Anesthesiology
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The frequency and severity of oxyhemoglobin desaturation was compared in 49 patients receiving epidural morphine, 5 mg (n = 21); patient-controlled analgesia (PCA) using meperidine (n = 20); or intramuscular (im) meperidine (n = 8) for postoperative analgesia following elective cesarean section performed with epidural anesthesia. Oxygen saturation (SpO2) was monitored for 24 h using a pulse oximeter; data were continuously collected and stored every 30 s via an interface connected to a computer. For analysis purposes, SpO2 was divided into five categories: 96-100%, 91-95%, 86-90%, 81-85%, and less than or equal to 80%. ⋯ PCA patients spent the longest cumulative time with SpO2 between 91 and 95%, 231 +/- 49 min (mean +/- SEM), compared with only 112 +/- 30 min and 152 +/- 42 min for the epidural and im groups, respectively (P less than 0.05 vs. epidural group). PCA patients also spent longest with SpO2 at 86-90% (19 +/- 10 min, vs. 6 +/- 3 and 0.5 +/- 0.3 min for the epidural and im groups, respectively), although this difference was not statistically significant. Severe desaturation episodes, defined as SpO2 less than or equal to 85% for more than 30 s, occurred in 71% of patients in the epidural group, 30% in the PCA group, and 63% in the im group (P less than 0.05 PCA vs. epidural and im).(ABSTRACT TRUNCATED AT 250 WORDS)
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Pharmacokinetics and blood concentrations of bupivacaine were studied after intercostal nerve blocks were performed intraoperatively using 1.5 mg.kg-1 in 11 neonates (age 0-28 days) and 11 infants between age 1 and 6 months. The study aimed to provide pharmacokinetic data that are limited in these age groups, and to identify any adverse effects of intercostal nerve block in infancy. Arterial blood samples were taken at 0, 5, 10, 15, 20, 30, 60, 120, 240, and 360 min. ⋯ Patients were further divided into those with acyanotic and cyanotic disease. Cyanotic infants were significantly heavier than acyanotic infants (P less than 0.05), but no other differences were demonstrated. No adverse effects resulting from the technique were identified.(ABSTRACT TRUNCATED AT 250 WORDS)
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Recovery from inhalation anesthesia is often marked by the occurrence of postoperative tremor that resembles shivering, which is known to be associated with an increase in oxygen uptake (VO2), CO2 output (VCO2), and minute ventilation (VE). This study determined the time course of the ventilatory changes observed during the first hour of recovery from isoflurane anesthesia. Ten patients (ASA PS 1) scheduled for minor orthopedic surgery (knee arthroscopy) were included in this study. ⋯ Postoperative tremor was observed in all patients within 7.1 +/- 1.2 min (mean +/- SEM) after isoflurane discontinuation and was associated with a marked increase in the following: VO2, from 173 +/- 26 ml/min at the end of anesthesia to 457 +/- 88 ml/min; VCO2, from 149 +/- 18 ml/min at the end of anesthesia to 573 +/- 98 ml/min; and VE, from 6.8 +/- 0.7 l/min at the end of anesthesia to 16.6 +/- 2.8 l/min (values obtained 20 min after isoflurane discontinuation). In three patients during intense shivering, VO2, VCO2, and VE reached peak values higher than 800 ml/min, 1,300 ml/min and 30 l/min, respectively. This study shows that postoperative tremor following isoflurane anesthesia may be associated with prolonged and large increases in oxygen uptake, CO2 output, and minute ventilation.