Acta anaesthesiologica Scandinavica. Supplementum
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Acta Anaesthesiol Scand Suppl · Jan 1995
Comparative StudyEffect of neostigmine at different levels of mivacurium-induced neuromuscular blockade.
The effectiveness of neostigmine 40 micrograms/kg for antagonism of two different levels of neuromuscular blockade, induced by a bolus dose of mivacurium 0.15 mg/kg, was studied in 45 patients. The patients were anaesthetized with thiopentone, fentanyl, nitrous oxide in oxygen, and enflurane. Neostigmine was administered at either 10% recovery of the twitch height (TH10) at the adductor pollicis muscle (n = 14) or upon reappearance of the first response at the orbicularis oculi muscle (OO1) after train-of-four (TOF) stimulation (n = 16), the latter representing a deeper degree of neuromuscular blockade. ⋯ However, the time needed to reach a T4/T1 ratio > or = 0.8 was similar in both the early and late neostigmine administration groups, being 9 min faster than in the control group. It can be concluded that there is no advantage in administering neostigmine at profound neuromuscular blockade to achieve clinically adequate recovery (T4/T1 ratio > or = 0.8). However, the time between injection of mivacurium and TH25 may be shortened by using neostigmine at profound neuromuscular blockade, a procedure which may be useful in case of unpredictably difficult intubation, since diaphragmatic movements usually reappear at TH25.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Comparative StudyMivacurium in short to intermediate surgical procedures.
Mivacurium, a new benzylisoquinoline muscle relaxant, appears to be close to the ideal for short to intermediate surgical procedures. Ideal properties of such an agent are discussed, in addition to indications for muscle relaxation in such procedures. Two studies are presented, showing the onset and offset times of mivacurium and its cardiovascular stability in both young and elderly patients. It is concluded that it is a well-tolerated and appropriate agent for use in short to intermediate surgical procedures in those patients with normal plasma cholinesterase function, despite a slight prolongation of action in the elderly.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Comparative StudyPharmacokinetics of 51W89: preliminary data.
The pharmacokinetics of the 1R cis-1'R cis-isomer of atracurium (51W89) and its metabolite, laudanosine, were studied in 11 healthy patients with normal renal function and in 12 patients with chronic renal failure undergoing regular dialysis. A bolus dose of 51W89 (0.1 mg/kg) was given, and the plasma concentration was measured at regular intervals for 480 min. The elimination half-life of 51W89 was significantly longer in renal failure patients than in healthy controls (38.9 min vs 30.6 min; P < 0.05). The plasma laudanosine levels were lower than those reported after an equipotent dose of atracurium besylate. 51W89 may have a prolonged effect in renal failure patients.
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As a consequence of its rapid hydrolysis by plasma cholinesterase, mivacurium has a short duration of action, and recovery from neuromuscular blockade is rapid (5-95% twitch recovery = 13-15 min). Mivacurium is easy to titrate to individual patient requirements; the average infusion rate to maintain neuromuscular blockade at 89-99% twitch suppression during N2O/opioid anaesthesia is 6-7 micrograms/kg per min in adults and approximately 14 micrograms/kg per min in children. There is no evidence of a cumulative effect of mivacurium; recovery is unaffected by dose administered or duration of infusion. These characteristics make mivacurium a very suitable agent for use by infusion.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Comparative StudyA comparative study of two near infrared spectrophotometers for the assessment of cerebral haemodynamics.
Conventional near infrared spectroscopy (NIRS), introduced by Jöbsis in 1977, can be considered as a reliable trend monitor for cerebral oxygenation. Quantisation, however, is complex and cumbersome. Recently a relatively simple system for cerebral oximetry (INVOS 3100, Somanetics Corporation, USA) was developed, measuring the regional oxygen saturation (rSO2) in the capillary bed of the cerebrum, presented as a numerical figure for easy interpretation. ⋯ Increased cerebral blood flow induced by hypercapnia was detected by both conventional NIRS and the INVOS. Decreased cerebral blood flow induced by hypocapnia could only be detected by conventional NIRS. It was concluded that due to the variation in displayed rSO2 and the high amount of averaging in the algorithm the INVOS instrument does not yet provide more information than conventional NIRS.