The Ultimate Vital Sign?
Importance of Capnography in EMS
Joshua Erdman, BS, CCEMT-P
UW Emergency Education Center
The full cycle
CO2
CO2
CO2
O2
O2
O2
Capnography
CO2
The full cycle and
our other vital signs
CO2
CO2
EKG
RR
Pulse
O2
O2
BP O2
Pulse ox
The full cycle
• Measuring CO2 allows us to look at:
– Ventilation
– Perfusion
– Cellular metabolism
• And all instantly!
Capnography
• Technology uses the Infrared absorbing
capability of CO2 to determine the amount
in a sample of air
• Gives us a measurement in mmHg
• Can graph this amount over time
Technology
• Two types
– Mainstream
• Advantage: Fast
• Disadvantages: Bulky, usually only for intubated patients
– Sidestream
• Advantages: Small samples, able to be used for spontaneous breathers
• Disadvantages: Slight time delay (<0.5 seconds)
Normal Capnogram
Capnogram Waveform
Phase
phase I
Termed
A→B
baseline
Variables
A = completion of inspiration
B = beginning of expiration
Gas from
Large airways
Oropharynx
nasopharynx
phase II
B→C
expiratory
upstroke
C = slowing of exhaled flow
Intermediate airways mixes with phase
I air
phase III
C→D
alveolar plateau
D = end expiration = PETCO2
Mixed gas displaced by alveolar gas
phase IV
D→E
inspiratory
downstroke
E= end inspiration
Inspiratory gas has little CO2
Typical capnogram
Capno vs. Pulse ox
Intubations
• The #1 reason most paramedics know to
use capnography
• AHA now identifies as the BEST way to
confirm your tube (2010 guidelines)
Sudden change while bagging…
Sudden decrease!
Ventilation rates
• Normal value should be 35-45 mmHg
• When ventilating,
– if too LOW, you need to SLOW
ETCO2
Vent. rate
– if too HIGH, you need to FLY (go faster)
What the…?
What’s going on here?
Exponential decrease in CO2
CPR in progress
CPR uses
•
•
•
•
Effective compressions
ROSC
Termination of CPR
Should I even have started?
Spontaneous breathers
• Asthma vs. hyperventilation
Hyperventilation
Bronchospasm
Spontaneous breathers
•
•
•
•
•
•
Overdose
CHF
Ketoacidosis
Sepsis
Hyperthermia
MI, especially right-sided or inferior wall
Hmmm…
In summary….
• Legal defense for intubations
• Immediate indication of changes in
ventilation or perfusion
• Many clinical diagnosis possibilities when
taken in consideration of other signs and
symptoms
Thanks!
• Joshua Erdman
• UW Emergency Education Center
• jerdman@uwhealth.org