Can death unrelated to secondary causes be predicted in intubated comatose tricyclic antidepressant-poisoned patients?

Abstract

Context. It has been stated that the level of consciousness at presentation is the most sensitive clinical predictor of dysrhythmia and seizure in patients with tricyclic antidepressant (TCA) overdose. Objective. To assess the prognostic value of the clinical characteristics and electrocardiographic (ECG) parameters in intubated comatose TCA-poisoned patients for predicting death. Materials and methods. In this retrospective, unmatched case-control study – conducted in Loghman-Hakim Poison Hospital in Tehran, Iran, between March 2005 and September 2010 – the medical charts of 25 non-survived (cases) and 72 survived (controls) TCA-poisoned patients, initially presenting with deep coma (GCS ≤ 8) and being intubated before or after hospital presentation, were evaluated. Exclusion criteria were multiple drug ingestion, head trauma, underlying heart diseases, history of previous convulsive disorders, and late death. Age, gender, specific TCA ingested, manner of poisoning, time between ingestion and presentation, occurrence of seizure, and the patient's initial emergency department vital signs were extracted and recorded. The first 12-lead ECG performed after hospital presentation was evaluated. Results. Ten cases and none of the controls had advanced ECG changes (ventricular fibrillation, torsades des pointes, or asystole). Using a logistic regression model, from variables with a statistically significant difference between the two groups (i.e. ingestion of nortriptyline and amitriptyline, pulse and respiratory rates at presentation, occurrence of seizure [before and after presentation or both], height of R wave in lead aVR, T40-ms frontal plane QRS axis, and occurrence of premature ventricular contraction), only seizure after hospital presentation reached significance regarding prediction of death (OR = 40.88; 95% CI = 9.93–168.39; p < 0.001). Conclusion. Neither ECG parameters nor clinical characteristics of the intubated comatose patients with TCA toxicity predicts death in patients who had not died due to the secondary causes. The only prognostic indicator of death in such patients is seizure after hospital presentation.