End Tidal CO2 EtCO2 Monitoring

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End Tidal CO2(EtCO2) Monitoring
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EtCO2 Monitoring

• Capnography is a snapshot in time
• Changes will bring other changes as the body
  tries to maintain homeostasis

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EtCO2 Monitoring

• End-tidal CO2 (EtCO2) monitoring (Capnography)
  is a non-invasive method of determining
  Carbon Dioxide levels in intubated and
  non-intubated patients
• Using infra-red technology, we can monitor
  exhaled breath to determine CO2 levels
  numerically and by waveform.

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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 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
The heart pumps the freshly oxygenated blood
throughout the body to the cells where oxygen is
consumed (metabolism), and carbon dioxide,
produced as a byproduct, diffuses out of the
cells into the vascular system.
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EtCO2 Monitoring

• Carbon dioxide-rich blood is then pumped through
  the pulmonary capillary bed where the carbon
  dioxide diffuses across the alveolar capillary
  membrane and is exhaled via the nose or mouth.

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EtCO2 Monitoring

• Carbon Dioxide is a colorless, odorless gas
• Concentration in air 0.03
• CO2 produced by cell metabolism
• Transported from cell in 3 forms
• 65 as bicarb following conversion
• 25 bound to blood proteins (hemoglobin)
• 10 in plasma solution
• PaCO2 reflects plasma solution

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EtCO2 Monitoring

• Measurement methods
• Single, one-point-in-time EtCO2 measurements may
  be done using the visual colorimetric method
  where a litmus paper device attached to a
  patients endotracheal tube undergoes a
  chemical reaction and color change in the
  presence of CO2.
• Electronic devices can furnish continuous informa
  tion they 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

• CO2 sensors may be mainstream, located directly
  on the patients endotracheal tube, or
  sidestream, remote from the patient.
• Mainstream sampling occurs at the airway of an
  intubated patient and is not 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

• In sidestream capnographs the exhaled CO2
  is aspirated via ETT, cannula, or mask through a
  510 foot long sampling tube connected to the
  instrument for analysis this method is intended
  for the non- intubated patient.
• 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.
• Microstream technology is used in Zoll Monitors

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EtCO2 Monitoring

• EtCO2 monitoring is continuous changes in
  ventilation status are immediately seen (CO2
  diffuses across the capillary- alveolar membrane
  lt 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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EtCO2 Monitoring

• EtCO2 Numerical Values
• Normal 35-45mmHg
• lt 35mmHg Hyperventilation
• Respiratory alkalosis
• gt 45mmHg Hypoventilation
• Respiratory acidosis
• 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
• 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 describes the respiratory baseline
• It measures the CO2-free gas in the deadspace of
  the airways

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EtCO2 Monitoring

• B-C is also known as the expiratory upstroke,
  where alveolar air mixes with dead space air

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EtCO2 Monitoring

• C-D is the expiratory plateau, exhalation of
  mostly alveolar gas (should be straight)
• Point D is the EtCO2 level at the end of a normal
  exhaled breath (35-45mmHg)

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EtCO2 Monitoring

• D-E is inspiration, inhalation of CO2-free gas,
  and rapid return of waveform to baseline

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EtCO2 Monitoring
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EtCO2 Monitoring

• Changes in the capnogram or EtCO2 levels reflect
  changes in metabolism, circulation, equipment
  function, or as we are most interested
  in, ventilation
• EtCO2 can reliably be used to determine without
  ABGs, PaCO2 in patients with normal matching
  of ventilation and perfusion (EtCO2 is normally
  1-5mmHg less than PaCO2).

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EtCO2 Monitoring

• EtCO2 in specific settings
• Non-Intubated patients
• Asthma COPD
• CHF/Pulmonary Edema
• Pulmonary Embolus
• Head Injury
• What? Those are expensive!

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EtCO2 Monitoring

• Asthma and COPD
• EtCO2 can provide information on
  the ventilatory status of the patient,
  which, combined with other assessments,
  can guide treatment

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EtCO2 Monitoring

• Asthma and COPD (Contd)
• Waveforms can indicate need for
  bronchodilators (shark fin waveform)

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EtCO2 Monitoring

• Ventilatory assistance and/or intubation may be
  considered with severe dyspnea and respiratory
  acidosis (PaCO2 gt55mmHg or EtCO2 gt50mmHg)
• Severe asthma attacks may also include Pulsus
  Paradoxus greater than 20mmHg
• Also consider ALOC in decision-making
• 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 decr
  eased (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 Hypocapnea ? Cerebral
  Ischemia
• Target end tidal C02 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
• Most often used to identify esophageal intubatio
  ns accidental extubations (head/neck motion
  can cause ETT movement of 5 cm)
• Waveforms and 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 (why?)

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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

• Rapid Assessment Triage Tool
• Critically ill patients
• Victims of chemical terrorism
• Obtain ABCs in 15 seconds
• A waveform patent airway
• B waveform graphic representation of
  breathing
• C normal EtCO2 adequate perfusion

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EtCO2 Monitoring

• No motion artifact (uncooperative pt?)
• Reliable in low perfusion states
• Accurate reliable in seizing patients
• Apneic, seizing patient
• No waveform No chest wall movement
• Ineffectively ventilating seizing patient
• Low waveform low EtCO2
• Effectively ventilating seizing patient
• Normal waveform normal EtCO2

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EtCO2 Monitoring

• Capnography in Terror
• Common conditions diagnosed by capnography
• Apnea
• No waveform, no chest wall movement, no breath
  sounds
• Upper respiratory obstruction
• No waveform, chest wall moving, no breath sounds,
  responsive to airway realignment maneuvers
  (waveform returns)
• Laryngospasm
• No waveform, chest wall moving, no breath sounds,
  unresponsive to airway realignment, responds to
  PPV
• Bronchospasm
• shark fin waveform
• Respiratory failure
• Values gt 70 mmHg in pt w/o COPD

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EtCO2 Monitoring
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EtCO2 Monitoring
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EtCO2 Monitoring
Triage using EtCO2
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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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Oh, yeah 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.
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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)