Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe site of action of epidural fentanyl in humans: the difference between infusion and bolus administration.
Most published studies suggesting that epidural fentanyl acts predominantly at spinal sites administered the drug as a bolus injection, whereas most studies suggesting that it acts predominantly at supraspinal sites administered the drug as an infusion. In this study we tested the hypothesis that the mode of administration (bolus versus infusion) of epidural fentanyl determines its site of action. Ten healthy volunteers were enrolled in this randomized, double-blinded, cross-over study. On separate study days fentanyl was administered into the epidural space as a bolus (0.03 mg followed by 0.1 mg 210 min later) and as an infusion (0.03 mg/h followed by 0.1 mg/hr 210 min later for 200 min). Using a thermal and electrical experimental pain model, the heat ( degrees C) and electrical current (mA) causing maximum tolerable pain were assessed repetitively over a period of 420 min. The analgesic efficacy measures were obtained at a lumbar and a cranial dermatome. Plasma fentanyl concentrations were determined throughout the study. Epidural bolus administration of fentanyl resulted in segmental analgesia (leg > head), whereas the epidural infusion of fentanyl produced nonsegmental analgesia (leg = head). There was a significant linear relationship between the analgesic effect and the plasma concentration of fentanyl for the epidural infusion but not for the epidural bolus administration of fentanyl. These findings support our hypothesis and might explain the apparent conflict in the literature regarding the site of action of epidural fentanyl. ⋯ In an experimental pain study in volunteers, epidural fentanyl caused segmental analgesia when administered as a bolus and nonsegmental systemic analgesia when administered as a continuous infusion. This finding may help resolve the long-standing controversy surrounding the site of action of epidural fentanyl.
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Anesthesia and analgesia · Nov 2003
Randomized Controlled Trial Comparative Study Clinical TrialSpinal mechanisms contribute to analgesia produced by epidural sufentanil combined with bupivacaine for postoperative analgesia.
When used alone, lipid-soluble epidural opioids are thought to produce analgesia supraspinally via systemic absorption. However, spinal opioids and local anesthetics have been shown to act synergistically at the spinal level in animal studies. We, therefore, tested the hypothesis that sufentanil requirements will be less when given epidurally than IV in patients simultaneously given epidural bupivacaine after major abdominal surgery. Forty patients were anesthetized with isoflurane and epidural bupivacaine for major abdominal surgery. After surgery, each was given a continuous epidural infusion of bupivacaine at a rate of 5 mg/h and sufentanil patient-controlled analgesia (PCA). In a randomized, double-blinded fashion, the sufentanil was given either epidurally or IV. PCA settings were the same in each group. For 60 hrs after surgery, the following variables were measured: pain scores at rest, during mobilization, and during coughing; extension of sensory block; side effects; and sufentanil consumption. Pain scores, extension of sensory block, and the incidence of side effects did not differ between the two groups. Consumption of sufentanil in the epidural group was half that of the IV group (48 h after surgery: 107 +/- 57 microg versus 207 +/- 100 microg for the epidural and IV groups, respectively; P < 0.05). We conclude that spinal mechanisms contribute to the analgesia produced by epidural sufentanil in combination with a local anesthetic. ⋯ When combined with epidural bupivacaine, the sufentanil requirement was 50% less when given epidurally than IV. Epidural sufentanil thus appears to have a spinal mechanism of action.
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Anesthesia and analgesia · Nov 2003
Randomized Controlled Trial Clinical TrialThe use of a continuous popliteal sciatic nerve block after surgery involving the foot and ankle: does it improve the quality of recovery?
Popliteal sciatic nerve block is a commonly used technique for surgery involving the foot and ankle. However, pain can be difficult to control as the local anesthetic block wears off. Therefore, we hypothesized that extending the block by using a continuous infusion of bupivacaine (0.25%) would provide improved pain management and might facilitate the recovery process after foot or ankle surgery. In this randomized, double-blinded, placebo-controlled study, 24 consenting patients undergoing foot or ankle surgery with a standardized general anesthetic technique were studied. Before surgery, a popliteal sciatic nerve block was performed in all patients with an 18-gauge Tuohy epidural needle and a peripheral nerve stimulator. After injection of bupivacaine 0.25% 30 mL and placement of a 20-gauge catheter, patients were randomly assigned to receive either 0.9% saline (control) or bupivacaine 0.25% at a constant rate of 5 mL/h for up to 48 h after surgery. An 11-point verbal rating scale (0 = no pain to 10 = worst pain imaginable) was used to assess the severity of pain. Opioid analgesic use was recorded at specific time intervals after surgery. Follow-up evaluations were performed at 24 h, 48 h, 72 h, and 1 week after surgery to assess pain scores, as well as patient satisfaction with their pain management and quality of recovery, by using a 100-point verbal rating scale (1 = highly dissatisfied to 100 = highly satisfied). In the bupivacaine group, there was a statistically significant reduction in the maximal pain scores (>50%) and in opioid use (>60%) during the postoperative period compared with the control group. Patient satisfaction with postoperative pain management (95 +/- 3 versus 77 +/- 13) and quality of recovery (96 +/- 7 versus 83 +/- 14) was significantly improved in the bupivacaine group (versus control). In addition, 40% of the patients in the bupivacaine group (versus none in the control group) were able to be discharged home on the day of surgery (P = 0.087). In conclusion, a continuous infusion of bupivacaine 0.25% decreased postoperative pain and the need for opioid analgesic rescue medication after orthopedic surgery involving the foot and ankle, leading to improved patient satisfaction and quality of recovery. ⋯ A continuous infusion of bupivacaine 0.25% (versus saline) at the popliteal fossa by using a simple elastomeric pump is an effective method of decreasing postoperative pain, reducing the opioid analgesic requirement, and increasing patient satisfaction with pain management after orthopedic surgery involving the foot and ankle. More importantly, the use of the continuous sciatic nerve block in the popliteal fossa facilitated an earlier discharge after lower extremity surgery.
