Pulse Oximetry & Pulse Oximetry & CapnographyCapnography

Ray TaylorRay Taylor

Valencia Community CollegeValencia Community College

Department of Emergency Medical ServicesDepartment of Emergency Medical Services

NoticeNotice All rights reserved. All rights reserved. Slide show used with permission only for the Slide show used with permission only for the

purposes of educating emergency medical purposes of educating emergency medical providers (EMTs and Paramedics) providers (EMTs and Paramedics)

No portion of this presentation may be No portion of this presentation may be reproduced, stored in a retrieval system in any reproduced, stored in a retrieval system in any form or by any means (including but not limited form or by any means (including but not limited to electronic, mechanical, photocopying etc.) to electronic, mechanical, photocopying etc.) without prior written permission from the authorwithout prior written permission from the author

CAPNOGRAPHY IS THE VITAL SIGN CAPNOGRAPHY IS THE VITAL SIGN FOR VENTILATIONFOR VENTILATION

(what we should evaluate)(what we should evaluate)

OXIMETRY IS THE VITAL SIGN FOR OXIMETRY IS THE VITAL SIGN FOR OXYGENTATIONOXYGENTATION

(what we have historically used)(what we have historically used)

CapnographyCapnography Definition: Definition:

– Noninvasive measurement of the partial pressure of C02 Noninvasive measurement of the partial pressure of C02 in exhaled airin exhaled air

– Provides instantaneous information aboutProvides instantaneous information about VentilationVentilation

– How effectively C02 is being eliminated by the pulmonary system How effectively C02 is being eliminated by the pulmonary system

PerfusionPerfusion– How effectively C02 is being transported through the vascular How effectively C02 is being transported through the vascular

systemsystem

MetabolismMetabolism– How effectively C02 is being produced by cellular metabolismHow effectively C02 is being produced by cellular metabolism

Physiology ReviewPhysiology Review The fundamental purpose of The fundamental purpose of

ventilation and circulation is to supply ventilation and circulation is to supply OO22 to the tissues’ cells and to remove to the tissues’ cells and to remove COCO22..

The conducting airways (from the The conducting airways (from the nasal/oral cavities extending to the nasal/oral cavities extending to the smallest bronchioles) serve as a smallest bronchioles) serve as a conduit for gas exchange between conduit for gas exchange between the atmosphere and the cells.the atmosphere and the cells.– This portion of the respiratory This portion of the respiratory

system is referred to as system is referred to as “anatomic dead space,” because “anatomic dead space,” because no gas exchange occurs there.no gas exchange occurs there.

– On average, 30% of inspired tidal On average, 30% of inspired tidal volume is “dead”.volume is “dead”.

Respiration (gas exchange) occurs in Respiration (gas exchange) occurs in the alveoli.the alveoli.

Physiology ReviewPhysiology Review

All cells produce COAll cells produce CO22 as a as a

metabolic byproduct of the metabolic byproduct of the oxidative breakdown of fuels.oxidative breakdown of fuels.– Factors such as body Factors such as body

temperature, exercise and temperature, exercise and nutrition affect the amount of nutrition affect the amount of COCO22 produced. produced.

COCO22 easily diffuses out of the easily diffuses out of the

cells and into the vasculature, cells and into the vasculature, where it is carried back to the where it is carried back to the right side of the heart and on to right side of the heart and on to the pulmonary system - to the the pulmonary system - to the pulmonary capillaries pulmonary capillaries surrounding the alveoli.surrounding the alveoli.

Physiology ReviewPhysiology Review

As ambient, nearly COAs ambient, nearly CO22-free -free

air is drawn into each alveolus air is drawn into each alveolus during inspiration, the COduring inspiration, the CO22 in in

the blood diffuses across the the blood diffuses across the capillary and alveolar walls capillary and alveolar walls into the alveolar space.into the alveolar space.

Normally, one pass of the Normally, one pass of the blood through the alveolar blood through the alveolar capillary bed allows the partial capillary bed allows the partial pressures of COpressures of CO22 in the alveoli in the alveoli

and the arterial blood to nearly and the arterial blood to nearly equalize.equalize.

Respiratory Physiology

Aveolus

.

Blood from right side of heart

Reoxygenated blood

Blood to left side of heart

Red blood cellsCapillary

(low in O, high in CO)

2

2

(high in O, low in CO)2 2

O2

CO2 CO2

CO2

CO2

O2

CO2O2

ExhalationExhalation

Exhalation can be divided into 3 Exhalation can be divided into 3 phases:phases:– Phase 1: Expiration from dead Phase 1: Expiration from dead

bronchiolar space – no CObronchiolar space – no CO22 yet yet exhaledexhaled

– Phase 2: Mixture of dead space Phase 2: Mixture of dead space air + alveolar COair + alveolar CO22 reaches the reaches the mouthmouth

Known as alveolar washout and Known as alveolar washout and recruitmentrecruitment

– Phase 3: Nearly pure, COPhase 3: Nearly pure, CO22-rich -rich alveolar air is exhaledalveolar air is exhaled

Called the alveolar plateauCalled the alveolar plateau

End-tidal COEnd-tidal CO22

The peak partial pressure of The peak partial pressure of COCO22 during exhalation (the during exhalation (the highest level of expired COhighest level of expired CO22 reached during exhalation) is reached during exhalation) is known as the end-tidal COknown as the end-tidal CO2 2

(EtCO(EtCO22).).– Normally occurs at the end of Normally occurs at the end of

the alveolar plateauthe alveolar plateau

EtCOEtCO22 is a reflection of alveolar is a reflection of alveolar ventilation, COventilation, CO22 production and production and pulmonary blood flow.pulmonary blood flow.– Can be thought of as the blood Can be thought of as the blood

pressure of metabolismpressure of metabolism

End-tidal COEnd-tidal CO22

In healthy people, the EtCOIn healthy people, the EtCO22 is within 5 is within 5

mmHg of the partial pressure of COmmHg of the partial pressure of CO22 in in

arterial blood (PaCOarterial blood (PaCO22).).

