A modified rapid sequence intubation (RSI) approach is usually preferred in shocked patients, including:
- use of low dose, titrated induction agents to avoid haemodynamic compromise
- avoidance of apnoea (e.g. via spontaneous breathing or supported ventilation) to avoid exacerbation of coexistent acidaemia
- appropriate use of IV fluids and/or inotropes/ vasopressors
- The mantra is “Resuscitate before you intubate!”
- Richard Levitan has termed this approach “resuscitation sequence intubation” (Levitan, 2015).
“Shock is an anaesthetic” (attributed to Richard Dutton, former Chief Of Anaesthesia at Shock Trauma, Baltimore) so the basic building block of rapid sequence intubation (RSI) is “roc/sux-tube-apology” in a shocked patient with altered mental state
- Use judicious doses of induction agents to make the procedure is as non-distressing as possible, without compromising safety
- Remember that the primary objective is to keep the patient alive while achieving intubation
- Peri-intubation hypotension is associated with increased mortality
- The most important risk factors for death and complications prior to intubation are (Schwartz et al 1995):
- haemodynamic instability
- a requirement for vasopressor agents
- underlying disease
- inadequate resuscitation
- cardio-depressant effects of induction agents
- decreased venous return due to increased intra-thoracic pressure resulting from positive pressure ventilation, including positive-end expiratory pressure (PEEP)
- haemodynamic effects of worsening acidosis during apnoea
- adequately fluid resuscitate prior to, and during, intubation
- consider using a pressor agent (e.g. adrenaline) prior to intubation to prop up blood pressure before the administration of an induction agent
- choose an induction agent and a dose that is least likely to exacerbate hypotension (e.g. ketamine)
- mitigate against high intra-thoracic pressures by avoiding excessive tidal volumes, PEEP, and dynamic hyperinflation when ventilating
CHOICE AND DOSES OF AGENTS
- the dose of any induction agent used may be more important than the choice of the agent — consider using lower doses than usual, regardless of the agent used
- ketamine is the induction agent of choice in the shock patient (see below)
- traditionally, many intensivists used fentanyl and midazolam in low doses as their mainstays for the induction of shocked patients; however, onset is very slow in patients with shock (e.g. up to or greater than 5 minutes)
- even propofol and thiopentone can be used in the shocked patient, but as little as 10% of the usual dose may be all that is needed and onset is slowed — higher doses may lead to profound haemodynamic compromise (Morris et al, 2009)
- etomidate is not available in Australia, and may be best avoided due to ongoing concerns:
- it causes adrenal suppression which may be linked to increased mortality in septic patients (though many argue that etomidate is safe)
- it is unreliable as an induction agent in reduced doses (even in shocked patients)
- use higher doses than usual as the onset for any given dose will be slower
- e.g. suxamethonium 2mg/kg IV TBW (total body weight), or
- e.g. rocuronium 1.6 mg/kg IV IBW (ideal body weight) (some centers use up to 2 mg/kg IV IBW)
- The compounding effect of uncorrected respiratory acidosis from apnea (regardless of the agents used) may be lethal
- During apnea from RSI, supported ventilation may be necessary for patients with profound metabolic acidosis
- Ketamine is the least cardio-depressant induction agent available (Morris et al, 2009; Gelissen et al, 1996)
- Ketamine usually exhibits a stimulatory effect on the cardiovascular system
- the mechanism is poorly understood but probably involves a centrally mediated sympathetic response and inhibition of noradrenaline re-uptake
- In the severely shocked patient beware of catecholamine depletion or resistance to further catecholamine effect. The direct effects of ketamine on myocardial depression may outweigh the indirect sympathetic effects and haemodynamic collapse may still occur. This is more likely to occur if:
- high doses of ketamine, based on dose-dependent negative inotropy observed in vitro (Gelissen et al, 1996), and
- in patients with a higher shock index (Miller et al, 2016).
