Anaesthesia
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An investigation of end-tidal carbon dioxide tension changes was carried out in 19 healthy adult patients undergoing laparoscopic cholecystectomy. Following induction of anaesthesia, and throughout surgery, the end-tidal carbon dioxide tension was continuously monitored by capnography. ⋯ Correlation of the individual maximum end-tidal carbon dioxide tension during laparoscopy with the corresponding baseline value prior to carbon dioxide insufflation showed a positive linear relationship (correlation coefficient 0.86). The correlation showed that an end-tidal carbon dioxide tension of 5.32 kPa (40 mmHg) can be achieved during laparoscopy when the baseline value is adjusted to around 4.0 kPa (30 mmHg).
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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-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.
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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.