– Normal values of both are between Normal values of both are between 35-4535-45 mmHg.mmHg. 4.5% – 6 %4.5% – 6 %

Normal Endtidal CO2Normal Endtidal CO2

Normal 35-45 Normal 35-45 mmHgmmHg

Waveform reflects Waveform reflects how close numerical how close numerical value is to actual value is to actual end tidal volumeend tidal volume

Square = GOODSquare = GOODHump = BADHump = BAD

A-B: Early Exhalation, C02 free (dead space)B-C: Combination of dead space and alveolar gasC-D: Alveolar plateauD: End Tidal C02 D-E: Inhalation

Depth = Height

Pulse OximetryPulse Oximetry

The pulse oximeter is a The pulse oximeter is a noninvasive device that noninvasive device that measures the oxygen measures the oxygen saturation of your patient’s saturation of your patient’s blood.blood.

The pulse oximeter The pulse oximeter consists of a probe consists of a probe attached to the patient's attached to the patient's finger or ear lobe which is finger or ear lobe which is linked to a computerized linked to a computerized unit. unit.

How does a Pulse Oximeter work?How does a Pulse Oximeter work?

The probe directs two lights The probe directs two lights (one red, one infrared) (one red, one infrared) through tissue (finger, through tissue (finger, earlobe, etc.) earlobe, etc.)

The lights are absorbed The lights are absorbed differently depending on differently depending on oxygen attached to oxygen attached to hemoglobin moleculehemoglobin molecule

The result is a measurement The result is a measurement of the patient’s oxygen of the patient’s oxygen saturation on the hemoglobin saturation on the hemoglobin moleculemolecule

Function of Pulse OximeterFunction of Pulse Oximeter

Determines delivery of Determines delivery of oxygen to peripheral oxygen to peripheral tissuestissues

Measures the oxygen Measures the oxygen saturation of your patient’s saturation of your patient’s bloodblood

Helps to quantify the Helps to quantify the effectiveness of your effectiveness of your interventionsinterventions– oxygen therapy, oxygen therapy,

medications, suctioning, medications, suctioning, BVMBVM

IndicationsIndications

A depressed respiratory drive (e.g., narcotic A depressed respiratory drive (e.g., narcotic overdose)overdose)

An increased resistance in the respiratory airways An increased resistance in the respiratory airways (e.g., asthma)(e.g., asthma)

A reduced capacity of the blood to transport oxygen A reduced capacity of the blood to transport oxygen (e.g., shock, anemia)(e.g., shock, anemia)

All patients (additional vital sign)All patients (additional vital sign)

SaO2 v. SpO2SaO2 v. SpO2 PaO2 is actual amount of oxygen dissolved in arterial PaO2 is actual amount of oxygen dissolved in arterial

bloodblood– measured by blood gases measured by blood gases – expressed in mmHgexpressed in mmHg

SaO2 is percentage of hemoglobin saturated by SaO2 is percentage of hemoglobin saturated by oxygenoxygen– measured by blood gases measured by blood gases – expressed in percentageexpressed in percentage

SpO2 is percentage of hemoglobin saturated by SpO2 is percentage of hemoglobin saturated by oxygenoxygen– measured by pulse oximetermeasured by pulse oximeter– expressed in percentageexpressed in percentage

Normal Pulse Oximetry ReadingsNormal Pulse Oximetry Readings

Normal lab values range between 95-100%Normal lab values range between 95-100%

Readings between 93% and 97% may be Readings between 93% and 97% may be normal for some patients (COPD)normal for some patients (COPD)

Oxygen (at minimum) should be applied for Oxygen (at minimum) should be applied for readings below 90%readings below 90%

Pitfalls of the Pulse OximeterPitfalls of the Pulse Oximeter

Certain medical conditions can alter the Certain medical conditions can alter the machines interpretation, and give false readingsmachines interpretation, and give false readings

Certain environmental conditions can also Certain environmental conditions can also produce false readingproduce false reading

In the following situations the In the following situations the pulse oximeter readings may not pulse oximeter readings may not

be accurate:be accurate:

A reduction in peripheral pulsatile blood flow A reduction in peripheral pulsatile blood flow produced by peripheral vasoconstriction produced by peripheral vasoconstriction (hypovolemia, severe hypotension, cold, cardiac (hypovolemia, severe hypotension, cold, cardiac failure, some cardiac arrhythmias) or peripheral failure, some cardiac arrhythmias) or peripheral vascular disease. vascular disease.

The presence of methemoglobin will prevent the The presence of methemoglobin will prevent the oximeter from working accurately and the oximeter from working accurately and the readings will tend towards 85%, regardless of readings will tend towards 85%, regardless of the true saturation. the true saturation.

In the following situations the In the following situations the pulse oximeter readings may not pulse oximeter readings may not

be accurate:be accurate:

Carboxyhemoglobin( hemoglobin combined Carboxyhemoglobin( hemoglobin combined with carbon monoxide [COHb]) is lumped in with carbon monoxide [COHb]) is lumped in with oxyhemoglobin (Owith oxyhemoglobin (O22Hb), thus producing Hb), thus producing

incorrect readings. incorrect readings.

A person could have 15% COHb on board (or A person could have 15% COHb on board (or more), plus 80% Omore), plus 80% O22Hb, but the pulse-Ox Hb, but the pulse-Ox

reading would still be 95% saturation.reading would still be 95% saturation.

