Emergency Strategy - How to treat tricyclic antidepressant overdose
Emergency Strategy - How to treat tricyclic antidepressant overdoses
Tricyclic antidepressant include clomipramine, imipramine, desipramine, amitriptyline, doxepin, nortriptyline and protriptyline. Overdose of tricyclic antidepressant is common in suicidal patient.
The symptoms of overdose will typically develop over 2 hours of ingestions. The symptoms may include anti cholinergic effects such as myoclonic jerks, tachycardia, dryness of the mucous membrane and skin , mydriasis, urinary retention and ileus. Tricyclic antidepressant will act as peripheral and central acting anticholinergic.
Cardiovascular effect such as hypoperfusion, hypotension, pulmonary edema, sinus tachycardia, blocks of electrical conduction, ventricular arrhythmias and supraventricular arrhythmias. Tricyclic antidepressant will slow the arterioventricular and intraventricular conduction and causing depression of the myocardial infarction.
Central nervous system effects are stupor, respiratory depression, seizures, coma, confusion and agitation. The tricyclic antidepressant will inhibit the re uptake of the serotonin or noradrenaline in the brain.
The investigations require are full blood count, urea and electrolytes,arterial blood gases, chest x ray, ECG, urinalysis , CPK, creatinine and glucose. Specific findings on ECG are prolongation of the QT intervals, prolongation of the PR interval, sinus tachycardia, non specific ST - T waves changes and tachycardia. It is common to diagnose tricyclic antidepressant as prolongation of the QRS complex on the ECG, coma and stupor patient. These ECG and clinical findings are reliable enough to confirm the present of tricyclic antidepressant overdose. Plasma level measurement of the tricyclic antidepressant is not required.
The management initially will focus on maintaining the adequate airway, breathing, ventilation and circulation. Gastric emptying is delay by tricyclic antidepressant. Gastric lavage is considered. It is useful to considered repeated administration of activated charcoal . Consider cathartic and stop it if the patient developed diarrhea. Patient acid - base balance require regular monitoring. It is important to correct acidosis which carry the risk of arrhythmias. It is also important to maintain arterial pH around 7.45- 7.55. This can be performed by IV infusion of sodium bicarbonate ( alkalinisation procedure) and useful in treating conduction disturbance, convulsions, supraventricular and ventricular arrhythmias and hypotension. This procedure is performed if the QRS interval is more than 100 msec. Continuous cardiac monitoring is important.
The effective form of alkalinization is achieved if the arterial pH is around 7.45- 7.55 and for intubated patient, he is hyperventilated with PaCO2 not less than 25 mmHg. Large amount of sodium administration should be avoided.
Sodium bicarbonate is also useful in treating arrhythmias. It may stops arrhythmias in patient without acidosis. Complete heart block may require temporary ventricular pacing. anti- arrhythmic drugs especially class 1A anti - arrhythmic agents are contraindicated. Anti - arrhythmic agents are also considered when the cardiac output is significantly compromised. Anti - arrhythmic agents may aggregate the adverse effects of tricyclic antidepressant on myocardium ( due to the negative inotropes and the effect on membrane)). Phenytoin and lignocaine are usually considered. in cases of recurrent convulsions. Noradrenaline is considered in case of hypotension which is fail to be treated initially with administration of fluid and not responsive to alkalinization. Hemodialysis and forced diuresis are not considered in overdose of tricyclic antidepressant.
Tricyclic antidepressant include clomipramine, imipramine, desipramine, amitriptyline, doxepin, nortriptyline and protriptyline. Overdose of tricyclic antidepressant is common in suicidal patient.
The symptoms of overdose will typically develop over 2 hours of ingestions. The symptoms may include anti cholinergic effects such as myoclonic jerks, tachycardia, dryness of the mucous membrane and skin , mydriasis, urinary retention and ileus. Tricyclic antidepressant will act as peripheral and central acting anticholinergic.
Cardiovascular effect such as hypoperfusion, hypotension, pulmonary edema, sinus tachycardia, blocks of electrical conduction, ventricular arrhythmias and supraventricular arrhythmias. Tricyclic antidepressant will slow the arterioventricular and intraventricular conduction and causing depression of the myocardial infarction.
Central nervous system effects are stupor, respiratory depression, seizures, coma, confusion and agitation. The tricyclic antidepressant will inhibit the re uptake of the serotonin or noradrenaline in the brain.
The investigations require are full blood count, urea and electrolytes,arterial blood gases, chest x ray, ECG, urinalysis , CPK, creatinine and glucose. Specific findings on ECG are prolongation of the QT intervals, prolongation of the PR interval, sinus tachycardia, non specific ST - T waves changes and tachycardia. It is common to diagnose tricyclic antidepressant as prolongation of the QRS complex on the ECG, coma and stupor patient. These ECG and clinical findings are reliable enough to confirm the present of tricyclic antidepressant overdose. Plasma level measurement of the tricyclic antidepressant is not required.
The management initially will focus on maintaining the adequate airway, breathing, ventilation and circulation. Gastric emptying is delay by tricyclic antidepressant. Gastric lavage is considered. It is useful to considered repeated administration of activated charcoal . Consider cathartic and stop it if the patient developed diarrhea. Patient acid - base balance require regular monitoring. It is important to correct acidosis which carry the risk of arrhythmias. It is also important to maintain arterial pH around 7.45- 7.55. This can be performed by IV infusion of sodium bicarbonate ( alkalinisation procedure) and useful in treating conduction disturbance, convulsions, supraventricular and ventricular arrhythmias and hypotension. This procedure is performed if the QRS interval is more than 100 msec. Continuous cardiac monitoring is important.
The effective form of alkalinization is achieved if the arterial pH is around 7.45- 7.55 and for intubated patient, he is hyperventilated with PaCO2 not less than 25 mmHg. Large amount of sodium administration should be avoided.
Sodium bicarbonate is also useful in treating arrhythmias. It may stops arrhythmias in patient without acidosis. Complete heart block may require temporary ventricular pacing. anti- arrhythmic drugs especially class 1A anti - arrhythmic agents are contraindicated. Anti - arrhythmic agents are also considered when the cardiac output is significantly compromised. Anti - arrhythmic agents may aggregate the adverse effects of tricyclic antidepressant on myocardium ( due to the negative inotropes and the effect on membrane)). Phenytoin and lignocaine are usually considered. in cases of recurrent convulsions. Noradrenaline is considered in case of hypotension which is fail to be treated initially with administration of fluid and not responsive to alkalinization. Hemodialysis and forced diuresis are not considered in overdose of tricyclic antidepressant.
