Coma Due to Poisoning: Caution Urged in Intubation

Dr Pierre Margent

Tracheal intubation is recommended for comatose patients, but its use in individuals with altered consciousness due to acute poisoning remains uncertain. A French team conducted a large randomized trial to assess the risk–benefit ratio of a conservative approach in this context.

Patients with altered consciousness are at high risk for respiratory distress and pneumonia. Acute poisoning, whether from alcohol, drugs, or medications, is a nontraumatic cause of altered consciousness that often leads to intubation. In the United States alone, 20,000 patients with acute poisoning are intubated annually. While this practice aims to prevent the inhalation of gastric content and, consequently, pneumonia, intubation itself can cause hemodynamic instability, hypoxia, difficulties during tube insertion, or dental injuries. Until now, no study had attempted to evaluate the risk–benefit ratio of this practice in cases of toxic coma.

A Randomized Trial

The randomized trial conducted with a parallel, nonblinded design aimed to determine whether abstaining from intubation was equivalent to standard practice in certain situations. The study took place in 20 French emergency services and one intensive care unit. Participants were at least 18 years old with suspected acute poisoning and a Glasgow Coma Scale (GCS) score of less than 9. Pregnant women; prisoners; those requiring immediate intubation because of respiratory distress, cerebral edema, or other critical conditions; and those using cardiotoxic drugs or drugs that could be rapidly antagonized, such as opioids or sedatives, were excluded. Participants were randomized in a 1:1 ratio after hospital stratification. In the control group, the decision to intubate was at the discretion of the attending practitioner.

In the nonintubated by default group (the intervention group), a procedure could be performed later in case of respiratory distress, vomiting, or other complications. If abstaining, patients were closely monitored through oximetry, heart rate, GCS, etc. If intubation was required, it was performed under sedation (sedatives or hypnotics) and succinylcholine or rocuronium, after appropriate preoxygenation. In addition, capnography was recommended later to ensure proper endotracheal tube placement.

The primary outcome was a hierarchical composite outcome combining in-hospital death, duration of stay in the intensive care unit (ICU), and overall hospital stay (up to the 28th day). Secondary outcomes included, besides the aforementioned individual outcomes, the number of patients requiring mechanical ventilation, the proportion of admissions to the ICU, the incidence of pneumonia, and iatrogenic effects related to intubation itself.

Noninvasive Strategy's Advantages

The primary analysis included 225 participants, and 116 were in the intervention arm. The average age was 33 years, and 38% were women. The median GCS at inclusion was 6. Alcohol was the most frequently implicated toxin, accounting for 67% of observations. Fewer intubations were observed in the intervention group: 19 (16.4%) versus 63 (57.8%). Of the 19 patients eventually intubated in the intervention group, 16 had met at least one emergency intubation criterion. No deaths were recorded across the entire cohort.

In the intervention group, the median duration of stay in the ICU was 0 hours compared with 24.0 hours in the control group, resulting in a relative risk of 0.39. Hospitalization duration was 21.5 hours in the intervention group, compared with 37.0 hours, yielding a relative risk of 0.74. The win ratio (a method of analyzing composite parameters that prioritizes the most clinically significant event) for the composite criterion was 1.85 (P < .001). In a prespecified subgroup analysis, this ratio was 1.70 (P = .02) when the GCS was below 7. It was 1.42 when poisoning was caused by alcohol, benzodiazepines, gamma-hydroxybutyric acid, or gamma-butyrolactone.

It is essential to note, however, that this trial was not conducted blindly, and the Hawthorne effect may have influenced the physician's decision to intubate or not. Conversely, the study's strengths include a substantial cohort (225 patients), consideration of various parameters beyond pneumonia from aspiration, with a relative risk reduction of 53%. In addition, the etiology of toxic coma was not established in all cases. Finally, in cases of intubation, the use of a video laryngoscope or stylets was not specified.

In conclusion, for comatose patients with suspected acute poisoning, a conservative strategy aiming to avoid intubation as much as possible is associated with superior clinical benefits, in terms of the composite outcome of in-hospital mortality, duration of stay in intensive care or the hospital, and a decrease in adverse events.

This article was translated from JIM, which is part of the Medscape Professional Network. 

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