1. Clinical Cases in Capnography
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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

2. Mike McEvoy: www.mikemcevoy.com

3. 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)

4. 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.

5. Capnography Technologies
Sidestream (1st generation)
Sensor in remote location
Samples gas from circuit ( 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.

6. 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.

7. 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.

8. Know Your Equipment
It is important to know your equipment.

9. 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.

10. 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.

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

12. Cardiac Arrest

13. 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

14. 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

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

16. 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. 

17. CPR in Progress
Sudden increase in EtCO2
Likely suggests ROSC

18. What else would  EtCO2?
Bicarb administration

19. What else would  EtCO2?
Immediately after bicarb given:

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

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

22. 38 yo female, unconscious
Polydrug OD, no response to reversal agents. Initial capnogram:
Resp failure in absence of COPD = CO2 > 70

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

24. Cardiogenic Oscillations
Unknown etiology
Tx = PEEP

25. 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

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

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

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

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

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

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

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

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

34. 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.

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

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

37. 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.

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

39. 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.

40. 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 This waveform tracing illustrates how sensitive and accurate capnography is in detecting conditions of metabolic acidosis.

41. Critical Care Transport
75 yo heart failure pt. xfr for higher level of 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

42. 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 ;31:64-71.

43. 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 ;31:64-71.

44. 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

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

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

47. Titration of NIV
CPAP, BiPAP (but not HFNC)

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

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

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