Anesthesiology
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To demonstrate that sympathetic responses transmitted by the splanchnic nerve help maintain intravascular stability, 12 mongrel dogs (35-45 kg each), anesthetized with pentobarbital, were given two separate but identical hypotensive stimuli (mean arterial blood pressure of 60 mm Hg for 15 min) by the withdrawal of appropriate amounts of blood. The first stimulus was performed in the absence of drug or surgical manipulation. The second stimulus was performed after animals were subjected to no intervention (n = 4), bilateral splanchnic nerve section (n = 4), or spinal anesthesia (n = 4). ⋯ The volume of blood withdrawn to produce hypotension was similar (approximately 21 ml.kg-1). Bilateral splanchnic nerve section attenuated the adrenal medullary blood flow, arterial epinephrine concentration, and abdominal organ blood flow responses to hypotension by 86, 64, and 66%, respectively (P less than 0.008), and the blood volume withdrawn was reduced by 42% (P less than 0.02). Spinal anesthesia eliminated the adrenal medullary blood flow response to hypotension, attenuated the arterial epinephrine concentration and abdominal organ blood flow responses by 78 and 57%, respectively (P less than 0.01), and decreased the blood volume extracted by 55% (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Postoperative analgesia by intravenous clonidine.
Clonidine, an alpha 2 adrenoreceptor agonist, has nonopiate antinociceptive properties, which might be an alternative for postoperative analgesia free of opioid-induced side effects. To document the analgesic properties of intravenous clonidine during the postoperative period, 50 ASA physical status 1 patients, immediately after spinal fusion, were randomly assigned to two groups, blindly administered either clonidine (5 micrograms/kg infused the 1st h and then 0.3 microgram-1.kg-1.h-1 during 11 h) or a placebo. A visual analog scale graded from 0 (no pain) to 100 mm was used to assess pain before clonidine or placebo administration (T0), at the end of the loading dose (T1) and then every 2 h (T3, T5, T7, T9, and T11). ⋯ The pain score decreased from 42 +/- 5 to 26 +/- 3 mm (mean +/- standard error) in the clonidine group whereas it was unchanged in the placebo group despite a greater morphine requirement (dose for each patient: 3.8 +/- 1 vs. 10.8 +/- 1.2 mg). Clonidine delayed the onset of pain and the first request for morphine injection. Mean arterial pressure decreased to 74 +/- 2 mmHg in the clonidine group (-26 +/- 2 vs. -15 +/- 2% in the placebo group at T11) despite a significant increase in the cumulative fluid volume.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Comparative Study Clinical Trial
Combined epidural and general anesthesia versus general anesthesia for abdominal aortic surgery.
The goal of this randomized study of high-risk surgical patients was to determine whether intraoperative thoracic epidural anesthesia in combination with light general anesthesia alters postoperative morbidity when compared to a standard technique of "balanced" general anesthesia. A total of 173 patients scheduled for abdominal aortic reconstruction were admitted to the study; 86 were to receive "balanced" general anesthesia (group 1) and 87 thoracic epidural anesthesia in combination with light general anesthesia (group 2). Preoperative evaluation included standard clinical tools, dipyridamole thallium gammatomography, and radionuclide angiography. ⋯ In group 2, 6 patients with a nonfunctioning epidural catheter due to technical failure received a balanced general anesthesia and were eliminated from the study. During the postoperative period, group 2 received analgesia of subcutaneous morphine (n = 26), epidural fentanyl (n = 25), or epidural bupivacaine (n = 30). Cardiovascular morbidity did not differ between the two groups: 22 patients in group 1 and 19 patients in group 2 had a major postoperative cardiac event.(ABSTRACT TRUNCATED AT 250 WORDS)