Julie Zimmerman, MSN, RN, CCRN Clinical Nurse Specialist

Objectives

• Define capnography vs. end tidal CO2 (EtCO2) • Identify what normal vs. abnormal EtCO2 values

mean and what to do • Understand when to apply EtCO2 monitoring as

ordered

• Understand how to document EtCO2 in EPIC

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What is Ventilation? • Ventilation: movement of air in and out

of the lungs

• End tidal CO2 (EtCO2) is the measurement of carbon dioxide exhaled with each breath – Reflects breath-to-breath ventilation or air

movement

– Detects rapid or slow breathing pattern

• Note: Ventilation equals tidal volume (size of the breath) x respiratory rate.

V = TV x RR

A patient with 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.

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What is Respiration? • Respiration: Process of moving air between the

atmosphere and the alveoli. It is describes the distribution of air within the lungs to maintain appropriate concentrations of O2 and CO2 in the alveoli

– Supplemental O2 will “drive” a higher concentration of oxygen to diffuse across the alveolar capillary membrane and increase amount of O2 bound to Hbg and the SaO2!

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Pulse Oximetry / SpO2 Monitoring • SaO2 is a measurement of the oxygen Saturated on

each Hgb molecule and (SpO2) is this measurement determined by pulse oximetry – There is an inverse relationship between CO2 and O2 levels

when one goes ↑, the other goes ↓ – If a patient is receiving supplemental O2

– Normal inverse relationship is altered! – SpO2 will remain high despite a rising CO2 !

CO2 levels may rise with hypoventilation and the SpO2 will remain normal for 40 minutes!

A drop in SpO2 is a VERY LATE sign of hypoventilation

and apnea http://vam.anest.ufl.edu/Fu-Downs-Chest.pdf JLZ/MAR2012

What’s the difference between SpO2 and EtCO2?

Pulse Oximetry (SpO2) Measures Oxygenation

• Measures oxygen saturation on each Hgb molecule

• Reflects oxygenation

• Detects hypoxia

• Apnea and hypoventilation: – If a patient hypoventilates, oxygen

saturation can remain normal for 40 minutes!

– If a patient becomes suddenly

apneic, pulse oximetry will continue to show a high saturation!

EtCO2 Monitoring Measures

Ventilation

• Measures carbon dioxide exhaled

• Reflects breath-to-breath ventilation

• Detects hypoventilation

• Apnea and hypoventilation: – If a patient hypoventilates, EtCO2

will rise indicating accumulating CO2

– If a patient becomes suddenly apneic, an EtCO2 monitor will display “no breath” and alarm after 30 seconds.

Gold Standard

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Sedation Precedes Respiratory Depression

No patient has succumbed to (opioid induced) respiratory depression while awake. APS, 1999

Arousability is the key to assessing

sedation!

When patients are at risk for opioid induced respiratory depression, sedation level and EtCO2 monitoring is important.

If you feel your patient is at risk and does not have an order for EtCO2….ASK FOR ONE!

McCaffery, M., 2000, Hagle, M., 2004, Kim, J., 2003 JLZ/MAR2012

Why do we need to know the EtCO2 value?

The EtCO2 monitor can provide an EARLY WARNING of an impending respiratory crisis.

Normal EtCO2 is

between 35 and 45 mmHg

EtCO2 values lower or higher are NOT normal and need further

investigation

Capnography is the

evaluation of the CO2 waveform JLZ/MAR2012

HYPERventilation EtCO2 less than 35 mmHg “Hyperventilation/Hypocapnia”

• Hyperventilation can be caused by many factors from anxiety to bronchospasm to pulmonary embolus.

– Other reasons CO2 may be low: cardiac arrest, decreased cardiac output, hypotension, cold, severe pulmonary edema.

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HYPOventilation EtCO2 greater than 45mmHg = “Hypoventilation/Hypercapnia”

• Hypoventilation can be caused by altered mental status such as overdose, sedation, intoxication, postictal states, head trauma, stroke, or by a tiring CHF patient.

– Other reasons CO2 may be high: Increased cardiac output, fever, sepsis, pain, severe difficulty breathing, and/or depressed respirations due to chronic hypercapnia

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Sleep Disordered Breathing (SDB)

• Describes a group of breathing disorders characterized by abnormalities in the respiratory pattern (pauses in breathing) or the quantity of ventilation during sleep

Despite considerable progress, 75%-85% people remain undiagnosed!

