Transcript End Tidal CO2 Monitoring

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
“Snapshot in time”
Assists with patient assessment BUT:
–Do NOT replace eyes-on/hands-on care
–Are just one piece of clinical judgment
–ALL have pitfalls/malfunctions/limitations
–Is more complex than ever
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Non-invasive method of determining
Carbon Dioxide levels in intubated
and non-intubated patients
Uses infra-red technology, to monitor
exhaled breath to determine CO2
levels numerically and bywaveform
(capnogram).
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EtCO2 is directly related to the
ventilation status of the patient (as
opposed to SAo2, which relates
oxygenation of the patient)
Capnography can be used to verify
endotracheal tube/Combi-Tube &
King Airway placement and monitor
its position, assess ventilation and
treatments, and to evaluate
resuscitative efforts during CPR
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Review of Pulmonary
Anatomy & Physiology
Nasal Passages
Roof of the M outh

Epiglottis
Trachea (w indpipe)
Esophagus (food tube)

Pulm onary Vein
Bronchiole
Bronchi

Alveoli
The primary function of the
respiratory system is to
exchange carbon dioxide for
oxygen.
During inspiration, air enters
the
upper airway via the
nose
where it is
warmed, filtered,
and humidified
The inspired air flows through
the trachea and
bronchial tree to enter the
pulmonary alveoli
where
the oxygen diffuses
across the alveolar capillary
membrane into the blood.
EtCO2 Monitoring
Cellular Ventilation
Alveolar Ventilation
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Measurement methods
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Single, one-point-in-time (Easy-Cap).
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Electronic devices
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Continuous information
Utilize infrared (IR) spectroscopy to measure the
CO2
molecules’ absorption of IR light as the light
passes through a gas sample.
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Electronic Devices:

Mainstream
 Located directly on the patient’s endotracheal tube
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Sidestream
 Remote from the patient.
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Mainstream sampling
Occurs at the airway of an intubated patient
 Was not originally intended for use on non-intubated
patients.
 Heavy and bulky adapter and sensor assemblies may
make this method uncomfortable for non-intubated
patients.
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Sidestream sampling
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Exhaled CO2 isaspirated (at 50ml/min) via ETT,
cannula, or mask through a 5–10 foot long
sampling tube connected to the instrument
for analysis
Both mainstream and sidestream
technologies calculate the CO2 value and
waveform.
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A new technology, Microstream, utilizes a
modified sidestream sampling method, and
employs a microbeam IR sensor that
specifically isolates the CO2 waveform.
Microstream can be used on both intubated
and non-intubated patients.
EtCO2 Monitoring
• Continuous EtCO2 monitoring = changes are immediately seen
(CO2 diffuses across the capillary-alveolar membrane <½ second)
• Sa02 monitoring is also continuous, but relies on trending.
- and • The oxygen content in blood can maintain for several minutes
after apnea (especially w/ pre-oxygenation)
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Definitions
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Tachypnea
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Hyperventilation
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Abnormally rapid respiration
Increased minute volume that results in lowered CO2
levels (hypocapnia)
Hypoventilation

Reduced rate & depth of breathing that causes an
increase in carbon dioxide (hypercapnia)
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EtCO2 Numerical Values
(Ventilatory Assessment)
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Normal = 35-45mmHg
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< 35mmHg = Hyperventilation
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Respiratory alkalosis
> 45mmHg = Hypoventilation
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Respiratory acidosis
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EtCO2 Numerical Values
(Metabolic Assessment)
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Normal = 35-45mmHg
< 35mmHg = Metabolic Acidosis
> 45mmHg = Metabolic Alkalosis
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Dependant on 3 variables
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CO2 production
Delivery of blood to lungs
Alveolar ventilation
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Increased EtCO2
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Decreased CO2 clearance
 Decreased central drive
 Muscle weakness
 Diffusion problems
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Increased CO2 Production

