7/29/2019 Medic UPdate 2003 Capno
1/33
End Tidal CO2: Riding the Wave
Harvey Conner, AS,NREMT-P
7/29/2019 Medic UPdate 2003 Capno
2/33
Objectives
Review carbon dioxide chemistry, physiology in the
human bodyReview methods for measuring carbon dioxide in
exhaled air
Describe the normal capnogram
Discuss physiological and pathological factors affectingthe capnogram
7/29/2019 Medic UPdate 2003 Capno
3/33
Why ETCO2?????
The AHA in their Guidelines 2000 identified
ETCO2as the Gold Standard in confirmationof ET tube placement.
ACEP has followed AHAs lead and also
emphasized ETCO2 as the standard indetermining ET tube placement.
These two combined have provided the EMS
community with a national standard of care
In other words you had better do it!
7/29/2019 Medic UPdate 2003 Capno
4/33
Oxygen-> lungs -> alveoli -> blood
muscles + organs
Oxygen
cells
Oxygen
Oxygen
+
Glucose
energy
CO2
blood
lungs
CO2
breath
CO2
Physiology
7/29/2019 Medic UPdate 2003 Capno
5/33
Terminology
Capnometry Measurement of CO2 in the airway during
respiration
Capnography
Graphic display of this measurement over time
7/29/2019 Medic UPdate 2003 Capno
6/33
Methods for measuring PetCO2
7/29/2019 Medic UPdate 2003 Capno
7/33
Methods for reporting PetCO2
Partial pressure (mmHg)
Percentage (%)
1% = 7.6 mmHg
7/29/2019 Medic UPdate 2003 Capno
8/33
pH sensitiveIndicator is metacresol purple
Color change yellow-purple
Avoids red-green spectrum
(8% of population is red-green color blind)
Colorimetric method
7/29/2019 Medic UPdate 2003 Capno
9/33
A (purple) = < 4 mm Hg
B (tan) = 4-15 mm Hg
C (yellow) = > 15 mm Hg
Colorimetric method
7/29/2019 Medic UPdate 2003 Capno
10/33
7/29/2019 Medic UPdate 2003 Capno
11/33
7/29/2019 Medic UPdate 2003 Capno
12/33
PetCO2 device types
1.Sidestream
2.Mainstream
For the purposes of this lecture
well look at sidestream devices
only
7/29/2019 Medic UPdate 2003 Capno
13/33
Sidestream analysis
Aspirate gas from exhaled air
columnLightweight port
Easy to use on non-intubated
patient
Sample line easily plugged by
secretions2-3 sec delay
Extraneous air leaks
7/29/2019 Medic UPdate 2003 Capno
14/33
PetCO2 device types
Sidestream
Quantative = numerical or
sliding bar scale Qualatative= graphic
representation of wave form
along with numerical values
7/29/2019 Medic UPdate 2003 Capno
15/33
PetCO2 device types
SidestreamQuantative = numerical or sliding bar scale
7/29/2019 Medic UPdate 2003 Capno
16/33
7/29/2019 Medic UPdate 2003 Capno
17/33
PetCO2 device typesSidestream
Qualatative= graphic representation of wave
form along with numerical values
7/29/2019 Medic UPdate 2003 Capno
18/33
Capnographic waveform
Zero baseline (A-B)
Rapid, sharp rise (B-C)
Alveolarplateau (C-D)
End tidal value (D)
Rapid, sharp downstroke (D-E)
7/29/2019 Medic UPdate 2003 Capno
19/33
Waveform A-B
Respiratory baseline
Exhalation of CO2 free gas indead space
Value should be zero
Increased value with re-breathing
7/29/2019 Medic UPdate 2003 Capno
20/33
Waveform B-C
Sharp rise
Exhalation of mixed dead spaceand alveolar gas from aciniwith the shortest transit times
Less steep upstroke due tomechanical problem,
broncho-spasm, obstruction
7/29/2019 Medic UPdate 2003 Capno
21/33
Waveform C-D
Alveolar plateau
Exhalation of mostly alveolargas
Should be nearly flat
Upward slanting due touneven emptying of alveoli(asthma, obstruc-tion,
COPD)
7/29/2019 Medic UPdate 2003 Capno
22/33
Point D
End-tidal CO2 value that
is recorded by acapnometer this is
nearly = to PaCO2
7/29/2019 Medic UPdate 2003 Capno
23/33
Waveform D-E
Sharp downstroke
Inhalation of CO2
free gas
Nearly vertical drop tobaseline
Slope prolonged with leaky ETcuff or other leaks inexpiratory circuit
7/29/2019 Medic UPdate 2003 Capno
24/33
Factors affecting PetCO2
Production (metabolism)
Delivery (blood flow)
Elimination (ventilation)
7/29/2019 Medic UPdate 2003 Capno
25/33
Factors affecting PetCO2
Production (metabolism)
Hypothermia
Fever
Hyperthyroidism
7/29/2019 Medic UPdate 2003 Capno
26/33
Factors affecting PetCO2
Delivery (blood flow)
Cardiac arrest/CPR Shock
PE
O%
4%
PetCO2
Garnett AR, Ornato JP, Gonzalez ER et al. JAMA 1987; 257:512-4
7/29/2019 Medic UPdate 2003 Capno
27/33
Factors affecting PetCO2
Elimination (ventilation) Determination of ET placement
Garnett AR, Gervin CA, Gervin AS. Ann Emerg Med 1989; 18:387-90
In trachea
In esophagus
7/29/2019 Medic UPdate 2003 Capno
28/33
Factors affecting PetCO2
Elimination (ventilation)
Hyperventilation (low PetCO2)
Hypoventilation (high PetCO2)
7/29/2019 Medic UPdate 2003 Capno
29/33
Respiratory patterns that inhibit completealveolar emptying
Asthma
COPD
Hyperventilation without allowing for complete
exhalation Ventilation with inadequate tidal volumes
High frequency jet ventilation
7/29/2019 Medic UPdate 2003 Capno
30/33
ETCO2 Evolving Technology
The Oridion Corp. has
produced sidestreamsampling devices that now
work on nonintubated
patients. This type of
ETCO2
monitoring allows
the device to be used on
breathing patients and
holds great promise for use
in the management of
patients withbronchospastic disease
like Asthma.
7/29/2019 Medic UPdate 2003 Capno
31/33
The SHARK FIN
The TOP HAT
7/29/2019 Medic UPdate 2003 Capno
32/33
7/29/2019 Medic UPdate 2003 Capno
33/33
Summary
Reviewed carbon dioxide chemistry, physiology in the
human bodyReviewed methods for measuring carbon dioxide inexhaled air
Described the normal capnogram
Discussed physiological and pathological factors affectingthe capnogram
Acknowledgements:
This presentation was developed through the use ofseveral resources available on the internet. I wish tothank those individuals for their generosity in providingthis information.
H. Conner
Top Related