COMPARISON OF INTUBATING CONDITIONS AFTER ADMINISTRATION OF ORG 9426 (ROCURONIUM) AND SUXAMETHONIUM

We have assessed intubating conditions after administrationof Org 9426 (rocuronium) 600 fig kg^–1 at 60 or 90s ingroups of 20 patients anaesthetized with thiopentone, nitrousoxide in oxygen and small doses of fentanyl, and compared thedata with those obtained after suxamethonium 1 mg kg^–1in similar groups of patients. The influence of prior suxamethoniumadministration on the potency of Org 9426 was studied also byconstructing a dose-response curve. Intubating conditions afterOrg 9426 were found to be clinically acceptable (good or excellent)in 95% of patients at 60 s and in all patients at 90 s and inall patients at both times after suxamethonium. The averagetime for the onset of block following Org 9426 at this dosewas 89 s (which is shorter than with any of the currently availablenon-depolarizing neuromuscular blocking drugs); the durationof clinical relaxation (25% recovery of twitch height) 30 min.Prior administration of suxamethonium did not appear to influencethe potency of Org 9426.     

DOSE-RESPONSE RELATIONSHIPS FOR NEOSTIGMINE ANTAGONISM OF VECURONIUM-INDUCED NEUROMUSCULAR BLOCK IN ADULTS AND THE ELDERLY

We have studied the dose-response relationship for neostigminein 36 adult (ages 18-50 yr) and 36 elderly (ages > 70 yr)subjects during antagonism of neuromuscular block induced byvecuronium. All patients received vecuronium 0.08 mg kg^–1and neuromuscular block was monitoredmechanomyo-graphicallyusing the train-of-four (TOF) mode of stimulation. Six patientsof each age group were allocated randomly to receive neostigmine5, 15, 25, 35 or 45 µg kg^–1 or saline at 10% recoveryof T1 (first response in the TOF). TOF ratios were recordedcontinuously over the next 10 min and the values at 1-min intervalsfrom 5 min onwards were used to construct the dose-responserelationships. There was a significant difference (P < 0,05)in the time to spontaneous recovery of T1 to 10% between theadults (24 (SD 5.5) min) and the elderly (33 (7.8) min). Dose-responsecurves for neostigmine were parallel in the two age groups,but those for the. elderly were significantly to the right ofthe curves for the adults. This sggests an apparently lesserrelative potency of neostigmine, or the requirement of a largerdose, in the elderly for attaining antagonism of a moderatelyintense vecuronium block at the same time as in adults.     

PATHOGENESIS OF SUXAMETHONIUM-INDUCED MUSCLE DAMAGE IN THE BIVENTER CERVICIS MUSCLE IN THE CHICK

Muscle damage induced by suxamethonium, and the influence ofhalothane on it, has been examined by measuring the efflux ofcreatine kinase (CK) in the biventer cervicis muscle of thechick. Whereas halothane and suxamethonium alone did not increasethe enzyme efflux significantly, the combination of the twowas associated with significant increase in the concentrationof CK in the bathing medium by 59–157%. The increase inCK was prevented by adding chlorpromazine 100 µmol litre^–1to the medium, suggesting the involvement of phospholipasesin the pathogenesis of suxamethonium-induced muscle damage.     

Anticholinergic prophylaxis does not prevent emesis following strabismus surgery in children

One hundred and twenty-one children were studied in this prospective, randomized double-blind, placebo-controlled comparison of the effectiveness of anticholinergic prophylaxis for the prevention of emetic symptoms following strabismus surgery. The children were allocated to three groups, to receive placebo (n= 40), glycopyrrolate (n= 40) or atropine (n= 41). The incidence of intraoperative oculocardiac reflex (OCR) and of postoperative emetic symptoms for 24 h was recorded. The incidence of OCR was 55% in the placebo group compared with 5% and 2% in the glycopyrrolate and atropine groups respectively (P < 0.05). Thirty percent (12/40) of patients in the placebo group, 25% (10/40) in the glycopyrrolate group, and 22% (9/41) in the atropine group experienced nausea and/or vomiting (difference not significant). It is concluded that prophylactic administration of anticholinergic agents during strabismus surgery in children despite being effective against the occurrence of the oculocardiac reflex, does not reduce the incidence of emetic symptoms.     

An evaluation of Org NC 45 (vecuronium) in paediatric anaesthesia

Vecuronium (Org NC 45) was evaluated as a neuromuscular blocking agent in children and compared with pancuronium in a double-blind study. Satisfactory intubating conditions were present 90 seconds after 0.1 mg/kg of either drug. The onset of complete block was quicker after vecuronium but the greatest difference was found in the duration to 25% recovery which was significantly shorter with vecuronium (20 min) compared with pancuronium (48 min). The use of vecuronium was associated with cardiovascular stability and no clinical evidence of histamine release. Antagonism of the block was readily achieved with neostigmine.     

Anticholinergic drugs in anaesthesia

A survey was carried out amongst anaesthetists in the United Kingdom and Ireland regarding the use of anticholinergic drugs. Sixty-two per cent of these anaesthetists use these drugs routinely in premedication. The drugs are nearly always atropine or hyoscine and are used mainly for reducing secretions and protection against vagal stimulation. A longer-acting drug was desired by 22% and 60% would like to use an orally effective anticholinergic drug. Though quite a number of minor side effects are high-lighted, the majority do not consider these serious enough to stop routine use. There is now a tendency amongst many anaesthetists either not to use these drugs routinely or use them less often, more rationally and in reduced dosage.     

Comparison of the haemodynamic effects of mivacurium and atracurium during fentanyl anaesthesia

We have measured the haemodynamic effects of mivacurium 0.15and 0.2 mg kg^–1, and atracurium 0.5 mg kg^–1 administeredover 10–15 s in patients undergoing coronary artery bypasssurgery under fentanyl anaesthesia. There were no significanthaemodynamic changes in the atracurium group, other than a transientdecrease in pulmonary arterial wedge pressure. Changes in heartrate were small in all three groups. Mivacurium 0.15 mg kg^–1produced changes of only small magnitude (12% decrease in meanarterial pressure and 16% decrease in systemic vascular resistanceindex) however, mivacurium 0.2 mg kg^–1 produced a 25%reduction in mean arterial pressure, a 14% increase in cardiacindex and a 35% decrease in systemic vascular resistance index.Erythema developed in two, three and seven patients after atracurium,mivacurium 0.15mgkg^–1 and mivacurium 0.2 mg kg^–1,respectively. One patient exhibited a 54% decrease in mean arterialpressure, generalized erythema and bronchospasm after mivacurium0.2mg kg^–1. The haemodynamic changes with mivacurium suggestedhistamine release. (Br. J. Anaesth. 1995; 74: 330–332)