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
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Fever
Burns
Hyperthyroidism
Seizure
Bicarbonate Rx
ROSC
Release of tourniquet/Reperfusion
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Decreased EtCO2
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Increased CO2 Clearance
 Hyperventilation
 Acidosis ( ↓ HCO3 levels 2° to ↑ Hydrogen)
 Decreased CO2 production
 Hypothermia
 Sedation
 Paralysis
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Decreased Delivery to Lungs
 Decreased cardiac output
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V/Q Mismatch
 Ventilating non-perfused lungs
(pulmonary edema)
Ventilation/Perfusion Ratio (V/Q)
• Effective pulmonary gas exchange depends on
balanced V/Q ratio
• Alveolar Dead Space (atelectasis/pneumonia)
(V > Q =  CO2 content)
• Shunting (blood bypasses alveoli w/o picking up o2)
(V < Q =  CO2 content)
• 2 types of shunting:
•Anatomical – blood moves from right to left
heart w/o passing through lungs (congenital)
•Physiological – blood shunts past alveoli w/o
picking up o2
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Ventilation/Perfusion Ratio (V/Q)
V/Q Mismatch
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Inadequate ventilation, perfusion or both
3 types
 Physiological Shunt (V<Q)
 Blood passes alveoli
 Severe hypoxia w/ > 20% bypassed blood
 Pneumonia, atalectasis, tumor, mucous plug
 Alveolar Dead Space (V>Q)
 Inadequate perfusion exists
 Pulmonary Embolus, Cardiogenic shock, mechanical ventilation w/ 
tidal volumes
 Silent Unit ( V &  Q)
 Both ventilation & perfusion are decreased
 Pneumothorax & ARDS
More Air Less Blood
V>Q
Equal Air and Blood
V=Q
More Blood Less Air
V<Q
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Components of the normal
capnogram
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A - B =respiratory baseline
CO2-free gas in the deadspace of the
airways
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B-C (expiratory upstroke)
Alveolar air mixes with dead space air
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C-D (expiratory plateau)
Exhalation of mostly alveolar gas
(should be straight)
Point D = measurement point
(35-45mmHg)
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D-E =inspiration
Inhalation of CO2-free gas
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Changes in the capnogram or EtCO2
levels:
Changes in ventilation
 Changes in metabolism
 Changes in circulation
 Equipment failure
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EtCO2 in specific settings
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Non-Intubated patients
Asthma & COPD
 CHF/Pulmonary Edema
 Pulmonary Embolus
 Head Injury
 Metabolic Illnesses
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Asthma and COPD
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Provides information on the ventilatory status of the
patient
Combined with other assessments, can guide treatment
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Asthma and COPD (Cont’d)
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Shark fin waveform
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Asthma and COPD (Cont’d)
Ventilatory assistance and/or intubation
may be considered with severe dyspnea
and respiratory acidosis (EtCO2 >50mmHg)
18% of ventilated asthma patients suffer a
tension pneumothorax
New ACLS standards recommend ETI for
asthma patients who deteriorate despite
aggressive treatment.
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Emphysema
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EtCO2 & CHF/Pulmonary Edema
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Wave forms will be normal (there is no
bronchospasm)
Values may be increased (hypoventilation)
or decreased (hyperventilation)
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Pulmonary Embolus
“Normal” waveform but low numerical value
(why?)
Look for other signs and symptoms
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Pulmonary Embolus
Note near “normal” waveform, but angled CD section (indicates alveolar dead space)
Head Injury
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EtC02 is very useful in monitoring intubated headinjured patients.
Hyperventilation = Hypocapnia =  Cerebral Ischemia
Target EtC02 value of 35-38 mmHg
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Hypothermia
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Hyperventilation
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Hypoventilation
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EtCO2 in the Intubated Patient
Identifies esophageal intubations & accidental
extubations (head/neck motion can cause
ETT movement of 5 cm)
Waveforms/numerical values are absent
or greatly diminished
Do not rely on capnography alone to assure
intubation!
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Tracheal –vs- Esophageal
Intubation
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Esophageal Intubation
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Esophageal Intubation w/carbonated
beverages
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EtCO2 and cardiac output
Values <20mmHg = unsuccessful resuscitation
 Low (20-30mmHg) = good CPR or recovering heart
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• EtCO2 and cardiac output
• Sudden increase in value = ROSC
Cardiac arrest survivors had an average ETCO2 of 18mmHg,
20 minutes into an arrest while non survivors averaged 6.
In another study, survivors averaged 19, and non-survivors 5.
EtCO2 and cardiac output
Successful defibrillation = pulses &  EtcO2
EtCO2 and cardiac output
Because ETCO2 measures cardiac output, rescuer
fatigue during CPR will show up as decreasing ETCO2.
Change in rescuers – Note  values w/ non-fatigued compressor
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Right Mainstem Bronchus Intubation
Numerical Values and Waveforms may/may not
change, but SAo2 will drop
Kinked ET Tube
No alveolar plateau – very limited gas exchange
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Spontaneous Respirations in the
paralyzed patient
(Curare
Cleft)
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Metabolic States
Diabetes/Dehydration
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EtCO2 tracks serum HCO3 & degree of
acidosis ( EtcO2 = metabolic acidosis)
Helps to distinguish DKA from NKHHC and
dehydration
Metabolic States
Synypnea is seen across the country and
is defined as when emergency
department waiting room patients have
the same respiratory rate.
Troubleshooting
Sudden increase in EtCO2
Malignant Hyperthermia
Ventilation of previously unventilated lung
Increase of blood pressure
Release of tourniquet
Bicarb causes a temporary <2 minute rise in ETCO2
Troubleshooting
EtCO2 values 0
Extubation/Movement into hypopharynx
Ventilator disconnection or failure
EtCO2 defect
ETT kink
Troubleshooting
Sudden decrease EtCO2 (not to 0)
Leak or obstruction in system
Partial disconnect
Partial airway obstruction (secretions)
High-dose epi can cause a decrease (unk why)
Troubleshooting
Change in Baseline
Calibration error
Mechanical failure
Water in system
Troubleshooting
Continual, exponential decrease in EtCO2
Pulmonary Embolism
Cardiac Arrest
Sudden hypotension/hypovolemia
Severe hyperventilation
Troubleshooting
Gradual increase in EtCO2
Rising body temperature
Hypoventilation
Partial airway obstruction (foreign body)
Reactive airway disease
Many special thanks to:

JEMS Magazine (http://www.jems.com/)
 Peter Canning, EMT-P (http://emscapnography.blogspot.com/)
 Dr. Baruch Krauss ([email protected])
 Bhavani-Shankar Kodali MD (http://www.capnography.com/)
 Bob Page, AAS, NREMT-P, CCEMT-P
 Steve Berry (https://www.iamnotanambulancedriver.com/mm5/merchant.mvc?)
 Dr. Reuben Strayer ([email protected])
 UTSW/BIOTEL EMS SYSTEM (http://www.utsouthwestern.edu/)
 Oridion Medical Systems (http://www.oridion.com/global/english/home.html)
 Blogborgymi (http://blogborygmi.blogspot.com/)
 University of Adelaide, South Australia
(http://www.health.adelaide.edu.au/paed-anaes/talks/CO2/capnography.html)