Articles: general-anesthesia.
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Anasthesiol Intensivmed Notfallmed Schmerzther · Oct 1994
Review[Perioperative EEG monitoring: studies of the electrophysiological arousal mechanism].
Electroencephalogram recordings have been advocated for assessment of changes in cerebral function during anaesthesia. Controversy exists on the specificity of EEG parameters indicating depth of anaesthesia, because cortical electrical activity is modulated not only by drugs but also by a variety of exogenous and endogenous stimuli. In clinical practice, EEG measures often fail to accurately predict anaesthetic depth since the effects of nociceptive stimulation on the EEG are still not well defined. ⋯ The occurrence of slow EEG wave patterns may be related to functional blockade of the ascending activating system of the brain stem. In contrast, slowing of the EEG is comparable to EEG changes seen with increasing concentrations of anaesthetics. This indicates the difficulty to discriminate arousal phenomena from drug effects using EEG monitoring alone.(ABSTRACT TRUNCATED AT 250 WORDS)
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Conscious awareness is an infrequent complication of general anesthesia. All methods of anesthesia have been implicated, and no method guarantees amnesia. This article examines implicit and explicit memory and discusses factors associated with awareness. ⋯ Strategies to block threatening auditory stimuli include use of earphones, music tapes, white noise, reassuring statements, or positive suggestion. Behavioral anesthesia decreases patient stress to enhance recovery. Evidence of patient benefit resulting from therapeutic suggestion is inconclusive.
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Monaldi Arch Chest Dis · Sep 1994
ReviewAtelectasis formation and gas exchange impairment during anaesthesia.
Anaesthesia is accompanied by impaired oxygenation of the blood, and sometimes hypoxaemia may develop despite an increased oxygen fraction of the inspired gas. The major cause of this derangement is shunt, an effect of prompt atelectasis formation in dependent lung regions. An additional cause is ventilation/perfusion (V/Q) mismatch, possibly produced by intermittent airway closure. The magnitude of shunt and size of atelectasis are independent of the age of the patient, whereas V/Q mismatch increases with age, explaining the age dependent impairment of oxygenation.
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Anaesth Intensive Care · Aug 1994
ReviewControl of carbon dioxide levels during neuroanaesthesia: current practice and an appraisal of our reliance upon capnography.
With the widespread availability of capnography, many anaesthetists have swung away from formally verifying hypocapnia by intraoperative arterial blood gas analysis and, instead, have come to rely upon capnography as an acceptable and constant predictor of arterial CO2 tension (PaCO2) during neurosurgery. However, the nature of the arterial-end-tidal CO2 gradient is complex, and is frequently unexpectedly large, or even negative. The importance of close intraoperative CO2 control during neurosurgery--more specifically, routine hyperventilation, and our reliance upon capnography to guide intraoperative management--is reappraised. There is a growing appreciation of the adverse effects of hyperventilation and hypocarbia, especially upon abnormal or ischaemic brain, and it is clear that capnography alone cannot be used to confidently predict the true PaCO2 during neuroanaesthesia.