Anaesthesia
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Randomized Controlled Trial Clinical Trial
Delayed ACTH response to human corticotropin releasing hormone during cardiopulmonary bypass under diazepam-high dose fentanyl anaesthesia.
The inhibitory effect of high dose fentanyl (0.1 mg.kg-1) and diazepam (0.5 mg.kg-1) anaesthesia on the pituitary-adrenal response to coronary artery surgery during cardiopulmonary bypass was assessed by comparison of the adrenocorticotropic hormone and cortisol responses to intravenous boluses of either 0.1 mg (n = 14) or 0.2 mg (n = 14) human corticotropin releasing hormone administered 5 min after starting cardiopulmonary bypass, with the responses obtained in a control group (n = 14). Blood samples were taken before inducing anaesthesia, just before cardiopulmonary bypass and at 5, 20, 35, 50, 65 and 80 min thereafter. ⋯ Plasma cortisol concentrations did not vary between the three groups at any sampling time. During cardiopulmonary bypass the early adrenocorticotropic responses to human corticotropin releasing hormone are blunted but later there is a good response, suggesting that the inhibitory effect of high dose fentanyl and diazepam anaesthesia takes place in the hypothalamus.
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Randomized Controlled Trial Clinical Trial
Teaching fibreoptic intubation. Effect of alfentanil on the haemodynamic response.
A technique for teaching fibreoptic orotracheal intubation in patients under general anaesthesia is described and evaluated. A standard general anaesthetic was administered to 60 patients presenting for elective gynaecological surgery. Patients were randomly assigned to receive either alfentanil 10 micrograms.kg-1 or a placebo, and to be intubated either by a consultant experienced in the use of the fibreoptic bronchoscope or by an inexperienced trainee under instruction. ⋯ The hypertensive response to fibreoptic intubation was suppressed in those patients who received alfentanil (p < 0.001). The increase in heart rate was not suppressed, but was attenuated when these patients were compared with those who had received the placebo (p < 0.001). Alfentanil 10 micrograms.kg-1 minimises the haemodynamic response when teaching fibreoptic orotracheal intubation under general anaesthesia.
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Randomized Controlled Trial Comparative Study Clinical Trial
A comparison of different modes of noninvasive ventilatory support: effects on ventilation and inspiratory muscle effort.
The aims of noninvasive ventilation include the correction of hypoventilation and unloading of inspiratory muscles. Volume cycled flow generators, bi-level positive airway pressure and continuous positive airway pressure techniques have all been used with face and nasal masks. We have compared these modes of ventilatory support, administered by a nasal mask in stable, awake outpatients with chronic obstructive pulmonary disease or neuromusculo-skeletal disease in respect of their effects on ventilation, inspiratory muscle effort and oxygen saturation. ⋯ Only the volume cycled flow generator increased minute ventilation significantly. Ventilation and inspiratory muscle effort were unaffected by continuous positive airway pressure but oxygen saturation was lower than during spontaneous ventilation. In awake, stable outpatients acclimatised to nasal ventilation there were no clinically significant differences between volume cycled flow generator and bi-level positive airway pressure techniques, but continuous positive airway pressure was less effective.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intra-ocular pressure during cardiopulmonary bypass--a comparison of crystalloid and colloid priming solutions.
Raised intra-ocular pressure secondary to alterations in plasma oncotic pressure has been implicated in the development of optic neuropathy after cardiopulmonary bypass. Patients presenting for open heart surgery received either crystalloid (n = 9) or colloid (n = 10) priming solutions for cardiopulmonary bypass. No differences in intra-ocular pressure or plasma oncotic pressure occurred between the groups before the onset of cardiopulmonary bypass. ⋯ At the same time plasma oncotic pressure decreased from approximately 20 mmHg in both groups to 10.6 mmHg with crystalloid and 15.7 mmHg with colloid primed cardiopulmonary bypass solutions (p < 0.05). Over the following hour of cardiopulmonary bypass, intra-ocular pressure and plasma oncotic pressure tended to return towards their pre-cardiopulmonary bypass values. Changes in plasma oncotic pressure, through fluid shifts, may have contributed towards this unexpected increase in intra-ocular pressure with crystalloid primed cardiopulmonary bypass.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intra-operative patient-controlled sedation and patient attitude to control. A crossover comparison of patient preference for patient-controlled propofol and propofol by continuous infusion.
Intra-operative patient controlled sedation with propofol (bolus dose 18 mg over 5.4 s; lockout period 1 min) has been compared to continuous propofol infusion (3.6 mg.kg-1.h-1) in a randomised crossover study of 38 ASA 1 or 2 day surgery patients undergoing two-stage bilateral extraction of third molar teeth under local anaesthesia (76 procedures). Mean (SD) propofol used (mg.kg-1) was less with patient-controlled sedation (2.39 (1.28) than with the infusion (2.58 (0.84)) but the difference was not statistically significant. There were only minor differences between the methods in postoperative recovery of cognitive function and no differences for patient cooperation and surgeon's satisfaction with sedation. ⋯ Sedation was no deeper than eyelid closure with response to command in all 76 procedures. This level was reached in all 38 infusion cases but in only 26 cases with patient-controlled sedation, where 12 patients remained less sedated (p < 0.01). Patient-controlled sedation with propofol provided safe sedation and was strongly preferred over the infusion by a large proportion of patients.