Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of alfentanil and ketamine infusions in combination with midazolam for outpatient lithotripsy.
Sixty unpremedicated outpatients undergoing elective extracorporeal shock wave lithotripsy using an unmodified Dornier HM-3 lithotriptor were randomly assigned to receive an intravenous infusion of either alfentanil or ketamine as an adjuvant to midazolam for sedation and analgesia. Although both drug regimens allowed the maximal number of shock waves and energy level, the alfentanil group had significantly better calculi fragmentation (78% vs. 50% of patients with fragments less than 2 mm). Ketamine infusion provided superior intraoperative cardiorespiratory stability; however, it was associated with more disruptive movements (22 vs. 5) and dreaming (35% vs. 5%) during the procedure (P less than 0.05). ⋯ The incidence of postoperative nausea was decreased (not significantly) in the alfentanil group (32% vs. 54%). The mean anesthesia time was similar in both groups; however, discharge times (means +/- standard deviations) were shorter in the alfentanil group (142 +/- 42 min vs. 161 +/- 31 min, P = 0.05). These data suggest that although both techniques proved effective for anesthesia in outpatients undergoing immersion lithotripsy, alfentanil is superior to ketamine as part of a sedative-analgesic technique because of the improved recovery profile and calculi fragmentation.
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To examine the association between anemia and postoperative apnea in former preterm infants, 24 former preterm infants of less than 60 weeks postconceptual age undergoing inguinal hernia repair were studied. A hematocrit of at least 25% was required for study participation. General endotracheal inhalational anesthesia, supplemented with neuromuscular blockade and controlled ventilation, was used. ⋯ Anemic infants had an 80% incidence of postoperative apnea versus 21% in infants with a normal hematocrit (P less than .03). In the infants who developed postoperative prolonged apnea and/or bradycardia, a prior history of apnea was equally present in both groups (21% in group 1 and 20% in group 2). This study shows that anemia in former preterm infants can be associated with an increased incidence of postoperative apnea.
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Prior reports suggest cerebral blood flow (CBF) responses to changing bypass (systemic) flow rates may differ between alpha-stat and pH-stat management. To compare the effect of blood gas management upon CBF responses to changing systemic flow and pressure, 15 New Zealand White rabbits, anesthetized with fentanyl and diazepam, underwent nonpulsatile cardiopulmonary bypass at 25 degrees C. One group of animals (n = 8) was randomized to alpha-stat blood gas management that maintained arterial carbon dioxide tension (PaCO2) approximately 40 mmHg when measured at 37 degrees C. ⋯ There were no significant differences between groups with respect to bypass flow rate, mean arterial pressure (MAP), central venous pressure, temperature, hematocrit, arterial oxygen tension (PaCO2), or bypass duration at any measurement point. MAP decreased significantly, from approximately 80 to approximately 65 mmHg with decreasing bypass flow (P = 0.0001). Over the entire range of bypass flows, CBF decreased with decreasing bypass flow (P = 0.001), and the degree of change was equivalent among regions and between groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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The anesthetic interactions of midazolam and fentanyl were determined in terms of enflurane MAC reduction in dogs. In part 1, 8 animals received an intravenous (iv) loading dose of fentanyl followed by a constant infusion at 0.05 micrograms.kg-1.min-1 to produce a stable enflurane MAC reduction of approximately 20%. Midazolam was then administered in a series of three incremental loading doses and infusions (2.4, 9.6, and 28.8 micrograms.kg-1.min-1 previously determined to produce enflurane MAC reductions of approximately 30, 45, and 60%, respectively. ⋯ The fentanyl concentrations in plasma remained stable at 1.0 +/- 0.3 ng/ml (mean +/- standard deviation [SD], part 1) and 3.1 +/- 0.5 ng/ml (part 2) throughout the study and, in the absence of midazolam, reduced enflurane MAC by 28 +/- 11 and 44 +/- 5%, respectively. The addition of midazolam produced significant further reductions in enflurane MAC, but the reductions were less than those predicted on the basis of an additive interaction. Naloxone returned enflurane MAC reduction to that expected for midazolam alone (part 1).(ABSTRACT TRUNCATED AT 250 WORDS)