Pulse Oximetry v. CapnographyPulse Oximetry v. Capnography

Oxygenation is Oxygenation is measured by pulse measured by pulse oximetryoximetry

Ventilation is Ventilation is measured and measured and monitored with monitored with capnographycapnography

Comparison of Comparison of Capnograhy and OximetryCapnograhy and Oximetry

Capnographs and pulse oximeters present different Capnographs and pulse oximeters present different views of the same cardiopulmonary processes. views of the same cardiopulmonary processes. Oximeters measure saturated hemoglobin in peripheral Oximeters measure saturated hemoglobin in peripheral blood and provide additional information about the blood and provide additional information about the adequacy of lung perfusion and oxygen delivery to the adequacy of lung perfusion and oxygen delivery to the tissues.tissues.– Many sources recommend monitoring both SpOMany sources recommend monitoring both SpO22 and and

EtCOEtCO22 on intubated and non-intubated patients. on intubated and non-intubated patients.

However, pulse oximetry is a However, pulse oximetry is a late indicatorlate indicator of O of O22 supply, and is less sensitive than capnography. It does supply, and is less sensitive than capnography. It does not afford a complete picture of ventilatory status.not afford a complete picture of ventilatory status.

ComparisonComparison

Accurate pulse oximetry measurement is Accurate pulse oximetry measurement is dependent upon adequate peripheral perfusion dependent upon adequate peripheral perfusion and may be unreliable in patients who have and may be unreliable in patients who have compromised peripheral circulation.compromised peripheral circulation.

Capnography continuously and nearly Capnography continuously and nearly instantaneously measures pulmonary ventilation instantaneously measures pulmonary ventilation and is able to rapidly detect small changes in and is able to rapidly detect small changes in cardio-respiratory function before oximeter cardio-respiratory function before oximeter readings change.readings change.

Healthy patients can maintain SaO2 > 90% for Healthy patients can maintain SaO2 > 90% for minutes even with inadequate ventilation.minutes even with inadequate ventilation.

TerminologyTerminology

Capnos = smokeCapnos = smoke

Capnometer = number (EtCOCapnometer = number (EtCO22))

Capnograph = number + digitized signalCapnograph = number + digitized signal

CapnographyCapnography((Quantitative EtCOQuantitative EtCO22 Detectors Detectors))

Capnography is a form of Capnography is a form of noninvasive monitoring of noninvasive monitoring of the end-tidal carbon dioxide the end-tidal carbon dioxide (EtCO(EtCO22) levels in the ) levels in the

patient’s exhaled breath.patient’s exhaled breath.

Capnography refers to a Capnography refers to a unit that displays both a unit that displays both a numeric EtCOnumeric EtCO22 value and a value and a

COCO2 2 waveform waveform

(capnograph). (capnograph).

DefinitionsDefinitions CapnographyCapnography is the is the

measurement of exhaled CO2measurement of exhaled CO2 CapnometerCapnometer gives a gives a

numerical or quantitative numerical or quantitative (precise) measurement of (precise) measurement of exhaled CO2exhaled CO2

CapnographCapnograph gives both a gives both a numerical reading of exhaled numerical reading of exhaled CO2 plus a tracingCO2 plus a tracing

End-tidal CO2End-tidal CO2 (EtCO2) is the (EtCO2) is the measurement of CO2 at the measurement of CO2 at the end of exhalationend of exhalation

Cardiac ECGCardiac ECG

Pulmonary ECGPulmonary ECG

Oxygen -> lungs -> alveoli -> blood

muscles + organs

Oxygen

cells

Oxygen

Oxygen +Glucose

energy

CO2

blood

lungs

CO2

breath

CO2

Oxygenation and Ventilation

Phase I (A-B)Phase I (A-B)Dead Space VentilationDead Space Ventilation

Represents the beginning of exhalation where the dead space is cleared from the Represents the beginning of exhalation where the dead space is cleared from the upper airwayupper airway

A B

C D

E

I

Phase IIPhase IIAscending Phase (B – C)Ascending Phase (B – C)

Represents the rapid rise in C02 concentration in the breath stream as the C02 from Represents the rapid rise in C02 concentration in the breath stream as the C02 from the alveoli reaches the upper airwaythe alveoli reaches the upper airway

A B

C D

EII

Phase IIIPhase IIIAlveolar Plateau(C-D)Alveolar Plateau(C-D)

Represents the C02 concentration reaching a uniform level in the entire breath stream Represents the C02 concentration reaching a uniform level in the entire breath stream from alveolus to the nose. from alveolus to the nose.

A B

C D

E

III

End-Tidal COEnd-Tidal CO2 2

Point D represents the maximum C02 concentration at the end of the tidal breath Point D represents the maximum C02 concentration at the end of the tidal breath (Appropriately named end-tidal C02). This is the number that appears on the monitor (Appropriately named end-tidal C02). This is the number that appears on the monitor

A B

C D

E

End-Tidal

Phase IV (D-E)Phase IV (D-E)Descending Phase-Inspiratory LimbDescending Phase-Inspiratory Limb

Represents the inspiratory cycleRepresents the inspiratory cycle

A B

C D

EIV

Normal CONormal CO22 Waveform Waveform

Normal CONormal CO22 Waveform Waveform

How does Capnography work?How does Capnography work? The most common technologies The most common technologies

utilize infrared (IR) spectroscopyutilize infrared (IR) spectroscopy

Measures the absorption of Measures the absorption of wavelengths of IR light by COwavelengths of IR light by CO22 molecules as the IR light passes molecules as the IR light passes through a gas sample through a gas sample

The amount of IR light that is The amount of IR light that is absorbed reflects the amount of absorbed reflects the amount of COCO22 present and electronically present and electronically calculates a valuecalculates a value

Mainstream/SidestreamMainstream/Sidestream

The value that we are most The value that we are most interested in occurs at the point of interested in occurs at the point of maximum exhalation and is known maximum exhalation and is known as the end-tidal COas the end-tidal CO22 (EtCO (EtCO22))

