardiac OutputMeasure of Cellular Metabolism

Confirm ET-Tube PlacementMeasure of VentilationMeasure of Cardiac OutputMeasure of Cellular Metabolism

Ven

tilat

ion C

irculation

Metabolism


Continuous waveform capnography is recommended in addition to clinical assessment as the most reliable method of confirming and monitoring correct placement of an endotracheal tube (Class I, LOE A). 2010 AHA Recommendations

Continuous waveform capnography is recommended in addition to clinical assessment as the most reliable method of confirming and monitoring correct placement of an endotracheal tube (Class I, LOE A). 2010 AHA Recommendations


Studies on wave form capnography "have shown 100% sensitivity and 100% specificity in identifying correct endotracheal tube placement.”

Colormetric ETCO2 devices should only be used "when waveform capnography is not available (Class IIa, LOE B)."

Studies on wave form capnography "have shown 100% sensitivity and 100% specificity in identifying correct endotracheal tube placement.”

Colormetric ETCO2 devices should only be used "when waveform capnography is not available (Class IIa, LOE B)."


It is reasonable to consider using quantitative waveform capnography in intubated patients to monitor CPR quality, optimize chest compressions, and detect ROSC during chest compressions or when rhythm check reveals an organized rhythm (Class IIb, LOE C). 2010 AHA Recommendations

It is reasonable to consider using quantitative waveform capnography in intubated patients to monitor CPR quality, optimize chest compressions, and detect ROSC during chest compressions or when rhythm check reveals an organized rhythm (Class IIb, LOE C). 2010 AHA Recommendations


If PETCO2 abruptly increases to a normal value (35 to 40 mm Hg), it is reasonable to consider that this is an indicator of ROSC (Class IIa, LOE B). 2010 AHA Recommendations

If PETCO2 abruptly increases to a normal value (35 to 40 mm Hg), it is reasonable to consider that this is an indicator of ROSC (Class IIa, LOE B). 2010 AHA Recommendations

CapnographyCapnography

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CO2: 38

Circulation Ventilation

Metabolism

Oxygenation vs.VentilationOxygenation vs.Ventilation

Oxygenation Ventilation

Measured with pulse oximeter Measured by capnography

Changes take a long time to display Changes display instantly

Oxygenation is how we get oxygen to the tissue. Oxygen is inhaled into the lungs where gas exchange occurs at the capillary-alveolar membrane. Oxygen is transported to the tissues through the blood stream.

Ventilation (the movement of air) is how we get rid of carbon dioxide. Carbon dioxide is carried back through the blood and exhaled by the lungs through the alveoli.

Capnography vs OximeteryCapnography vs Oximetery

Capnography gives an immediate picture of the patient’s condition.

Pulse oximetry is delayed.

If you hold your breath… Capnography will show immediate apnea. O2 Saturations will remain normal for a

prolonged period of time.

Capnography gives an immediate picture of the patient’s condition.

Pulse oximetry is delayed.

If you hold your breath… Capnography will show immediate apnea. O2 Saturations will remain normal for a

prolonged period of time.

Circulation & MetabolismCirculation & Metabolism

While capnography is a direct measurement of ventilation in the lungs, it also indirectly measures metabolism and circulation. Increased Cardiac Output = Increased ETCO2 Decreased Cardiac Output = Decreased ETCO2

“O2 is the smoke from the flames of metabolism.”

-Ray Fowler, M.D. Dallas, Street Doc’s Society

While capnography is a direct measurement of ventilation in the lungs, it also indirectly measures metabolism and circulation. Increased Cardiac Output = Increased ETCO2 Decreased Cardiac Output = Decreased ETCO2

“O2 is the smoke from the flames of metabolism.”

-Ray Fowler, M.D. Dallas, Street Doc’s Society

PaCO2 vs. PeTCO2 PaCO2 vs. PeTCO2

PaCO2= Partial Pressure of Carbon Dioxide in arterial blood gases. The PaCO2 is measured by drawing the

ABGs, which also measure the arterial PH.If ventilation and perfusion are stable

PaCO2 should correlate to PetCO2.

