Complications
The incidence of ventricular arrhythmias requiring therapy other than sodium bicarbonate is very low.
In most cases, antiarrhythmic drugs should be avoided and other symptoms corrected (such as hypotension, hypoxia, hypokalemia, and acidosis) as a priority. Sodium bicarbonate is the treatment of choice. If antiarrhythmics are used, avoid class IA, IC, II, and III drugs, which can increase cardiotoxicity and elongate the QT interval.[11]
After an acute overdose, vital signs and ECG findings may resolve. The patient is commonly left with a residual anticholinergic delirium which manifests as agitation, garbled speech, and disorientation with visual and/or tactile hallucinations.
This usually resolves spontaneously within 1 to 2 days; however, benzodiazepines may be of benefit for patients with severe agitation.
In a retrospective study of one intensive care unit, 6.2% of patients had seizures.[11]
Often seizures are self-limiting, so treatment is unnecessary. Correction of hypoxia and acidosis is vital.
If seizure activity persists and treatment is warranted, benzodiazepines are the treatment of choice, followed by barbiturates or propofol, if needed. Phenytoin is contraindicated as it does not improve seizures and may worsen cardiac toxicity.[11][43]
In patients who die from tricyclic antidepressant (TCA) overdose, 52% present with coma.[11] One retrospective study found that 17% of TCA overdoses result in coma.[11]
Changes in consciousness level can occur rapidly, and coma is strongly associated with risk of developing further complications of toxicity. Coma is often associated with respiratory depression requiring intubation and ventilatory support. Flumazenil should not be given to reverse benzodiazepine toxicity in mixed overdoses since this can precipitate seizures.
After initial ingestion, effects upon the myocardium may cause potent alpha-1 receptor antagonism and profound hypotension. Combined with wide complex tachycardia, cardiovascular collapse quickly ensues in the absence of supportive measures.[11]
Cardiac arrest caused by TCAs should be treated by systemic alkalinization with sodium bicarbonate and hyperventilation. Standard cardiac resuscitation efforts should be implemented. Attempts at resuscitation should continue for at least 1 hour.
Use of this content is subject to our disclaimer