Anesthesia and analgesia
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Anesthesia and analgesia · Apr 1999
Perioperative plasma endothelin-1 and Big endothelin-1 concentrations in elderly patients undergoing major surgical procedures.
Plasma concentrations of the vasoconstrictor endothelin-1 (ET-1) increase during acute physiologic stress, but the role of ET-1 in the pathophysiology of stress remains largely undefined. Whether ET-1 mediates thermoregulatory changes in vasomotor tone is unknown. ET-1 and its more stable precursor, Big ET-1, were measured in plasma obtained at several perioperative time points from 95 consecutive elderly patients (mean age 70 +/- 1 yr) randomized to receive either normothermic or hypothermic perioperative care while undergoing major surgical procedures. In the postoperative period, there were no significant changes in plasma ET-1 concentrations, but Big ET-1 concentrations increased considerably (P < 0.0001). There were no significant differences in mean ET-1 or Big ET-1 levels in normothermic and hypothermic patients. Preoperative and postoperative ET-1 concentrations were significantly higher in patients with a history of hypertension (P < 0.002) and in those requiring treatment for postoperative hypertension (P < 0.003). Patients with cancer and those undergoing abdominal surgery had significantly higher Big ET-1 concentrations (P < 0.0001 and P < 0.003, respectively). These data support the hypothesis that Big ET-1 is a more sensitive measure of endothelin system activation after major surgery. Premorbid conditions and location and type of surgery influence perioperative ET-1/Big ET-1 concentrations. ⋯ The endothelin response seems to be significantly associated with perioperative hemodynamic aberrations. The endothelin-1 (ET-1) precursor Big ET-1 is a more sensitive measure of the endothelin system activation in response to surgical stress than ET-1 alone. Thermoregulatory vasoconstriction in response to mild perioperative hypothermia occurs independently of the endothelin system.
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Anesthesia and analgesia · Apr 1999
Isoflurane and sodium nitroprusside reduce the depressant effects of protamine sulfate on isolated ischemic rat hearts.
The administration of protamine sulfate (protamine) to reverse the action of heparin is associated with adverse reactions. We studied the effects of protamine and isoflurane on isolated, perfused rat hearts previously subjected to cardioplegic ischemia. Hearts were perfused with oxygenated Krebs-Henseleit (KH) solution for 30 min, then subjected to cardioplegic ischemia for 30 min (KCl 16 mEq/L at 31 degrees C) and 5 min reperfusion. Drug exposure lasted 15 min, and the recovery period was 60 min. Test groups were control, protamine (10 microg/mL), isoflurane (1.5%), protamine +/- isoflurane, sodium nitroprusside (SNP) (2.5 ng/mL), and SNP +/- protamine. Left ventricular developed pressure (LVP), coronary flow, and myocardial oxygen consumption were depressed by protamine to 30% +/- 4%, 47% +/- 4%, and 39% +/- 4% of baseline (P < 0.001 versus control), respectively. Isoflurane and SNP afforded partial protection from the effects of protamine: LVP was 57% +/- 5% and 51% +/- 3% of baseline, respectively (P < 0.05 versus protamine alone and control); coronary flow was 70% +/- 6% and 97% +/- 12% of baseline, respectively (P < 0.05 versus protamine alone; P < 0.05 for isoflurane versus control); and O2 consumption was 69% +/- 6% and 88% +/- 15% of baseline, respectively (P < 0.05 versus protamine; P < 0.05 for isoflurane versus control). In this model, protamine-induced myocardial depression and coronary vasoconstriction were less pronounced in the presence of either isoflurane or SNP. ⋯ We examined the interactions of isoflurane, sodium nitroprusside, and protamine in a rat heart model and found that both isoflurane and sodium nitroprusside partially protect the heart from the depressant effects of protamine. This finding is significant, as these drugs are often used in heart surgery.
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Anesthesia and analgesia · Apr 1999
Comment Letter Comparative StudyComparison of the laryngeal mask airway and cuffed oropharyngeal airway: alternative hypotheses.