Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · Jan 1978
Operating room nurses' psychomotor and driving skills after occupational exposure to halothane and nitrous oxide.
Concentrations of halothane and nitrous oxide were assayed by gas chromatography throughout a working day in three operating theatres and in the end-tidal air of 19 nurses 15 and 60 min after leaving the theatres. Perceptual, psychomotor and driving skills were measured in these nurses and in 11 younger nurses working in the wards of the same hospital. A complicated psychomotor test battery and a driving simulator were used. ⋯ Despite their higher age and exposure to the operating room environment, the driving skills of the operating room nurses were similar to those of the ward nurses. The results suggest that tolerance to anaesthetic gases develops among operating room personnel. No impairment of driving skills can be expected after daily exposure to halothan and nitrous oxide among long-term employees in operating theatres.
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Acta Anaesthesiol Scand · Jan 1978
The clinical character of local anesthetics: a function of frequency-dependent conduction block.
It is clinically recognized fact that some local anesthetics have a proclivity for inhibition of motor nerves, while others preferentially affect sensory and sympathetic fibers. On the basis that sensory fibers have a frequency threshold for transmission of nociceptive stimuli and that somatic motor fibers have no such frequency threshold, we hypothesized that this variation may be due to differences in the effect of local anesthetics on axonal refractory period. Frog sciatic nerves were partially blocked with lidocaine, bupivacaine, tetracaine and etidocaine, and then stimulated in trains of 17 pulses, at frequencies between 3 and 100 Hz. ⋯ At a comparable level of partial block (50% at 100 Hz), tetracaine and etidocaine showed only a 10% difference between 3 and 100 Hz, while with bupivacaine and lidocaine there was a 30% drop between these two frequencies. This excellent correlation between the laboratory and clinical phenomenon supports our hypothesis. Local anesthetics which have a minimal effect on the refractory period yield enhanced motor block; whereas local anesthetics with a large effect on the refractory period are relatively more potent blockers of sensory and sympathetic transmission.
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Acta Anaesthesiol Scand · Jan 1978
Cardiovascular effects of local adrenaline infiltration during neurolept analgesia and adrenergic beta-receptor blockade in man.
The adrenergic beta-receptor blocking drug, alprenolol, was given together with atropine to 15 patients during neurolept analgesia (NLA) in order to prevent adrenaline-induced cardiac arrhythmias. Four patients operated on without adrenergic beta-receptor blockade formed the control group. Three of them developed tachyarrhythmias, ventricular tachycardia, multifocal ventricular extrasystoles and supraventricular tachycardia. ⋯ NLA alone does not protect the heart against adrenaline-induced arrhythmias. It does, however, seem to be compatible with an adrenergic beta-receptor blockade, which in turn provides partial protection against adrenaline-induced arrhythmias. The occasionally developing arrhythmias can then be terminated with specific adrenergic beta blockers.
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Acta Anaesthesiol Scand · Jan 1978
Cerebral autoregulation in unconscious patients with brain injury.
In 18 unconscious patients with traumatic brain injury, the cerebral autoregulation was tested during the first 2-3 weeks after the acute trauma. Regional cerebral blood flow (rCBF) was measured by the intra-arterial 133xenon washout method before and after an increase of about 20% in the mean arterial blood pressure (MABP) by angiotensin. The difference between MABP and intraventricular pressure (IVP) was used as cerebral perfusion pressure (PP). ⋯ Regional loss of autoregulation indicated by a 20% flow increase was observed in 29 out of 35 studies (83%), while hemispheric loss of autoregulation was observed in only one study. The results of the autoregulation tests were unrelated to the clinical outcome, the presence of brain-stem lesion, and the ventricular fluid pH, lactate and lactate/pyruvate ratio. In repeated studies, a gradual normalization of the autoregulation was observed about 5 days after the acute trauma.
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Three anaesthetic circuits for use in nose-piece application of inhalation analgesia are described. An ejector flowmeter is used for the scavenging of overspill gas.