- Consider doses as low as 0.25 to 0.5mg/kg IV IBW, rather than the usual 1-2 mg/kg IV IBW, for RSI of the shock patient
- be wary that sub-dissociative doses of ketamine may cause agitation or abnormal behaviour, this may require up-titration of the administered ketamine dose to induce dissociation, however most profoundly shocked patients have some degree of decreased level of consciousness
- Rapid administration of ketamine alone can render the patient apnoeic
- in the RSI setting, apnea will occur anyway from the administration of paralytics (see the comments above) but has important implications when ketamine is used in other settings such as procedural sedation or delayed sequence intubation (DSI)
- A phase II multi-centre trial in ICU patients showed that a bundle of therapy, which included fluid loading and early vasopressor use to treat abnormal haemodynamics, reduced life-threatening complications following intubation. This included marked reduction in severe cardiovscular collapse (by nearly 50%). (Jaber et al, 2009).
Slides for the talk “No Apologies: Intubation of the Shocked Patient”, given at EuSEM Congress 2015 in Torino, Italy:
References and Links
- Dewhirst E, Frazier WJ, Leder M, Fraser DD, Tobias JD. Cardiac Arrest Following Ketamine Administration for Rapid Sequence Intubation. J Intensive Care Med. 2012 May 29.
- Heffner AC, Swords D, Kline JA, Jones AE. The frequency and significance of postintubation hypotension during emergency airway management. J Crit Care. 2012 Aug;27(4):417.e9-13.
- Gelissen HP, Epema AH, Henning RH, Krijnen HJ, Hennis PJ, den Hertog A. Inotropic effects of propofol, thiopental, midazolam, etomidate, and ketamine on isolated human atrial muscle. Anesthesiology. 1996;84(2):397–403. doi:10.1097/00000542-199602000-00019
- Heier T, Caldwell JE. Rapid tracheal intubation with large-dose rocuronium: a probability-based approach. Anesth Analg. 2000 Jan;90(1):175-9.
- Jaber S, Jung B, Corne P, et al. An intervention to decrease complications related to endotracheal intubation in the intensive care unit: a prospective, multiple-center study. Intensive care medicine. 2010; 36(2):248-55.
- Jabre P, et al; KETASED Collaborative Study Group. Etomidate versus ketamine for rapid sequence intubation in acutely ill patients: a multicentre randomised controlled trial. Lancet. 2009 Jul 25;374(9686):293-300.
- Leeuwenburg T. Airway Management of the Critically Ill Patient: Modifications of Traditional Rapid Sequence Induction and Intubation. Critical Care Horizons [Internet]. 2015
- Lippmann M, Appel PL, Mok MS, Shoemaker WC. Sequential cardiorespiratory patterns of anaesthetic induction with ketamine in critically ill patients. Crit Care Med. 1983 Sep;11(9):730-4.
- Miller M, Kruit N, Heldreich C. Hemodynamic Response After Rapid Sequence Induction With Ketamine in Out-of-Hospital Patients at Risk of Shock as Defined by the Shock Index. Annals of emergency medicine. 2016.
- Morris C, Perris A, Klein J, Mahoney P. Anaesthesia in haemodynamically compromised emergency patients: does ketamine represent the best choice of induction agent? Anaesthesia. 2009 May;64(5):532-9. doi: 10.1111/j.1365-2044.2008.05835.x.
- Scherzer D, Leder M, Tobias JD. Pro-con debate: etomidate or ketamine for rapid sequence intubation in pediatric patients. J Pediatr Pharmacol Ther. 2012 Apr;17(2):142-9.
- Schwartz DE, Matthay MA, Cohen NH. Death and other complications of emergency airway management in critically ill adults. A prospective investigation of 297 tracheal intubations. Anesthesiology. 1995 Feb;82(2):367-76.
FOAM and web resources
- Levitan R. Timing Resuscitation Sequence Intubation for Critically Ill Patients – ACEP Now [Internet]. ACEP Now. 2015 [cited 16 September 2015]. Available from: http://www.acepnow.com/article/timing-resuscitation-sequence-intubation-for-critically-ill-patients/
- EMCrit RACC Podcast 216 – The Hemodynamically Neutral Intubation (2017)
- EMCrit Podcast 104 – Laryngoscope as a Murder Weapon Series: Hemodynamic Kills (2013)
- EMCrit Podcast 30 – Hemorrhagic Shock Resuscitation (2012)
- MDAware — Ketamine is a Heckuva Drug (2012)
- PHARM — Assassin’s Creed and Peri-intubation Hypotension (2013)
- ResusME — Ketamine & cardiovascular stability (2013)