Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1994
Randomized Controlled Trial Comparative Study Clinical TrialComparisons of tetracaine spinal anesthesia with clonidine or phenylephrine in normotensive and hypertensive humans.
To compare the hemodynamics and anesthetic effects of spinal tetracaine containing either clonidine or phenylephrine administered to normotensive or hypertensive patients, we studied 75 patients allocated to one of three groups, each of which included nine hypertensive patients: clonidine group (n = 25) received 2 mL of 0.5% tetracaine (10 mg) containing clonidine (0.15 mg); phenylephrine group (n = 25) received 2 mL of 0.5% tetracaine (10 mg) containing phenylephrine (3 mg); and control group (n = 25) received 2 mL of 0.5% tetracaine (10 mg) alone. Analgesic levels and the intensity of motor block obtained did not differ significantly among the three groups. ⋯ Mean blood pressure (MBP) in both hypertensive and normotensive patients given tetracaine-clonidine remained approximately 20% lower than that in the control group for as long as 7 h after the injection (P < 0.05). We conclude that the inclusion of clonidine can provide similar effects to that of phenylephrine with respect to prolongation of hyperbaric tetracaine spinal anesthesia, but could cause more hypotension, without bradycardia, in both normotensive and hypertensive patients for a prolonged time (i.e., 420 min).
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Anesthesia and analgesia · Jan 1994
Randomized Controlled Trial Comparative Study Clinical TrialCoagulation tests, blood loss, and transfusion requirements in platelet-rich plasmapheresed versus nonpheresed cardiac surgery patients.
The results of several studies suggest that acute platelet-rich plasmapheresis decreases blood loss and allogeneic blood product transfusion requirements in cardiac surgery patients. We designed a randomized, prospective study to determine whether acute platelet-rich plasmapheresis decreases blood loss and allogeneic transfusion requirements in primary cardiac surgery patients. Forty patients were randomized to a control or pheresis group. ⋯ Chest tube drainage and transfusion requirements were recorded. There were no differences in the coagulation tests, platelet counts, chest tube drainage, or allogeneic blood product transfusion requirements between the two groups at any time. The authors conclude that the use of acute platelet-rich plasmapheresis in primary cardiac surgery patients does not decrease chest tube drainage or the need for allogeneic blood transfusions.
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Anesthesia and analgesia · Jan 1994
Randomized Controlled Trial Clinical TrialFentanyl or alfentanil decreases the minimum alveolar anesthetic concentration of isoflurane in surgical patients.
The minimum alveolar anesthetic concentration (MAC) is an accepted potency measure for inhaled anesthetics. There is no generally accepted intraoperative measure of opioid potency, partly because of the difficulty in obtaining steady state biophase concentrations. We have studied the relative potency of fentanyl and alfentanil by using computer-assisted continuous infusions (CACI), in terms of reduction of isoflurane MAC. ⋯ The maximum likelihood solution to a logistic regression model showed that fentanyl 0.5 ng/mL (95% confidence intervals [CI], 0-4.6 ng/mL) or alfentanil 28.8 ng/mL (95% CI, 0-70.9 ng/mL) resulted in a 50% isoflurane MAC reduction. In the logistic regression model, age or weight were not significant factors in the model. These results suggest that the comparative intraoperative potency ratio for alfentanil and fentanyl is 58:1, and that this methodology allows for direct intraoperative comparisons of opioid potency.