3/30/12. Luke J. Gasowski BS, BSRT, NREMT-P, FP-C, CCP-C, RRT-NPS

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1 Luke J. Gasowski BS, BSRT, NREMT-P, FP-C, CCP-C, RRT-NPS 1) Define and describe ETCO 2 2) Explain methods of measuring ETCO 2 3) Describe various clinical applications of ETCO 2 4) Describe the relationship between ETCO 2 and PaCO 2 5) Describe the relationship between ETCO 2 and ph 6) Identify common waveforms and EtCO2 application Ventilation, Metabolism, Circulation Basic principles of CO 2 Capnography Measurement PaCO 2, PACO 2 and ETCO 2 ph correlation CPR Interpreting capnograms 1

2 The measurement of end-tidal CO 2 (ET CO 2 ) currently is the optimal method of continuously monitoring the adequacy of ventilation and circulation in the adult, child, and infant. Used by anesthesiologists since the 1970s Standard of care in the OR since 1991 New recommendations and standards now expanding utilization The ability for which gas enters and leaves the lungs Inhaled Air % oxygen (O 2 ) 78 % nitrogen (N 2 ) 0.04 % carbon dioxide (CO 2 ) 1 % inert gases Exhaled Air approx. 16 % oxygen (O 2 ) 78 % nitrogen (N 2 ) approx. 5 % carbon dioxide (CO 2 ) 1 % inert gases 2

3 A waste product of normal cellular metabolism Must have adequate blood flow for gas exchange Must have ventilation to blow-off the CO 2 ETCO 2 concentration CO 2 production in the cells CO 2 transport CO 2 elimination in the lungs Changes in ETCO 2 can be a reliable indicator in metabolic changes Metabolic Increased ETCO 2 Fever, sepsis, shivering, convulsions, malignant hyperthermia Metabolic Decreased ETCO 2 Hypothermia, paralytics, sedation ETCO 2 transport to the lungs is dependent on adequate cardiovascular function With ventilation constant, changes in ETCO 2 can indicate circulation changes Circulatory Increased ETCO 2 Return of Spontaneous Circulation Circulatory Decreased ETCO 2 Low cardiac output, hypovolemia, hypotension 3

4 ETCO 2 can be a guide for determining the ventilation requirement of a patient Ventilatory changes in ETCO 2 are affected by RATE and volume Ventilatory Increased ETCO 2 Hypoventilation, COPD, Asthma Ventilatory Decreased ETCO 2 Hyperventilation, Rescuer excitement with BVM Capnography is the measurement of exhaled CO 2 The number is usually displayed in millimeters of Mercury(mm Hg) Capnography provides the clinician with a waveform showing exhaled CO 2 over time. Is used to confirm, monitor, and document ET tube intubation Is used to monitor the ventilatory status of a non-intubated patient Sedation, pain management, asthma, COPD, head injury, shock Colorimetric Disposable devices based on the reaction of litmus paper (purple/blue = no CO 2, yellow = CO 2 ) Infrared Absorption (IR) Mainstream or side stream Mainstream Device directly measuring at ET tube Requires more calibration and is more easliy damaged Sidestream A sample of air is pumped to the sensor Usually self calibrated More protected 4

5 Arterial CO 2 (PaCO 2 ) normal is mmhg Alveolar CO 2 (PACO 2 ) is the CO 2 diffused into the lungs from PaCO 2 ETCO 2 is the exhaled CO 2 and is 2-5 mmhg lower than PaCO 2 Arterial blood gas (ABG) analysis is the hallmark for assessing a patient s acidbase, oxygenation, and ventilation levels. ETCO 2 is often used to predict PaCO 2 Accurate information about the rate and rhythm of respiration can be obtained by sampling CO2 using nasal cannulas Calculating respiratory rate by monitoring chest wall movements. Impedance devices can give false positives as chest wall movements persist during obstructive apnea. Detection of obstructive apnea necessitates the evaluation of oral-nasal airflow. 5

