Clinical Cases in Capnography #AMTC15 @AMTC TheAMTC Mike McEvoy, PhD, NRP, RN, CCRN EMS Coordinator – Saratoga County, NY EMS Editor – Fire Engineering magazine Cardiac Surgical ICU RN & Chair Resuscitation Committee – Albany Medical Center

Mike McEvoy: www.mikemcevoy.com

Technology (PHASEIN) EMMA™ (Masimo) Capnometers are portable, provide more information than colorimetric devices but lack a waveform which would be helpful for visualizing trends and tend to be somewhat bulky (which means they may add additional weight to an advanced airway, potentially dislodging an endotracheal tube). In 2012, the EMMA Capnometer (Masimo Corp., Irvine CA) was redesigned to include a waveform which transformed the capnometer into a waveform capnography device. (PHASEIN) EMMA™ (Masimo)

Infrared Spectroscopy CO2 absorbs 4.26 µm wavelength Infrared light aimed at sample Infrared sensors detect absorption and calculate CO2 CO2 in gas form absorbs light at the 4.26 micrometer spectrum.

Capnography Technologies Sidestream (1st generation) Sensor in remote location Samples gas from circuit (150-250 mL/min) Mainstream (2nd generation) Sensor in the airway First generation CO2 technologies were sidestream devices. The sensor was in a remote location and sampled large amounts of gas from the respiratory circuit in order to make measurements. This large volume sampling mandated that sidestream analyzers have moisture traps. Second generation devices moved the sensor into the airway itself.

Capnography Technologies Microstream® (next generation) Sensor in remote location Samples only 50 mL/min from circuit Third generation devices (Microstream) work in a similar fashion to sidestream devices but sample significantly less air from the line, eliminating the need for a large moisture trap and allowing use in very small patients and in spontaneously breathing patients. Moisture is trapped by a filter placed in the Microstream connector.

Capnography Technologies Nomoline® (next generation) Sensor in remote location Samples only 50 mL/min from circuit Third generation devices (Microstream) work in a similar fashion to sidestream devices but sample significantly less air from the line, eliminating the need for a large moisture trap and allowing use in very small patients and in spontaneously breathing patients. Moisture is trapped by a filter placed in the Microstream connector.

Know Your Equipment It is important to know your equipment.

Oridion  Covidien  Medtronic Airway adapter plugs into port Be sure adapter is tightly attached If not seated, waveform may flatten An important consideration in using capnography is to assure that the connector is tightly screwed into the monitor. If the connector is not firmly seated, atmospheric air will be pulled into the monitor from around the connector, resulting in poor or no end-tidal CO readings.

Esophageal Intubation How many breaths are necessary to evacuate gastric CO2? 6 breaths The standard practice for “washing out” gastric CO2 is to provide 6 breaths and then measure CO2. If the tube is in the esophagus, 6 breaths will wash out any gastric CO2.

Back to CO2… What does exhaled CO2 tell us? Ventilation Perfusion Metabolism Back to CO2 – exhaled CO2 provides information about ventilation, perfusion, and metabolism.

Cardiac Arrest

Goals During Cardiac Arrest Try to maintain a minimum EtCO2 of ? 10 mmHg Push HARD (> 2” or 5 cm) FAST (at least 100) Change rescuer Every 2 minutes

CPR in progress: goal = 10? Compression depth Compression rate Compressor Extreme acidosis Futility Other? Reasons for low EtCO2 during CPR can be related to any of these. > 25 more reasonable

Chest Compression Oscillations CPR – What Causes This? Notice the small “ripples” ? Compressions generate air movement – this expels CO2 Chest Compression Oscillations ? Wholey theoretical

Warning Incidence of cardiac oscillations is high in cardiac arrest (73%) Does NOT imply tube is tracheal Several reports of oscillations with esophageal ET tubes! Idris AH, Daya M, Owens P, O'Neill S, Helfenbein ED, Babaeizadeh S, Zhou SH. Resuscitation Science Symposium - Abstract 83: High Incidence of Chest Compression Oscillations Associated With Capnography During Out-of-Hospital Cardiopulmonary Resuscitation.  Circulation. 2010; 122: A83. 

CPR in Progress Sudden increase in EtCO2 Likely suggests ROSC

What else would  EtCO2? Bicarb administration

What else would  EtCO2? Immediately after bicarb given:

How long does this last? Return to slightly > baseline (5 min):

Post-arrest (ROSC) patient HR 103, SpO2 99%, NIBP 102/54 EtCO2 8

38 yo female, unconscious Polydrug OD, no response to reversal agents. Initial capnogram: Resp failure in absence of COPD = CO2 > 70

Drug Overdose 39 yo female unresponsive poly-drug OD – hypotensive, intubated You cannot determine her EtCO2 “Cardiogenic oscillations”

Cardiogenic Oscillations Unknown etiology Tx = PEEP

Capnography Waveform End-tidal End-tidal (EtCO2) is the end point of expiration. This is the point on the waveform that produces the numeric CO2 value. 25