PaCO2= Partial Pressure of Carbon Dioxide in arterial blood gases. The PaCO2 is measured by drawing the

ABGs, which also measure the arterial PH.If ventilation and perfusion are stable

PaCO2 should correlate to PetCO2.

V/Q MismatchV/Q Mismatch

If ventilation or perfusion are unstable, a Ventilation/Perfusion (V/Q) mismatch can occur.

This will alter the correlation between PaC02 and PetCO2.

This V/Q mismatch can be caused by blood shunting.

If ventilation or perfusion are unstable, a Ventilation/Perfusion (V/Q) mismatch can occur.

This will alter the correlation between PaC02 and PetCO2.

This V/Q mismatch can be caused by blood shunting.

Normal ETCO2Normal ETCO2

Normal ETCO2 35 to 45 mmHg

*Alterations in nasopharyngeal anatomy, and device obstruction may alter the ETCO2 reading.

Normal ETCO2 35 to 45 mmHg

*Alterations in nasopharyngeal anatomy, and device obstruction may alter the ETCO2 reading.

ETCO2ETCO2

A is the start of alveolar expirationA-B is the exhalation upstroke where

dead space gas mixes with lung gas

A is the start of alveolar expirationA-B is the exhalation upstroke where

dead space gas mixes with lung gas

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A

B C

D A

B C

D

ETCO2ETCO2

B-C is the continuation of exhalation, or the plateau(all the gas is alveolar now, rich in C02)

B-C is the continuation of exhalation, or the plateau(all the gas is alveolar now, rich in C02)

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A

B C

D A

B C

D

ETCO2ETCO2

C is the end-tidal value - the peak concentration

C is the end-tidal value - the peak concentration

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A

B C

D A

B C

D

ETCO2ETCO2

C-D is the inspiration washoutD-A is post inspiration/dead space

exhalation

C-D is the inspiration washoutD-A is post inspiration/dead space

exhalation

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A

B C

D A

B C

D

Abnormal ETCO2Abnormal ETCO2

ETCO2 Less Than 35 mmHg "Hypocapnia” Respiratory Alkalosis

ETCO2 Greater Than 45 mmHg "Hypercapnia” Respiratory Acidosis

“End-Tidal CO2 reading without a waveform is like a heart rate without an ECG recording.”

-Bob Page, Riding the Waves

ETCO2 Less Than 35 mmHg "Hypocapnia” Respiratory Alkalosis

ETCO2 Greater Than 45 mmHg "Hypercapnia” Respiratory Acidosis

“End-Tidal CO2 reading without a waveform is like a heart rate without an ECG recording.”

-Bob Page, Riding the Waves

IntubationIntubation

There is no better indicator of proper ET-Tube placement than waveform capnography.

The presence of a waveform indicates a tube is correctly placed in the trachea.

There is no better indicator of proper ET-Tube placement than waveform capnography.

The presence of a waveform indicates a tube is correctly placed in the trachea.

Bad TubeGood Tube


ETCO2 = 0 mmHg The tube is in the esophagus!!! Cardiac arrest with prolonged downtime Spontaneous apnea

ETCO2 = 0 mmHg The tube is in the esophagus!!! Cardiac arrest with prolonged downtime Spontaneous apnea


Intubated patient with ETCO2 of 0 mmHg

DOPE Pneumonic D - Dislodgement O - Obstruction P - Pneumothorax E - Equipment


DOPE Pneumonic D - Dislodgement O - Obstruction P - Pneumothorax E - Equipment



DOPE Pneumonic D - Dislodgement - check the tube! O - Obstruction - suction P - Pneumothorax - check lung sounds E - Equipment - check the vent


DOPE Pneumonic D - Dislodgement - check the tube! O - Obstruction - suction P - Pneumothorax - check lung sounds E - Equipment - check the vent


Intubation Trick Attach the ETCO2 detector to the ET-tube

prior to attempting intubation. You should see some waveforms as you

get close to the vocal cords with the spontaneously breathing patient.

May be useful if CPR is in progress as well.

Intubation Trick Attach the ETCO2 detector to the ET-tube

prior to attempting intubation. You should see some waveforms as you

get close to the vocal cords with the spontaneously breathing patient.

