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Capnography Mike McEvoy, PhD, NRP, RN, CCRN EMS Coordinator – Saratoga County, NY EMS Editor – Fire Engineering magazine Cardiac Surgical ICU RN & Chair.

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Presentation on theme: "Capnography Mike McEvoy, PhD, NRP, RN, CCRN EMS Coordinator – Saratoga County, NY EMS Editor – Fire Engineering magazine Cardiac Surgical ICU RN & Chair."— Presentation transcript:

1 Capnography 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:

3 Outline: Carbon dioxide Capnography – what, where, why? Oxygenation Ventilation EtCO 2 equipment Waveforms Uses Cases

4 Carbon Dioxide = CO 2 2 oxygen atoms + 1 carbon atom Trace gas on earth ( %) CO2 produced by: –Coal combustion (hydrocarbons) –Fermentation of beer –Respiration of living organisms Plants: sunlight + CO 2 + water  O 2

5 Carbon Dioxide = CO 2 Human body produces 2.3 # per day Solid form = dry ice Gas = fire extinguishers, carbonated drinks…

6 CO 2 (Carbon Dioxide) Greenhouse gas (heavier than air) –Global warming –Ocean acidification (carbonic acid)

7 Oxygen  Lungs  alveoli  blood Muscles + Organs Oxygen Cells Oxygen + Glucose ENERGY CO 2 Blood Lungs CO 2 Breath CO 2 Physiology of Metabolism

8 Carbon Dioxide Oxygen (O 2 ) enters the body through the lungs and is used to produce energy This process is called metabolism Carbon Dioxide (CO 2 ) is the waste product of metabolism

9 Typical Gas Percentages GasAtmosphericExhaled Nitrogen (N 2 )78%74% Oxygen (O 2 )21%16% Carbon Dioxide (CO 2 ) 0.04%4% Water (H 2 O)0.5%6% Normal Exhaled CO 2 = 35 – 45 mmHg

10 CO 2 In the Blood CO 2 is your drive to breathe  CO 2 causes air hunger Goal is to maintain PaCO 2 at 40 –Body adjusts respiratory rate & depth Oxygen does not affect respirations

11 Question: What would happen if you injected CO 2 into the blood? Respiratory rate and depth would 

12 Question: Why do swimmers who hyperventilate loose consciousness underwater?  CO 2 eliminates the drive to breathe

13 Measuring Exhaled CO 2 Colorimetric Capnometry Capnography Turns yellow when CO2 is detected

14 Colorimetric Pros Accurate Cheap (~$10-15) Changes color when CO 2 present Work for 2+ hours Disposable Cons Secretions Not quantitative Adds dead space False positives Hard to read at night

15 Measuring Exhaled CO 2 Colorimetric Capnometry Capnography

16 Capnometry Cons No waveform Does not trend Bulky adapter/unit Pros Numeric value + RR Portable Cheaper than waveform capnography PHASEIN EMMA™ (Masimo)

17 Measuring Exhaled CO 2 Colorimetric Capnometry Capnography

18 Pros Numeric value + RR Waveform Trending Very accurate Cons Expensive Fragile Warm-up time (some units) Secretions Temperature sensitive (some)

19 Infrared Spectroscopy CO 2 absorbs 4.26 µm wavelength Infrared light aimed at sample Infrared sensors detect absorption and calculate CO 2

20 Capnography Technologies Sidestream (1 st generation) –Sensor in remote location –Samples gas from circuit ( mL/min) Mainstream (2 nd generation) –Sensor in the airway

21 Capnography Technologies Microstream ® (next generation) –Sensor in remote location –Samples only 50 mL/min from circuit

22 SpO 2 versus EtCO 2

23 Oxygenation and Ventilation Oxygenation (Pulse Ox) –O 2 for metabolism –SpO 2 measures % of O 2 in RBCs –Reflects changes in oxygenation within 5 minutes Ventilation (Capnography) –CO 2 from metabolism –EtCO 2 measures exhaled CO 2 at point of exit –Reflects changes in ventilation within 10 seconds

