Hypotension in severe tricyclic antidepressant overdose

Area of Science:

• Emergency Medicine
• Clinical Toxicology
• Cardiology

Background:

• Severe tricyclic antidepressant (TCA) overdose presents significant clinical challenges.
• Hypotension is a critical complication in TCA overdose, necessitating a clear understanding of its incidence and predictors.
• Previous research has explored various factors, but the independent contribution of TCA levels and QRS duration to hypotension requires further elucidation.

Purpose of the Study:

• To determine the incidence of hypotension in patients with severe acute TCA overdose.
• To identify clinical factors, including TCA levels and QRS interval, associated with the development of hypotension.
• To evaluate the relationship between hypotension and other adverse outcomes such as seizures, arrhythmias, aspiration pneumonia, and pulmonary edema.

Main Methods:

• Prospective evaluation of 64 patients presenting with severe acute TCA overdose.
• Definition of severe overdose based on QRS interval (≥0.10 seconds), TCA level (≥500 ng/mL), or Grade IV coma.
• Utilized regression and multivariate logistic regression analyses to assess correlations and associations.

Main Results:

• The overall incidence of admission hypotension (systolic BP < 95 mmHg) was 34% (22 of 64 patients).
• Systolic blood pressure showed poor correlation with TCA levels (r = -0.37) and maximal QRS interval (r = -0.17).
• Hypotension was inversely associated with the occurrence of arrhythmias and pulmonary edema (P < 0.01), but not with seizures or aspiration pneumonia.

Conclusions:

• Hypotension is a frequent complication of severe TCA overdose, occurring independently of TCA concentration and QRS duration.
• Hypotension is a significant predictor of arrhythmias and pulmonary edema in this patient population.
• Seizures and aspiration pneumonia appear to be unrelated to the initial blood pressure status in severe TCA overdose.