End Tidal CO2 (EtCO2) Monitoring

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End Tidal CO2(EtCO2) Monitoring
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EtCO2 Monitoring

• 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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EtCO2 Monitoring

• 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
  by waveform (capnogram).

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EtCO2 Monitoring

• 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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EtCO2 Monitoring

• Review of Pulmonary Anatomy Physiology
• 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.

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EtCO2 Monitoring
Cellular Ventilation
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EtCO2 Monitoring

• Alveolar Ventilation

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EtCO2 Monitoring

• Measurement methods
• Single, one-point-in-time (Easy-Cap).
• Electronic devices
• 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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EtCO2 Monitoring

• Electronic Devices
• Mainstream
• Located directly on the patients endotracheal
  tube
• Sidestream
• Remote from the patient.
• 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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EtCO2 Monitoring

• Sidestream sampling
• Exhaled CO2 is aspirated (at 50ml/min) via ETT,
  cannula, or mask through a 510 foot long
  sampling tube connected to the instrument for
  analysis
• Both mainstream and sidestream technologies calcul
  ate the CO2 value and waveform.

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EtCO2 Monitoring

• 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.

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EtCO2 Monitoring

• Continuous EtCO2 monitoring changes are
  immediately seen (CO2 diffuses across the
  capillary-alveolar membrane lt½ 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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EtCO2 Monitoring

• Definitions
• Tachypnea
• Abnormally rapid respiration
• Hyperventilation
• 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 Monitoring

• EtCO2 Numerical Values (Ventilatory Assessment)
• Normal 35-45mmHg
• lt 35mmHg Hyperventilation
• Respiratory alkalosis
• gt 45mmHg Hypoventilation
• Respiratory acidosis

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EtCO2 Monitoring

• EtCO2 Numerical Values (Metabolic Assessment)
• Normal 35-45mmHg
• lt 35mmHg Metabolic Acidosis
• gt 45mmHg Metabolic Alkalosis
• Dependant on 3 variables
• CO2 production
• Delivery of blood to lungs
• Alveolar ventilation

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EtCO2 Monitoring

• Increased EtCO2
• Decreased CO2 clearance
• Decreased central drive
• Muscle weakness
• Diffusion problems
• Increased CO2 Production
• Fever
• Burns
• Hyperthyroidism
• Seizure
• Bicarbonate Rx
• ROSC
• Release of tourniquet/Reperfusion

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EtCO2 Monitoring

• Decreased EtCO2
• Increased CO2 Clearance
• Hyperventilation
• Acidosis ( ? HCO3 levels 2 to ? Hydrogen)
• Decreased CO2 production
• Hypothermia
• Sedation
• Paralysis
• Decreased Delivery to Lungs
• Decreased cardiac output
• V/Q Mismatch
• Ventilating non-perfused lungs (pulmonary
  edema)

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EtCO2 Monitoring

• Ventilation/Perfusion Ratio (V/Q)
• Effective pulmonary gas exchange depends
  on balanced V/Q ratio
• Alveolar Dead Space (atelectasis/pneumonia)
  (V gt Q ? CO2 content)
• Shunting (blood bypasses alveoli w/o picking up
  o2) (V lt 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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EtCO2 Monitoring
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EtCO2 Monitoring

• Ventilation/Perfusion Ratio (V/Q)
• V/Q Mismatch
• Inadequate ventilation, perfusion or both
• 3 types
• Physiological Shunt (VltQ)
• Blood passes alveoli
• Severe hypoxia w/ gt 20 bypassed blood
• Pneumonia, atalectasis, tumor, mucous plug
• Alveolar Dead Space (VgtQ)
• Inadequate perfusion exists
• Pulmonary Embolus, Cardiogenic shock, mechanical
  ventilation w/ ? tidal volumes
• Silent Unit (? V ? Q)
• Both ventilation perfusion are decreased
• Pneumothorax ARDS

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EtCO2 Monitoring
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EtCO2 Monitoring
More Air Less Blood V gt Q
Equal Air and Blood V Q
More Blood Less Air V lt Q
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EtCO2 Monitoring

• Components of the normal capnogram

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EtCO2 Monitoring

• A - B respiratory baseline
• CO2-free gas in the deadspace of the airways

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EtCO2 Monitoring

• B-C (expiratory upstroke)
• Alveolar air mixes with dead space air

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EtCO2 Monitoring

• C-D (expiratory plateau)
• Exhalation of mostly alveolar gas (should be
  straight)
• Point D measurement point (35-45mmHg)

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EtCO2 Monitoring

• D-E inspiration
• Inhalation of CO2-free gas

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EtCO2 Monitoring
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EtCO2 Monitoring

• Changes in the capnogram or EtCO2 levels
• Changes in ventilation
• Changes in metabolism
• Changes in circulation
• Equipment failure

