British journal of anaesthesia
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We describe a new indicator dilution method of measuring cardiac output in man. A bolus injection of lithium chloride 0.6 mmol was given via a central venous catheter and arterial plasma [Li+] recorded using a specially developed sensor incorporating an Li(+)-selective electrode. Cardiac output was derived from the lithium dilution curve, with a correction for packed cell volume. ⋯ For each sensor, one LiDCO was measured immediately before and one immediately after three TD estimations and mean values of LiDCO and TD derived. The correlation coefficient, r, was 0.89; slope of the regression 0.84; y intercept 0.72; bias 0.3 (0.5) litre min-1 (mean (TD-LiDCO) (1 SD). LiDCO appeared to be a safe, simple and accurate technique which does not require insertion of a pulmonary artery catheter.
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We have studied the effects of bolus doses of midazolam 0.15 mg kg-1 i.v. on intracranial pressure (ICP), mean arterial pressure (MAP) and cerebral perfusion pressure (CPP) in 12 patients with severe head injury (Glasgow Coma Scale score < or = 6). The study was performed in patients aged 17-44 yr who were sedated (phenoperidine 20 micrograms kg-1 h-1) and paralysed (vecuronium 2 mg h-1). Midazolam reduced MAP from 89.0 mmHg to 75.0 mmHg (P < 0.0001), while CPP decreased from 71.0 mmHg to 55.8 mmHg (P < 0.0001). ⋯ However, when control ICP was less than 18 mmHg (n = 7 patients), an increase in ICP was observed. The remaining five patients (control ICP > or = 18 mmHg) exhibited a slight decrease in ICP. These findings suggest that bolus administration of midazolam should be performed with great caution in patients with severe head injury, especially when ICP is less than 18 mmHg.
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Randomized Controlled Trial Comparative Study Clinical Trial
Teaching fibreoptic nasotracheal intubation with and without closed circuit television.
We have compared the progress of anaesthetists taught fibreoptic nasotracheal intubation with the aid of a closed circuit television (CCTV) system with that of anaesthetists taught by traditional methods. Twenty anaesthetists were allocated randomly to either the video or traditional training group. A graduated training programme was used in which the first stage was an introduction to techniques and apparatus and the second stage was practice on an airway model. ⋯ All the video-controlled intubations were successful. There was no significant difference between the number of successful traditional intubations in the two groups (90% video, 92% traditional). CCTV appears to enhance substantially the rate of acquisition of fibreoptic nasotracheal intubation skills.
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A fault in the assembly of a Matrix Large Animal Circle anaesthetic machine resulted in reversal of fresh gas flow through the vaporizer. The fault was discovered only after the sudden development of excessive depth of anaesthesia in two equine patients. Laboratory investigations were conducted to determine the effect of flow reversal on vaporizer output. Results indicated that output concentration was approximately doubled under these conditions.
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Editorial Comment Review
Postdural puncture headache and extradural blood patch.