Predicting severity of tricyclic antidepressant overdose.
The measurement of plasma concentration, a prolonged QRS interval, and level of consciousness have all been recommended as useful indicators of toxicity following tricyclic antidepressant overdose. The aims of this study were firstly, to determine the relative prognostic value of each of these indicators and secondly, to assess when a patient can be discharged safely from the intensive care unit. Data were evaluated on 67 patients with tricyclic antidepressant overdose from four centers. Plasma tricyclic antidepressant concentrations were measured, coma grade was evaluated using the Matthew-Lawson Coma Scale and a ECG was obtained from 23 patients on admission. Complications such as convulsions, hypotension, arrhythmias, and need for intubation and ventilation were recorded. Thirty patients developed complications and no patient died. Coma grade was the best predictor of outcome. The development of serious complications is unlikely in patients whose level of consciousness is grade II or less and who are admitted to hospital more than 6 h after overdose. Plasma tricyclic antidepressant concentration was of no additional value in predicting toxic complications or deciding when the patient could leave the intensive care unit. Our study suggests that an alert and orientated patient with a QRS duration less than 100 ms is the best indicator for safe transfer to a medical or psychiatric ward.