Clinical Application of ETC02Clinical Application of ETC02

Verification of Verification of endotracheal tube endotracheal tube placementplacement

Continuous monitoring of Continuous monitoring of tube location during tube location during transporttransport

Gauging the effectiveness Gauging the effectiveness of resuscitiation and of resuscitiation and prognosis during cardiac prognosis during cardiac arrestarrest

Titrating EtC02 levels in Titrating EtC02 levels in patients with suspected patients with suspected increases in intracranial increases in intracranial pressurepressure

Determining prognosis in Determining prognosis in traumatrauma

Determining adequacy of Determining adequacy of ventilationventilation

Physiology of CapnographyPhysiology of Capnography

During cellular respiration, small During cellular respiration, small amounts of COamounts of CO22 are excreted are excreted

via exhalationvia exhalation When no cellular respiration is When no cellular respiration is

occurring, even if ventilation is, occurring, even if ventilation is, there will be no CO2 exhaledthere will be no CO2 exhaled– In poor perfusion states (cardiac In poor perfusion states (cardiac

arrest) no CO2 is transported to arrest) no CO2 is transported to the lungs to be exhaled, so a the lungs to be exhaled, so a low reading will occurlow reading will occur

– In poor ventilation states In poor ventilation states (hypoventilation) CO2 is (hypoventilation) CO2 is retained, so a high reading will retained, so a high reading will occuroccur

ETT AlgorithmETT Algorithm

According to the AHA, in the According to the AHA, in the prehospital setting, prehospital setting, unrecognized misplacement of unrecognized misplacement of tracheal tubes has been tracheal tubes has been reported in as many as 25% reported in as many as 25% (Katz and Falk, 2001) of (Katz and Falk, 2001) of patients.patients.

In an effort to protect against In an effort to protect against unrecognized esophageal unrecognized esophageal intubations, current AHA training intubations, current AHA training programs strongly recommend programs strongly recommend that COthat CO2 2 detection devices be detection devices be

placed on all intubated patients.placed on all intubated patients.

ET Tube VerificationET Tube Verification(It can be harder than we think)(It can be harder than we think)

Syringe/BulbTrachlight Auscultatio

nI just know

Experience

Inexperience

Combitube

Facial Trauma

VomitusMucus

RSI

Recreational Drugs

Blood

Movement

Seizures

Short/fat neck

Infant/child

Confirmation of ET Tube Confirmation of ET Tube PlacementPlacement

Data confirm that physical assessment Data confirm that physical assessment procedures to confirm ET tube placement can be procedures to confirm ET tube placement can be misleading.misleading.– Movement of air through the esophagus may be difficult to Movement of air through the esophagus may be difficult to

differentiate breath sounds, and may create chest rise.differentiate breath sounds, and may create chest rise.– Breath sounds and/or normal chest wall expansion may be Breath sounds and/or normal chest wall expansion may be

difficult to confirm in victims with traumatic thoracic injury.difficult to confirm in victims with traumatic thoracic injury.– Lung sounds can be transmitted to the epigastrium in pedsLung sounds can be transmitted to the epigastrium in peds– Misting appears in a high % of esophageally-placed ET tubes.Misting appears in a high % of esophageally-placed ET tubes.– Difficult to confidently confirm ET tube placement in patients with Difficult to confidently confirm ET tube placement in patients with

severe bronchoconstriction.severe bronchoconstriction.– Unvisualized nasal ET tubes may be difficult to confirm.Unvisualized nasal ET tubes may be difficult to confirm.

IntubationIntubation The ETT algorithm should The ETT algorithm should

effectively eliminate the effectively eliminate the

possibility of an esophageal possibility of an esophageal

intubation from going intubation from going

undetected.undetected.

It includes a:It includes a: Physiologic method (ET COPhysiologic method (ET CO22

detection) detection) Clinical method (auscultation) Clinical method (auscultation)

Colorimetric COColorimetric CO2 2

(Qualitative EtCO(Qualitative EtCO22 Detectors) Detectors)

When gas exchange from proper BVM or ET When gas exchange from proper BVM or ET ventilation is adequate, small amounts of COventilation is adequate, small amounts of CO22 are are

excreted from the patient via exhalation. excreted from the patient via exhalation.

If a sufficient concentration of COIf a sufficient concentration of CO22 is detected, the is detected, the

color strip will change from purple to tan to yellow.color strip will change from purple to tan to yellow.

The yellow color indicates adequate ventilation and The yellow color indicates adequate ventilation and good air exchange.good air exchange.

Colorimetric COColorimetric CO2 2

Uses litmus paper that changes Uses litmus paper that changes color when it comes in contact with color when it comes in contact with CO2CO2Will not change color if no CO2 is Will not change color if no CO2 is flowing across paperflowing across paperColor strip will change from purple Color strip will change from purple to tan to yellowto tan to yellowColor can change from breath to Color can change from breath to breathbreathThe yellow color indicates The yellow color indicates adequate ventilation and good air adequate ventilation and good air exchangeexchange

Fun Facts about Colorimetric Fun Facts about Colorimetric DevicesDevices

A Range (Purple):A Range (Purple): <4 mmHg EtCO<4 mmHg EtCO22

0.03% to < 0.5% EtCO0.03% to < 0.5% EtCO22

B Range (Tan):B Range (Tan): 4 to <15 mmHg EtCO4 to <15 mmHg EtCO22

0.5% to < 2% EtCO0.5% to < 2% EtCO22

C Range (Yellow):C Range (Yellow): 15 to 38 mmHg EtCO15 to 38 mmHg EtCO22

2% to 5% EtCO2% to 5% EtCO22

Evaluate color of device Evaluate color of device after 6 full breathsafter 6 full breaths..– This allows any COThis allows any CO22 in the stomach (produced by the ingestion of in the stomach (produced by the ingestion of

certain beverages and medications, or by expired air bagged into certain beverages and medications, or by expired air bagged into the stomach prior to intubation) to be blown off.the stomach prior to intubation) to be blown off.

