Anaesthesia
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Historical Article
The development of appartus for intermittent negative pressure respiration.
The history of tank and cuirass respirators from the first known use of the intermittent negative pressure principle in 1832 to 1918, on the threshold of its extensive use in the treatment of respiratory paralysis, has been related. A second article will consider the period 1918 to the present day and suggest that negative pressure apparatus-particularly the cuirass respirator-still has its uses.
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Propanidid was used for the induction of anaesthesia at Caesarean section in 50 healthy mothers. All parturients were considered to have normal placental function. Anaesthesia was maintained with nitrous oxide, oxygen, muscle relaxant and controlled ventilation. ⋯ Propanidid, therefore, appeared to be associated with a greater degree of foetal acidaemia than did thiopentone. In addition, painful factual recall during surgery was encountered in 6 percent of cases. It is concluded that propanidid, although theoretically offering advantages over thiopentone to the obstetric anaesthetist, in practice, did not fulfil this promise.
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The Bain anaesthetic breathing system-a modified Mapleson 'D' circuit10-had been evaluated during anaesthesia using controlled ventilation. Results obtained from over 140 patients show that a highly predictable PaCO2 may be obtained by adjusting the fresh gas inflow according to body weight in patients weighing over 40 kg (mean PaCO2 at a fresh gas inflow of 70 ml/kg/minute=40.8 mmHg; mean PaCO2 at a fresh gas inflow of 100 ml/kg/minute=34.3 mmHg). ⋯ In addition, the circuit is lightweight, disposable but re-usable, facilitates pollution control and is easily used as an independent resuscitator. It is suggested that it may qualify as a universal breathing system.
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A simple modification of a B. O. C. slide valve is presented, for controlling the injector flow in venturi ventilation.