Anaesthesia and intensive care
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Anaesth Intensive Care · Oct 2000
Effects of the laryngeal mask airway on the lower oesophageal barrier pressure in children.
The effects of laryngeal mask airway (LMA) insertion and cuff inflation on lower oesophageal sphincter, gastric and barrier pressure, and the relationship of the LMA cuff pressure and volume on the change in the barrier pressure were studied in 20 children. Subjects were aged one to five years, undergoing eye examination under general anaesthesia. There was no significant change in barrier pressure after insertion and inflation of the LMA compared with baseline measures. ⋯ Two patients had marked decreases (10 to 15 mmHg) in barrier pressure after the LMA insertion. These decreases in barrier pressure would be expected to increase the risk of gastro-oesophageal reflux. We conclude that, although LMA use had little effect on barrier pressure in most children, occasional children will have potentially clinically significant decreases in barrier pressure with use of the LMA.
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Anaesth Intensive Care · Aug 2000
Electroencephalographic indices related to hypnosis and amnesia during propofol anaesthesia for cardioversion.
Most previous studies which have assessed the depth of anaesthesia using the Bispectral Index (BIS) have used multi-agent anaesthetics with relatively slow induction and recovery times. Elevation of electroencephalographic (EEG) Beta/Alpha Ratio has been linked to onset of midazolam amnesia. Propofol anaesthesia for cardioversion in 19 patients enabled us to profile the changes in BIS and Beta/Alpha Ratio during a short, single-agent anaesthetic with a relatively rapid induction and recovery period. ⋯ An early EEG Beta/Alpha Ratio peak occurred at a mean of 4.6 s (SD = 16.6) after clinical amnesia onset and a late peak at a mean 58 s (SD = 144) after eye opening. There was no significant EEG response to cardioversion. We conclude that: (1) in rapidly changing conditions, the value of the BIS most accurately reflects the level of consciousness of the patient about 60 s in the past, and (2) the onset and offset of propofol-induced amnesia commonly corresponds to a peak in Beta/Alpha Ratio of the EEG.
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Anaesth Intensive Care · Aug 2000
Randomized Controlled Trial Clinical TrialPostoperative sore throat and hoarseness following tracheal intubation using air or saline to inflate the cuff--a randomized controlled trial.
Sore throat and hoarseness following tracheal intubation is common. The aetiology may include high tracheal cuff pressures. We performed a double-blind, randomized controlled trial in 126 intubated patients to compare the incidence and severity of sore throat and hoarseness following inflation of the cuff using air or saline. ⋯ There was no statistically significant difference between the groups (air 15.9%, saline 14.5%). In the air group mean intra-cuff pressure increased significantly (start 14.0 mmHg, end 40.9 mmHg), while in the saline group there was no significant increase (start 12.7 mmHg, end 14.6 mmHg). The substitution of saline reliably results in sustained low intra-cuff pressures but high tracheal cuff pressure is not an important factor in the development of sore throat or hoarseness postoperatively within the pressure range and duration of operation studied.
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Anaesth Intensive Care · Aug 2000
Randomized Controlled Trial Clinical TrialPre-emptive analgesia with epidural morphine or morphine and bupivacaine.
Studies of preemptive analgesia in humans have shown conflicting results. The study design, patient population and the duration of assessment of postoperative pain are important in the evaluation of preemptive analgesia. We carried out a prospective, randomized, double-blind controlled study in 80 patients of physical status ASA 1-3 undergoing upper abdominal and thoracic surgery. ⋯ Pre MB compared to Pre M had significantly decreased total postoperative morphine requirements (P < 0.0001) and number of top-ups (P < 0.0001). Epidural morphine plus bupivacaine is effective as a preemptive analgesic. Morphine plus bupivacaine has better efficacy than morphine given alone before the induction of anaesthesia.
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Anaesth Intensive Care · Aug 2000
Randomized Controlled Trial Clinical TrialEffect of bolus dose of remifentanil on haemodynamic response to tracheal intubation.
A randomized placebo-controlled double-blinded study was conducted in 40 ASA 1 and 2 patients to determine the dose response of remifentanil in attenuating the haemodynamic response to tracheal intubation. Patients were allocated to one of four groups: placebo, remifentanil 1 microgram.kg-1, remifentanil 2 micrograms.kg-1 and remifentanil 4 micrograms.kg-1. A propofol target-controlled infusion was started at 4 micrograms.ml-1 and incrementally titrated to loss of verbal contact. ⋯ Systolic blood pressure following intubation increased by 30% in the placebo group, 10% in the 1 microgram.kg-1 group and remained unchanged in the 2 micrograms.kg-1 and 4 micrograms.kg-1 groups. Remifentanil 1 microgram.kg-1 attenuated the rise in heart rate and systolic blood pressure. Remifentanil 2 micrograms.kg-1 blocked the haemodynamic response completely: no further benefit was shown from increasing the dose to 4 micrograms.kg-1.