Intubating the Critically Ill Patient

Intro / Main Questions

The following is a review of the most recent literature regarding intubation of critically ill patients. Specifically, the following questions will be addressed:

What is the safest way to intubate a hypotensive patient?

Which patients are at risk for peri-intubation hypotension and cardiac arrest?

What other special circumstances should be considered in intubating critically ill patients?

Recap Basics

  • Prep: Assess for difficult airway, have backup plan
  • Pre-oxygenation: NRB vs NIPPV or manual ventilation (if SpO2 <91%) and passive O2 w/ 5L NC.
  • Pre-treatment (optional): Atropine for <1yr, lidocaine for reactive airway and increased ICP, fentanyl for increased ICP and CV emergency
  • Induction: Etomidate, ketamine, propofol, thiopental, or midazolam/fentanyl
  • Paralysis: Succinylcholine 45 sec, rocuronuim 60 sec
  • Placement: Most skilled personnel, minimize # of attempts
  • Post procedure: Lung-protective vent settings, confirm placement, ABG, HOB to 30-45 to improve lung mechanics, in-line suction, NG/OG, humidify air, sedation/analgesia

What’s New

Cardiac arrest complicating endotracheal intubation (ETI)1

Two independent variables associated with post-ETI arrest:

  1. Pre-induction shock index (SI = HR/SBP) > 0.9: OR increases 1.16 for every 0.1 increase in SI
  2. Weight: OR increases 1.37 for every 10kg increase in weight

Predicting post-intubation hypotension (PIH)2

  • SI > 0.8 associated with increased risk
  • PIH associated with increased in-hospital mortality

How to intubate the hypotensive patient3

  • Pre-treat scopolamine if able: 0.4mg IVP induces amnesia, decreases secretions
  • Have crystalloid (sepsis) or blood/FFP (trauma) infusing
  • Norepi BEFORE intubation to get MAP >80, can use PIV until CVC can be placed post-intubation
  • Have bolus dose pressor ready: epi 5mcg 1:100,000 (not phenylephrine)
  • Midazolam/fentanyl takes too long to act (3-5 min); don’t use it for induction
  • Decrease dose of induction agent: e.g. 10% of normal propofol dose or middle ground dosing ketamine 0.25-0.5 mg/kg, but actually need more of etomidate
  • Paralytic is cardiac output-dependent, therefore pt in shock requires higher dose: succinylcholine 2mg/kg or rocuronium 1.6mg/kg
  • Vent: low and slow (+pressure will drop BP); low PS/PEEP, start tidal volume (Vt) 6ml/kg

Delayed Sequence Intubation (DSI)3

  • For delirious patient with hypoxia, this is alternative to bagging the patient
  • Requires having vent immediately available
  • Ketamine (1-2mg/kg then aliquots of 0.5mg/kg) to disassociate patient
  • Ketamine keeps airway reflexes and does not suppress respirations
  • Vomiting happens during EMERGENCE, not sedation
  • Wait 3 minutes while patient breathes through NRB or NIPPV (if not saturating well on NRB then has shunt physiology and needs PEEP)
  • Paralytic then wait 45 seconds
  • Intubate

