British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Influence of dose and timing of administration of morphine on postoperative pain and analgesic requirements.
In a randomized, double-blind study, we have investigated the effect of dose and timing of administration of morphine on postoperative pain and analgesic requirements in 60 patients undergoing hysterectomy, with or without salpingo-oophorectomy. Patients were allocated randomly to one of three groups: during standardized general anaesthesia, group post received morphine 0.15 mg kg-1 i.v. at peritoneal closure after hysterectomy; group pre-low received morphine 0.15 mg kg-1 on induction of anaesthesia; and group pre-high received morphine 0.3 mg kg-1 on induction of anaesthesia. ⋯ Pain scores (at rest and on movement) were similar in the three groups. A large dose of morphine 0.3 mg kg-1 i.v. on induction of anaesthesia significantly reduced postoperative PCA morphine requirements compared with the smaller dose (0.15 mg kg-1) administered at induction or peritoneal closure, in patients undergoing hysterectomy, with or without salpingo-oophorectomy.
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Clinical Trial Controlled Clinical Trial
Laryngeal mask airway performance: effect of cuff deflation during anaesthesia.
We studied the effect of deflating the laryngeal mask airway (LMA) cuff in situ on recorded respiratory tidal ventilation in 30 spontaneously breathing anaesthetized patients. Another 26 patients were studied in whom the LMA cuff was undisturbed. ⋯ Complete cuff deflation, however, resulted in a 17% decrease in mean tidal ventilation (P < 0.05), with two patients (6%) demonstrating a substantial leak around the cuff and airway obstruction. The practice of complete cuff deflation during the recovery period from anaesthesia cannot be recommended.
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It has been suggested that haemodilution with saline may increase whole blood coagulation. This study was conducted in two parts. First, we investigated the effect of in vitro dilution of blood with saline on whole blood coagulation as measured by the thrombelastogram (TEG). ⋯ The r time, k time and r + k time were decreased relative to control in both diluent groups. The alpha angles were increased compared with control in both groups while maximum amplitude was unchanged in the Haemaccel diluted group. We conclude that haemodilution per se increases the coagulability of whole blood in vitro, but that saline haemodilution has a more marked effect on final clot strength.
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We have compared cardiorespiratory variables in anaesthetized piglets whose lungs were ventilated with oxygen in nitrous oxide (N2O group) or nitrogen (N group) after right ventricular carbon dioxide boluses (0.5 or 1 ml kg-1; n = 12) or slow graded injections (n = 6). Boluses affected all variables studied significantly (P < 0.05) except mean systolic arterial pressure. Significant changes in PE'CO2 (P = 0.012) and PaO2 (P = 0.048) values were observed in the N2O group. ⋯ Volumes and time required to induce a 50% increase in mean pulmonary arterial pressure differed significantly between groups (P < 0.05). We conclude that nitrous oxide worsened the effects of rapid and slow carbon dioxide emboli on cardiopulmonary variables. Rapid carbon dioxide embolism altered respiratory and haemodynamic variables, while slow carbon dioxide embolism changed only respiratory variables.