Anaesthesia and intensive care
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Anaesth Intensive Care · May 1992
Randomized Controlled Trial Comparative Study Clinical TrialThe addition of pethidine to epidural bupivacaine in labour--effect of changing bupivacaine strength.
The effects of varying the strength of bupivacaine used in epidurals for the relief of labour pain was examined. The trial randomly allocated sixty women in the first stage of labour to one of three groups. All women were of ASA status 1 or 2 and had uncomplicated pregnancies. ⋯ This study suggests that when epidural pethidine 25 mg is added to local anaesthetic solutions of bupivacaine, adequate analgesia for the first stage of labour is achieved with the 0.125% bupivacaine solution. The use of stronger solutions of bupivacaine achieves no greater degree of analgesia nor longer duration of action, although the onset of analgesia may be faster with the stronger solutions. Further investigations are needed to determine if 25 mg of pethidine is the best choice of dose to use under these circumstances.
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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 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
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).