Hyperkalaemia associated with haemorrhagic shock in rabbits: modification by succinylcholine, vecuronium and blood transfusion.

In haemorrhagic patients, hyperkalaemia may occur after succinylcholine administration. We investigated in haemorrhagic rabbits whether vecuronium caused hyperkalaemia and if blood transfusion prevented succinylcholine-induced hyperkalaemia. Rabbits were lightly anaesthetized with halothane/N2O and 30-35 ml/kg blood were withdrawn to cause arterial pH to decrease to approximately 7.0-7.1. Group C (n = 12) received 3 ml saline, Group S (n = 13) received succinylcholine 1 mg/kg, Group V (n = 7) received vecuronium 0.25 mg/kg and Group T (n = 9) was transfused with 10 ml/kg blood 10 min prior to receiving succinylcholine 1 mg/kg. K+ analysis was repeated at 5 min, and at 10 min in most animals. Haemorrhage increased K+ (nmol.1-1, mean +/- SD): Group C, 3.4 +/- 0.3 to 6.8 +/- 1.8; Group S, 3.8 +/- 0.5 to 6.9 +/- 2.3; Group V, 3.8 +/- 0.3 to 7.1 +/- 1.9; Group T, 3.6 +/- 0.5 to 7.6 +/- 2.9. K+ decreased in Group T (to 5.4 +/- 1.8) after blood transfusion. K+ increased at 5 min in Group S (to 8.7 +/- 2.6) and at 10 min for Group C (to 8.4 +/- 1.7) and Group T (to 7.2 +/- 2.3). The K+ increase at 5 min for Group S (1.8 +/- 0.8) was significantly higher than those for Group C (1.0 +/- 0.6) or Group V (0.9 +/- 0.4), but was not different from that of Group T (1.5 +/- 0.7). We conclude that haemorrhage and succinylcholine cause hyperkalaemia in rabbits. Muscle relaxation itself does not appear to be a factor, but transfusion may lessen the hyperkalaemia.