– Inaccurate if contaminated with secretions, blood, emesis, acidic Inaccurate if contaminated with secretions, blood, emesis, acidic meds, etc.meds, etc.

Pitfalls of the Colorimetric Pitfalls of the Colorimetric COCO22 Detection Devices Detection Devices

Cannot provide a specific CO2 Cannot provide a specific CO2 valuevalue

Susceptible to failure if litmus Susceptible to failure if litmus paper is contaminated with body paper is contaminated with body fluids (airway secretions, vomit, fluids (airway secretions, vomit, etc.)etc.)

Has limited time value (normally Has limited time value (normally <2 hours<2 hours

Subject to expiration (usually 2 Subject to expiration (usually 2 years)years)

Six ventilations are necessary Six ventilations are necessary prior to interpretation in cardiac prior to interpretation in cardiac arrest patient to ensure potential arrest patient to ensure potential residual CO2 has been removedresidual CO2 has been removed

Indications for CapnographyIndications for Capnography

All intubated patientsAll intubated patients– colorimetric colorimetric

capnometercapnometer– electronic electronic

capnographercapnographer

AHA, NAEMSP, ACEP AHA, NAEMSP, ACEP all mandate use of all mandate use of secondary devices to secondary devices to confirm tube placementconfirm tube placement All critical care patients All critical care patients

Waveform DisplaysWaveform Displays(Quantitative Device)(Quantitative Device)

The waveform (capnograph) The waveform (capnograph) provides a graph measured provides a graph measured in time of the inspiratory and in time of the inspiratory and expiratory phases of the expiratory phases of the respiratory cycle. respiratory cycle.

By interpreting the waveform By interpreting the waveform we can make a number of we can make a number of assumptions about the assumptions about the clinical stability of a patient clinical stability of a patient and the effectiveness of and the effectiveness of intervention.intervention.

CapnographyCapnography

The waveform is The waveform is divided into 4 phases.divided into 4 phases.

Phases I, II and III Phases I, II and III occur during, and occur during, and reflect, the three reflect, the three phases of exhalation.phases of exhalation.

Phase IV occurs Phase IV occurs during, and reflects, during, and reflects, inspiration.inspiration.

Capnogram: Phase ICapnogram: Phase I

Phase I occurs during Phase I occurs during exhalation of air from exhalation of air from the anatomic dead the anatomic dead space, which normally space, which normally contains no COcontains no CO22..

This part of the curve This part of the curve is normally flat, is normally flat, providing a steady providing a steady baseline.baseline.

Capnogram: Phase IICapnogram: Phase II

Phase II occurs during Phase II occurs during alveolar washout and alveolar washout and recruitment, with a recruitment, with a mixture of dead space mixture of dead space and alveolar air being and alveolar air being exhaled.exhaled.

Phase II normally Phase II normally consists of a steep consists of a steep upward slope.upward slope.

Capnogram: Phase IIICapnogram: Phase III

Phase III is the alveolar Phase III is the alveolar plateau, with expired gas plateau, with expired gas coming from the alveoli.coming from the alveoli.

In patients with normal In patients with normal respiratory mechanics, this respiratory mechanics, this portion of the curve is flat, portion of the curve is flat, with a gentle upward with a gentle upward slope.slope.

The highest point on this The highest point on this slope represents the slope represents the EtCOEtCO22 value. value.

Capnogram: Phase IVCapnogram: Phase IV

Atmospheric air contains Atmospheric air contains negligible amounts of COnegligible amounts of CO22..

Phase IV occurs during Phase IV occurs during inspiration, where the inspiration, where the EtCOEtCO22 level normally drops level normally drops rapidly to zero.rapidly to zero.– Unless COUnless CO22 is present in is present in

the inspired air, as the inspired air, as occurs when expired air occurs when expired air is rebreathedis rebreathed

This part of the waveform is This part of the waveform is a steep, downward slope.a steep, downward slope.

Phases of ventilationPhases of ventilation

Normal capnographyNormal capnography

Capnography Waveform PatternsCapnography Waveform Patterns

45

0

45

0

45

0HypoventilationHypoventilation

HyperventilationHyperventilation

NormalNormal

Apnea/Esophageal IntubationApnea/Esophageal Intubation

Prolonged cardiac arrest with diffuse cellular deathProlonged cardiac arrest with diffuse cellular deathTracheal placement with inadequate pulmonary blood flow (poor chest compressions)Tracheal placement with inadequate pulmonary blood flow (poor chest compressions)

ETT obstructionETT obstructionComplete airway obstruction distal to the ETT (eg, foreign body)Complete airway obstruction distal to the ETT (eg, foreign body)

Technical malfunction of the monitor or tubingTechnical malfunction of the monitor or tubing

Tracheal IntubationTracheal Intubation

Esophageal IntubationEsophageal Intubation

No capnography reading (waveform plus or EtCO2 detection) via your BVM, you are not in. “Full waveform is essential”

Unsuccessful IntubationUnsuccessful Intubation

Comparison CapnographComparison Capnograph

The tube has been extubated and is no longer in the tracheaRemove at once!!

LMA with CapnographyLMA with Capnography

Abnormal TracingsAbnormal Tracings

Rebreathing Rebreathing Cause:Cause:

– Breathing in a mixture of both oxygen and carbon Breathing in a mixture of both oxygen and carbon dioxide (think rebreather mask)dioxide (think rebreather mask)

Abnormal TracesAbnormal Traces

Sloping Plateau Sloping Plateau Cause:Cause:

– Obstructive airway disease, because of Obstructive airway disease, because of impairment of V/Q ratio.impairment of V/Q ratio.

