British journal of anaesthesia
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Comparative Study
An alternative method of increasing PCO2 using apnoea and continuous positive airway pressure.
We have examined the use of continuous positive airway pressure (CPAP) and apnoeic oxygenation for restoration of spontaneous breathing at the end of anaesthesia after controlled ventilation. We studied 45 adult patients without a history of acute or chronic respiratory disturbances. Anaesthesia was induced with thiopentone or propofol and maintained with nitrous oxide and enflurane in oxygen. ⋯ All patients were well oxygenated (PO2 mean 43.5 kPa, range 21-76 kPa) when spontaneous ventilation started. The pH was close to 7.28 in most cases (mean 7.28, range 7.21-7.32), and PCO2 varied in the range 6.6-9.9 kPa (mean 7.9 kPa). It is concluded that the method is safe with regard to oxygenation and acid-base balance.
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Review Comparative Study
The value of pre-emptive analgesia in the treatment of postoperative pain.
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Comparative Study
Comparison of in vitro contracture testing with ryanodine, halothane and caffeine in malignant hyperthermia and other neuromuscular disorders.
In vitro exposure of living skeletal muscle to ryanodine has been proposed as a potentially specific test for malignant hyperthermia (MH). In this study we have compared in vitro contracture responses to halothane, caffeine and ryanodine in skeletal muscle specimens obtained from 155 patients attending for diagnosis of susceptibility of MH and also from six patients having muscle biopsy for diagnosis of other neuromuscular disorders. Although the ryanodine contracture test was not specific for MH, the results suggest it may greatly aid (in conjunction with the standard halothane and caffeine contracture tests) the accurate phenotyping of individuals that is essential for the further genetic analysis of MH.
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We have examined the prolongation of a maintenance dose of vecuronium after an intubating dose of pipecuronium in 45 patients who received either pipecuronium 70 micrograms kg-1 or vecuronium 200 micrograms kg-1 i.v. for tracheal intubation, followed by either pipecuronium 10 micrograms kg-1 or vecuronium 15 micrograms kg-1 for maintenance of neuromuscular block. The duration of the vecuronium maintenance dose was greater after pipecuronium (40 (SD 12) min) than after vecuronium (29 (9) min) (P = 0.02). The duration of pipecuronium after pipecuronium (49 (15) min) was similar to that of vecuronium after pipecuronium. We conclude that the duration of action of vecuronium is prolonged by prior administration of pipecuronium.
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We have studied the automatic administration of alfentanil during alfentanil-nitrous oxide anaesthesia in 11 patients using a closed-loop feedback control system based on EEG analysis. We chose a median EEG frequency of 2-4 Hz as the EEG set point. ⋯ The average effective therapeutic infusion of alfentanil was 0.140 (0.032) mg min-1. We conclude that EEG feedback control may be useful in assessing and defining the dose requirements of alfentanil.