Endotracheal Intubation Preoxygenation

Aka: Endotracheal Intubation Preoxygenation, Intubation Preoxygenation, Apneic Oxygenation, Oops Mnemonic, Delayed Sequence Intubation, Dissociative Awake Intubation

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II. Background

  1. Preoxygenation is critical to maximizing time to attempt intubation
    1. "Only contraindication to preoxygenation is that the patient is on fire"
    2. Baro (2012) APLS, HCMC, Minneapolis
  2. Oops Mnemonic (Levitan)
    1. Oxygen On
      1. Apply 15 lpm by Nasal Cannula for Apneic Oxygenation
    2. Pull Mandible forward
    3. Sit patient up (to 20 degrees)
  3. Nasal oxgenation
    1. Dr. Levitan describes the nose as the neglected orifice
    2. Vomit and plastic via the mouth
    3. Oxygen and ventilation via the nose
      1. More efficient Oxygen Delivery
      2. Nasal oxygen is much more comfortable than full masks
  4. Resources
    1. http://www.epmonthly.com/features/current-features/the-neglected-orifice-/

III. Technique: Patient positioning

  1. Alveolar ventilation and oygenation improves with head of bed elevated
    1. Semi-recumbent position with head of bed elevated 20 degrees or
    2. Head of bed elevated in reverse trendelenburg position if spine precautions

IV. Technique: Apneic Oxygenation (Levitan Technique)

  1. Continue oxygen throughout intubation to prolong period of safe apnea
  2. Passive Apneic Oxygenation increases oxygen reservoir in lungs by 6 fold
    1. Oxygen continues to be absorbed passively at a rate of 250 ml/min during apnea
    2. Carbon dioxide slowly accumulates during apnea
      1. Increases at a rate of 10 ml/min (3-5 mmHg increased pCO2/minute)
    3. Apneic Oxygenation has sustained patients at 98-100% Oxygen Saturation for up to 55 minutes
      1. Severe acidosis resulted (due to hypercarbia), but no Hypoxia occurred
      2. http://www.rtjournalonline.com/apneic oxygenation in man-Frumin Anesthes 1959.pdf
      3. Frumin (1959) Anesthesiology 20:789-98 [PubMed]
    4. Allows for significant increase in safe intubation time
    5. Oxygen carrying capacity and delivery is dependent on 3 factors
      1. Requires patent alveoli, patent upper airway and adequate Hemoglobin
  3. Technique
    1. Consider delivery via Nasal Trumpet once patient sedated
    2. Oxygen by Nasal Cannula at 15 L/min (in addition to oxygen by Non-Rebreather Mask)
    3. Children: Use 5 L/min by Nasal Cannula until sedated and then increase
    4. Awake patients: Start with 5 L/min and titrate to 15 L/min by Nasal Cannula
    5. Obesity: Consider high flow rates that continue during intubation (prone to rapid desaturation)
      1. High Flow Nasal Cannula
      2. Standard Nasal Cannula at very high wall rates (e.g. 40 L/min)
  4. Efficacy
    1. Without Apneic Oxygenation, one third of intubations desaturate to <90% (median time 80 seconds)
      1. Bodily (2016) Ann Emerg Med 67(3): 389-95 +PMID:26164643 [PubMed]
    2. Apneic Oxygenation improves Endotracheal Intubation first pass success
      1. Sakles (2016) Acad Emerg Med 23(6): 703-10 +PMID:26836712 [PubMed]

V. Technique: Preoxygenation

  1. Functional Residual Capacity (FRC) and Oxygen Reserves
    1. FRC is the lung's end-expiratory gas reserve and is 25 to 30 mL/kg in adults (2 L in a 70 kg adult)
    2. Goal of preoxygenation is to replace other gases (esp. nitrogen, de-nitrogenation) with oxygen
    3. Oxygen concentration of FRC may be increased with various techniques (as below)
      1. Very high oxygen flow rates (Flush Rate or HFNC) are most effective at denitrogenation
    4. Avoid removing oxygen source in non-apneic patients
      1. A few patient breaths of room air source, will quickly replace oxygen in FRC
  2. Standard pre-oxygenation
    1. Deliver oxygen with standard reservoir Non-Rebreather Mask
      1. Ideally administer additional oxygen by Nasal Cannula at 15 lpm (see above)
    2. Oxygen flow rate on regulator set to maximum (typically 15-60 L/min)
      1. Flush rate is with the oxygen valve open to full providing 40 to 70 lpm
      2. Typical emergency department oxygen tubing diameter can carry 40-50 lpm
      3. Best pre-oxygenation is at flush-rate with bag-valve mask, non-rebreather, Bipap
      4. Non-rebreather at flush rate can provide >90% FIO2
        1. Contrast with typical 60% (due to mask leak with room air entrainment)
      5. Driver (2017) Ann Emerg Med 69(1):1-6 +PMID:27522310 [PubMed]
    3. Preoxygenate for at least 3 minutes
  3. Rapid pre-oxygenation (if alert)
    1. Deliver oxygen with tight fitting mask at FIO2 90% or higher
      1. In ED, Non-Rebreather Mask at flush rate (>40 lpm) AND oxygen by Nasal Cannula 15 lpm
    2. Patient takes 8 breaths of full Tidal Volume (maximal inhalation and exhalation)

