VERAPAMIL OVERDOSAGE UNRESPONSIVE TO DEXTROSE/INSULIN THERAPY

Objective: Insulin/dextrose has been advocated in recent reports to rapidly improve haemodynamic parameters in calcium channel blocker poisoning. We report a case of verapamil overdose unresponsive to this and conventional therapies. Case Report: A 58-year-old male with a history of myocardial infarction, hypertension and an aortic lesion presented to the Accident and Emergency Department with severe chest and abdominal pain with guarding. Although the patient was conscious blood pressure was initially unrecordable and was then recorded at 70/50 mmHg after administration of intravenous fluids. Peripheral pulses were unpalpable. His medication on admission consisted of frusemide, verapamil, warfarin and amlodipine. Arterial blood gas analysis revealed metabolic acidosis, hypercarbia and hypoxia (pH 7.28, [PCO.sub.2] 7.49 kPa, [HCO.sub.3] 11.8 mmol/L, SBE-12.2 mmol/L, [O.sub.2] 82.8, SBC 13.4 mmol/L). ECG showed sinus bradycardia (rate 62) and left-bundle-branch block. Other biochemical abnormalities included hyperglycaemia (13.5) slightly elevated liver enzymes (ALT 84 IU/L, AST 63 IU/L) creatinine 197 [micro]mol/L, creatinine kinase 295 IU/L (troponin level negative) and an INR of 4.17. The patient denied self-poisoning and blood toxicology (including paracetamol) was negative. A chest x-ray revealed cardiomegaly and possible mediastinal widening. Echocardiography was consistent with findings at a previous examination. Abdominal ultrasound and CT scans demonstrated no abnormalities. The patient developed respiratory failure and was intubated and ventilated. Calcium channel blocker poisoning was suspected because of the bradyarrhythmias, hyperglycaemia and hypotension unresponsive to treatment. Management at this point was supportive with large doses of inotropes. Intravenous calcium chloride, glucagon, sodium bicarbonate, dextrose/ insulin were given and a temporary pacemaker was inserted to treat severe bradycardia. Renal replacement therapy was started because of deteriorating renal function. Verapamil level was taken on the second day and retrospectively confirmed the self-poisoning (Verapamil 1740 [micro]g/L and norverapamil 850 [micro]g/L, target range for both is 100-200). Continuous veno-veno haemodialysis (CVVHD) was again attempted owing to rapidly elevating liver transaminases (ALT 1252 IU/L, AST 1377 IU/L) but this was tolerated poorly and discontinued. The patient died two days post admission to the Intensive Care Unit despite these interventions. Conclusion: This report demonstrates calcium channel blocker poisoning unresponsive to standard interventions of intravenous fluids and inotropes, calcium chloride salts, glucagon and pacing. The patient was also treated with dextrose/insulin (insulin euglycaemia), a novel therapy suggested in literature, but this did not show any benefit.
Herbert JX(1), O'Malley C(2), Tracey JA(1), Dwyer R(2), Power M(2). (1) The National Poisons Information Centre, Beaumont Hospital, (2) Dept. of Anaesthesia, Beaumont Hospital, Dublin, [...]