Articles: general-anesthesia.
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Tidal volume (VT) delivered by mechanical ventilation during anesthesia may be influenced by factors related not only to the patient and the breathing circuit, but also to the interaction between the anesthesia machine and the anesthesia ventilator. To characterize this interaction, we studied in a test lung the effect of fresh-gas-flow (FGF) (0.25, 2.5, 5, and 10 L/min), inspiratory-to-expiratory time ratio (I:E) (1:1, 1:2, and 1:3), and ventilatory frequency (8, 12, and 16 breaths/min) at fixed ventilator bellows excursions of 300, 600, and 900 ml. The influence of these variables was also estimated mathematically for a pediatric situation: a bellows excursion of 50 ml at 20 and 30 breaths/min. ⋯ Thus it is possible in the pediatric situation to increase the delivered VT by sixfold without changing the ventilator bellows excursion. The magnitude of the changes was slightly larger for the VT settings for adult patients because of the slower respiratory rate. This VT augmentation can be predicted by the product of FGF (ml/s) and inspiratory time (seconds).(ABSTRACT TRUNCATED AT 250 WORDS)
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The anaesthetic management of a 26-year-old woman who sustained an unstable fracture of C2 when 40 weeks pregnant, is described.
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Randomized Controlled Trial Clinical Trial
Anesthesia and hypertension: the effect of clonidine on perioperative hemodynamics and isoflurane requirements.
Thirty patients (ASA physical status II-III) with a history of arterial hypertension, whose blood pressure (BP) control varied from normotension to moderate hypertension (diastolic BP less than 110 mmHg), scheduled for elective surgery under general anesthesia, were randomly assigned to two groups. Group 1 was premedicated 90-120 min prior to induction with diazepam 0.15 mg X kg-1 po; group 2, in addition, received clonidine 5 micrograms X kg-1 po. Anesthetic depth was assessed by on-line aperiodic analysis of the electroencephalogram. ⋯ In group 2, clonidine produced a rapid preoperative control of systolic and diastolic BP from 166 +/- 32/95 +/- 14 to 136 +/- 80 +/- 11 (P less than 0.01), was more effective in blunting the reflex tachycardia associated with laryngoscopy and endotracheal intubation than lidocaine-fentanyl pretreatment. It significantly reduced the intraoperative lability (coefficient of variation) of systolic (P less than 0.01) and diastolic BP and heart rate (HR) (P less than 0.05), and resulted in significantly slower HR during recovery (P less than 0.01). Anesthetic requirements for isoflurane were reduced 40% (P less than 0.01) in group 2; narcotic supplementation was also significantly reduced (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)