VI. Technique: Positive Pressure Ventilation

  1. Indicated if pre-oxygenation methods above do not increase Oxygen Saturation greater than 93-95%
    1. Suggests shunting with under-oxygenated alveoli or hypoventilation (see rapid desaturation causes below)
    2. Avoid insufflating Stomach (aspiration risk) by avoiding inspiratory pressures >15 mmHg
    3. Consider induction dose of Ketamine if patient cannot tolerate CPAP or BIPAP (see delayed sequence as below)
    4. Consider Awake Nasotracheal Intubation
  2. Delivery options if ventilation and oxygenation needed (poor Ventilatory effort, Obesity)
    1. See Non-Invasive Positive Pressure Ventilation
    2. BIPAP
      1. May be preferred over CPAP if respiratory effort is inadequate
    3. Bag Valve Mask with PEEP Valve (5-15 cm H2O)
  3. Delivery options if only oxygenation needed (adequate pre-intubation Ventilatory effort)
    1. See Non-Invasive Positive Pressure Ventilation
    2. CPAP
      1. Typical positive pressure pre-oxygenation method
      2. May be used for positive-pressure pre-oxygenation regardless of mental status
        1. Assumes a setting of impending intubation
    3. High Flow Nasal Cannula
      1. May be continued during intubation (but greater risk of pathogen aerosolization to intubator)
      2. Frat (2015) N Engl J Med 372(23): 2185-96 [PubMed]
      3. Miguel-Montanes (2015) Crit Care Med 43(3): 574-83 [PubMed]
  4. Avoid over aggressive Positive Pressure Ventilation (risk of aspiration)
    1. Practice optimal Bag-Valve-Mask technique
      1. Bag slowly and gently (Squeeze-release-release-release-release, Squeeze...)
      2. Two person technique (two handed mask seal by one person, other person squeezes bag)
    2. Patient with airway reflexes
      1. Place two Nasal Airways OR
      2. Ventilate via Nasal Trumpet (with 15 mm ET adapter) and mouth closed
    3. Patient without airway reflexes (e.g. comatose)
      1. Place orotracheal tube and two Nasal Airways OR
      2. Laryngeal Mask Airway
    4. References
      1. Strayer in Herbert (2018) EM:Rap 18(11):1-3
  5. Prepare for failed intubation attempt
    1. Maintain readiness to immediately reaaply positive pressure (BiPAP, Bag Valve Mask)
    2. Have triple set-up available (two intubation methods, LMA or other rescue airway device, Cricothyrotomy)
  6. Efficacy
    1. Positive Pressure Ventilation is associated with less post-intubation Hypoxia than standard preoxygenation
      1. Nava (2009) Lancet 374(9685): 250-9 [PubMed]
      2. Baillard (2006) Am J Respir Crit Care Med 174(2): 171-7 [PubMed]

VII. Technique: Delayed Sequence Intubation (DSI) or Dissociative Awake Intubation (Weingart and Levitan)

  1. Indications
    1. Unable to preoxygenate a severely hypoxic COPD or Asthma patient
    2. Unable to preoxygenate an uncooperative, angry, aggitated or innebriated patient
    3. Trauma patients undergoing intubation
      1. Associated with decreased peri-intubation apnea and better first pass success
      2. Bandyopadhyay (2023) Anesth Analg 136(5):913-9 +PMID: 37058727 [PubMed]
  2. Sedation
    1. Ketamine 1 mg/kg IV slow push (risk of brief apnea with rapid injection)
    2. Even adult doses of 20-30 mg IV may be sufficient for Delayed Sequence
    3. Consider a second Ketamine dose at 0.5 mg/kg IV push
  3. Apply High Flow Oxygen
    1. Nasal Cannula at 15 L/min AND
    2. Bag-valve-Mask with PEEP Valve at 5-15 cm H2O (or CPAP or BIPAP)
      1. Positive End-Expiratory Pressure is required for technique
      2. Alveoli will otherwise close and not allow oxygenation
  4. Reposition patient
    1. Upright or semi-upright (head of bed at 20 degrees)
  5. Evaluate if oxygenation adequate with above High Flow Oxygen (Oxygen Saturation 95% or greater)
    1. Oxygen Saturation 95% or greater
      1. Preoxygenate for 2-3 minutes
    2. Oxygen Saturation <95%
      1. Suggests shunt pathology (Atelectasis or airway with blood or other fluid)
      2. Use Positive Pressure Ventilation methods (CPAP, BiPAP, BVM with PEEP Valve) as described above
  6. Intubation (if still needed for persistent Hypoxia or respiratory distress)
    1. Follow Rapid Sequence Intubation Algorithym with paralytic (using Ketamine above as the induction agent)
  7. References
    1. Orman and Weingart in Herbert (2018) EM:Rap 18(1): 10
    2. Braude and Weingart in Herbert (2014) EM:Rap 14(6): 12-13
    3. Weingart (2015) Ann Emerg Med 65(4): 349-55 +PMID: 25447559 [PubMed]
    4. Weingart (2012) Ann Emerg Med 59(3): 165-75 [PubMed]

VIII. Precautions: Conditions with fast desaturation on intubation attempts (mnemonic: POPS)

  1. Mechanisms
    1. Low Functional Residual Capacity
    2. Increased Oxygen Consumption
  2. Pediatrics
  3. Obesity
  4. Pregnancy (consider upright intubation)
    1. Fetal Hemoglobin is oxygen avid
  5. Smoke Inhalation
    1. Carbon Monoxide Poisoning
    2. Cyanide Poisoning

IX. References

  1. Braude and Levitan in Herbert (2012) EM:RAP 12(4): 1
  2. Weingart and Swaminathan in Swadron (2023) EM:Rap 23(9)
  3. Levitan (2013) Practical Airway Management Course, Baltimore
  4. Delay (2008) Anesth Analg 107(5): 1707-13 [PubMed]
  5. Weingart (2012) Ann Emerg Med 59(3):165-75 [PubMed]

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