No abstract

This study investigates the effect on the heart and blood vessels of various rates of administration of boluses of a relatively new potent opiate, remifentanil, to patients with coronary artery disease. The results show that remifentanil should be given only by slow infusion to such patients.

Intubating conditions have been assessed at 60 s following administration of vecuronium 0.1 mg kg-1 or atracurium 0.5 mg kg-1 given either as a single dose after induction of anaesthesia with thiopentone or in divided doses; vecuronium 0.015 mg kg-1 followed 4 or 6 min later by 0.085 mg kg-1, or atracurium 0.075 mg kg-1 followed 4 or 6 min later by 0.425 mg kg-1. In the divided dose groups the smaller initial (priming) dose was given prior to induction of anaesthesia. Onset and duration of clinical relaxation were assessed using a peripheral nerve stimulator. The intubating conditions at 60 s improved significantly, with the use of relaxants in divided doses being acceptable in 80 and 70% of patients, respectively, with vecuronium and atracurium, but the conditions are not as good as those commonly found using suxamethonium. Priming at 6 min has no advantage over priming at 4 min. The onset of complete block was accelerated with priming, but the difference was not significant. The duration of clinical relaxation of vecuronium was significantly prolonged by giving it in divided doses. Unpleasant awareness of muscle weakness was observed in 15 patients, requiring early induction of anaesthesia in five of them.

Full HLA-A,B and DR typing was carried out on 92 women with proteinuric pre-eclampsia, 80 of their husbands and 46 of their babies. The results were compared with corresponding data from 65 normotensive pregnancies involving primiparous women. The frequency of HLA-DR4 was increased in the pre-eclamptic women (RR 3.1; p less than 0.005) and in the babies of pre-eclamptic pregnancies (RR 2.6; p less than 0.03). The strongest association, however, was with sharing of HLA-DR4 between mother and fetus (RR 4.2; p = 0.01). There was no increase in HLA antigen sharing in general between spouses or maternal-fetal pairs in pre-eclampsia. Nor did pre-eclamptic women exhibit increased homozygosity in general at any HLA locus. We conclude that genetic susceptibility to pre-eclampsia depends at least partly on fetomaternal compatibility for a gene or genes associated with HLA-DR4.

No abstract

Fade in the train-of-four (TOF) responses during onset of neuromuscular block was studied following administration of atracurium (225 or 450 micrograms/kg), vecuronium (40 or 80 micrograms/kg), pancuronium (60 or 120 micrograms/kg) and tubocurarine (450 micrograms/kg). TOF ratios were measured at approximate heights of T1 (first response in the TOF) of 75, 50 and 25%. Fade in TOF increased as the height of T1 decreased, with maximum fade being observed at T1 of 25%. The greatest difference between relaxants was observed at T1 of 25%, vecuronium showing the least fade and pancuronium, atracurium and tubocurarine showing increasing fade, in that order. The difference between atracurium and tubocurarine or between vecuronium and pancuronium was not significant, but the degree of TOF fade was significantly greater with atracurium and tubocurarine in comparison to vecuronium or pancuronium.

The potency of vecuronium was determined using single bolus dose administrations of 10-50 micrograms kg-1 in 28 patients anaesthetized with thiopentone, nitrous oxide, oxygen and fentanyl. The results were compared with those previously obtained using a cumulative dose technique in a comparable group of 10 patients. The 50% and 95% blocking doses (ED50 and ED95) of vecuronium were found to be 23.1 and 39.6 micrograms kg-1, respectively. These were significantly lower than the 30.5 and 56.7 micrograms kg-1 obtained previously using the cumulative dose technique. We recommend the use of single bolus dose method of determining potency for relatively shorter-acting drugs like vecuronium.

Antagonism of vecuronium-induced neuromuscular blockade was attempted, at varying degrees of spontaneous recovery, with edrophonium 0.5 mg kg-1 or neostigmine 0.05 mg kg-1 in two groups of 20 patients. Neuromuscular blockade was monitored using a train-of-four (TOF) stimulation. Adequate antagonism of neuromuscular blockade, defined as a sustained TOF ratio of 0.7 or more, was attained in all 20 patients given neostigmine and in 13 out of 20 given edrophonium. Five of the remaining seven patients given edrophonium had shown three or less responses to TOF stimulation before antagonism. While the time to onset of the action of edrophonium (22 s) was not significantly shorter than neostigmine (26 s), the time taken to attain a TOF ratio of 0.7 was significantly shorter with edrophonium (67 s compared with 194 s with neostigmine). It is concluded that edrophonium 0.5 mg kg-1 does not consistently antagonize vecuronium-induced neuromuscular blockade, particularly if there are three or less responses to a TOF stimulation present before antagonism.