British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
A low concentration of nitrous oxide reduces dyspnoea produced by a combination of hypercapnia and severe elastic load.
We have measured how a low concentration of nitrous oxide affected respiratory sensation and ventilation. Severe dyspnoea was induced in nine normal subjects by a combination of hypercapnia and inspiratory elastic load (50 cm H2O litre-1). Subjects were asked to rate their sensation of respiratory discomfort using a visual analogue scale (VAS) while breathing either 20% nitrous oxide or 20% nitrogen gas mixture. ⋯ Inhalation of 20% nitrous oxide reduced the sensation of respiratory discomfort from a median VAS score of 6.5 (range 5.0-8.1) before inhalation to 3.6 (2.4-5.9) during inhalation (P < 0.05). There was no significant change in minute ventilation but tidal volume increased during inhalation of 20% nitrogen did not alter VAS scores or ventilatory variables. We found that a low concentration of nitrous oxide greatly alleviated the intensity of dyspnoea without changing respiratory load compensation.
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Randomized Controlled Trial Clinical Trial
Ketoprofen, diclofenac or ketorolac for pain after tonsillectomy in adults?
We have compared the analgesic and opioid sparing effect of three i.v. non-steroidal anti-inflammatory drugs with placebo in a randomized, double-blind, placebo-controlled study in 80 adult patients after elective tonsillectomy. A standard anaesthetic was used. After induction of anaesthesia, patients received ketoprofen 100 mg, diclofenac 75 mg or ketorolac 30 mg by i.v. infusion over 30 min. ⋯ The incidence of nausea was 44-54%. There were no differences in the incidence of other adverse reactions. We conclude that all three non-steroidal anti-inflammatory drugs were superior to placebo after tonsillectomy.
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The potential for serious complications after venous air embolism and successful malpractice liability claims are the principle reasons for the dramatic decline in the use of the sitting position in neurosurgical practice. Although there have been several studies substantiating the relative safety compared with the prone or park bench positions, its use will continue to decline as neurosurgeons abandon its application and trainees in neurosurgery are not exposed to its relative merits. How can individual surgeons continue to use this position? Will individual, difficult surgical access cases be denied the obvious technical advantages of the sitting position? Limited use of the sitting position should remain in the neurosurgeon's armamentarium. ⋯ Measures to minimize hypotension associated with the sitting position include a slow, staged positioning over 5-10 min and use of the 'G suit' inflated with compressed air applied to the lower extremities and pelvis. Use of the sitting or upright position for patients undergoing posterior fossa and cervical spine surgery presents unique challenges for the anaesthetist. With appropriate patient selection and preparation, and using prudent intraoperative monitoring and anaesthetic techniques, selected patients should still benefit from the optimum access to mid-line lesions, improved cerebral venous decompression, lower intracranial pressure and enhanced gravity drainage of blood and CSF associated with the sitting position.
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Comparative Study Clinical Trial Controlled Clinical Trial
Predicting outcome after cardiac surgery: comparison of global haemodynamic and tonometric variables.
To compare how outcome can be predicted from global haemodynamic compared with regional perfusion-related variables (gastric intramucosal pH (pHi) and intramucosal-arterial PCO2 difference (delta PCO2)), we measured global haemodynamics, gastric pHi and delta PCO2 in 68 haemodynamically compromised patients after cardiac surgery on admission to the intensive care unit (ICU) and 12 h later. Overall mortality rate in the ICU was 19.1%. ⋯ Our data showed that global, routinely monitored, haemodynamic variables are better early predictors of outcome after cardiac surgery than regional, tonometric variables. This conclusion does not support hypoperfusion of the gastrointestinal tract as an early determinant of outcome after cardiac surgery.
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Comparative Study
Coating of extracorporeal circuit with heparin does not prevent sequestration of propofol in vitro.
Propofol is sequestered in extracorporeal circuits, but the factors responsible for the phenomenon are mostly unknown. We have compared two extracorporeal circuits (oxygenators, reservoirs and tubings) coated with heparin with two corresponding uncoated circuits for their capacity to sequester propofol in vitro. Three experiments were conducted with each circuit. ⋯ Propofol concentrations decreased to 22-32% of the initial predicted concentration of 2 micrograms ml-1 in the circuits (no significant difference between circuits). With greater concentrations, the circuits did not become saturated with propofol, even with the highest predicted concentration of 200 micrograms ml-1. We conclude that propofol was sequestered in extracorporeal circuits in vitro, irrespective of coating the circuit with heparin.