Anaesthesia and intensive care
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Anaesth Intensive Care · May 1992
Prediction of difficult laryngoscopy: an assessment of the thyromental distance and Mallampati predictive tests.
Two hundred and fifty patients were assessed preoperatively using the Mallampati classification and by measuring their thyromental distances. The ease or difficulty of direct laryngoscopy was assessed at the time of induction of anaesthesia. ⋯ It was found that both assessments predicted less than two in three difficult laryngoscopies and had high false positive rates. It was found that external laryngeal pressure often improved the view of the glottis in difficult laryngoscopies.
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Intradermal testing and RIA testing for specific IgE antibodies to neuromuscular blocking drugs (NMBDs) were performed in patients referred to an Anaesthetic Allergy Clinic. Six patients were initially investigated four to 29 years after clinical anaphylaxis during anaesthesia and two of these patients and sixteen others were investigated by intradermal testing on two occasions at least four years apart. Seven patients had RIA tests for NMBD-specific IgE antibodies on two occasions at the time of skin testing. ⋯ In one patient all tests became negative and in another the skin test became negative but the positive RIA persisted. Evidence of antibodies to NMBDs persisted in 21 of 22 patients who had had anaphylactic reactions to these drugs during anaesthesia. In the absence of evidence of allergy diminishing with time in the majority of patients it would seem wise to avoid drugs responsible for reactions for the rest of the patient's life.
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Anaesth Intensive Care · May 1992
The effects of oxytocin on the pulmonary and systemic circulation in pregnant ewes.
The haemodynamic effects of oxytocin on the pulmonary and systemic circulation were studied in six awake, pregnant (greater than 140 days gestation) ewes. Bolus doses of oxytocin 0.2 units/kg and then 0.8 units/kg were administered. A dose of 0.2 units/kg resulted in small but significant increases in mean pulmonary artery pressure (14%, P less than 0.05) and pulmonary vascular resistance (24%, P less than 0.05. ⋯ Acute pulmonary hypertension was then induced with glass bead microemboli (150-200 microns), with an increase in pulmonary artery pressure of 26 mmHg and pulmonary vascular resistance of 448 dyn. s. cm-5. Boluses of oxytocin 0.2 and 0.8 units/kg were then administered. There were no significant changes, except for a 30% increase in systemic vascular resistance at one minute after oxytocin, 0.8 units/kg (P less than 0.05).
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Anaesth Intensive Care · May 1992
The relationship between a person's height and appropriate endotracheal tube length.
The relationship between a person's height and the dimensions of that person's upper airways has been studied in adult subjects. Using this relationship, formulae have been derived which predict appropriate lengths for endotracheal tubes. The formulae are as follows: 1. ⋯ Orotracheal tube (teeth to mid-point of trachea + 3 cm) = Subject height (cm)/10 + 5 3. Nasotracheal tube (external naris to mid-point of trachea) = Subject height (cm)/10 + 8 These formulae are not foolproof but provide a useful working guide. All usual comfirmatory tests of correct placement should be employed.
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Anaesth Intensive Care · May 1992
Propofol is a 'safe' anaesthetic agent in malignant hyperthermia susceptible patients.
In this study we investigated in vitro and in vivo effects of propofol in malignant hyperthermia susceptible (MHS) patients in order to assess the safety of propofol infusion as a non-triggering anaesthetic technique for diagnostic and therapeutic procedures. In vitro, human MHS muscle samples were exposed to propofol and changes in (a) baseline tension and (b) contracture tension on exposure to halothane and caffeine were measured. In vivo, (a) anaesthesia was induced in ten muscle biopsy positive MHS patients with propofol 2.5 mg/kg and (b) anaesthesia was produced in five muscle biopsy positive MHS patients with infusions of propofol up to 10 mg/kg/hr. ⋯ In vivo, no evidence of an MH response was detected following induction or maintenance of anaesthesia with propofol. Our results and literature review are in agreement that propofol is a 'safe' induction and maintenance agent in MHS patients. Propofol can be used for muscle biopsy anaesthesia because it does not alter the sensitivity of diagnostic muscle biopsy testing.