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EtCO2 Monitoring

• EtCO2 in specific settings
• Non-Intubated patients
• Asthma COPD
• CHF/Pulmonary Edema
• Pulmonary Embolus
• Head Injury
• Metabolic Illnesses

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EtCO2 Monitoring

• Asthma and COPD
• Provides information on the ventilatory status of
  the patient
• Combined with other assessments, can guide
  treatment

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EtCO2 Monitoring

• Asthma and COPD (Contd)
• Shark fin waveform

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EtCO2 Monitoring

• Asthma and COPD (Contd)
• Ventilatory assistance and/or intubation may be
  considered with severe dyspnea and respiratory
  acidosis (EtCO2 gt50mmHg)
• 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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EtCO2 Monitoring

• Emphysema

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EtCO2 Monitoring

• EtCO2 CHF/Pulmonary Edema
• Wave forms will be normal (there is
  no bronchospasm)
• Values may be increased (hypoventilation) or
  decreased (hyperventilation)

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EtCO2 Monitoring

• Pulmonary Embolus
• Normal waveform but low numerical value (why?)
• Look for other signs and symptoms

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EtCO2 Monitoring

• Pulmonary Embolus
• Note near normal waveform, but angled
  C-D section (indicates alveolar dead space)

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EtCO2 Monitoring
Head Injury

• EtC02 is very useful in monitoring intubated
  head- injured patients.
• Hyperventilation Hypocapnia ? Cerebral
  Ischemia
• Target EtC02 value of 35-38 mmHg

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EtCO2 Monitoring

• Hypothermia

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EtCO2 Monitoring

• Hyperventilation

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EtCO2 Monitoring

• Hypoventilation

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EtCO2 Monitoring

• 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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EtCO2 Monitoring

• Tracheal vs- Esophageal Intubation

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EtCO2 Monitoring

• Esophageal Intubation

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EtCO2 Monitoring

• Esophageal Intubation w/carbonated beverages

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EtCO2 Monitoring

• EtCO2 and cardiac output
• Values lt20mmHg unsuccessful resuscitation
• Low (20-30mmHg) good CPR or recovering heart

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EtCO2 Monitoring

• 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.
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EtCO2 Monitoring
EtCO2 and cardiac output
Successful defibrillation pulses ? EtcO2
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EtCO2 Monitoring
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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EtCO2 Monitoring

• Right Mainstem Bronchus Intubation
• Numerical Values and Waveforms may/may
  not change, but SAo2 will drop

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EtCO2 Monitoring
Kinked ET Tube
No alveolar plateau very limited gas exchange
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EtCO2 Monitoring

• Spontaneous Respirations in the paralyzed patient
  (Curare Cleft)

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EtCO2 Monitoring

• Metabolic States
• Diabetes/Dehydration
• EtCO2 tracks serum HCO3 degree of acidosis (?
  EtcO2 metabolic acidosis)
• Helps to distinguish DKA from NKHHC
  and dehydration

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EtCO2 Monitoring
Metabolic States
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EtCO2 monitoring will show you the correct
respiratory rate, too.Define Synypnea
EtCO2 Monitoring
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EtCO2 Monitoring
Synypnea is seen across the country and is
defined as when emergency department waiting room
patients have the same respiratory rate.
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EtCO2 Monitoring
Troubleshooting
Sudden increase in EtCO2
Malignant Hyperthermia Ventilation of previously
unventilated lung Increase of blood
pressure Release of tourniquet Bicarb causes a
temporary lt2 minute rise in ETCO2
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EtCO2 Monitoring
Troubleshooting
EtCO2 values 0
Extubation/Movement into hypopharynx Ventilator
disconnection or failure EtCO2 defect ETT kink
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EtCO2 Monitoring
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)
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EtCO2 Monitoring
Troubleshooting
Change in Baseline
Calibration error Mechanical failure Water in
system
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EtCO2 Monitoring
Troubleshooting
Continual, exponential decrease in EtCO2
Pulmonary Embolism Cardiac Arrest Sudden
hypotension/hypovolemia Severe hyperventilation
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EtCO2 Monitoring
Troubleshooting
Gradual increase in EtCO2
Rising body temperature Hypoventilation Partial
airway obstruction (foreign body) Reactive airway
disease
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• Many special thanks to
• JEMS Magazine (http//www.jems.com/)
• Peter Canning, EMT-P (http//emscapnography.blogs
  pot.com/)
• Dr. Baruch Krauss (baruch.krauss_at_tch.harvard.edu)
  
• 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 (reuben.strayer_at_mail.mcgill.ca
  )
• UTSW/BIOTEL EMS SYSTEM (http//www.utsouthwestern
  .edu/)
• Oridion Medical Systems (http//www.oridion.com/g
  lobal/english/home.html)
• Blogborgymi (http//blogborygmi.blogspot.com/)
• University of Adelaide, South Australia
• (http//www.health.adelaide.edu.au/paed-anaes/talk
  s/CO2/capnography.html)