COCO22 Waveforms Waveforms

Normal

Bronchospasm

Trending is Key to monitoring Trending is Key to monitoring Respiratory FailureRespiratory Failure

Acute exacerbation of COPDAcute exacerbation of COPDAsthmaAsthmaPneumoniaPneumoniaCHFCHFRespiratory Muscle FatigueRespiratory Muscle FatigueHypoventilation SyndromesHypoventilation Syndromes IS THE PATIENT RESPONDING TO THERAPY IS THE PATIENT RESPONDING TO THERAPY

OR NOT?OR NOT?

TrendingTrending

Trending of Trending of capnography provides capnography provides a continuous view of a continuous view of the patient’s ventilatory the patient’s ventilatory statusstatus

Early detection allows Early detection allows for early interventionfor early intervention

Trending is a simple Trending is a simple tool that does not tool that does not stress an already stress an already failing systemfailing system

Video versus Snapshot

Phases of AsthmaPhases of Asthma

HyperventilationHyperventilation– mildmild

TiringTiring– moderatemoderate

TiredTired– severesevere

Phases of AsthmaPhases of Asthma

40 mmHg

25-30

40

50+

Normal

Mild

Moderate

Severe

EtCOEtCO22 Trending Trending

50

5560

50 50

45

40

Using Capnography in AsthmaUsing Capnography in Asthma

Diagnoses presence of bronchospasmDiagnoses presence of bronchospasm– WaveformWaveform

Assesses severity of AsthmaAssesses severity of Asthma– EtCOEtCO22 trends trends

Gauges response to treatmentGauges response to treatment– EtCOEtCO22 trends trends

COPDCOPD

Baseline COBaseline CO22 is higher is higher– > 50mm Hg> 50mm Hg

Follow COFollow CO22 trends to: trends to:–Establish baselineEstablish baseline–Track response to treatmentTrack response to treatment

COPDCOPD

Determine who is a CODetermine who is a CO22 retainer retainer

– EtCOEtCO22 trends trends

COPD vs. CHFCOPD vs. CHF

– WaveformWaveform

Hypoventilation StatesHypoventilation States

Altered mental statusAltered mental status

Abnormal breathingAbnormal breathing

45

HypoventilationHypoventilation

Hypoventilation StatesHypoventilation States

SedationSedation AnalgesiaAnalgesia ETOH ETOH

intoxicationintoxication Drug IngestionDrug Ingestion

Postictal statesPostictal states Head traumaHead trauma MeningitisMeningitis EncephalitisEncephalitis

Abnormal TracesAbnormal Traces

Cardiac Oscillations Cardiac Oscillations Cause:Cause:

– Cardiac impulses transmitted to capnographCardiac impulses transmitted to capnograph

Abnormal TracesAbnormal Traces

““Curare cleft”Curare cleft” Cause:Cause:

– Asynchronous spontaneous breathing in an Asynchronous spontaneous breathing in an intubated patientintubated patient

With a poor to nonexistent waveform, the endotracheal tube is likely With a poor to nonexistent waveform, the endotracheal tube is likely in the esophagus, though consider other possible causes, such as in the esophagus, though consider other possible causes, such as airway disconnection, ventilator failure, cardiac arrest (especially airway disconnection, ventilator failure, cardiac arrest (especially with poor BLS) or decompensated shock. Remember, if no CO2 is with poor BLS) or decompensated shock. Remember, if no CO2 is

being exhaled, then no waveform or numerical reading will be being exhaled, then no waveform or numerical reading will be displayed.displayed.

What could a poor or non-existent wave form indicate?What could a poor or non-existent wave form indicate?

0

30

60

Case Study #1Case Study #1

32 yo 90 kg female presents in acute 32 yo 90 kg female presents in acute respiratory distressrespiratory distress

Cyanotic, short word sentencingCyanotic, short word sentencingRespiratory rate is shallow and labored at 24Respiratory rate is shallow and labored at 24Expiratory phase is prolonged due to gas Expiratory phase is prolonged due to gas

trappingtrappingHeart rate of 140, strong and bounding at the Heart rate of 140, strong and bounding at the

radialradialBP 170/88BP 170/88

Patient is clutching her Albuterol inhaler Patient is clutching her Albuterol inhaler (self-administered 15 puffs (self-administered 15 puffs

prior to your arrival)prior to your arrival)ETC0ETC022 value was beginning to rise value was beginning to rise

EtC02: 52 mmHg

BLS assisted ventilations via Bag Valve Mask with BLS assisted ventilations via Bag Valve Mask with 100% O2100% O2

Epinephrine 1:1000 SQ adminEpinephrine 1:1000 SQ admin

Paramedic prepares for nasal intubationParamedic prepares for nasal intubation

Treatment

Patient ArrestsPatient Arrests

As the nasal tube is being advanced, As the nasal tube is being advanced, patient arrestspatient arrests

Paramedic pushes the tube in anyway, Paramedic pushes the tube in anyway, but it is found to be in the esophagusbut it is found to be in the esophagus

Tube immediately withdrawnTube immediately withdrawn

Tube ConfirmationTube ConfirmationCords visualized during intubationCords visualized during intubationPatient is successfully intubated orally Patient is successfully intubated orally Auscultation reveals no discernible breath Auscultation reveals no discernible breath

sounds anterior chest wallsounds anterior chest wallAbdominal auscultation is equally silentAbdominal auscultation is equally silentMinimal chest riseMinimal chest risePositive misting and condensation in the Positive misting and condensation in the

tubetubeBulb aspirated syringe flows free-airBulb aspirated syringe flows free-air

What is the next step?What is the next step?