24 Oxygen  Lungs  alveoli  blood Muscles + Organs Oxygen Cells Oxygen + Glucos e ENERGY CO 2 Blood Lungs CO 2 Breath CO 2 Physiology of Metabolism

25 Pulse Oximetry Problems: Accuracy Motion & artifact Dyshemoglobins Perfusion

26 Pulse Oximetry

27

28 Model of Light Absorption At Measurement Site Without Motion AC Variable light absorption due pulsatile volume of arterial blood DC Constant light absorption due to non-pulsatile arterial blood. DC Constant light absorption due to venous blood. DC Constant light absorption due to tissue, bone,... Absorption Time

29 Model of Light Absorption At Measurement Site With Motion AC Variable light absorption due pulsatile volume of arterial blood DC Constant light absorption due to non-pulsatile arterial blood. AC Variable light absorption due to moving venous blood DC Constant light absorption due to venous blood. DC Constant light absorption due to tissue, bone... Time Absorption

30 Influence of Perfusion on Accuracy of Conventional Pulse Oximetry During Motion Good Perfusion (Conventional PO) SpaO 2 =98 SpvO 2 =88 SpO 2 =93 Poor Perfusion (Conventional PO) SpO 2 =74 SpaO 2 =98 SpvO 2 =50

31 Post Processor R & IR Digitized, Filtered & Normalized R/IR MEASUREMENT T CONFIDENCE % Saturation Conventional Pulse Oximetry Algorithm 3 options during motion or low perfusion: 1. Freeze last good value 2. Lengthen averaging cycle 3. Zero out

32 Next Generation Pulse Oximetry

33

34 Masimo SET: Signal Extraction Technology SET “Parallel Engines” R/IR (Conventional Pulse Oximetry) Confidence Based Arbitrator 0 50% 66% 97% 100%SpO2% Post Processor Digitized, Filtered & Normalized % Saturation SST TM Proprietary Algorithm 4 DST SET – 97% DST TM FST TM MEASUREMENT CONFIDENCE MEASUREMENT CONFIDENCE MEASUREMENT CONFIDENCE MEASUREMENT CONFIDENCE MEASUREMENT CONFIDENCE R & IR

35 Discrete Saturation Transform (DST) 0 50% 66% 86% 97% 100% SpO% SpO 2 % Measure Through Motion Pulse Oximetry Separating - accurate Conventional Pulse Oximetry 0 50% 66% 86% 97% 100% SpO% SpO 2 % Averaging - inaccurate Variable Constant Variable Constant SET separates the venous and arterial saturation values (conventional oximetry averages the values to produce a reading)

36 Carbon Monoxide (CO) Gas: –Colorless –Odorless –Tasteless –Nonirritating Physical Properties: –Vapor Density = 0.97 –LEL/UEL = 12.5 – 74% –IDLH = 1200 ppm

37 Limitations of Pulse Oximetry Barker SJ, Tremper KK. The Effect of Carbon Monoxide Inhalation on Pulse Oximetry and Transcutaneous PO 2. Anesthesiology 1987; 66: SpCO-SpO 2 Gap: The fractional difference between actual SaO 2 and display of SpO 2 (2 wavelength oximetry) in presence of carboxyhemoglobin From Conventional Pulse Oximeter From invasive CO- Oximeter Blood Sample Conventional pulse oximetry can not distinguish between COHb and O 2 Hb

38 Pulse CO-oximetry

39 Uses multiple wavelengths of light Differentiates CO from O 2

40 Hgb Signatures: Physics of O 2 Pathways

41 SpCO User Concerns 1.Multiple wavelengths of light (8+) = Probe Placement: –Probe fits the finger –Centered over nail bed 2.Visible spectrum light = Protect from ambient light –Sunlight, strobes, etc.

