A literature review addresses the myth that ketamine is contraindicated in head injured patients. They summarise articles from the 1970’s which identified an association between ketamine and increased ICP in patients with abnormal cerebrospinal fluid pathways (such as those caused by aqueductal stenosis, obstructive hydrocephalus and other mass effects). In more recent studies no statistically significant increase in ICP was observed following the administration of ketamine in patients with head injury; some of the studies showed a net increase in CPP following ketamine administration. They list ketamine’s stable haemodynamic profile and potential neuroprotective effects as further rationale for its use.
The authors boldly summarise:
‘Based on its pharmacological properties, ketamine appears to be the perfect agent for the induction of head-injured patients for intubation.’
Myth: ketamine should not be used as an induction agent for intubation in patients with head injury
CJEM. 2010 Mar;12(2):154-7
A review article in Anesthesia and Analgesia provides a summary of the literature surrounding RSI controversies.
- Should a pre-determined dose of induction drug be given or should it be titrated to effect prior to giving suxamethonium?
- Should fast acting opioids be coadministered to blunt the pressor response?
- What is the optimal dose of suxamethonium?
- Should defasciculating doses of neuromuscular blocking drugs be given?
- What is the ‘priming’ technique with rocuronium and is it necessary?
- Is it really bad to bag-mask ventilate the patient after induction prior to intubation? Which patients might this benefit?
- Should patients with full stomachs be anaesthetised sitting up, supine, or head down?
- Is cricoid pressure a good or a bad thing?
Not surprisingly the jury is still out on these, which is of course why they remain ‘controversies’. The review article provides a readable, interesting, and up to date summary of the evidence to date.
Rapid Sequence Induction and Intubation: Current Controversy
Anesth Analg. 2010 May 110(5):1318-25
In an a priori substudy of the CORTICUS multi-centre, randomised, double-blind, placebo-controlled trial of hydrocortisone in septic shock, the use and timing of etomidate administration was examined in relation to outcome.
Of 499 analysable patients, 96 (19.2%) received etomidate within the 72 h prior to inclusion. The proportion of non-responders to ACTH was significantly higher in patients who were given etomidate than in other patients (61.0 vs. 44.6%, P = 0.004). Etomidate therapy was associated with a higher 28-day mortality in univariate analysis (P = 0.02) and after correction for severity of illness (42.7 vs. 30.5%; P=0.06 and P=0.03) in two multi-variant models. Hydrocortisone administration did not change the mortality of patients receiving etomidate (45 vs. 40%).
Some of the previous attacks on etomidate have not been founded on the most rigorous evidence. However this study adds further to the difficulty in justifying etomidate’s use when a perfectly acceptable alternative (ketamine) exists for rapid sequence induction in the haemodynamically unstable septic patient.
The effects of etomidate on adrenal responsiveness and mortality in patients with septic shock.
Intensive Care Med. 2009 Nov;35(11):1868-76
Finally a well designed blinded randomised controlled trial on this subject. 0.3 mg/kg etomidate was compared with 2mg/kg ketamine for RSI in 655 patients requiring emergency intubation in the pre-hospital, emergency department, or intensive care unit environments. No difference was observed in intubation conditions or the primary endpoint of maximum SOFA score in the first three days, although the etomidate group had a higher rate of adrenal insufficiency as defined by response to an ACTH test.
Etomidate versus ketamine for rapid sequence intubation in acutely ill patients: a multicentre randomised controlled trial.
Lancet. 2009 Jul 25;374(9686):293-300
In contrast to literature showing high intubation failure rates by ground paramedics, a review over eight years of 369 intubations by flight paramedics and nurses showed successful tracheal intubation in 92.1% cases. Of the 369 intubation encounters, rapid sequence medications were given in 345. The authors ascribe their success to both initial training and mandatory ongoing practice and demonstration of competencies.
Performance of endotracheal intubation and rescue techniques by emergency services personnel in an air medical service
Prehosp Emerg Care. 2009 Jan-Mar;13(1):44-9
Careflight Queensland report a 9 month series of intubations by their doctor-paramedic HEMS teams who performed 39 intubations (and assisted hospital doctors in an additonal 4), of which less than half were pre-hospital. There was one failed intubation, successfully ventilated with a laryngeal mask airway.
Emergency intubation: a prospective multicentre descriptive audit in an Australian helicopter emergency medical service.
Emerg Med J. 2009 Jan;26(1):65-9