Intubation Difficulty in Poisoned Patients by Coma Scale
Intubation Difficulty in Poisoned Patients by Coma Scale
ABSTRACT & COMMENTARY
Source: Adnet F, Intubation difficulty in poisoned patients: Association with initial Glasgow Coma Scale score. Acad Emerg Med 1998;5:123-127.
Adnet and colleagues set out to determine whether the initial Glasgow Coma Scale score (GCS) is predictive of intubation difficulty in poisoned patients requiring intubation in the field. The study was conducted in France, where ambulances are typically staffed by a physician or nurse anesthetist. This was an observational study. No interventions were performed for the purposes of the research. Intubation was performed using the physician's or nurse's technique of choice, using various drugs, including midazolam, etomidate, thiopental, propofol, neuromuscular blockade with any agent, or no drugs at all. Included were patients intubated orally or nasotracheally. There were 394 consecutive intubations studied, and the intubations were graded on level of difficulty using the number of attempts as an index. Furthermore, the degree of glottic exposure was graded using the Cormack Scale.
The purpose of the study was to compare GCS to intubation difficulty. As one would expect, it was difficult to make any sense of an observational study with so many variables. But when the raw comparison was made, those patients with an initial GCS of 7-9 had the highest percent of difficult intubations. Of those patients who were difficult to intubate, 71% had poor laryngoscopic visualization. Abnet et al conclude that patients with a GCS of 7-9 are more difficult to intubate. They also note that patients who were intubated using neuromuscular blockage with sedation and those who were sedated with propofol were easily intubated. They do not attempt to control for this unbelievably confounding variable in their analysis of the relationship of intubation difficulty to GCS. They did note that patients with a GCS higher than 10 were probably too alert to intubate without deep sedation or neuromuscular blockade, which may account for easier intubation in that group.
COMMENT BY JEFFREY W. RUNGE, MD, FACEP
Although the intent of the study was to look only at the association of GCS with difficulty of intubation, there are more important messages in the data. Although only 46 of 394 patients were intubated the correct way, using rapid sequence induction (RSI) with sedation and neuromuscular blockade, those who received RSI were easily intubated, irrespective of GCS. Those who were intubated the wrong way, with sedation alone or without any pharmacologic intervention, were difficult to intubate.
It has been about a decade since emergency physicians recognized that "brute-tane" induction is not the correct way to take care of a patient's airway. Thanks to the efforts of a few academic emergency physicians who caused the standard of care to evolve by virtue of their teaching and their advocacy of emergency physicians performing RSI, patients are receiving much better airway care in the ED. Even the most turf-conscious anesthesiologists working in hospitals with emergency physicians who are experienced in the use of RSI techniques have become advocates of emergency physicians performing this procedure. Routine intubation without the aid of properly administered sedation and paralysis is simply below the standard of care for patients who are not in cardiac or pulmonary arrest. A difficult intubation is, by nature, a less safe intubation.
The focus of this study is in the out-of-hospital realm. What becomes standard of care in the ED eventually spreads into the ambulance and helicopter. This study of out-of-hospital intubation demonstrates a clear difference between the right way and the wrong way to perform the procedure. In the United States, emergency air transport crews are often staffed by nurse-paramedic teams or nurse-respiratory therapist teams who successfully use RSI under protocols without the presence of a physician. But, for most paramedic systems in the United States, "brute-tane" is still the drug of choice. How long will it be before all paramedics are taught the pharmacology, procedures, and complication management of RSI in the field? I believe it will take years of research studies more directed than this one to move the thinking of EMS directors and state medical boards toward safer out-of-hospital airway management.
There is a caveat to this discussion that should not go unstated. The implementation of RSI in the field should not be taken lightly, however, because the intervention can be lethal if done improperly. It is essential that physicians and physician extenders who would use this technique be properly trained and understand, in detail, the pharmacology of all the drugs. Procedures and instruments necessary for proper technique must be mastered, as should the techniques for getting out of a jam should an intubation not be readily accomplished in the face of neuromuscular paralysis.
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