Avoiding complications during ETI/PPV4

Hypotension
  • Local anesthesia only if possible or
  • Small titrated dose of sedative (0.3mg/kg propofol based on ideal weight)
  • Begin volume resuscitation before ETI
  • Have pressor ready
  • Start w/ PEEP 5 (0 for COPD) and Vt = 6 ml/kg then titrate up for plateau pressure (Pplt) = 20-30
Acid-base complications
  • Avoid hypotension as above
  • Choose initial setting similar to the pt’s respiratory status prior to ETI (but RR <30 to avoid auto-PEEP)
  • ABG in 15 minutes
  • If complicated by seizure (lactic acidosis) hyperventilate 25-30/min and give bicarb if unstable or insufficient time to document acidosis as cause
Asthmatic
  • Permissive hypercapnea
  • Reduce RR
  • Reduce Vt
  • Reduce iTime / increased expiratory time (promote full exhalation)
  • Keep Pplt <30cm H2O
  • May need sedation / muscle relaxation to decrease RR
Dyspnea / hypoxemia despite high FiO2 (ARDS)
  • Begin w/ Vt 6ml/kg
  • Titrate Vt to maintain Pplt <30
  • Incr PEEP by 3-5 q2-3min and decr Vt to keep Pplt 25-30 until SpO2 >90% on FiO2 = 60%
  • Ensure patient-ventilator synchrony
Traumatic Brain Injury
  • Pre-treatment optional (not evidence-based): Lidocaine 1.5 mg/kg 3 min prior then fentanyl 3 mcg/kg if not hypotensive
  • Induction: Etomidate 0.3 mg/kg or ketamine 1-2 mg/kg if hypo or normotensive
  • Paralysis: Succinylcholine preferred (rocuronium is ok too)
  • Hyperventilate temporarily if patient continues to deteriorate after osmotic agents

Bottom Line / Pearls & Pitfalls

  • BVM with PEEP valve and NC at 10L is “poor man” CPAP
  • Don’t bag before or in between attempts if SpO2 >90%
  • All induction agents can induce hypotension, but ketamine generally causes a sympathetic “surge” with middle ground dosing
  • Be wary of ketamine in patients with CAD, cardiac emergency, hypertension and tachycardia
  • Absolute contraindications to ketamine: age <3months and history of schizophrenia
  • Shock patient requires lower dose of induction agent (except etomidate) and higher dose of paralytic
  • Succinylcholine contraindications: FH of malignant hyperthermia, hyperkalemia, burns > 24h, crush injuries > 3 days, sepsis after 7 days, congenital / acquired myopathies, denervation illness, chronic neuropathy
  • Apply pressure to cricoid, not the thyroid cartilage for Sellick
  • Start low and slow with the vent, +pressure will drop BP even further
  • Have post-intubation checklist

Sources / Further Reading

  1. Heffner A, et al. Incidence and factors associated with cardiac arrest complicating emergency airway management. Resuscitation 84 (2013) 1500-1504.
  2. Heffner A, et al. Predictors of the complication of postintubation hypotension during emergency airway management. Journal of Critical Care (2012) 27, 587–593.
  3. Weingart S. Preoxygenation, Reoxygenation, and Delayed Sequence Intubation in the Emergency Department. The Journal of Emergency Medicine April 2010.
  4. Manthous, CA. Avoiding Circulatory Complications During Endotracheal Intubation and Initiation of Positive Pressure Ventilation. The Journal of Emergency Medicine, Vol. 38, No. 5, pp. 622–631, 2010.
  5. Griesdale D, et al. Airway Management in Critically Ill Patients. Lung (2011) 189:181–192.
  6. Heffner A, et al. The frequency and significance of postintubation hypotension during emergency airway management.  Journal of Critical Care (2012) 27, 417.e9-417.e13.
  7. Reynolds S. Airway Management of the Critically Ill Patient Rapid-Sequence Intubation. Chest Vol 127, Issue 4 (April 2005).
  8. Green SM, et al. Clinical Practice Guideline for Emergency Department Ketamine Dissociative Sedation: 2011 Update. Ann Emerg Med. 2011;57:449-461.
  9. Sehdev RS, et al. Ketamine for rapid sequence intubation in patients with head injury in the emergency department. Emergency Medicine Australasia (2006) 18, 37–44.
  10. Price B, et al. Hemodynamic consequences of ketamine vs etomidate for endotracheal intubation in the air medical setting. American Journal of Emergency Medicine 31 (2013) 1124–1132.
  11. Robinson N. In patients with head injury undergoing rapid sequence intubation, does pretreatment with intravenous lignocaine/lidocaine lead to an improved neurological outcome? A review of the literature. Emerg Med J 2001;18:453–457.
  12. Orebaugh SL. Succinylcholine: Adverse Effects and Alternatives in Emergency Medicine. Am J Emerg Med 1999;17:715-721.
  13. MacLennan N. Anesthesia for Major Thermal Injury. Anesthesiology 1998; 89:749-70.

