Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2003
The effect of sevoflurane and propofol on cerebral neurotransmitter concentrations during cerebral ischemia in rats.
Sevoflurane and propofol are neuroprotective possibly by attenuating central or peripheral catecholamines. We evaluated the effect of these anesthetics on circulating catecholamines and brain neurotransmitters during ischemia in rats. Forty male Sprague-Dawley rats were randomly assigned to one of the following treatment groups: fentanyl and N(2)O/O(2) (control), 2.0% sevoflurane, 0.8-1.2 mg x kg(-1) x min(-1) of propofol, and sham-operated rats with fentanyl and N(2)O/O(2). Ischemia (30 min) was produced by unilateral common carotid artery occlusion plus hemorrhagic hypotension to a mean arterial blood pressure of 32 +/- 2 mm Hg. Pericranial temperature, arterial blood gases, and pH value were maintained constant. Cerebral catecholamine and glutamate concentrations, sampled by microdialysis, and plasma catecholamine concentrations were analyzed using high-pressure liquid chromatography. During ischemia, circulating catecholamines were almost completely suppressed by propofol but only modestly decreased with sevoflurane. Sevoflurane and propofol suppressed brain norepinephrine concentration increases by 75% and 58%, respectively, compared with controls. Intra-ischemia cerebral glutamate concentration was decreased by 60% with both sevoflurane and propofol. These results question a role of circulating catecholamines as a common mechanism for cerebral protection during sevoflurane and propofol. A role of brain tissue catecholamines in mediating ischemic injury is consistent with our results. ⋯ During incomplete cerebral ischemia, the neuroprotective anesthetics sevoflurane and propofol suppressed cerebral increases in norepinephrine and glutamate concentrations. In contrast, propofol, but not sevoflurane, suppressed the ischemia-induced increase in circulating catecholamines to baseline levels. The results question a role for plasma catecholamines in cerebral ischemic injury.
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Anesthesia and analgesia · Oct 2003
Randomized Controlled Trial Clinical TrialIntraoperative intravenous ketamine in combination with epidural analgesia: postoperative analgesia after renal surgery.
We designed this double-blinded, randomized, controlled study to evaluate the effect of small-dose ketamine IV in combination with epidural morphine and bupivacaine on postoperative pain after renal surgery. An epidural catheter was inserted, and the administration of morphine and bupivacaine was started before surgery. Forty patients were assigned to one of two groups (ketamine or control). The ketamine group was administered a ketamine bolus and infusion during surgery. The median visual analog pain scale (VAS) scores at rest were significantly lower in the ketamine group during the first 6 h (P < 0.01). VAS pain scores on coughing were also significantly lower in the ketamine group (P < 0.01). Cumulative postoperative total analgesic consumption was less in the ketamine group on Days 1 and 2 (P < 0.001). The first analgesic demand time was shorter in the control group (9.2 +/- 11.5 min) than in the ketamine group (22.3 +/- 17.1 min) (P < 0.0001). The incidence of nausea and pruritus was more frequent in the control group (P < 0.05). In conclusion, postoperative analgesia was more effective when spinal cord and brain sensitization were blocked by a combination of epidural morphine/bupivacaine and IV ketamine. ⋯ Renal nociception conducted multisegmentally by both the spinal nerves (T10 to L1) and the vagus nerve cannot be blocked by epidural analgesia alone. We demonstrated that IV ketamine had an improved analgesic or opioid-sparing effect when it was combined with epidural bupivacaine and morphine after renal surgery.
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Anesthesia and analgesia · Oct 2003
Clinical TrialBlood use in patients undergoing coronary artery bypass surgery: impact of cardiopulmonary bypass pump, hematocrit, gender, age, and body weight.
We investigated the impact of cardiopulmonary bypass pump (CPB), hematocrit, gender, age, and body weight on blood use in patients undergoing coronary artery bypass graft surgery at a major university hospital. Participants were 1235 consecutive patients undergoing primary coronary artery surgery over a period of 2 yr (1999 and 2000); 681 patients underwent coronary surgery with use of CPB, and 554 patients underwent off-pump coronary artery bypass surgery using a median sternotomy incision. There were 881 males and 354 females. Average packed red blood cells (PRBC) transfusion for patients on CPB was 3.4 U compared with 1.6 U for the off-pump group (P = <0.001). Patients on CPB received more frequent PRBC transfusion (72.5%) compared with 45.7% of off-pump patients (P = <0.001). Average PRBC transfusion for males was 2.2 U compared with 3.6 U for females (P = <0.001). A lower percentage of males (52.6%) than females (79.4%) received transfusion (P = <0.001). The impact of CPB, off-pump status, preoperative hematocrit <35%, gender, age >or=65 yr, and weight
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Anesthesia and analgesia · Oct 2003
Clinical TrialConfirmation of direct epidural catheter placement using nerve stimulation in pediatric anesthesia.
We evaluated the success rate of using low current electrical stimulation (the Tsui test) to identify and confirm direct epidural catheter placement in a pediatric population. Thirty subjects received a standard anesthetic and administration of the Tsui test on epidural placement. The distribution of myotomal activity was recorded. The intended and actual level of the epidural catheter was compared. Myotomal activity was seen in all patients but one. The median current resulting in myotomal activity was 5.3 mA. The median difference between the intended and actual level as confirmed on radiograph was 1.8 levels. The clinical success rate was 93.9%. The positive predictive value of the Tsui test was 82%; i.e., in 23 of 28 cases, the Tsui test correctly identified the position of the epidural catheter tip within 2 vertebral levels. The test did not offer any added advantage when used in the setting of directly placed epidural catheters in our institution over "blind" methods already used to confirm catheter position when using cutaneous landmarks and test dosing. ⋯ A new technique to confirm epidural catheter position uses low current electrical stimulation in pediatric patients. This study evaluated the use of electrical stimulation in 30 pediatric patients for directly placed catheters. Electrical stimulation did not provide any advantage over conventional methods (e.g., cutaneous landmarks) for confirmation of catheter position.
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Anesthesia and analgesia · Oct 2003
Comparative StudyRelative performance of the level 1 and ranger pressure infusion devices.
Pressure infusion devices are often used to administer fluids in the operating room, but they may rarely be associated with serious venous air embolism. We studied the performance of the Level 1 and the Ranger Pressure Infusor in the laboratory. The Ranger delivered less air and delivered fluid faster than the Level 1 but did not warm fluid or blood as well. Although the Ranger device may be safer in terms of the risk of air embolism, its inferior warming performance shows that the optimal pressure infusion device has yet to be manufactured. ⋯ Pressure infusion devices are widely used to treat patients with large-volume blood loss. The use of these devices may subject patients to the risk of venous air embolism. Our study found the new Ranger device to be superior to the widely used Level 1 in air elimination.