British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Extradural clonidine infusions for analgesia after total hip replacement.
We have examined the effectiveness of extradural clonidine infusions for postoperative analgesia and the effect of clonidine on extradural morphine. In a double-blind, controlled study, patients, undergoing total hip replacement were allocated randomly to receive one of two doses of extradural clonidine (25 micrograms h-1 or 50 micrograms h-1), low dose extradural morphine or a combination of morphine and clonidine. ⋯ Arterial pressure was reduced in the clonidine groups, although the incidence of clinical hypotension was low. There were no significant differences between the groups in emetic symptoms or urinary retention.
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Randomized Controlled Trial Clinical Trial
Myocardial depressant effect of nitrous oxide after coronary artery bypass graft surgery.
We have studied the cardiovascular effects of nitrous oxide after cardiac ischaemia-reperfusion injury caused by aortic cross-clamping and unclamping during coronary artery bypass grafting (CABG). At the time of chest closure, 20 patients were allocated randomly to receive oxygen and air (FIO2 = 0.5) or 50% nitrous oxide in oxygen in addition to anaesthesia with fentanyl. Nitrous oxide significantly decreased mean arterial pressure (P less than 0.01) and cardiac index (P less than 0.05), which suggests that nitrous oxide with fentanyl may significantly depress left ventricular performance after CABG. Although ischaemia-reperfusion cardiac injury did not appear to increase the myocardial depressant effect of nitrous oxide, the use of nitrous oxide is not recommended immediately after CABG.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of pre- vs postoperative inguinal field block on postoperative pain after herniorrhaphy.
The analgesic effects of an identical inguinal field block, performed before or immediately after inguinal herniorrhaphy, were evaluated in 32 healthy patients in a double-blind, randomized study. During surgery, all patients received a light general anaesthesia with thiopentone, alfentanil and nitrous oxide in oxygen. After induction of general anaesthesia, patients were allocated randomly to receive an inguinal field block with lignocaine, either 15 min before operation or immediately after operation, after closure of the surgical wound, but before the patients were awake. ⋯ No significant differences between the groups were observed in VAS scores or verbal pain scores during rest or ambulation at any time. There was no significant difference in time to first request for morphine or total morphine consumption. These results do not show pre-emptive analgesia with a conventional inguinal field block to be of clinical importance compared with a similar block administered after operation.
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Randomized Controlled Trial Clinical Trial
Rapid administration of crystalloid preload does not decrease the incidence of hypotension after spinal anaesthesia for elective caesarean section.
Twenty parturients undergoing elective Caesarean section were allocated randomly to receive crystalloid preload 20 ml kg-1 over either 20 min or 10 min before spinal anaesthesia. Significant hypotension (systolic arterial pressure less than 100 mm Hg and less than 80% of baseline value) occurred in six of the 10 patients in the 20-min preload group and seven of 10 patients in the 10-min preload group (ns). ⋯ Three patients in the 10-min group had clinically unacceptable increases in central venous pressure. This study has demonstrated that rapid administration of crystalloid preload before spinal anaesthesia did not decrease the incidence or severity of hypotension, and questions the role of crystalloid preload.
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Comparative Study
Response of 10 pulse oximeters to an in vitro test system.
Pulse oximeters are often used in situations in which severe hypoxaemia may occur. We have developed an in vitro system to test the accuracy of pulse oximeter calibration. ⋯ The oximeters tested varied widely in their accuracy and linearity. We conclude that the system can test the accuracy, reproducibility and linearity of response of pulse oximeter readings at low oxyhaemoglobin saturations.