Capnography: The Window Into Your

1
CapnographyThe Window Into Your Patient
Talk Code 682
Mike McEvoy, PhD, RN, CCRN, REMT-P Senior Staff
RN Cardiothoracic Surgical ICUs Albany
Medical Ctr EMS Coordinator Saratoga County,
New York EMS Editor Fire Engineering
Magazine EMS Director New York State
Association of Fire Chiefs
2

• mikemcevoy.com

3
SpO2 versus EtCO2
4
(No Transcript)
5
Contrasting Pulse Ox with Capnography Pulse
oximetry measure oxygen going OUT from the
heart Capnography measures what is coming
BACK from the periphery Two Different Concepts
6
Oxygenation and Ventilation

• Oxygenation (Pulse Ox)
• O2 for metabolism
• SpO2 measures of O2 in RBCs
• Reflects changes in oxygenation within 5 minutes

• Ventilation (Capnography)
• CO2 from metabolism
• EtCO2 measures exhaled CO2 at point of exit
• Reflects changes in ventilation within 10 seconds

7
What is Capnography?

• Capnos Greek for smoke
• From the fire of life ? metabolism
• CO2 is the waste product of metabolism
• Carbon Dioxide is a compound molecule
• 2 oxygen 1 carbon
• Odorless heavier than atmospheric air
• Green plants scavenge excess CO2
• 0.03 concentration in room air
• Resting adults produce 2.5 mg/kg/min

8
Capnography Basics

• Carbon Dioxide (CO2)
• Produced by all living cells
• Diffused into the bloodstream
• Transported to the lungs
• Perfused into the alveoli
• Exhaled through the airway

9
Measuring Exhaled CO2
Colorimetric Capnometry Capnography
10
Measuring Exhaled CO2
Colorimetric Capnometry Capnography
11
Measuring Exhaled CO2
Colorimetric Capnometry Capnography
12
Waveform Capnography

• Available for spontaneously breathing and for
  intubated patients

13
Capnography is the window INTO the patient
14
Normal Capnography Waveform

• Normal range is 35-45 mmHg
• Height total CO2
• Length time/rate

15
Capnogram Phases
D
C
End-tidal
A
B
E

• Inhale

16
Capnogram Phases
D
C
End-tidal
A
B
E

• Exhale (dead space)

17
Capnogram Phases
D
C
End-tidal
A
B
E

• Exhale (rapid rise)

18
Capnogram Phases
D
C
End-tidal
A
B
E

• Exhale (plateau)

19
Capnogram Phases
D
C
End-tidal
A
B
E

• End of the wave of exhalation

20
How Capnography Can Help

• Airway
• Breathing
• Circulation

21
What Happened?
The endotracheal tube became dislodged!
22

• Apnea
• Airway Obstruction
• Displaced airway (esophageal)
• Airway or vent disconnection
• Vent malfunction
• Cardiac Arrest

23
What about the Pulse Ox?
Sp02
98
24
Normal
Esophageal tube
25
Breathing
26
Capnography Waveforms
Normal
Hyperventilation
45
0
Hypoventilation
45
0
27
Rebreathing

• Possible causes
• Faulty expiratory valve
• Inadequate inspiratory flow
• Breath stacking (wrong mode, undersedated)
• Malfunction of CO2 absorber system

28
Whats the SHAPE?
29
The Shark Fin

• Possible causes
• Partially kinked or occluded artificial airway
• Presence of foreign body in the airway
• Obstruction in expiratory limb of vent circuit
• Bronchospasm

30
Bronchospasm (asthma)

• Mild

• Moderate

31
Marked bronchospasm
32
AirwayLeaking tube cuff
33

• Curare Cleft
• Appears when NMBAs begin to wear off
• Depth of cleft inversely proportional to degree
  of blockade

34
Circulation The lungs and the heart are
inextricably tied together
35
CO2 clearance reflects perfusion
In other words CO2 production is largely
dependent on oxygen consumption!
36
Cardiac Arrest

• Little O2 delivery or consumption
• Little CO2 production or venous return

Little Need to Ventilate!
37

• Use EtCO2 as guide to avoid
• overventilation during
• resuscitation
• lt 20 slooooow down
• gt 40 increase breaths
• Increased CO2 may ROSC

38
Decision to Call the Code

• 120 prehospital patients in nontraumatic cardiac
  arrest
• EtCO2 had 90 sensitivity in predicting ROSC
• Maximal level of lt10mmHg during the first 20
  minutes after intubation was never associated
  with ROSC

Source Canitneau J. P. 1996. End-tidal carbon
dioxide during cardiopulmonary resuscitation in
humans presenting mostly with asystole, Critical
Care Medicine 24 791-796
39
What about other shock states?
These data suggest that respiratory rate alone
cannot be used to predict measured capnography
levels.
R. Fowler, P. Pepe September, 2007
40
Wide a-A gradient
?
EtCO2 11 PaCO2 28
41
Something is blocking gas exchange

• Pulmonary embolism
• PNA, ALI or ARDS
• Shunting
• Low CO state
• Very low HCO3

42
Test your patient is seizing
43
Thank You !
Talk Code 682