Anaesthesia
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Clinical Trial
Use of the Combitube for airway maintenance during percutaneous dilatational tracheostomy.
The Combitube airway allows short-term ventilation during cardiopulmonary resuscitation and can be useful in the management of the difficult airway. In a prospective observational study we assessed its use during percutaneous dilatational tracheostomy (PDT). Twenty-one intensive care patients scheduled for elective PDT had their tracheal tube replaced by a Combitube airway retaining the same ventilator settings. ⋯ A high mean (SD) transmural pressure of 14.7 (5) kPa was exerted by the distal cuff. The Combitube provided a satisfactory alternative airway to the tracheal tube during performance of PDT in 85% of our patients. Potential problems associated with its use in intensive care patients are outlined.
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A spreadsheet model of a circle breathing system and a 70-kg anaesthetised 'standard man' has been used to simulate the first 20 min of low-flow anaesthesia with halothane, enflurane, isoflurane, sevoflurane and desflurane in oxygen. It is shown that, with the fresh-gas flow set initially equal to the total ventilation and the fresh-gas partial pressure to 3 MAC, the end-expired partial pressure can be raised to 1 MAC in 1 min with desflurane and sevoflurane, 1.5 min with isoflurane, 2.5 min with enflurane and 4 min with halothane. Sequences of lower fresh-gas flow and partial pressure settings are given for then maintaining 1 MAC end-expired partial pressure, with a minimum usage of anaesthetic, e.g. 13 ml of liquid desflurane in 20 min (of which only 33% is taken up by the patient) if the minimum acceptable flow is 11.min-1, or 8 ml (with 57% in the patient) if the minimum is 250 ml.min-1.
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Letter Case Reports
Caesarean delivery during cardiac arrest in late pregnancy.