Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialSmart technology improves patient-controlled analgesia: a preliminary report.
A new adaptive system has been designed to improve patient-controlled analgesia through the use of a variable bolus dose and a variable background infusion of analgesic. A novel hand set allows patients to rate their own pain on a linear scale of 1 to 10. Data derived from the hand set signals are used by an expert algorithm to repeatedly adapt the drug dosage of the bolus and of the background infusion according to both current pain intensity and the patient's response to previous dosage. To test the system, we performed a small pilot clinical study, using a randomized, double-blinded, cross-over design. The new system was alternated with a conventional system every 12 h. Use of the new system was associated with significantly lower pain scores and fewer bolus requests but more analgesic administration, though without increased adverse effects. It was very well accepted by both patients and clinical staff. ⋯ Pain relief after surgery is often best provided by patient-controlled analgesia, which uses an IV infusion pump and a patient-activated switch. We have developed a new computer-controlled or "smart" patient-controlled analgesia that rapidly learns a patient's individual needs and provides continuously tailored pain relief.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialThe effective dose of dexamethasone for antiemesis after major gynecological surgery.
This double-blind, randomized, placebo-controlled study evaluated the minimum effective dose of dexamethasone for postoperative antiemesis. One-hundred fifty women scheduled for major gynecological surgery were randomly assigned to receive dexamethasone 10 mg (D10), 5 mg (D5), 2.5 mg (D2.5), 1.25 mg (D1.25), or placebo (P) before the induction of general anesthesia. A standardized general anesthesia technique was used. Postoperative pain was treated with bolus IV doses of morphine via a patient-controlled analgesia device. Patients were assessed for incidence of vomiting at 4, 8, 12, and 24 h after surgery. A total of 6, 6, 8, 15, and 19 patients in Groups D10, D5, D2.5, D1.25, and Group P experienced vomiting at least once within the first postoperative 24 h, respectively. Dexamethasone 10 mg, 5 mg, and 2.5 mg was more effective than dexamethasone 1.25 mg or placebo for antiemesis (P < 0.05). The difference in antiemetic effect among the 10 mg, 5 mg, and 2.5 mg groups was similar. The results suggest that 2.5 mg is the minimum effective dose of dexamethasone for postoperative antiemesis in patients undergoing general anesthesia for major gynecological surgery. ⋯ Although dexamethasone is effective for antiemesis, major side effects may accompany its perioperative use. To achieve the best antiemesis with the fewest side effects, dexamethasone 10 mg, 5 mg, 2.5 mg, and 1.25 mg were compared with placebo in surgical patients. We found 2.5 mg to be the minimum effective dose without discernible side effects.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Comparative Study Clinical TrialInhaled nitric oxide versus intravenous vasodilators in severe pulmonary hypertension after cardiac surgery.
Inhaled nitric oxide (iNO) is superior to i.v. vasodilators for treatment of pulmonary hypertension (PH) after cardiac surgery, but iNO is a potentially toxic gas, and patient subsets who benefit from iNO are not yet clearly defined. We administered iNO 40 ppm, prostaglandin E1 (PGE1) 0.1 microg x kg(-1) min(-1), and nitroglycerin (NTG) 3 to 5 microg x kg(-1) min(-1), in a randomized crossover study to 14 adult patients with severe PH after cardiac surgery. iNO, PGE1, and NTG were of similar efficacy in reducing pulmonary vascular resistance (P = 0.003). iNO induced selective pulmonary vasodilation, while PGE1 and NTG had significant concomitant systemic vasodilatory effects. iNO led to an increase in cardiac index (CI) (P = 0.012), and PGE1 increased CI (P = 0.006) and right ventricular (RV) ejection fraction (P = 0.015), while NTG had no effect on CI and RV performance. After study completion, patients continued with PGE1 administration with favorable in-hospital outcome. We conclude that PH per se, even if severe, does not necessarily imply postoperative RV dysfunction, and selective pulmonary vasodilation with iNO may not be superior to PGE1 with regard to CI and RV performance. ⋯ In a prospective, randomized crossover study of inhaled nitric oxide (iNO) versus IV vasodilators, performed in adult patients with severe pulmonary hypertension but preserved right ventricular function after cardiac surgery, iNO was not superior to IV prostaglandin E1 with regard to cardiac index and right ventricular performance. Considering the potential toxicity of iNO, better definition of patient subsets with a positive benefit/risk ratio is warranted.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialExpression of genes for proinflammatory cytokines in alveolar macrophages during propofol and isoflurane anesthesia.
Anesthesia and surgery induce macrophage aggregation and neutrophil influx, responses that characterize an inflammatory reaction in the distal airway. We thus evaluated the time-dependent expression of genes for proinflammatory cytokines during propofol and isoflurane anesthesia. We studied patients anesthetized with propofol (n = 20) or isoflurane (n = 20). Alveolar macrophages were harvested by bronchoalveolar lavage immediately, 2, 4, and 6 h after induction of anesthesia, and at the end of surgery. RNA was extracted from harvested cells and cDNA was synthesized by reverse transcription. Expression of interleukin-1beta (IL-1beta), IL-6, IL-8, interferon gamma, and tumor necrosis factor-alpha was measured by semiquantitative polymerase chain reaction using beta-actin as an internal standard. We observed two 10-fold increases in gene expression of all proinflammatory cytokines except IL-6. The increases in IL-8 and interferon gamma were 1.5-3 times greater during isoflurane than propofol anesthesia. Expression of the genes for IL-1beta and tumor necrosis factor-alpha was similar with each anesthetic. Our data thus indicate that the pulmonary inflammatory response accompanying anesthesia and surgery is accompanied by the expression of proinflammatory cytokines, and that this expression was in some cases greater during isoflurane than propofol anesthesia. ⋯ Gene expression of proinflammatory cytokines in alveolar macrophages increased significantly over time. The increases were greater during isoflurane than propofol anesthesia, suggesting that inflammatory responses at transcriptional levels in alveolar macrophages are modulated by the type and duration of anesthesia.