May be useful if CPR is in progress as well.


Capnography can be used with supraglottic airway devices

Paramedics should document the use of capnography This benefits the paramedic!!! There is no dispute when a waveform is

present.

Capnography can be used with supraglottic airway devices

Paramedics should document the use of capnography This benefits the paramedic!!! There is no dispute when a waveform is

present.



Waveform vs. Colorimetric Capnography In colorimetric capnography a filter attached

to an ET tube changes color from purple to yellow when it detects carbon dioxide It is not continuous has no waveform no number no alarms is easily contaminated is hard to read in dark can give false readings.

Waveform vs. Colorimetric Capnography In colorimetric capnography a filter attached

to an ET tube changes color from purple to yellow when it detects carbon dioxide It is not continuous has no waveform no number no alarms is easily contaminated is hard to read in dark can give false readings.

Monitoring VentilationMonitoring Ventilation

Hyperventilation decreases ETCO2

Other causes of decreased ETCO2 Cardiac arrest Decreased cardiac output Hypotension Cold Severe pulmonary edema

Hyperventilation decreases ETCO2

Other causes of decreased ETCO2 Cardiac arrest Decreased cardiac output Hypotension Cold Severe pulmonary edema


Hyperventilation

Hypothermia

Hyperventilation

Hypothermia

Ventilation

Metabolism


Ventilation equals tidal volume x respiratory rate.

A patient taking in a large tidal volume can still hyperventilate with a normal respiratory rate just as a person with a small tidal volume can hypoventilate with a normal respiratory rate.

Ventilation equals tidal volume x respiratory rate.

A patient taking in a large tidal volume can still hyperventilate with a normal respiratory rate just as a person with a small tidal volume can hypoventilate with a normal respiratory rate.


Hypoventilation causes an increased ETCO2 (hypocapnia)

Other causes of increased ETCO2: Increased cardiac output Fever Pain severe difficulty breathing depressed respirations chronic hypercapnia

Hypoventilation causes an increased ETCO2 (hypocapnia)

Other causes of increased ETCO2: Increased cardiac output Fever Pain severe difficulty breathing depressed respirations chronic hypercapnia


Hypoventilation

Malignant Hyperthermia

Hypoventilation


Ventilation

Metabolism


Monitor The Trend! A steadily rising ETCO2 (as the patient

begins to hypoventilate) can help a paramedic anticipate when a patient may soon require assisted ventilations or intubation.

Monitor The Trend! A steadily rising ETCO2 (as the patient

begins to hypoventilate) can help a paramedic anticipate when a patient may soon require assisted ventilations or intubation.


Capnography should be used to monitor any patients receiving pain management or sedation (enough to alter their mental status) for evidence of hypoventilation and/or apnea.

Capnography should be used to monitor any patients receiving pain management or sedation (enough to alter their mental status) for evidence of hypoventilation and/or apnea.

Sign ofOverdose


Capnography is also essential in sedated, intubated patients. A small notch in the wave form indicates the patient is beginning to arouse from sedation, starting to breathe on their own, and will need additional medication to prevent them from "bucking" the tube. Called “curare cleft”

Capnography is also essential in sedated, intubated patients. A small notch in the wave form indicates the patient is beginning to arouse from sedation, starting to breathe on their own, and will need additional medication to prevent them from "bucking" the tube. Called “curare cleft”


“Curare cleft”“Curare cleft”


“Curare cleft”“Curare cleft”

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A

B C

D A

B C

D


End-tidal CO2 monitoring on non-intubated patients is an excellent way to assess the severity of Asthma/COPD, and the effectiveness of treatment. Bronchospasm will produce a characteristic “Shark fin” wave form, as the patient has to struggle to exhale

End-tidal CO2 monitoring on non-intubated patients is an excellent way to assess the severity of Asthma/COPD, and the effectiveness of treatment. Bronchospasm will produce a characteristic “Shark fin” wave form, as the patient has to struggle to exhale


Bronchospasm “Shark Fin”Bronchospasm “Shark Fin”


Bronchospasm “Shark Fin”Bronchospasm “Shark Fin”

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B


Drug Overdoses Some EMS systems permit medics to

administer Narcan only to unresponsive patients with suspected opiate overdoses with respiratory rates less than 10.