– Obstructive sleep apnea (OSA), repetitive or partial collapse of the pharyngeal airway during sleep for > 10 sec and abrupt arousal to resume breathing. • Airflow is absent

– Central sleep apnea (CSA), brain fails to signal the respiratory muscles to facilitate breathing • Both airflow & ventilatory effort are absent

Both are exacerbated with the use of opioids and sedatives!

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Sleep Disordered Breathing (SDB) • Who is at risk?

– STOPBANG – is a screening tool used to identify those at risk.

– Performed in the pre-op clinic and noted in EMR

• Treatment – If patient is identified to be

“at risk” they are placed on continuous pulse oximetry monitoring (at least telemetry LOC) after surgery

– Continuous positive airway pressure (CPAP) or (BiPap) may be needed to keep the airway open

• Snoring • Tired • Observed not

breathing • Blood Pressure

(elevated) • BMI • Age • Neck circumference • Gender

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Opioids and Sleep Disordered Breathing

• Opioids

– Decrease respiratory rate even at low doses

– Decrease in tidal volume at high doses

– OSA and CSA patients are vulnerable to these effects and are at risk for hypoventilation due to over sedation when receiving opioid analgesia

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Beginning October 1st

• IV PCA order set will automatically include ETCO2 monitoring for the duration of the order.

– The ordering physician may discontinue this order at any time.

– If the goals of care change, this order may be discontinued.

• This level of monitoring is not intended for those patients receiving end of life care

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Beginning Oct. 1, all patients receiving IV PCA will have an order for EtCO2 monitoring

Alarm Settings

EtCO2 high 60 mmHg – low 10 mmHg *Alarm* RR slows to < 6bpm *Alarm*

– further trending to 4bpm will pause PCA!

Apnea of 30 seconds *Alarm*

• Provide patient education along with EtCO2 monitoring to promote compliance!!

• Monitor your patient for drowsiness or drifting off to sleep during

conversation – This is unacceptable! Assess respiratory status and sedation level closely and inform

MD if the patient appears to be too drowsy! – Assess respiratory history using the Trend button to identify if RR has been slowing

or CO2 is rising or high – If the patient is unarousable, stop the PCA and consider implementing reversal

agent or implementing ESO for respiratory depression/arrest or call RRT/Code Blue and notify primary MD.

What should I do?

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FIRST: Look for the order in Nursing

Misc.

Document with every vital sign and

PRN

SECOND: Select and ADD to doc flow sheet

THIRD: Enter EtCO2 and O2 values on doc flow sheet JLZ/MAR2012

Documentation in the Care Plan

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FAQ’s • What if my patient refuses?

– First ask why? This is a patient safety device. • “Our goal is to provide you with adequate pain management;

however, these medications have a side effect of lowering your respiratory rate to an unsafe low if you happen to be sensitive to them.

• The nasal cannula device will identify this quickly and sound an alarm that is intended to wake you up.

• This is important because we want to be sure you CAN wake up.

• If you feel the alarm is keeping you from resting, please let your nurse know so they can investigate why.”

– Then provide the patient with the educational

handout. (Available in English and Spanish) • If the patient still refuses, document that in your charting and

let the MD know to DC the order.

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FAQ’s

• What if my patient has CPAP? EtCO2 monitoring is possible with CPAP. Request the assistance of the Respiratory Therapist.

• Remember, if there is humidification, the Capnoline nasal prongs may malfunction and alarm erroneously.

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Troubleshooting Alarms

• What if the alarms are driving me and my patient crazy? – On the Alaris brain, look at the Trend data by selecting

EtCO2 on the main screen and select Trend Button. This will show you exactly how the patient has been breathing and when the alarms have sounded. Remember, if the RR trends down to a rate of 6, the pump will alarm a low RR.

– Once a RR rate slows to a rate of 4, the PCA dose will pause and you must select Restart to begin PCA therapy again

– EtCO2 > 60 will alarm, consider respiratory pattern of the patient and assess for hypoventilation.

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Troubleshooting Alarms • Consider the IV PCA dose. Is it too much for this patient and

causing them to be too drowsy? • Identify if the patient has an obstructive respiratory pattern by

watching the waveform? – This may warrant further investigation from the MD. Notify MD of

your suspicion of apnea.

• Has the Capnoline nasal cannula sensor gotten moist from skin oils, or humidification? This will cause the module to alarm erroneously. – Any O2 therapy that includes humidification will cause the EtCO2 to

read erroneously

• Is the patient a “mouth breather” and the sensor is not detecting respirations? – Reposition tubing and reset pump. – EtCO2 may not be an option for this patient. Document and notify

the MD to DC order if unable to obtain accurate reading.

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