Anesthesiology
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Review
Opioid analgesics in anesthesia: with special reference to their use in cardiovascular anesthesia.
In this article, an attempt has been made to review the use of receptor stimulating pure agonist opioids in anesthesia, especially in patients with cardiovascular disease. Particular emphasis has been placed on the use of opioids in high doses to produce anesthesia, techniques that recently have become popular in cardiovascular anesthesia. A major benefit of opioid anesthesia is the cardiovascular stability obtained during induction and throughout operation, even in patients with severely impaired cardiac function. ⋯ The use of very large doses of opioids also will prolong postoperative respiratory depression. High doses of opioids can reduce or prevent the hormonal and metabolic responses to the stress of surgery. However, even very large doses of fentanyl or its newer analogues do not prevent marked increases in plasma catecholamine concentrations in response to cardiopulmonary bypass.(ABSTRACT TRUNCATED AT 400 WORDS)
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Comparative Study
Ventilatory and analgesic effects of dezocine in humans.
The respiratory depressant and analgesic effects of intravenous dezocine were evaluated in six healthy volunteers. Single 0.15 mg/kg doses were compared with identical amounts of morphine, and the two drugs were given in combination. Five successive 0.15 mg/kg doses of dezocine also were given to identify dose-effect relationships. ⋯ Dezocine is therefore an effective analgesic with morphine-like effects. In human subjects it appears to be a slightly more potent analgesic than morphine in identical clinical doses (0.15 mg/kg). Dezocine is similar to other agonist-antagonist analgesics in that it exhibits a ceiling effect for respiratory depression that parallels its analgesic activity.
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Hepatic arterial blood flow (HABF) and portal blood flow (PBF) were measured in 18 dogs while awake and during isoflurane and halothane anesthesia. Surgical preparation 1 week before the measurements consisted of a left thoracotomy, placement of a left atrial catheter, and insertion of another catheter into the distal aorta via the left femoral artery. Cardiac output and liver blood flow were determined using microspheres at three stages: stage 1-awake state; stage 2-after 45 min of 1 MAC of isoflurane (eight dogs) or halothane (10 dogs) anesthesia; and stage 3-after 45 min of 2 MAC of inhalation anesthesia. ⋯ HABF correlated with CI and MAP during halothane (r = 0.74 and 0.71, respectively) but did not correlate with systemic hemodynamic variables during isoflurane. ICG half-life significantly increased during 1 and 2 MAC of halothane anesthesia. The degree of increase did not correlate with the level of anesthesia or the decrease in total hepatic blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)
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The hormonal responses to surgical stress were examined in 10 patients scheduled for elective gynecologic laparotomy. Anesthesia was induced with either thiopental, 4 mg/kg, or etomidate, 0.35 mg/kg, and maintained with nitrous oxide and enflurane. Plasma cortisol, aldosterone, ACTH, and catecholamines were measured during the 24 h after the induction of anesthesia. ⋯ In the patients receiving thiopental, both cortisol and aldosterone concentrations were greater than the baseline value (P less than 0.05) in the second to fourth hours after induction. In the etomidate group, the plasma concentrations of cortisol were less than baseline values (P less than 0.05) in the first and second hours after induction of anesthesia and both cortisol and aldosterone were lower than those in the thiopental group (P less than 0.05) in the half to fourth hours after induction. These results confirm an earlier report of the suppression of cortisol after etomidate administration and, because aldosterone also was suppressed, suggests that etomidate exerts its effect by inhibiting early stages of steroidogenesis in the adrenal cortex.
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Comparative Study
Etomidate inhibits adrenocortical function in surgical patients.
Postoperative adrenocortical function was compared in 23 out-patients receiving either thiopental, 4 mg/kg, for induction and a thiopental infusion, 0.26 mg . kg-1 . min-1, in combination with nitrous oxide 70% for maintenance of anesthesia (control); etomidate, 0.4 mg/kg, for induction followed by an etomidate infusion, 0.02 mg . kg-1 . min-1, and nitrous oxide 70% for maintenance (etomidate I); or etomidate, 0.4 mg/kg, for induction and a thiopental infusion, 0.22 mg . kg-1 . min-1, in combination with nitrous oxide 70% for maintenance (etomidate II). The norepinephrine response to anesthesia and surgery did not differ significantly between the three groups. ⋯ Similarly, the postoperative aldosterone levels in the control group increased normally in response to ACTH (+ 10.2 +/- 3.0 ng/dl) but decreased in both the etomidate I and etomidate II groups (-3.0 +/- 0.7 ng/dl and -3.3 +/- 1.0 ng/dl, respectively). Because ACTH was administered exogenously, etomidate-induced suppression of adrenocortical response appeared to be a direct effect on the adrenal gland, which was present at a time when the serum etomidate levels were in the subhypnotic range.(ABSTRACT TRUNCATED AT 250 WORDS)