British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Subarachnoid anaesthesia: comparison of hyperbaric solutions of bupivacaine and amethocaine.
Hyperbaric solutions of 0.5% bupivacaine and 0.5% amethocaine (2 and 3 ml) were compared in a double-blind study of 40 patients receiving subarachnoid anaesthesia for urological surgery. The drugs produced similar and satisfactory analgesia in the tested concentrations and volumes. Motor blockade was more profound and longer lasting with amethocaine.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of bupivacaine and etidocaine in extradural blockade.
In a randomized, double-blind study, 40 female patients underwent major gynaecological surgery with extradural anaesthesia provided by 0.75% bupivacaine, 0.75% bupivacaine with adrenaline 5 micrograms ml-1, 1.5% etidocaine or 1.5% etidocaine with adrenaline 5 micrograms ml-1, 20 ml in each case. In all patients the resultant blockade was suitable for intra-abdominal pelvic surgery. Mean maximum spread of analgesia was around T3/4 with all four drugs. ⋯ There were no differences in the durations of motor blockade. Objective measurements of the duration of sensory blockade showed that there were no differences between the drugs and that the addition of adrenaline increased the duration of blockade. However, pain returned sooner following etidocaine than bupivacaine, and the additive effect of adrenaline was to increase this period of subjective analgesia.
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Intrathecal morphine was given to 56 children undergoing open-heart surgery. The first 27 patients received 0.03 mg kg-1 and the other 29 received 0.02 mg kg-1. Satisfactory postoperative analgesia, lasting for 22 h or longer, was obtained in over 60% of the patients in each group. Respiratory depression occurred in six of the first group (0.03 mg kg-1), and three in the second (0.02 mg kg-1), most frequently between 3.5 and 4.5 h after the administration of the intrathecal morphine.
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Using the single breath test for carbon dioxide (SBT-CO2), the components of physiological deadspace were investigated during anaesthesia with IPPV in 58 patients. A square-wave inspiratory flow and an end-inspiratory pause (25% and 10% of cycle time, respectively) were used. At tidal volumes of 0.45 litre (f = 17 b.p.m.), and 0.75 litre (f = 9 b.p.m.), median values for VDphys/VT were 0.44 and 0.31. ⋯ The median arterial--end-tidal PCO2 difference, (PaCO2-PE'CO2), was 0.6 kPa at small and 0.3 kPa at large tidal volumes (P less than 0.001). Three patients had zero and four had negative (PaCO2-PE'CO2) values at large tidal volumes. When phase III slopes steeply, negative (PaCO2-PE'CO2) values may be observed in the presence of alveolar deadspace.
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Prolonged anaesthesia with nitrous oxide inactivates vitamin B12 and impairs DNA synthesis in bone marrow cells. The use of parenteral folinic acid in the prevention of these toxic effects has been studied in 11 patients, ventilated artificially with nitrous oxide in oxygen for 24 h. ⋯ They were assessed morphologically and with the deoxyuridine suppression test. Folinic acid 30 mg immediately before anaesthesia and 30 mg 12 h later, prevented the toxic effects of nitrous oxide in four out of five patients, whereas smaller amounts of folinic acid (between 3 and 36 mg in 24 h), were ineffective.