British journal of anaesthesia
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A vaporizing system for closed circuit "programmed" anaesthesia is described. Despite its location within the circuit, the vaporizer controls directly the input of volatile anaesthetic agents irrespective of fluctuations in ventilation of the anaesthetized subject. It is interfaced easily with electronic controllers and has an accuracy approaching 1.0% under laboratory conditions. During experimental anaesthesia, it maintained stable end-tidial concentrations of halothane at 1.2 MAC (the intended value) despite wide variations in ventilation.
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Biography Historical Article
A history of nitrous oxide and oxygen anaesthesia. IVC: Henry Hill Hickman in his time.
Previous verdicts on Hickman set the scene. The genealogy of Hickman and his wife is explored, disclosing the identities of "Poor Mrs Dudley of Shut End" and "Thomas Dudley of Kingswinford". Some previous evidence is explained by the bankruptcy of Hickman's father-in-law. The dubious means whereby Hickman qualified prematurely are examined.
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The trachea of a man who had cut his own throat was successfully intubated using a fibreoptic laryngoscope after attempts at conventional oral intubation had failed. The advantages of the fibreoptic instrument and the method of use in such an injury are discussed.
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Comparative Study
A method for comparing endotracheal cuffs. A controlled study of tracheal trauma in dogs.
Damage to the trachea produced in dogs by large and small residual volume cuffs during 6 h of IPPV was compared using a specially designed endotracheal tube. The cuffs under evaluation were adjusted to exert similar average pressures on the tracheal wall, so that many of the variables believed responsible for tracheal injury were controlled. ⋯ The maximum estimated pressure transmitted to the tracheal wall, derived from these compliance curves, was found to equal the peak airway pressure in the presence of a small air leak past each cuff. At various tracheal wall pressures there were only very minor differences in tracheal damage between the large and small residual volume cuffs tested.
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The minimum resistance of expiratory Heidbrink-type value has been assessed by determining the pressure decrease across the values at a flow rate of 30 litre min--1. The average resistance of 70 valves currently in clinical use was 318 Pa at that flow rate and about 44% had resistances greater than the limit of 294 Pa previously suggested. The resistances obtained in new valves were either similar or fractionally greater. Valves being introduced as parts of scavenging systems appeared, on the whole, to have lower resistances.