We report a case of cardiac arrhythmia occurring in a Guillain-Barré syndrome (GBS) patient after succinylcholine administration during third endotracheal intubation, on day 13 of illness. The probable cause of arrhythmia is succinylcholine-induced hyperkalemia. Of interest, this case demonstrated in the same patient that arrhythmia only occurred during third intubation, when duration of illness is prolonged, and not during previous two intubation episodes, despite succinylcholine was also being used. In GBS, muscle denervation resulted in up-regulation of acetylcholine receptors at neuromuscular junctions, causing the muscle cell membrane to become supersensitive to succinylcholine, leading to severe hyperkalemia and arrhythmia when succinylcholine was administered.
A prospective study to correlate clinical digoxin toxicity with serum digoxin levels was carried out in 67 patients of whom 24 were clinically toxic and 43 were asymptomatic. The patients were clinically diagnosed to be toxic based on typical cardiac arrhythmias (n = 11) or non-cardiac symptoms (n = 13). Blood samples were collected at least six hours after the last digoxin dose and the sera assayed for digoxin using a radioimmunoassay method. The mean serum digoxin level in the toxic group (x1 = 2.09 +/- 1.28 ng/ml) was significantly higher than in the non-toxic group (x2 = 1.20 +/- 0.75 ng/ml), p less than 0.01. All the non-toxic patients had serum digoxin levels below 3 ng/ml. However, there was a considerable overlap of serum digoxin levels between the two groups of patients. Serum level cannot be the sole criterion in diagnosing digoxin toxicity. Nevertheless, raised serum digoxin levels especially above 3 ng/ml, in the presence of suggestive clinical features is strongly suggestive of toxicity.
The case is reported of a patient who suffered severe acute hypertension, cardiac arrhythmia, and myocardial infarction probably as a direct effect of phenylephrine overdose. Instillation of the drops during surgery probably enhanced the systemic absorption of a significant amount of the drug. Therefore it should be used during surgery with caution, especially in elderly patients and those with cardiovascular disease.