British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Hypotension during subarachnoid anaesthesia: haemodynamic analysis of three treatments.
We have compared three methods of preventing hypotension during subarachnoid anaesthesia. We attempted to maintain systolic arterial pressure (SAP) greater than 75% of baseline by use of i.v. fluids (preloading with normal saline 16 ml kg-1 and, if necessary, three subsequent boluses of 2.5 ml kg-1), an infusion of metaraminol titrated as necessary between 0 and 5 mg h-1 and an infusion of ephedrine titrated as necessary between 0 and 120 mg h-1. SAP and mean arterial pressure (MAP) were measured by automated oscillotonometry, central venous pressure (CVP) by a manometer and cardiac index (CI), stroke index (SI) and heart rate (HR) by transthoracic electrical bioimpedance. ⋯ The main cardiovascular change was decreased HR (15 (8)%; P = 0.0001). Ephedrine failed to maintain SAP in two of 12 patients and was accompanied by several cardiovascular changes: HR (21 (12)%; P = 0.001) increased and SI (16 (10)%; P = 0.0001), CVP (3.8 (1.5) cm H2O; P = 0.0001) and SVRI (24 (6)%; P = 0.0001) decreased. Treatment failures resulted from failures to maintain SVRI in the fluid group and CVP and SVRI in the ephedrine group.
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Randomized Controlled Trial Clinical Trial
Memory for auditory material presented during anaesthesia.
We have assessed postoperative memory for lists of 10 neutral words, presented by tape recording, in patients anaesthetized by a standardized technique comprising thiopentone 5 mg kg-1, midazolam 0.07 mg kg-1, fentanyl 3 micrograms kg-1 and 70% nitrous oxide in oxygen, using both free recall and a test in which the subject was asked to indicate the presented words from a larger list. Twenty-four patients were exposed to one of four tape-recorded lists of words and 24 were presented with a blank tape. There was no instance of free recall of presented words. Analysis of the responses in the implicit memory test revealed no difference between the performance of the patients who had been exposed to a word list and those who had not.
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Randomized Controlled Trial Clinical Trial
Hypertonic saline prehydration in patients undergoing transurethral resection of the prostate under spinal anaesthesia.
Thirty-three patients undergoing elective transurethral resection of the prostate were allocated randomly to receive either 0.9% isotonic saline 7 ml kg-1 (16 patients), or 3% hypertonic saline 7 ml kg-1 (17 patients) as a preload before spinal anaesthesia. After spinal anaesthesia, the incidence of systolic arterial pressure < 75% of control value was greater in the normal saline group than in the hypertonic saline group. Also, the mean dose of phenylephrine required to maintain arterial pressure > 75% of the baseline value was significantly greater in the normal saline group than in the hypertonic saline group.