British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Cricoid pressure impedes placement of the laryngeal mask airway and subsequent tracheal intubation through the mask.
We have studied 40 patients to see if cricoid pressure affects the success rate of ventilation through, and the position of, the laryngeal mask and subsequent fiberscope-aided tracheal intubation. Adequate ventilation of the lungs was produced through the laryngeal mask in 19 of 20 patients in the control group, but in only 10 of 20 patients in the cricoid pressure group (P < 0.002). ⋯ Release of cricoid pressure after placement of the laryngeal mask improved the view of the glottis, but tracheal intubation was still difficult because of laryngeal deviation. These results show that cricoid pressure impedes placement of the laryngeal mask and subsequent fiberscope-aided tracheal intubation.
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Randomized Controlled Trial Clinical Trial
MAC reduction of isoflurane by sufentanil.
We have shown previously that a plasma fentanyl concentration of 1.67 ng ml-1 reduced the MAC of isoflurane by 50%. By comparing equal degrees of MAC reduction by sufentanil, we may determine the potency ratio of these opioids. Seventy-six patients were allocated randomly to receive predetermined infusions of sufentanil, and end-tidal concentrations of isoflurane in oxygen. ⋯ The MAC reduction of isoflurane produced by sufentanil was obtained using a logistic regression model. A sufentanil plasma concentration of 0.145 ng ml-1 (95% confidence limits 0.04, 0.26 ng ml-1) resulted in a 50% reduction in the MAC of isoflurane. At a plasma concentration greater than 0.5 ng ml-1, sufentanil exhibited a ceiling effect.
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Randomized Controlled Trial Clinical Trial
Retrobulbar block fails to prevent an increase in serum cortisol concentration on emergence from anaesthesia after cataract surgery.
We have studied 30 elderly patients undergoing cataract surgery, allocated randomly to receive general anesthesia, local anaesthesia by retrobulbar block or general anaesthesia combined with retrobulbar block given after induction. Retrobulbar block alone prevented the increases in circulating cortisol and glucose values which occurred in those patients receiving general anaesthesia alone. Retrobulbar block given after induction of general anaesthesia, however, suppressed the cortisol and glucose response during surgery, but did not prevent a marked increase in cortisol concentrations during the immediate postoperative period. The results suggest a hormonal response to emergence from anaesthesia which has hitherto been masked by the stress response to surgery itself.
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Randomized Controlled Trial Comparative Study Clinical Trial
Diamorphine-bupivacaine mixture compared with plain bupivacaine for analgesia.
We have studied the efficacy of two extradural infusions (10 ml h-1) in 50 patients in active labour. Patients in the diamorphine group (n = 25) received 0.0625% plain bupivacaine 6.25 mg h-1 mixed with 0.005% diamorphine 0.5 mg h-1 and those in the control group (n = 25) received 0.125% plain bupivacaine 12.5 mg h-1. ⋯ There were no differences in the incidence of hypotension, instrumental vaginal delivery, number of "top-ups", duration of the second stage or extent of motor block. However, patients in the diamorphine group had a high incidence of pruritus (44%, compared with 0% in the control group (P < 0.01)).