Discussion Questions / Future Exploration

  1. Therapeutic intervention aimed at optimizing pre-intubation hemodynamics
  2. Optimal drugs for intubating hemodynamically unstable patients
  3. Optimal drug combinations for intubation of other subsets of critically ill patients
Edited by Alex Koyfman, MD

15 thoughts on “Intubating the Critically Ill Patient”

  1. This is a great review of intubating the crashing patient. I like that you include both the hypotensive as well as the sick hypertensive/tachycardic patient.

    The only thing I don’t agree with here is the use of cricoid pressure. Pretty good evidence says it doesn’t do much except make ventilation harder and worsen the glottic view.

  2. Thanks, excellent review. Just a few thoughts and pointers from my side. Often refer to this as the physiological difficult airway with an “airway lethal triad – hypoxia, hypotension and acidosis”. I am very wary of ketamine as ketamine relies on a secondary sympathomimetic effect for its cardiovascular stability, haemodynamic compromise may occur in patients who are catecholamine depleted. I usually advocated half dose induction agent if used in these patients.Also post intubation ventilation is critical. How should you ventilate someone with a pre induction ph of 7.1 and a RR of 50 and severe hypoxia? Key is pre intubation management with CPAP,fluids, pressors, bicarb and lots of prayer! With many of these patients I have experienced a “clean kill”, a brady asystolic arrest immediately post intubation if an RSI is attempted. I have had some success with a laryngeal block, xylocaine spray of the tongue and hypopharynx, lignocaine nebs and with 200mcg Fentanyl.

  3. update: according to more recent literature schizophrenia is arguably no longer a contraindication to ketamine, leaving only children <3 months…

    Le Cong M. Ketamine sedation for patients with acute agitation and psychiatric illness requiring aeromedical retrieval. Emerg Med J. 2012 Apr;29(4):335-7

  4. Very Informative Post, I have a few questions:

    1 – Dosing of RSI meds is based on TBW or IBW?
    2- In India, we use a lot of midaz for RSI induction, but it is not even mentioned as a choice of induction agent in many EM Textbooks? What is the reason for that?

    Thanks!

    1. 1. Dose sux by TBW. (Wiser SH and Zane RD: Neuromuscular Blocking Agents. In: Walls RM and Murphy MF, Manual of Emergency Airway Management, 3rd Edition. Philadelphia, Lippincott, Williams and Wilkins, 2008 ; p 408.) Dose induction agents by IBW for non-obese adults. For obese adults the situation is more complicated but Ron Wall’s Manual of Emergency Airway Management recommends using lean body weight: IBW + (TBW-IBW)x0.3.
      2. Midazolam is not ideal for RSI because the time of onset is too slow. Combining with fentanyl may shorten the onset a bit and give analgesia but is still inferior to faster induction agents.

      1. Midazolam (Versed) has been related to a decreased cardiac output in the severely septic patient or patient with significant cardiac disease, including acute MI.
        Dr Glenn Ekblad, Critical Care and Anesthesiologist.
        West Michigan AirCare,
        Kalamazoo Michigan.
        July 26,2016

  5. Very Informative Post, I have a few questions:

    1 – Dosing of RSI meds is based on TBW or IBW?
    2- In India, we use a lot of midaz for RSI induction, but it is not even mentioned as a choice of induction agent in many EM Textbooks? What is the reason for that?

    Thanks!

    1. 1. Dose sux by TBW. (Wiser SH and Zane RD: Neuromuscular Blocking Agents. In: Walls RM and Murphy MF, Manual of Emergency Airway Management, 3rd Edition. Philadelphia, Lippincott, Williams and Wilkins, 2008 ; p 408.) Dose induction agents by IBW for non-obese adults. For obese adults the situation is more complicated but Ron Wall’s Manual of Emergency Airway Management recommends using lean body weight: IBW (TBW-IBW)x0.3.
      2. Midazolam is not ideal for RSI because the time of onset is too slow. Combining with fentanyl may shorten the onset a bit and give analgesia but is still inferior to faster induction agents.

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