Auscultation doesn't really helpAuscultation doesn't really helpSpO2 is not reading (before or after)SpO2 is not reading (before or after)Remains difficult to ventilateRemains difficult to ventilate

– What other tool can you use to confirm the What other tool can you use to confirm the placement of the tube?placement of the tube?

– What else could be going on with this patient?What else could be going on with this patient?– Are we 100% sure we are in the trachea?Are we 100% sure we are in the trachea?

YES!!! We have an ETCOYES!!! We have an ETCO22

EtC02=22 mm Hg

Case Study #2: Cardiac ArrestCase Study #2: Cardiac Arrest

42 year old 90 kg, male, involved in 42 year old 90 kg, male, involved in motorcycle vs. truck MVA. The patient motorcycle vs. truck MVA. The patient is pinned under vehicle on highwayis pinned under vehicle on highway

approx. 8 min from local hospitalapprox. 8 min from local hospital

•Rapid extrication performed from underneath truck

•Pt. is unresponsive with weak, irregular carotid at 150bpm, and agonal respirations weak carotid

•Patient becomes pulseless and apneic, BLS/CPR is initiated

After intubation, the EtC0After intubation, the EtC02 2 read 25 and read 25 and

then dropped to 0 when the patient was then dropped to 0 when the patient was movedmoved

Corresponding waveformCorresponding waveform

After the patient was moved

C02 before the patient was moved

Where is the tube????Where is the tube????

Provider checked the number at the lipProvider checked the number at the lip– It had not changedIt had not changed

Listened to Breath SoundsListened to Breath Sounds– They were less audibleThey were less audible

The EtC0The EtC022 was 25, then dropped to 0 was 25, then dropped to 0

– Normal EtC0Normal EtC02 2 is between 35 to 45 mm Hgis between 35 to 45 mm Hg

The Endotracheal tube was removed and the The Endotracheal tube was removed and the patient was reintubatedpatient was reintubated

Corresponding Corresponding waveformwaveform

CO2 now back up CO2 now back up to 25mmHgto 25mmHg

Case Study #3Case Study #3

A 12 year old boy presented in acute A 12 year old boy presented in acute respiratory failure with copious secretions respiratory failure with copious secretions and was successfully orally intubated and and was successfully orally intubated and placed on a ventilator. placed on a ventilator.

The patient remained obtunded, cyanotic The patient remained obtunded, cyanotic and had little airway movement on and had little airway movement on auscultation.auscultation.

PresentationPresentation

Unconscious & Unconscious & unresponsiveunresponsive

Respiration's Respiration's unassisted remain unassisted remain agonalagonal

Heart rate of 136 strong Heart rate of 136 strong and regular at the and regular at the radialradial

Blood Pressure 138/56Blood Pressure 138/56 ETCOETCO22 32 mm HG 32 mm HG What does this

waveform show?

Answer:Answer:

A slow upstroke and A slow upstroke and incomplete emptying-incomplete emptying-

What could you do What could you do therapeutically?therapeutically?

The patient was suctioned and The patient was suctioned and given a bronchodilator treatmentgiven a bronchodilator treatment

What does this waveform show?What does this waveform show?

The waveform shows less The waveform shows less obstruction and more of an obstruction and more of an alveolar plateau = improvedalveolar plateau = improved

air movementair movement

AnswerAnswer::

Case Study # 4Case Study # 4

70 year old 60 kg female, status post cardiac 70 year old 60 kg female, status post cardiac arrest resuscitation by EMS She was arrest resuscitation by EMS She was resuscitated in the field and now being resuscitated in the field and now being transported to hospital. Enroutetransported to hospital. Enroute

Pt. is unconscious & unresponsive (orally Pt. is unconscious & unresponsive (orally intubated and on a vent)intubated and on a vent)

Vital SignsNo spontaneous respirationsBP 76/palpatedHeart rate is palpable only at the carotid at 136 weak and irregular

Cardiac monitor reveals Sinus Arrhythmia Cardiac monitor reveals Sinus Arrhythmia with multi-focal PVC's and coupletswith multi-focal PVC's and couplets

As you are debating Dopamine you notice As you are debating Dopamine you notice a change...a change...

EtC02 drops from 30 to 18 mm Hg

Patient’s perfusion decreases Patient’s perfusion decreases more………….CO2 dropsmore………….CO2 drops

furtherfurther

CPR is InitiatedCPR is Initiated

Now unable to palpate a carotid pulse

CPR was continued and CPR was continued and palpable pulses with palpable pulses with

compressions were present. compressions were present. The improved waveform:The improved waveform:

Cardiac compressions were Cardiac compressions were stopped and the patient was stopped and the patient was

found to be in ventricular found to be in ventricular fibrillationfibrillation

Attempt at defibrillation Attempt at defibrillation was unsuccessfulwas unsuccessful

Repeat defibrillation Repeat defibrillation

The patient is converted The patient is converted to normal sinus rhythm.to normal sinus rhythm.

Simple use of EtC02:Simple use of EtC02:

Capnography can be a Capnography can be a useful tool in determining useful tool in determining

the effectiveness of the effectiveness of pulmonary perfusion pulmonary perfusion

during a cardiac arrest.during a cardiac arrest.

CO2 Relationship to Cardiac OutputCO2 Relationship to Cardiac Output

In cardiac arrest and other low cardiac output states, the patient’scapnography will be lower than normal.

