European journal of anaesthesiology
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Randomized Controlled Trial Clinical Trial
Patient-controlled sedation using propofol: randomized, double-blind dose refinement.
This double-blind, randomized trial compared the onset of sedation with two patient-controlled sedation regimens, allowing a maximum of 16 or 25 mg min-1 propofol. Forty fit young patients presenting for elective surgery were asked to try to put themselves to sleep using the system. Onset times of sedative effect, slurred speech and amnesia were recorded. ⋯ Patients receiving 16 mg min-1 propofol were not reliably sedated within 5 min and took significantly longer to develop slurred speech and amnesia (P < 0.01 for both). We conclude that this maximum infusion rate does not produce amnesia or sedation rapidly enough to be clinically useful. A maximum infusion rate of 25 mg min-1 allowed rapid sedation in all patients without oversedation and may be an acceptable compromise between efficacy and safety.
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Comparative Study
Calculated and measured oxygen consumption in mechanically ventilated surgical patients in the early post-operative period.
Oxygen consumption (VO2) measured by indirect calorimetry (Nellcor-Puritan-Bennett 7250; Carlsbad, CA, USA) has been compared with VO2 calculated by the Fick method in 22 volume-controlled ventilated general surgical patients in the early post-operative period. For 198 pairs of measurements, VO2 Fick and VO2 indirect calorimetry correlated significantly (y = 1.00x - 35.8, P = 0.0001, r = 0.77). VO2 indirect calorimetry was 212 +/- 32 mL min-1 and VO2 Fick was 177 +/- 41 mL min-1 (P = 0.0001). ⋯ VO2 calculated by the Fick method did not accurately predict VO2 measured by indirect calorimetry, and the two methods were not interchangeable. VO2 calculated by the Fick method underestimated VO2 as measured by indirect calorimetry by a systematic quantity that could be attributed, in part, to VO2 of the lung. Indirect calorimetry should be the preferred method for measuring total body VO2 in mechanically ventilated surgical patients.
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Comparative Study
Restricted spinal anaesthesia for ambulatory surgery: a pilot study.
The increasing use of ambulatory surgery requires methods of anaesthesia that allow patients to be discharged soon after the operation is completed. Spinal anaesthesia is usually simple and quick, and the incidence of post-spinal headache has been reduced by using non-cutting small-gauge needles. Limiting the spread of spinal anaesthesia, as long as it still provides analgesia for surgery, should reduce the haemodynamic effects and speed recovery. ⋯ Two patients in the spinal group and nine patients in the epidural group were treated for hypotension (P < 0.05). One patient in the spinal group developed a post-spinal headache. One patient in the epidural group rated the anaesthesia poor.
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Sixteen patients suffering from rheumatoid or osteoarthritis of the shoulder joint were studied. All patients complained of pain and limitation of active movement of the shoulder joint. Combined neural blockade of the suprascapular nerve (SSNB) and articular branches of the circumflex nerve (ACNB) was carried out using 4 mL of 1% prilocaine and 4 mL of 6% aqueous phenol. ⋯ These findings were significant (P < 0.05). Further clinical evaluation of combined SSNB and ACNB in relation to previously reported methods of neural blockade of the shoulder joint is warranted using a randomized, controlled, comparative study. Conventional power calculations (80% power, 5% test) indicate that 17 patients per group would be necessary to detect one standard deviation (about 2 VASP) or 64 per group to detect a change of 0.5 standard deviations.
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The value of pulmonary artery catheterization is a matter for discussion. Previous studies suggest that direct measurements of intravascular volume distribution and cardiac volume indices may be of greater relevance than central venous and pulmonary capillary wedge pressure. We therefore used a thermo-dye dilution technique for the quantification of central blood volume, right ventricular end-diastolic volume and left heart volume in patients undergoing coronary artery bypass surgery. ⋯ Central venous pressure was significantly increased at 1 and 6 h, whereas right ventricular end-diastolic volume was increased only at 6 h post-operatively. Pulmonary capillary wedge pressure showed a tendency to increase whereas left heart and central blood volume decreased significantly after surgery. The results of the present study suggest that changes in cardiac filling pressure do not indicate changes in indices of cardiac volume in patients after coronary bypass surgery.