British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Comparison of the maternal and fetal effects associated with intermittent or continuous infusion of extradural analgesia.
Eighty normal primigravidae received an extradural dose of 0.25% bupivacaine and were then allocated randomly to receive "top-ups" of 0.25% bupivacaine (group A) or an infusion of 0.125% bupivacaine (group B). Group B received supplementary top-ups if required. Group A required more top-ups (147 vs 80) (P < 0.01). ⋯ More episodes in group A were related to top-ups (42/71 vs 18/69; P < 0.01) but the incidence of episodes after a top-up was similar (group A, 42/147 (28.6%); group B, 18/80 (22.5%)). In group A, 31/42 events (73.8%) were transient compared with 11/18 persistent episodes (61.1%) (> 10 min duration) in group B. However, the difference in the deceleratory patterns did not influence the condition of the fetuses at delivery.
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The postoperative period after major abdominal surgery is known to be a period of increased episodic oxygen desaturation. In order to assess the risk factors for episodic desaturation, we have studied 29 surgical patients using pulse oximetry during the preoperative night (Npre) when they received benzodiazepine premedication and breathed air, and also during the first three nights after operation when they received nasal oxygen supplementation. Modal oxygen saturation (SpO2) exceeded 95% during all nights studied. ⋯ At the same time, t90 and t85 correlated with body mass index (P = 0.02 and P = 0.05, respectively). During N2, t90 correlated with radiological lung consolidation (P = 0.05) and SpO2, nadir correlated with FEV1 (P = 0.03). We conclude that there are several mechanisms responsible for oxygen desaturation and that these mechanisms differ before and after surgery.
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The thrombelastograph (TEG) and bleeding time were performed before and 6 h after a single oral dose of aspirin 600 mg in a group of eight healthy volunteers and 12 pregnant patients. Measured TEG variables (r, k, r+k times and maximum amplitude) were unaltered after aspirin although there was a significant prolongation of the bleeding time in both groups. Although the TEG appeared not to detect aspirin-induced changes in platelet function, the TEG measures all phases of coagulation and the unaltered TEG after aspirin suggested a functioning coagulation system.
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Randomized Controlled Trial Clinical Trial
Learning during general anaesthesia: implicit recall after methohexitone or propofol infusion.
Forty-four patients undergoing coronary artery surgery were allocated randomly to receive an infusion of propofol or methohexitone as a hypnotic supplement to a fentanyl-based anaesthetic technique. A taped message was played to the patients, consisting of 10 words associated with prompt sentences and a suggestion for a specific postoperative behavioural response. Twenty patients (10 propofol and 10 methohexitone) (perioperative group) were exposed to the taped message during surgery and in the immediate postoperative period and the other 24 patients (postoperative group) were exposed to the tape only in the postoperative period, after return to the intensive care unit (ICU). ⋯ The patients who were played the tape whilst receiving identical infusion regimens for sedation in the ICU did not demonstrate implicit recall of the word associations in either the propofol or the methohexitone groups. There was no evidence of a response to the specific behavioural suggestion during the postoperative interview. The results confirm that auditory perception can occur during clinically adequate anaesthesia, and that suppression of auditory awareness or learning is a function of both the pharmacological degree of sedation and the degree of surgical stimulation.