42 Know Your Equipment

43 Back to CO 2 … What does exhaled CO 2 tell us? 1.Ventilation 2.Perfusion 3.Metabolism

44 Endotracheal Intubation

45 What Should Happen Lungs (Good) $tomach (Bad, Very Bad )

46 Anesthesia Litigation

47 Respiratory Damaging Events American Society for Anesthesiologists: Closed Claims Project Database, 2010 Capnography Introduced

48 #1 Capnography Use for EMS:

49 Guidelines 2005 EtCO 2 recommended to confirm ET tube placement

50 Intubated Patient Airway adapter plugs into LifePak ® Be sure adapter is tightly attached If not seated, waveform may flatten

51 Capnography Information Respiratory Rate End Tidal Carbon Dioxide Capnography Waveform

52 Capnography Waveforms The higher the waveform, the more CO 2 Normal EtCO 2 is 35 – 45 mmHg (usually the same as arterial CO 2 ) 0 45

53 Capnography Waveforms Hypoventilation Hyperventilation The length of the waveform corresponds to respiratory rate

54 Capnography Waveform Inspiration or manual ventilation with a bag- valve-mask or ventilator

55 Capnography Waveform Exhalation

56 End-tidal Capnography Waveform End-tidal (EtCO 2 ) is the end point of expiration. This is the point on the waveform that produces the numeric CO 2 value.

57 Capnogram Parts Phase I Start of exhalation No CO 2 (dead space)

58 Capnogram Parts Phase II Exhalation continues Rapid rise in CO 2 Mixing dead space & alveolar gases

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

60 Capnogram Parts Phase IV Rapid drop in CO 2 Start of inhalation

61 Capnogram Angles  (alpha angle)  (beta angle)  normal = 100 – 110° Airway obstruction will   normal = 90° Rebreathing will 

62 Capnography Waveforms Hypoventilation Normal Hyperventilation 45 0

63 Intubation You have intubated a 36 year old motorcyclist laying in the roadway HR 128, RR 14 by BVM, SpO 2 99% Esophageal intubation 6 breaths to evacuate gastric CO 2

64 98 Sp0 2 What about the Pulse Ox? SpO 2 will not drop for several minutes (5+ minutes)

65 Intubation You re-intubate the motorcyclist This is the capnography waveform: Is the tube in? Is the ventilation rate and depth appropriate?

66 During Transport Enroute to the trauma center, you observe this on the capnography: What happened? When is this most likely to occur? Tubes most commonly displace during patient movement

67 Ventilator Transport You are moving a 23 yo GSW to the head from a community ED to a neurosurgical ICU He is intubated and sedated: EtCO 2 = 35, RR = 24 “Curare Cleft” = diaphragmatic movement (breathing over drugs)

68 Ventilator Transport You don’t make any changes The patient appears to awaken: EtCO 2 = 30, RR = 38 “Curare Cleft” = diaphragmatic movement (breathing over drugs) “Bucking” ventilation needs drug tx

69 Ventilator Transport You are moving a ventilated patient The patient appears short of breath Waveform does not return to zero Baseline gradually increasing This is called “rebreathing”

70 Ventilator Transport You’re cardiac arrest reversal is unresponsive, on BVM ventilation BP 110/58, HR 90, RR 22, SpO 2 97 Is the patient ventilating? Causes: cuff leak, ETT displaced… NOT WELL

71 Cardiac Arrest

72 Carbon Dioxide (CO 2 ) Production Oxygen Circulation Respiration Carbon Dioxide

73 Carbon Dioxide (CO 2 ) Production Oxygen Circulation Respiration Carbon Dioxide Cardiac Arrest

74 AHA Guidelines 2010 Continuous quantitative waveform capnography recommended for intubated patients throughout peri- arrest period. In adults: 1.Confirm ETT placement 2.Monitor CPR quality 3.Detect ROSC with EtCO 2 values

75 1. Confirm ET placement When is an advanced airway most likely to become dislodged? During patient movement

76 2. Monitor the quality of CPR Try to maintain a minimum EtCO 2 of 10 mmHg Push HARD (> 2” or 5 cm) FAST (at least 100) Change rescuer Every 2 minutes

