Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe relative potency of oral transmucosal fentanyl citrate compared with intravenous morphine in the treatment of moderate to severe postoperative pain.
Pharmacokinetic studies have shown that oral transmucosal absorption of fentanyl is relatively rapid compared with gastrointestinal absorption, and it results in increased bioavailability. We designed this study to establish the relative potency of oral transmucosal fentanyl citrate (OTFC) compared with i.v. morphine in 133 postoperative patients. The morning after surgery, patients randomly received one dose of either OTFC (200 or 800 microg) and a placebo i.v. injection or i.v. morphine (2 or 10 mg) and an oral transmucosal placebo unit. Pain intensity, pain relief, time to meaningful pain relief, and time to remedication were recorded. Median time to onset of relief was approximately 5 min for all groups. Over the first hour, little difference among treatment groups was seen for pain intensity and pain relief. By 2 h after study drug administration, 800 microg of OTFC and 10 mg of i.v. morphine generally produced similar analgesia, which was better than the smaller doses. Duration of analgesia with the larger doses (800 microg of OTFC and 10 mg of morphine) was similar and longer that produced by the smaller doses. The larger doses of OTFC and morphine produced better and more sustained analgesia than 200 microg of OTFC or 2 mg of morphine. ⋯ The relative potency of oral transmucosal fentanyl citrate (OTFC) to i.v. morphine was 8-14:1. In this postoperative setting, OTFC produced rapid pain relief similar to that produced by i.v. morphine. The larger doses of OTFC (800 microg) and morphine (10 mg) produced better and more sustained analgesia than 200 microg of OTFC or 2 mg of morphine.
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Anesthesia and analgesia · Sep 1999
Clinical Trial Controlled Clinical TrialThe preoperative administration of intravenous dextromethorphan reduces postoperative morphine consumption.
We evaluated the effect of dextromethorphan on postoperative pain management. Sixty ASA physical status I-III female patients undergoing major abdominal surgery underwent standardized general anesthesia. Thirty patients received an i.v. infusion of dextromethorphan 5 mg/kg before anesthetic induction (Pre group), whereas the remaining 30 patients received the same volume of isotonic sodium chloride solution, followed by a postoperative i.v. infusion of dextromethorphan 5 mg/kg (Post group). Patients in the Pre group received the same volume of isotonic sodium chloride solution postoperatively. All patients were then treated with patient-controlled i.v. analgesia, which administered a 0.6-mg bolus of morphine on demand (maximal 4 h dose 20 mg). The mean visual analog pain score during cough or movement and at rest were similar in the two groups in the first 3 days postoperatively. However, Post group patients consumed more morphine than Pre group patients during the first 2 days (P < 0.01). The sedation scores, patient satisfaction, and the incidence of morphine-related side effects were similar between the two groups. We conclude that the preoperative administration of dextromethorphan 5 mg/kg reduces postoperative morphine consumption compared with postoperative administration. ⋯ In this double-blinded study, we found that the preoperative administration of i.v. dextromethorphan 5 mg/kg, compared with postoperative administration, reduces postoperative morphine consumption, which may provide clinical evidence of preemptive or preventive analgesic effects of dextromethorphan.
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Anesthesia and analgesia · Sep 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of antagonizing residual neuromuscular blockade by neostigmine and glycopyrrolate on nausea and vomiting after ambulatory surgery.