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Anesthesia and analgesia · Nov 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of intravenous pantoprazole and ranitidine for improving preoperative gastric fluid properties in adults undergoing elective surgery.
We studied pantoprazole, a new potent and fast-acting proton pump inhibitor. Its effects on preoperative gastric fluid volume and pH have not yet been determined. In this randomized, controlled trial, we examined the effects of preoperative IV pantoprazole or ranitidine on gastric pH and volume. Ninety patients (ASA status I and II, scheduled for elective surgery) were studied. One hour before surgery, patients in Group I (n = 30) were given IV saline 5 mL, those in Group II (n = 30) were given 40 mg of pantoprazole IV, and those in Group III (n = 30) were given 50 mg of ranitidine IV. A nasogastric tube was inserted immediately after anesthesia induction. Gastric contents were aspirated, and volume and pH were recorded. The pH values determined in Group I were 3.73 +/- 0.82; in Group II, they were 5.30 +/- 1.84; and in Group III, they were 4.80 +/- 1.40. There was no statistical difference between Groups 2 and 3, but there was a significant difference between Group I and Groups 2 and 3 (P < 0.0005). The volume of the gastric contents was 28.67 +/- 10.98 mL in Group I, 15.20 +/- 15.52 mL in Group II, and 7.77 +/- 11.17 mL in Group III. There was no statistical difference between Groups 2 and 3, but there was a statistically significant difference between Group I and Groups 2 and 3 (P < 0.0005). The proportion of patients considered "at risk" of significant lung injury should aspiration occur was 20% of Group I, 10% of Group II, and 3.3% of Group III. When statistically evaluated, there was no difference among groups. We concluded that the administration of IV pantoprazole and ranitidine 1 h before surgery is effective in reducing gastric pH and volume. ⋯ This randomized, controlled trial examined the effects of preoperative IV pantoprazole or ranitidine on gastric pH and volume. We concluded that IV pantoprazole and ranitidine, given 1 h before surgery, are effective in reducing gastric pH and volume.
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Anesthesia and analgesia · Nov 2003
Randomized Controlled Trial Clinical TrialA silicone-based wire-reinforced tracheal tube with a hemispherical bevel reduces nasal morbidity for nasotracheal intubation.
We tested the hypothesis that a silicone-based wire-reinforced tracheal tube with a hemispherical bevel is superior to a polyvinyl chloride (PVC)-based precurved tube with a conventional diagonal bevel for nasotracheal intubation. Eighty anesthetized paralyzed adults (ASA physical status I-II) requiring nasotracheal intubation for tonsillectomy were randomly allocated into two equal-sized groups for airway management with the silicone tracheal tube or PVC tracheal tube. Intubation was subdivided into three phases: 1). passage through the nose into the pharynx, 2). laryngoscope-guided passage into the glottic inlet, and 3). laryngoscope-guided passage into the trachea. A specific sequence of airway maneuvers was followed at each stage if it was unsuccessful. The number of attempts and intubation time were documented by an unblinded observer. The frequency of epistaxis and postoperative nasal complications was documented by blinded observers. There were no intubation failures. The number of attempts at pharyngeal (47 versus 56; P = 0.04) and tracheal (43 versus 55; P = 0.005) placement was smaller for the silicone tracheal tube, but the number of attempts at glottic placement was more (72 versus 49; P < 0.0001). Intubation time was similar. The frequency (32% versus 80%; P < 0.0001) and severity of epistaxis were less for the silicone tracheal tube. The total number of postoperative nasal symptoms was smaller for the silicone tracheal tube (10 versus 21; P < 0.05). We conclude that the pharyngeal and tracheal placement phases of nasotracheal intubation require fewer attempts with the silicone tracheal tube than the PVC tracheal tube but that the glottic placement phase requires more attempts. Nasal morbidity is less common with the silicone tracheal tube. ⋯ The pharyngeal and tracheal placement phases of nasotracheal intubation require fewer attempts with a silicone-based wire-reinforced tracheal tube with a hemispherical bevel than with a polyvinyl chloride-based precurved tracheal tube with a conventional diagonal bevel, but the glottic placement phase requires more attempts. Nasal morbidity is less common with the silicone tracheal tube.