77 CPR in progress: Compression depth Compression rate Compressor Extreme acidosis Futility Other?

78 High-Quality CPR =  CO 2

79 Wayne MA, Levine RL, Miller CC. “Use of End-tidal Carbon Dioxide to Predict Outcome in Prehospital Cardiac Arrest”. Annals of Emergency Medicine. 1995; 25(6): Levine RL., Wayne MA., Miller CC. “End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest.” New England Journal of Medicine. 1997;337(5): EtCO 2 to detect ROSC (Return Of Spontaneous Circulation) 90 pre-hospital intubated arrest patients 16 survivors 13 survivors: rapid rise in exhaled CO 2 was the earliest indicator of ROSC Before pulse or blood pressure were palpable

80 3. EtCO 2 to detect ROSC Question: Would bicarbonate  EtCO2? Answer: Yes

81 CPR – What Causes This? Notice the small “ripples” ? Compressions generate air movement – this expels CO 2

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

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

84 Effects of Treatments

85 Air Trapping Emphysema is results in prolonged expiration Increases  angle:

86 Unconscious 16 yo found unresponsive in high school locker room – unknown hx Hypoventilation (? pharmaceutical) Use capnography on EVERY patient you treat with narcotics!

87 Difficulty Breathing 14 yo asthmatic – severely SOB Hyperventilation No evidence of airway obstruction or air trapping

88 Difficulty Breathing 81 yo with COPD and heart failure Acutely short of breath Capnogram favors pulmonary edema (no evidence acute COPD exacerbation)

89 Same Patient – Diff Breather 81 yo with COPD and heart failure Acutely short of breath Capnogram favors COPD exacerbation

90 Chest Pain 51 yo with substernal chest pain No distress, STEMI work up “Cardiac oscillations” – cardiac pressures being transmitted to airway (ripple effect)

91 Perfusion and pH Cardiac arrest = no CO 2 –Capnography reflects perfusion –  cardiac output =  EtCO 2 CO 2 is transported in the blood as bicarbonate (HCO 3 ) –In severe acidosis,  HCO 3 =  EtCO 2

92 Post Cardiac Arrest Patient You have resuscitated a 47 yo pt. found in v-fib on a city bus The patient is unresponsive, ventilated by BVM; pulses are weak Suspect falling cardiac output!

93 17 yo pt. in DKA You are called to a physician office to transport a patient in DKA The patient is alert and oriented; blood sugar is reportedly 880

94 General Weakness Patient You are called to see a 75 yo heart failure pt. with general weakness She is cool, BP 80/50, HR 128 afib What does the capnography say? Cardiogenic Shock!

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

96 Review

97 Label Inhalation & Exhalation Expiration Inhalation

98 End-tidal CO 2 Where is EtCO 2 Measured? Normal EtCO 2 is35 – 45 mmHg

99 AHA Guidelines 2010 What are the three reasons for use of continuous quantitative waveform capnography during cardiac arrest? 1.Confirm ETT placement 2.Monitor CPR quality 3.Detect ROSC with EtCO 2 values

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

101 Review 14 yo patient, SOB, asthma hx Clutching her albuterol inhaler Slow upstroke = bronchospasm

102 Review 67 yo COPD patient, acute SOB SpO 2 97%, HR 88, BP 138/86 Normal waveform, hyperventilation

103 Review 74 yo ROSC post v-fib arrest, unconscious, on ventilator, VSS Cleft (“curare cleft”) suggests non- compliance with vent

104 Review 45 yo auto-pedestrian, bilateral tib- fib fractures, BP 120/60, HR 90, RR 16, SpO2 97%, EtCO2 45 Normal waveform

105 Review Elderly cancer pt., unresponsive at home in bed Normal waveform – hypoventilation RR 4, EtCO 2 75 (> than 70 in without COPD = respiratory failure)

106 Review 60 yo COPD patient fever, chest pain, denies SOB, using accessory muscles to breathe Prolonged expiration (   angle); air trapping – normal capnogram in emphysema

107 Review 90 year old cardiac arrest, immediately after endotracheal intubation: Esophageal intubation 6 breaths to evacuate gastric CO 2

108 Review 55 yo COPD patient with flu like s/s Cardiac oscillations – normal EtCO 2

109 Review 18 yo GSW to chest Profound hypoperfusion – arrest imminent

110 Questions? Thanks for your attention! Slides posted at:


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