Drug Overdoses Some EMS systems permit medics to

administer Narcan only to unresponsive patients with suspected opiate overdoses with respiratory rates less than 10.


Emphysema Down-sloping due to destruction of alveolar

capillary membranes & reduced gas exchange

Emphysema Down-sloping due to destruction of alveolar

capillary membranes & reduced gas exchange


Rebreathing Sometimes called “stacking breaths” Troubleshoot mechanical ventilator

Rebreathing Sometimes called “stacking breaths” Troubleshoot mechanical ventilator

Monitoring CirculationMonitoring Circulation

Cardiac Arrest A higher ETCO2 reading indicates a higher quality

of CPR. Pulseless patients generally present with ETCO2

readings from 10 to 15 mmHg A spike in ETCO2 indicates return of spontaneous

circulation (ROSC).

*ALWAYS SUSPECT A POSSIBLE PERFUSABLE RHYTHM WITH ELEVATED ETCO2 LEVELS!

Cardiac Arrest A higher ETCO2 reading indicates a higher quality

of CPR. Pulseless patients generally present with ETCO2

readings from 10 to 15 mmHg A spike in ETCO2 indicates return of spontaneous

circulation (ROSC).

*ALWAYS SUSPECT A POSSIBLE PERFUSABLE RHYTHM WITH ELEVATED ETCO2 LEVELS!


With cardiac arrest we have a circulatory compromise

With cardiac arrest we have a circulatory compromise

Circulation Ventilation

Metabolism



The O2 in the cells is metabolized, and CO2 is present, but stagnant in the body.

The return of circulation causes a washout of this CO2; which shows up as a spike in ETCO2 levels.

The O2 in the cells is metabolized, and CO2 is present, but stagnant in the body.

The return of circulation causes a washout of this CO2; which shows up as a spike in ETCO2 levels.CO2

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A sudden drop in ETCO2 may be an indication to check for a pulse.

A sudden drop in ETCO2 may be an indication to check for a pulse.

CO2

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"An end-tidal carbon dioxide level of 10 mmHg or less measured 20 minutes after the initiation of advanced cardiac life support accurately predicts death in patients with cardiac arrest associated with electrical activity but no pulse. Cardiopulmonary resuscitation may reasonably be terminated in such patients.” -Levine R, End-tidal Carbon Dioxide and Outcome of Out-of-Hospital Cardiac Arrest, New England Journal of Medicine, July 1997

"An end-tidal carbon dioxide level of 10 mmHg or less measured 20 minutes after the initiation of advanced cardiac life support accurately predicts death in patients with cardiac arrest associated with electrical activity but no pulse. Cardiopulmonary resuscitation may reasonably be terminated in such patients.” -Levine R, End-tidal Carbon Dioxide and Outcome of Out-of-Hospital Cardiac Arrest, New England Journal of Medicine, July 1997


“No patient who had an end-tidal carbon dioxide of level of less than 10 mm Hg survived. Conversely, in all 35 patients in whom spontaneous circulation was restored, end-tidal carbon dioxide rose to at least 18 mm Hg before the clinically detectable return of vital signs....The difference between survivors and nonsurvivors in 20 minute end-tidal carbon dioxide levels is dramatic and obvious.”

-ibid.

“No patient who had an end-tidal carbon dioxide of level of less than 10 mm Hg survived. Conversely, in all 35 patients in whom spontaneous circulation was restored, end-tidal carbon dioxide rose to at least 18 mm Hg before the clinically detectable return of vital signs....The difference between survivors and nonsurvivors in 20 minute end-tidal carbon dioxide levels is dramatic and obvious.”

-ibid.


Asphyxic vs. Cardiac Arrest Cardiac Arrest caused by asphyxia shows

a higher ETCO2 reading initially on the monitor.

This number should come down within the first minute of CPR.

Asphyxic vs. Cardiac Arrest Cardiac Arrest caused by asphyxia shows

a higher ETCO2 reading initially on the monitor.

This number should come down within the first minute of CPR.


End tidal CO2 monitoring can provide an early warning sign of shock.

