British journal of anaesthesia
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In two groups of anaesthetized dogs, with (n = 28) or without (n = 28) induced intracranial hypertension, we compared the effects on intracranial pressure (ICP) of the rapid administration of mannitol 2 g kg-1 i.v. at PaCO2 2.7, 4.0, 5.3, and 6.7 kPa (n = 7). In dogs with no induced intracranial hypertension, ICP increased during the administration of mannitol, reached a peak at 2 min after infusion, and then gradually decreased (P less than 0.05). More marked changes in ICP were observed in response to higher values of PaCO2 (P less than 0.05). ⋯ This was followed by a more gradual decrease which achieved pre-balloon inflation values 10 min after infusion. We postulate that the absence of the initial increase in ICP is the result of a concomitant decrease in arterial pressure, a reduction in the volume-pressure response of the brain, the failure of mannitol to dilate further the cerebral arterial vascular bed and a hitherto unnoticed early water-drawing effect. Our study confirmed the safety of rapidly expanding the circulating blood volume with mannitol in circumstances of increased ICP in dogs.
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Fifty-three infants with neural tube defects and 97 with other major congenital abnormalities have been reviewed. In only one case did the mother receive an anaesthetic before or during pregnancy and this anaesthetic is unlikely to have played any part in the outcome. The anaesthetic history was recorded for 471 mothers who booked consecutively for their confinements. ⋯ The corrected annual incidence of anaesthesia was about 20% (14% related to fertility). There were no fetal abnormalities, but two miscarriages in the women anaesthetized during pregnancy. There was one abnormal baby delivered to a women anaesthetized more than 12 weeks before the last menstrual period.
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Antagonism of atracurium-induced neuromuscular blockade with neostigmine (one or two doses of 2.5 mg) was compared, using electromyography, with spontaneous recovery. Two levels of blockade were studied, one in which the initial response of the train-of-four has reached 10% of control and the other 50% of control. Adequate recovery was considered to be present when the ratio of the fourth response to the first (train-of-four ratio) had reached 70%. ⋯ This acceleration of recovery after neostigmine was most marked with the greater degree of blockade, but two doses of neostigmine were no more effective than one. Spontaneous recovery to the train-of-four ratio of 70% was slow, in the order of 1 h after an initial dose of 0.5 mg kg-1 and 45 min after incremental doses of 0.2 mg kg-1. It is concluded that antagonism of atracurium with one dose of neostigmine is usually desirable, that two doses are unnecessary, and that spontaneous recovery is slower than is generally realized.
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Comparative Study
Propofol or thiopentone: effects on intraocular pressure associated with induction of anaesthesia and tracheal intubation (facilitated with suxamethonium).
Changes in intraocular pressure (IOP) were studied in patients given propofol 2.1 mg kg-1 (n = 30) or thiopentone 4.9 mg kg-1 (n = 30) followed by suxamethonium 1.0 mg kg-1 and tracheal intubation. Half the patients in each group received an additional smaller dose of the same induction agent (propofol 1.0 mg kg-1 or thiopentone 2.0 mg kg-1) immediately before intubation. Both agents produced significant decreases in IOP which were slightly more marked with propofol. ⋯ Intubation of the trachea produced the greatest increase in IOP, averaging about 25% above control in all groups except in the group given the additional dose of propofol, in whom IOP remained below control values throughout the process of induction and intubation. Ten patients (33%) experienced pain on injection with propofol. A decrease in systolic arterial pressure of more than 30% was observed in 12 patients (40%) receiving propofol, compared with three (10%) of those given thiopentone.
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Randomized Controlled Trial Comparative Study Clinical Trial
Antagonism of vecuronium-induced neuromuscular blockade with edrophonium or neostigmine.
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. ⋯ 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.