Intubation Using Sedation Without Neuromuscular Blockade: Say What?

ABSTRACT & COMMENTARY

Source: Garich TG, et al. Pre-hospital airway management in the acutely injured patient: The role of surgical cricothyrotomy revisited. J Trauma Inj Infec Crit Care 1998;45:312-314.

Authors from hannover, germany, have reported their use of a pre-hospital protocol for intubation of trauma patients that uses sedation without neuromuscular blockade. Garich and colleagues have maintained a registry of pre-hospital intubation cases, and report their results in 383 patients. They used a fixed protocol for endotracheal intubation, using only intravenous midazolam and fentanyl for sedation. Indications for intubation were comatose patients (GCS < 9), respiratory distress, hemodynamic instability, multi-system trauma, suspected thoracic trauma and three or more extremity fractures, and airway obstruction. The pre-hospital crew consisted of a physician (a resident in surgery at PGY-3 or higher) and a paramedic. Garich et al prepared this report because of their concerns over the inappropriately high use of surgical cricothyroidotomy in pre-hospital protocols that use neuromuscular blockade.

Of the 383 patients in the sample, 373 were successfully intubated by the time they reached the emergency department (ED), yielding a 97% success rate. The 10 patients who were not successfully intubated included eight who underwent cricothyroidotomy in the field (6 without previous attempts at intubation) and two with unrecognized esophageal intubation. Their conclusions are that pre-hospital endotracheal intubation can be accomplished by trained EMS personnel without the use of paralytic agents, and that the incidence of cricothyroidotomy can be kept low with proper training in field airway management.

Comment by Jeffrey W. Runge, MD, FACEP

This article is another example of several articles in the recent trauma literature that attempt to document successful endotracheal intubation using an inadequate technique of patient preparation. I chose this article for review because of the irony that just as emergency physicians are making great headway with the use of the time-tested techniques of rapid sequence intubation (RSI) using induction anesthetics and neuromuscular blockade, an approach that is a giant step backward appears in the literature. This article falls far short of constituting evidence for intubation using sedation only.

RSI done properly, with complete pharmacological control to make the patient suitable for a safe intubation, is now standard-of-care in emergency medicine. It may very well be standard of care in the future in the pre-hospital setting, once sufficient commitment is made to training and equipment for pre-hospital professionals.

Sedation with benzodiazepines and narcotics for intubation is the proverbial "20% solution." The profound sedation necessary to achieve adequate relaxation for intubation gives you all of the disadvantages of respiratory depression, myocardial depression, and hypotension, with none of the advantages of muscular relaxation. The protocol used by Garich et al includes the administration of 10-30 mg of midazolam with 250-500 mcg of fentanyl. Both of these drugs cause hypotension, do not reduce the risk of laryngeal spasm, and may increase the risk of vomiting and aspiration. Even at doses five times what is necessary for induction, 12.5% of the patients in this study required multiple attempts at intubation. More than half of the patients in this study were intubated because of coma, yet this protocol does nothing to address the increases in intracranial pressures caused by the act of intubation without neuromuscular paralysis. Nearly 15% of patients had multi-system trauma, the last people that should be subjected to iatrogenic hypotension. Their advocacy of avoiding neuromuscular blockade to avoid cricothyroidotomy is folly. A short-acting agent such as succinylcholine carries low risk in the hands of those well-trained in the procedures and complications of airway management.

The authors’ impetus for reporting these data is presumably a rate of surgical cricothyroidotomy after neuromuscular blockade that they deemed to be inappropriately high. But the reference Garich et al give for this assertion is a study from Tucson in which pre-hospital personnel performed 56 cricothyroidotomies in 376 patients requiring emergency airway management in the field.1 The Tucson EMS system, however, does not allow paramedics to use rapid sequence intubation techniques, so all of these cricothyroidotomies were performed without RSI. It should be argued that this rate of surgical cricothyroidotomy is unacceptably high, owing not to the use of RSI, but rather to its lack of use.

It is our duty as emergency physicians to insist on the highest standard of care for our injured patients. This includes patients at high risk of intracranial pressure from brain injury receiving interventions that do not exacerbate their problems with cerebral perfusion and secondary neuronal injury. In those patients who are bleeding, it is our duty to avoid exacerbating the problems of poor perfusion by avoiding medications that cause hypotension and myocardial depression. For those patients at risk for ARDS, the avoidance of vomiting and aspiration during airway control is of paramount importance.

All of these goals can be met through the use of carefully performed RSI using an induction agent that, given in proper doses, does not cause hypotension or myocardial depression followed by short acting neuromuscular blockade. At our institution, we also use intravenous lidocaine prior to other agents to mitigate rises in intracranial pressure, and atropine in children to block heightened vagal tone. The procedures for proper RSI should not be taken lightly, and all emergency physicians and pre-hospital personnel who use these techniques should be thoroughly trained in the pharmacology of the drugs, the manual techniques of intubation, and the use of alternative airway management devices such as the laryngeal mask and the Combitube. Training in the proper use of bag-valve-mask ventilation is also imperative, so that failed attempts at intubation with a neuromuscular blocking agent on board do not necessarily result in the need for surgical airway intervention in order to ventilate.

Articles such as this that attempt to document success using inferior techniques that put patients at risk should be recognized for what they are and dismissed.

Reference

1. Fortune JB. Efficacy of pre-hospital surgical cricothyroidotomy in trauma patients. J Trauma Inj Infec Crit Care 1997;44(5):832-838.