Cyanide toxicity following nitroprusside induced hypotension

Abstract

SODIUM NITROPI:tUSSmE was introduced for the elective induction of hypotension during general anaesthesia because of its apparent pharmacological efficacy. 1 Increased experience with this drug has led to the realization that its toxic potential is greater than previously believed. Several recently reported deaths following use of sodium nitroprusside have been attributed to the accumulation of the nitroprusside metabolite, cyanide. 2,s This has resulted in a series of revisions in the recommended dosage of sodium nitroprusside. Based on clinical experience and theoretical considerations, Davies, et al. "~ recommended that 3.5 mg/kg is the maximum dose of sodium nitroprusside that can be administered safely. Posner, et al.,4 in reporting their studies of nitroprusside-induced cyanide poisoning in baboons, further recommended that the sodium nitroprusside infusion rate be limited to 10/zg/kg/min and that the maximum dose not exceed 3 mg/kg. Most recently, Vesey, et al. '~ recommended that the total dose of sodium nitroprusside should not exceed 1.5 mg/kg during short-term infusions.In this paper the extent of cyanide accumulation and toxicity in patients receiving sodium nitroprusside infusions during intracranial surgery is reported. The doses of sodium nitroprusside employed in these studies fall within the range most recently recommended, that is, less than 1.5 mg/kg. PATIENTS AND METHODSEight female and five male patients (aged 13-66) undergoing surgery for repair of an intracranial aneurysm, were studied. Sodium nitroprusside was infused during the operation to produce hypotension as required by the surgeon. The infusion times and doses are listed in Table I. Five patients undergoing craniotomy without elective induction of hypotension were studied as a control group.Morphine and hyoscine were administered as premedication. All patients were operated on in a horizontal position. Anaesthesia was induced by thiopentone with tracheal intubation under pancuronium and was maintained using 65 per cent nitrous oxide in oxygen and morphine with intermittent pancuronium. A halothane

Effect of combined exposure to carbon monoxide and cyanides in selected forensic cases

“…This change has been demonstrated occurs at lower blood cyanide levels. 12 For cyanidric acid, 1 mg/l has been shown to be the minimum lethal concentration: 13 nonetheless, even for this volatile toxic agent, cases have been documented where death occurred with lower concentrations of cyanide. 3 In our first case the elevated concentration of carboxyhaemoglobin (80%) is accompanied by an elevated concentration of cyanide (9 mg/l).…”

Acute health risks related to the presence of cyanogenic glycosides in raw apricot kernels and products derived from raw apricot kernels

“…Some of the evidence for the toxicity threshold of 20 lM derives from clinical studies. For example, Aitken et al (1977) monitored eight female and five male patients (aged 13-66) receiving the hypotensive agent sodium nitroprusside (which contains 44% cyanide) undergoing surgery for repair of an intracranial aneurysm. They found that blood cyanide levels above 0.53 mg/L (20 lM) were associated with proportionately greater degrees of metabolic acidosis.…”

Safety and efficacy of urapidil and sodium nitroprusside in the treatment of hypertensive emergencies

“…However, accumulation of thiocyanates has been reported even 180 min after the start of sodium nitroprusside infusion [4][5][6][7]. Additionally, Patel et al demonstrated that toxicity developed over a wide range of nitroprusside doses suggesting that the development of cyanide toxicity remained unpredictable [8].…”