Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Clinical Trial Controlled Clinical Trial
"Priming" with neostigmine: failure to accelerate reversal of single twitch and train-of-four responses.
Train-of-four stimulation can shorten the apparent onset time of neuromuscular blocking drugs. This study was designed to verify whether the same occurred with neostigmine-assisted recovery, and whether this apparent acceleration could explain the previously reported effectiveness of the priming technique for reversal agents. Fourteen adults received atracurium, 0.5 mg.kg-1, during a thiopentone-nitrous oxide-enflurane anaesthetic. ⋯ No statistically significant differences were observed between single twitch in one arm and first twitch height of the train-of-four in the other arm for the next 10 min. With priming, first twitch height was 45 +/- (SEM) 5 per cent at 5 min and 85 +/- 6 per cent at 10 min, compared with 72 +/- 5 per cent (p less than 0.05) and 91 +/- 2 per cent (NS) respectively without priming. Train-of-four ratio was 28 +/- 3 per cent at 5 min and 65 +/- 5 per cent at 10 min with priming, versus 53 +/- 4 per cent (P less than 0.05) and 73 +/- 3 per cent (NS) respectively without priming.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study Clinical Trial Controlled Clinical Trial
Recovery room oxygenation: a comparison of nasal catheters and 40 per cent oxygen masks.
One hundred and sixty-one ASA physical status I-III patients undergoing elective surgery were evaluated using nasal catheters versus 40 per cent O2 venturi masks. Twenty-one per cent of the patients arrived in the recovery room with hypoxia as measured with a pulse oximeter (SaO2 less than 90 per cent). Fifteen minutes later all patients who arrived hypoxic were well oxygenated on their chosen oxygen therapy. ⋯ Patients having an endotracheal tube with intermittent positive pressure ventilation or having a premedication were more apt to be hypoxic on arrival. These last two factors were closely associated and may reflect bias. The patient's gender, history of smoking, presence of obstructive lung disease, not including asthma, location of incision, or type of anaesthetic were not statistically significant risk factors.
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Plasma lidocaine concentrations, latency of onset, and duration of anaesthesia, were determined after interscalene brachial plexus block in 16 patients presenting for elective upper limb surgery. Eight patients had normal renal function and eight had chronic renal failure, as determined by creatinine clearance. ⋯ The latency of onset and duration of anaesthesia were similar in both groups. One per cent lidocaine solution may be administered to patients with normal and impaired renal function to provide effective brachial plexus blockade for short surgical procedures.
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Postoperative effects of extended rewarming (ECR) after hypothermic cardiopulmonary bypass (CPB) were studied. All (n = 28) patients were rewarmed to a nasopharyngeal temperature exceeding 38 degrees C before terminating CPB. In 12 patients (control group) the rectal temperature (Tre) was 33.8 +/- 1.7 degrees C (mean +/- sd) at termination of CPB. ⋯ In seven non-shivering ECR group patients this coincided with significantly reduced metabolic and ventilatory demands but these improvements were not valid for the group as a whole. The required ventilation temporarily during postoperative rewarming in both groups increased to 250 per cent of the basal need. Extending CPB rewarming (to at least 36 degrees C Tre) was inefficient when used as the sole measure to reduce the untoward effects of residual hypothermia during recovery after cardiac surgery with hypothermic CPB.
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A 55-year-old, malignant hyperthermia-susceptible patient underwent myocardial revascularization without incident. Six hours postoperatively, he developed what was initially diagnosed as an MH crisis, for which he received intravenous dantrolene. The resultant muscle weakness prolonged the duration of postoperative mechanical ventilation and likely contributed to the development of a postoperative pneumonia. ⋯ The patient's pattern of rewarming following hypothermic cardiopulmonary bypass was similar to non-MH-susceptible patients. Because of the difficulty in diagnosing a MH crisis after hypothermic bypass, it is recommended that patients receive prophylactic dantrolene preoperatively and after bypass. Nondepolarizing muscle relaxants should be given postoperatively to prevent shivering and respiratory acidosis while patients rewarm.