The effects of neostigmine on the incidence of postoperative nausea and vomiting (PONV) are controversial. In this study, we evaluated the effects of neostigmine and glycopyrrolate on the incidence of PONV and the need for antiemetics in patients undergoing ambulatory surgery. One hundred healthy patients undergoing outpatient surgical procedures were included in the study. A standardized anesthetic technique was used for all patients. Patients were randomized to receive either mivacurium (n = 50) or rocuronium (n = 50) to achieve muscle paralysis. Bolus doses of mivacurium 2-4 mg or rocuronium 5-10 mg were administered to maintain one or two twitches of the train-of-four stimulation of the ulnar nerve at the wrist. After surgery, residual neuromuscular blockade was reversed with neostigmine 2.5 mg i.v. and glycopyrrolate 0.5 mg i.v. only if clinically deemed necessary (i.e., fade on train-of-four stimulation, inadequate tidal volume, reduced hand grip, or inability to maintain head lift). The incidence of PONV and the need for antiemetics were recorded in the post-anesthesia care unit (PACU), in the phase II unit, and 24 h after surgery. We compared patients who received neostigmine (n = 40) for reversal of residual neuromuscular blockade with those who did not (n = 60). More patients receiving rocuronium required reversal drugs than those receiving mivacurium (68% vs 10%). There were no differences in the incidence of nausea (18% vs 15%), vomiting (8% vs 12%), and the need for antiemetics (13% in both the groups) in the PACU between patients who received neostigmine and those who did not. In addition, the duration of PACU stay and the time to home-readiness were also similar between the groups. We conclude that, compared with rocuronium, the use of mivacurium decreases the need for reversal drugs. In addition, reversal of residual neuromuscular blockade with neostigmine does not increase the incidence of PONV or the need for antiemetic medications in patients undergoing ambulatory surgery. ⋯ In this study, we showed that the incidence of postoperative nausea and vomiting and the need for antiemetics do not increase with the use of neostigmine and glycopyrrolate for reversal of residual muscle paralysis.
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Anesthesia and analgesia · Sep 1999
Clinical TrialUse of abciximab-modified thrombelastography in patients undergoing cardiac surgery.
Thrombelastography (TEG) is a reliable coagulation monitoring system that can guide blood product transfusion in cardiac surgery. The maximum amplitude (MA) of TEG measures clot strength, which is dependent on both fibrinogen level and platelet function. Inhibition of platelet function with abciximab-fab is suggested to permit quantitative assessment of the contribution of fibrinogen to clot strength. We hypothesized that abciximab-modified TEG permits prediction of plasma fibrinogen levels and that the difference of standard MA and abciximab-modified MA (deltaMA) is a correlate for platelet function. We correlated abciximab-modified MA with plasma fibrinogen levels and deltaMA with platelet count in patients undergoing coronary revascularization. Correlation between plasma fibrinogen levels and abciximab-modified MA was significant (adjusted r2: 0.8; P < 0.0001). Correlation of deltaMA with platelet count was not significant when calculated in millimeters (adjusted r2: 0.04; P = 0.73). However, when deltaMA was calculated in dynes per square centimeter (deltaGMA), it correlated significantly with platelet count (adjusted r2: 0.51; P < 0.0001). We conclude that abciximab-modified TEG may therefore help to discriminate between hypofibrinogenemia and platelet dysfunction as a cause of decreased MA. ⋯ We examined the use of abciximab-modified thrombelastography in patients undergoing cardiac surgery. Modification of thrombelastography with abciximab-fab allows prediction of fibrinogen levels, despite coagulation altered by cardiac surgery. The difference of standard maximum amplitude and abciximab-modified maximum amplitude correlates with platelet function when expressed in dynes per square centimeter.
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Anesthesia and analgesia · Sep 1999
Cardiac output is a determinant of the initial concentrations of propofol after short-infusion administration.
Indicator dilution theory predicts that the first-pass pulmonary and systemic arterial concentrations of a drug will be inversely related to the cardiac output. For high-clearance drugs, these first-pass concentrations may contribute significantly to the measured arterial concentrations, which would therefore also be inversely related to cardiac output. We examined the cardiac output dependence of the initial kinetics of propofol in two separate studies using chronically instrumented sheep in which propofol (100 mg) was infused IV over 2 min. In the first study, steady-state periods of low, medium, and high cardiac output were achieved by altering carbon dioxide tension in six halothane-anesthetized sheep. The initial area under the curve and peak value of the pulmonary artery propofol concentrations were inversely related to cardiac output (R2 = 0.57 and 0.66, respectively). For the systemic arterial concentrations, these R2 values were 0.68 and 0.71, respectively. In our second study, transient reductions in cardiac output were achieved in five conscious sheep by administering a short infusion of metaraminol concurrently with propofol. Cardiac output was lowered by 2.2 L/min, and the area under the curve to 10 min of the arterial concentrations increased to 143% of control. ⋯ The initial arterial concentrations of propofol after IV administration were shown to be inversely related to cardiac output. This implies that cardiac output may be a determinant of the induction of anesthesia with propofol.