6 H + + HCO - 3 H 2 CO 3 H 2 O + CO 2 Normal ph = PaCO2, 10mm Hg = ph 0.08 Change from 40mmHg and 7.40 PaCO 2 > 45mmHg: Hypoventilation Respiratory acidosis PaCO 2 < 35mm Hg: Hyperventilation Respiratory alkalosis SpO 2 remains mostly unchanged after a considerable period of apnea ETCO 2 measurements exhibit significant change immediately Ventilation/breathing is controlled by CO 2 It is best to use both SpO 2 and ETCO 2 Capnography Carbon dioxide Reflects ventilation Hypoventilation / apnea detected immediately Reflects change in ventilation within 5 seconds Should be used with pulse oximetry Pulse oximetry Oxygen saturation Reflects oxygenation SpO2 changes lag when patient is hypoventilating or apneic Reflects change in oxygenation within 5 minutes Should be used with capnography 6

7 Adequacy of CPR is also easily assessed through capnography The measurement helps in assessing the effectiveness of CPR ETCO 2 levels have a strong correlation with cardiac output As cardiac output decreases during cardiopulmonary arrest, pulmonary blood flow diminishes, CO 2 available for exhalation is decreased, and ETCO 2 levels drop Attempt to maintain a minimum of 10 mmhg during CPR ETCO 2 can also help predict survival. Levine and colleagues reported 100% mortality in out of hospital cardiac arrests where ETCO 2 did not return to 10 mmhg after 20 minutes of CPR Return of Spontaneous Circulation Normal = 35 mmhg 45 mmhg 7

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11 Sampling tube obstruction Lose connection Suctioning through ETT Secretions PCA use with capnography The American Society of Anesthesiologists (ASA) is advising its members not to administer sedatives for upper endoscopies without the aid of a device to detect changes in the amount of carbon dioxide the patient is exhaling. The addition of a capnograph may help anticipate a patient s deterioration by warning of a decrease in respiratory rate and rise in end-tidal carbon dioxide. 11

12 Despite routine use of pulse oximetry in endoscopy over the past 20 years, the incidence of cardiopulmonary complications hasn t declined In contrast, anesthesia-related deaths have dropped since capnography monitoring during general anesthesia has been mandated in the US Capnography can detect early phases of respiratory depression, which can allow a more precise and safer titration of medications *Radaelli, F., Terruzzi, V., & Minoli, G. (2004) Extended/advanced monitoring techniques in gastrointestinal endoscopy. Gastrointestinal Endoscopy Clinics of North America. 14, Accurately monitors Respiratory Rate Monitors adequate ventilation with non-intubated patients Monitors potential risk of over-sedation resulting in Hypoventilation more effectively than pulse oximetry Early indicator of airway obstruction Early warning of apnea Adds an additional level of patient safety providing the caregiver with vital information to make accurate assessments and timely interventions for the patient. Where there is metabolism and ventilation there is CO 2 If an ET tube is correctly placed there should be a capnography reading AHA Guideline Capnography is more than just ET tube confirmation Ventilation status Prediction of ventilatory failure Real time respiratory rate ph and cardiac output correlation 12

13 What questions do you have? Voigt E, Pelikan J. CO 2 Measurement During Ventilation, Dräger Pilbeam S, Cairo J. Mechanical Ventilation - 4 th edition, Mosby, 2006 Wilkins R, Stoller J, Scanlan C. EGAN S Fundamentals of Respiratory Care 8 th edition, Mosby 2003 Ahrens T, Schallom L, Bettorf K, Ellner S, et al. End-tidal carbon dioxide measurements as a prognostic indicator of outcome in cardiac arrest, American Journal of Critical Care 2001 Nov;10(6):391-8 Levine RL, Wayne MA, Miller CC. End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest, New England Journal of Medicine 1997 Jul 31;.337(5):301-6 Silvestri S, Ralls GA, Krauss B, Thundiyil J, et al. Effectiveness of out-ofhospital use of continuous end-tidal carbon dioxide monitoring on rate of unrecognized misplaced intubation within a regional emergency services system, Annals of Emergency Medicine 2005 May;45(5): Bhende MS, LaCovey DC. End-tidal carbon dioxide monitoring in the prehospital setting, Prehospital Emergency Care 2001 Apr-Jun;5(2): Wayne MA, Slovis CM, Pirrallo RG. Management of difficult airways in the field Prehospital Emergency Care, 1999 Oct-Dec;3(4):