RISK OF SECONDARY NEUROMUSCULAR BLOCKADE AFTER TRANSFUSION OF AUTOLOGOUS BLOOD WITHDRAWN AFTER INJECTION OF MUSCLE-RELAXANTS

A secondary neuromuscular blockade can occur after transfusion of auto logous blood withdrawn after injection of muscle relaxants. In this st udy time course of muscle relaxation after transfusion of blood withdr awn before or after administration of atracurium (A) or vecuronium (V) was assessed. Forty adults undergoing haemorrhagic urologic surgery w ere included in the study. After induction of general anaesthesia and intubation of the trachea facilitated by local lidocaine, they were di vided into 4 groups. In groups Al and VI the blood units were withdraw n before injection of atracurium 0.5 mg - kg-1 or vecuronium 0.1 mg - kg-1. In group A2 and V2 the blood units were withdrawn after administ ration of muscle relaxants. Haematocrit was decreased to 0.30. The las t bolus of these muscle relaxant was injected 30 min before the end of surgical procedure. Autologous blood was transfused when train of fou r (T4R) recovered to 0.80. Electromyographic elicited responses to T4R stimulation were obtained every minute during the 4 first minutes aft er the beginning of transfusion (Tl to T4), thereafter every minute du ring the 5 first minutes after the end Of transfusion (T5 to T9), and finally every 5 minutes for 10 minutes (T10 and T11). There was a seco ndary neuromuscular blockade in patients of groups A2 and V2. The inte nsity of blockade was more important after vecuronium than after atrac turium (p< 0.01 from T2 to T11 between groups A2 and V2). In group A2, the T4R had not reached the control level at the end of the procedure (0.78 at T11 vs 0.80 at T0). These data emphasize the importance of w ithdrawing blood units before administration of muscle relaxants. In c ase of prior injection of vecuronium, patients must be kept under cont rolled ventilation until T4R had recovered. With atracurium a monitori ng of T4R seems to be sufficient.