Evaluation of Efficacy of CPREvaluation of Efficacy of CPRPatients in cardiopulmonary arrest produce no Patients in cardiopulmonary arrest produce no

EtCOEtCO22..During CPR (given a normal blood volume), During CPR (given a normal blood volume),

effective chest compressions circulate enough effective chest compressions circulate enough blood to return COblood to return CO22 from the tissue cells to the from the tissue cells to the pulmonary circuit. Combined with effective pulmonary circuit. Combined with effective ventilations, providers will be see improved EtCOventilations, providers will be see improved EtCO22 values – most likely lower-than-normal levels.values – most likely lower-than-normal levels.– ““EtCOEtCO22 concentration varies directly with pulmonary and systemic concentration varies directly with pulmonary and systemic

blood flows under conditions of constant minute ventilation. This blood flows under conditions of constant minute ventilation. This relationship holds true even during extremely low blood flow rates.” relationship holds true even during extremely low blood flow rates.” Ann Emer Med, 3/1994, 23:3, p. 571Ann Emer Med, 3/1994, 23:3, p. 571

ETCO2 is also an indication of ETCO2 is also an indication of successful resuscitationsuccessful resuscitation

Sanders et al, 1989 JAMA Sanders et al, 1989 JAMA noted a threshold for survival of noted a threshold for survival of ETCO2 >10 mmhg ETCO2 >10 mmhg

Successful = 15 (+/-) 4Successful = 15 (+/-) 4Unsuccessful = 7 (=/-) 5Unsuccessful = 7 (=/-) 5

Cardiac Arrest/Successful Cardiac Arrest/Successful ResuscitationResuscitation

Predicting ROSC in ArrestPredicting ROSC in ArrestStudies have shown a correlation with EtCOStudies have shown a correlation with EtCO22 levels levels

during a code and ROSC.during a code and ROSC. Annals of Emerg Med, June, 1995, 25:6, Annals of Emerg Med, June, 1995, 25:6, pages 756-761pages 756-761

EtCOEtCO22 values can predict non-resuscitatable patients. values can predict non-resuscitatable patients.We may see the development of protocols utilizing We may see the development of protocols utilizing

EtCOEtCO22 values in conjunction with the terminating values in conjunction with the terminating rhythm to determine calling codes in the field.rhythm to determine calling codes in the field.– Most sources cite an EtCOMost sources cite an EtCO22 value of 10 mmHg or less as an value of 10 mmHg or less as an

appropriate and predictive threshold.appropriate and predictive threshold. This is a This is a terminating – not initialterminating – not initial – value, – value,

measured after 20 minutes of standard ACLS measured after 20 minutes of standard ACLS interventions.interventions.

Early Detection of ROSCEarly Detection of ROSC If the patient in cardiac arrest has a return of If the patient in cardiac arrest has a return of

spontaneous circulation, EtCOspontaneous circulation, EtCO22 levels will rise levels will rise quickly to a higher level.quickly to a higher level.

EtCOEtCO22 detection may be the earliest indicator of detection may be the earliest indicator of this improvement in perfusion, and should be this improvement in perfusion, and should be confirmed by palpating for central and peripheral confirmed by palpating for central and peripheral pulses.pulses.– One study showed a marked rise in EtCOOne study showed a marked rise in EtCO22 levels just levels just

before conversion of PEA to a perfusing rhythm.before conversion of PEA to a perfusing rhythm. Before any return of measurable BP or palpable pulses!Before any return of measurable BP or palpable pulses!

Annals of Emergency Medicine, June, 1995, 25:6, Annals of Emergency Medicine, June, 1995, 25:6, page 762-767page 762-767

Causes of an Elevated Causes of an Elevated ETCO2ETCO2

MetabolismMetabolism– PainPain– HyperthermiaHyperthermia– Malignant hyperthermiaMalignant hyperthermia– ShiveringShivering

Circulatory SystemCirculatory System– Increased cardiac output Increased cardiac output

- with constant ventilation- with constant ventilation

Respiratory SystemRespiratory System– Respiratory Respiratory

insufficiencyinsufficiency– Respiratory depressionRespiratory depression– Obstructive lung Obstructive lung

diseasedisease

EquipmentEquipment– Defective exhalation Defective exhalation

valvevalve

Causes of a Decreased EtCOCauses of a Decreased EtCO22

MetabolismMetabolism– Overdose / sedationOverdose / sedation– HypothermiaHypothermia

Circulatory SystemCirculatory System– Cardiac arrestCardiac arrest– EmbolismEmbolism– Sudden hypovolemia Sudden hypovolemia

or hypotensionor hypotension

Respiratory SystemRespiratory System– Alveolar hyperventilationAlveolar hyperventilation– BronchospasmBronchospasm– Mucus pluggingMucus plugging

EquipmentEquipment– Leak in airway systemLeak in airway system– Partial airway obstructionPartial airway obstruction– ETT in hypopharynxETT in hypopharynx

Case Study #5Case Study #5A 26 year old male is being A 26 year old male is being

transported on the ventilator. Vital transported on the ventilator. Vital signs are stable. A normal signs are stable. A normal

capnographic waveform is present.capnographic waveform is present.

Suddenly the capnograph Suddenly the capnograph changes to this:changes to this:

EtC02: 5 - 20 variable

What does this mean?What does this mean?

What should you What should you check?check?

Check the patient firstCheck the patient first

Then check the Then check the connections connections

between the ETT between the ETT and breathing circuitand breathing circuit

And what was And what was found……?found……?

AnswerAnswer::

A partial disconnection causing a leak A partial disconnection causing a leak in the circuit was detected. The problem in the circuit was detected. The problem is corrected and the waveform returns is corrected and the waveform returns

to normalto normal

Summary PointsSummary Points Detection device -------------> Diagnostic monitoringDetection device -------------> Diagnostic monitoring

Static --------------------------> Dynamic monitoringStatic --------------------------> Dynamic monitoring

Advanced warning of ventilatory statusAdvanced warning of ventilatory status– Don’t be caught off guardDon’t be caught off guard– Avoid backing into a critical situationAvoid backing into a critical situation– Crash------------------->electiveCrash------------------->elective

Objective confirmation of clinical assessmentObjective confirmation of clinical assessment

Thank you!