Capnogram Parts Start of exhalation No CO2 (dead space) Phase I 26

Capnogram Parts Phase II Exhalation continues Rapid rise in CO2 Mixing dead space & alveolar gases 27

Capnogram Parts Phase III also called the Alveolar Plateau End exhalation All alveolar gas 28

Capnogram Parts Phase IV Rapid drop in CO2 Start of inhalation 29

Distorted Waveforms Depends on patient (awake, asleep) Can be multifactorial “Curare Cleft” = diaphragmatic movement “Bucking” ventilation Cuff leak, pharyngeal tube…

Capnogram Angles  (beta angle)  (alpha angle)  normal = 90°  with rebreathing  normal = 100 – 110°  with airway obstruction 31

Bronchospasm Asthma, COPD… Elevation of  angle, loss of alveolar plateau (“shark-fin” appearance) Degree of angle = severity

Effects of Treatments This is a patient with significant SOB. With nebulizer treatment, the waveform demonstrates resolution of the bronchospasm.

Air Trapping Emphysema is results in prolonged expiration Increases  angle: Emphysema results in air trapping (difficulty inhaling). Hence, the beta angle increases and the alveolar plateau dips downward.

COPD exacerbation vs. HF 81 yo with COPD and heart failure Acutely short of breath Capnogram favors pulmonary edema (no evidence acute COPD exacerbation)

Same Patient – acute dyspnea 81 yo with COPD and heart failure Acutely short of breath Capnogram favors COPD exacerbation

Importance of waveform 14 yo asthmatic – severely SOB Hyperventilation No evidence of airway obstruction or air trapping Fast respiratory rates are difficult for the capnography equipment to accurately track. Waveforms then, loose their crisp appearance in pediatric and neonatal patients as well as in adults with high respiratory rates.

Spontaneously Breathing Capnography helps assess: Accurate respiratory rate Airway patency (bronchospasm, air trapping, obstruction) Shock states Response to treatment

EtCO2 = perfusion and pH Capnography reflects perfusion  cardiac output =  EtCO2 CO2 is transported in the blood as bicarbonate (HCO3)  HCO3 =  EtCO2 In cardiac arrest, no CO2 is produced. In profound metabolic acidosis, CO2 is used in the blood to combine with the acids and is not exhaled. The lower the bicarb level in the blood (i.e., the more acidotic the patient) the lower the exhaled CO2 will be.

17 yo female GBW pH? 6.93 Ill appearing, orthostatic, A&Ox3 FSBG Serum glucose = 880 pH? 6.93 This is another waveform tracing from a 17-year-old in diabetic ketoacidosis. Note here again the extremely low cardiac arrest level EtCO2 of 6 millimeters of mercury, and a corresponsive pH of 6.93. This waveform tracing illustrates how sensitive and accurate capnography is in detecting conditions of metabolic acidosis.

Critical Care Transport 75 yo heart failure pt. xfr for higher level of care @ tertiary med center She is cool, BP 80/50, HR 128 afib What does the capnography say? Low perfusion associated with lactic acidosis will produce a low EtCO2! Cardiogenic Shock

Sepsis? EtCO2 reflects lactate & mortality Inverse, linear relationship  EtCO2 =  lactate Lactate requires blood testing 172 minutes lab, 21 minutes POC Capnography is instantaneous Hunter CL, Silvestri S, Dean M, Falk JL, Papa L. End-tidal carbon dioxide is associated with mortality and lactate in patients with suspected sepsis. Am J Emer Med. 2013;31:64-71.

Mean Values (n=201) 1.79 33 6.20 28 4.90 30 Lactate EtCO2 Criteria mmol/L EtCO2 Criteria Suspected Sepsis 1.79 33 2 SIRS criteria Severe Sepsis 6.20 28 Sepsis + end organ dysfunction Septic Shock 4.90 30 Sepsis + refractory hypotension Hunter CL, Silvestri S, Dean M, Falk JL, Papa L. End-tidal carbon dioxide is associated with mortality and lactate in patients with suspected sepsis. Am J Emer Med. 2013;31:64-71.

R/O Pulmonary Embolus 30 yo female smoker on BCP, SOB 104/80, P 110, 85% on NRBM 7.38, 70, 38, 22, -2.0, 85% EtCo2 = 40

PE? Same patient (same VS & ABG) 104/80, P 110, 85% on NRBM 7.38, 70, 38, 22, -2.0, 85% EtCo2 = 18

 Alveolar Perfusion A-a gradient (EtCO2 < PaCO2)

Titration of NIV CPAP, BiPAP (but not HFNC)

NIV: Nasal Capnography Requires cannula w/ pillow (oral)

Rounded Waveforms Be suspicious of rounded waveforms: These often imply low perfusion, acidosis, sepsis, poisoning or other metabolic derangements

Thanks for your attention! Slides posted at: www.mikemcevoy.com Questions? Thanks for your attention! Slides posted at: www.mikemcevoy.com Mike McEvoy Email: mcevoymike@aol.com Slides available at www.mikemcevoy.com -> choose “Open Bar” tab