Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1998
Comparative StudyThe effects of propofol on cerebral blood flow velocity and cerebral oxygen extraction during cardiopulmonary bypass.
We investigated the effects of burst-suppression doses of propofol on cerebral blood flow velocity (CBFV), cerebral oxygen extraction (COE), and dynamic autoregulation in 20 patients undergoing cardiac surgery. The experimental procedure was performed during nonpulsatile cardiopulmonary bypass (CPB) with stable hypothermia (32 degrees C) in fentanyl-anesthetized patients. Middle cerebral artery transcranial Doppler flow velocity, right jugular bulb oxygen saturation, and jugular venous pressure (JVP) were continuously measured. Dynamic autoregulation was tested by stepwise changes in mean arterial pressure (MAP) within a range of 40-80 mm Hg by sodium nitroprusside and phenylephrine before (control) and during propofol infusion, with a stable plasma concentration (approximately 9 microg/mL). Propofol induced a 35% decrease in CBFV (P < 0.0001) and a 10% decrease in COE (P < 0.05) compared with control. The slopes of the curves relating CBFV and COE to cerebral perfusion pressure (CPP = MAP - JVP) were less pronounced with propofol (P < 0.01 and P < 0.05, respectively). We conclude that propofol decreases CBFV and improves dynamic autoregulation during moderate hypothermic CPB. Furthermore, during propofol infusion, cerebral blood flow was in excess relative to oxygen demand, as indicated by the decrease in COE. ⋯ In this study, we evaluated the effects of propofol on continuously measured cerebral blood flow velocity (CBFV) and cerebral oxygen extraction as a function of perfusion pressure. Propofol induced 35% and 10% decreases in CBFV and cerebral oxygen extraction, respectively. The slope of the curve relating cerebral perfusion pressure to CBFV decreased with propofol.
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Anesthesia and analgesia · Jun 1998
Randomized Controlled Trial Comparative Study Clinical TrialArterial oxygenation and shunt fraction during one-lung ventilation: a comparison of isoflurane and sevoflurane.
The aim of this study was to evaluate the effect of isoflurane and sevoflurane on oxygenation and shunt fraction during one-lung ventilation (OLV). Twenty patients undergoing lobectomy for lung cancer and scheduled for long-term OLV were enrolled in this study. Patients were allocated to treatment with either isoflurane or sevoflurane. Arterial oxygenation, shunt fraction, and hemodynamics were evaluated at the end of two-lung ventilation; 20 min after the initiation of OLV; 20 min after the application of 4-cm positive end-expiratory pressure (PEEP) to the dependent lung; 20 min after 8-cm PEEP; and 20 min after the conversion from OLV to two-lung ventilation. There was no significant difference between isoflurane and sevoflurane with regard to oxygenation, shunt fraction, or hemodynamics during OLV. PaO2 values after the application of 4-cm PEEP increased from 131.1 +/- 11.8 mm Hg to 190.6 +/- 22.9 mm Hg in the isoflurane group (P < 0.05) and from 127.2 +/- 14.3 mm Hg to 192.4 +/- 26.9 mm Hg in the sevoflurane group (P < 0.05). The selection of either isoflurane or sevoflurane for OLV was made without regard to arterial oxygenation and shunt fraction. PEEP application to the dependent lung is useful for improving oxygenation during OLV, but 8-cm PEEP had no added effect compared with 4-cm PEEP. ⋯ We compared the effects of isoflurane and sevoflurane on oxygenation, hemodynamics, and shunt fraction during one-lung ventilation in 20 patients undergoing scheduled lobectomy for lung cancer. There was no significant difference between isoflurane and sevoflurane with regard to oxygenation, shunt fraction, and hemodynamics during one-lung ventilation. The application of 4-cm positive end-expiratory pressure increased the partial pressure of arterial oxygen during one-lung ventilation.
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Anesthesia and analgesia · Jun 1998
Randomized Controlled Trial Clinical TrialAdding ketamine in a multimodal patient-controlled epidural regimen reduces postoperative pain and analgesic consumption.
We designed this double-blind study to evaluate the effect of adding small-dose ketamine in a multimodal regimen of postoperative patient-controlled epidural analgesia (PCEA). Ninety-one patients, ASA physical status I-III, undergoing major surgery, received a standardized general anesthesia and epidural catheterization in an appropriate intervertebral space after surgery. A PCEA device was programmed to deliver a regimen of morphine 0.02 mg/mL, bupivacaine 0.8 mg/mL, and epinephrine 4 microg/mL, with the addition of ketamine 0.4 mg/mL (ketamine, n = 45) or without (control, n = 46). The mean visual analog pain scale (VAS) scores during cough or movement for the first 3 days after surgery were higher in the control group than in the ketamine group (P < 0.05), whereas the mean VAS score at rest for the first 2 days were higher in the control group than in the ketamine group (P < 0.05). Furthermore, patients in the control group consumed more multimodal analgesics than patients in the ketamine group for the first 2 days (P < 0.05). The sedation scores and the incidence of side effects (pruritus, nausea, emesis, sleep deprivation, motor block, and respiration depression) were similar between the two groups. We conclude that adding ketamine 0.4 mg/mL in a multimodal PCEA regimen provides better postoperative pain relief and decreases consumption of analgesics. ⋯ Many studies have evaluated one or a combination of two analgesics for postoperative pain control, but few have examined a multimodal approach using three or four different epidural analgesics. This study demonstrates an additive analgesic effect when ketamine is added to a multimodal analgesic treatment.