A patient with a sudden drop in cardiac output will show a drop in ETCO2 numbers that may be regardless of any change in breathing.

This has implications for trauma patients, cardiac patients - any patient at risk for shock.

End tidal CO2 monitoring can provide an early warning sign of shock.

A patient with a sudden drop in cardiac output will show a drop in ETCO2 numbers that may be regardless of any change in breathing.

This has implications for trauma patients, cardiac patients - any patient at risk for shock.


Pulmonary Embolus Pulmonary embolus will cause an increase

in the dead space in the lungs decreasing the alveoli available to offload carbon dioxide.

The ETCO2 will go down.

Pulmonary Embolus Pulmonary embolus will cause an increase

in the dead space in the lungs decreasing the alveoli available to offload carbon dioxide.

The ETCO2 will go down.

Monitoring MetabolismMonitoring Metabolism

DKA - Patients with DKA hyperventilate to lessen their acidosis.

The hyperventilation causes their PACO2 to go down. Kussmal’s respirations are rapid & deep.

DKA - Patients with DKA hyperventilate to lessen their acidosis.

The hyperventilation causes their PACO2 to go down. Kussmal’s respirations are rapid & deep.


Water + Carbon dioxide = Carbonic Acid Carbonic Acid = Hydrogen + Bicarbonate

Water + Carbon dioxide = Carbonic Acid Carbonic Acid = Hydrogen + Bicarbonate

H2O + CO2 H2CO3 H + HCO3


Hyperthermia Metabolism is on overdrive in fever, which

may cause ETCO2 to rise. Observing this phenomena can be live-saving in patients with malignant hyperthermia, a rare side effect of RSI (Rapid Sequence Induction).

Hyperthermia Metabolism is on overdrive in fever, which

may cause ETCO2 to rise. Observing this phenomena can be live-saving in patients with malignant hyperthermia, a rare side effect of RSI (Rapid Sequence Induction).


Sepsis ETCO2: 31-34 = Increased survivability ETCO2: Less than 30 = Increased morbidity

End-Tidal Carbon Dioxide Levels Are Associated with Mortality In Emergency Department Patients with Suspected Sepsis

-Hunter CL, et al. Orlando Regional Medical Center, Orlando, FL

Sepsis ETCO2: 31-34 = Increased survivability ETCO2: Less than 30 = Increased morbidity

End-Tidal Carbon Dioxide Levels Are Associated with Mortality In Emergency Department Patients with Suspected Sepsis

-Hunter CL, et al. Orlando Regional Medical Center, Orlando, FL

Abnormal ETCO2Abnormal ETCO2

Increased ETCO2

Decreased ETCO2

Ventilation HypoventilationBronchoconstrictionDrug overdose

HyperventilationDislodged ET-Tube

Circulation Good CPRReturn of pulse (ROSC)Increased cardiac output

ApneaCardiac ArrestPulmonary EdemaPulmonary Embolism

Metabolism Fever/HyperthermiaSeizureBurnsMuscle use

DKASepsisHypothermia

ScenariosScenarios

You just intubated a patient that had severe dyspnea using RSI successfully BP: 142/90 HR: 140 RR: Assisted BGL: 170

You just intubated a patient that had severe dyspnea using RSI successfully BP: 142/90 HR: 140 RR: Assisted BGL: 170

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ETCO2: 55


ScenariosScenarios

You have a 88 y/o male who has fallen on the ground, and is currently unconscious. BP: 114/70 HR: 50 RR: 10 BGL: 90

You have a 88 y/o male who has fallen on the ground, and is currently unconscious. BP: 114/70 HR: 50 RR: 10 BGL: 90

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ETCO2: 25

Hypothermia

ScenariosScenarios

You have a 75 y/o female patient with altered mental status BP: 100/40 HR: 130 RR: 30 BGL: 100

You have a 75 y/o female patient with altered mental status BP: 100/40 HR: 130 RR: 30 BGL: 100

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ETCO2: 25

SEPSIS

The EndThe End

This concludes this course on capnography.

Questions or feedback Email [email protected]

This concludes this course on capnography.

Questions or feedback Email [email protected]

Technology

Capnography