Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2003
Randomized Controlled Trial Clinical TrialThe efficacy of celecoxib premedication on postoperative pain and recovery times after ambulatory surgery: a dose-ranging study.
Recently, the Food and Drug Administration increased the celecoxib dosage recommendation from 200 mg to 400 mg for acute pain management. No studies have directly compared the analgesic efficacy of different doses of celecoxib for the prevention of postoperative pain. In this prospective, double-blinded, placebo-controlled study, we compared oral celecoxib 200 mg to 400 mg when administered for premedication of outpatients undergoing minor ear-nose-throat surgery. A total of 93 healthy outpatients were assigned to 1 of 3 study groups: control (placebo; n = 30), celecoxib 200 mg (n = 30), or celecoxib 400 mg (n = 33). The study drug was given orally 30-45 min before surgery, and all patients received a standardized general anesthetic technique. During the postoperative period, pain scores (0-10), recovery times, the need for rescue analgesics, quality of recovery (0-100), patient satisfaction with pain management (0-100), and side effects were recorded. Pain was assessed at 30-min intervals using a verbal rating scale, with 0 = no pain to 10 = worst pain imaginable, in the postanesthesia care unit and day surgery unit recovery areas and at 24 h after surgery. Celecoxib 400 mg was significantly more effective than 200 mg (and placebo) in reducing postoperative pain. Both celecoxib 200 mg and 400 mg were more effective than placebo in reducing the postoperative fentanyl requirement (74 +/- 67 micro g and 56 +/- 62 micro g versus 120 +/- 86 micro g, respectively). The larger dose of celecoxib significantly reduced the percentage of patients with severe pain at discharge (6% versus 37% and 30% in the celecoxib 200 mg and control groups, respectively). The median number of doses of oral analgesic medication after discharge was also significantly reduced in the celecoxib 400 mg group (0 versus 2 and 2 in the celecoxib 200 mg and control groups, respectively). However, no differences were found among the three study groups with respect to recovery times and secondary outcome variables (e.g., patient satisfaction and quality of recovery). We conclude that oral premedication with celecoxib 400 mg was more effective than 200 mg in reducing severe postoperative pain and the need for rescue analgesic medication in the postoperative period. ⋯ Oral premedication with celecoxib 400 mg was more effective than 200 mg in reducing postoperative pain and the need for rescue analgesic medication in the early postoperative period. However, neither dose of celecoxib was more effective than a placebo in facilitating the recovery process after outpatient surgery.
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Anesthesia and analgesia · Jun 2003
Randomized Controlled Trial Clinical TrialThe effects of epidural and general anesthesia on tissue oxygenation.
The risk of wound infections is inversely related to subcutaneous tissue oxygen tension. General anesthesia increases local blood flow by direct vasodilation and central inhibition of thermoregulatory vasoconstriction. Epidural anesthesia can increase perfusion in blocked regions by decreasing sympathetic tone. We therefore tested the hypothesis that epidural anesthesia increases tissue oxygen tension in awake and anesthetized subjects. Fifteen healthy volunteers underwent epidural, general, and combined epidural and general anesthesia. Subcutaneous tissue oxygen tension was measured using tonometers in the lateral upper arm and the lateral thigh. Epidural anesthesia to a T10 level was maintained with 0.75% mepivacaine. General anesthesia was maintained with 1.5% sevoflurane in 30% oxygen; 30% inspired oxygen was given via a sealed facemask during baseline and epidural anesthesia. Baseline subcutaneous tissue oxygen tensions for arm and thigh were 57 +/- 11 and 54 +/- 8 mm Hg, respectively. Epidural anesthesia significantly increased tissue oxygenation in the thigh by 9 mm Hg, to 63 +/- 7 mm Hg, without increasing arm oxygenation. Tissue oxygenation in the arm and thigh were similar during general anesthesia alone, 58 +/- 11 and 63 +/- 12 mm Hg. Arm oxygenation remained unchanged with the addition of epidural anesthesia; however, thigh subcutaneous oxygen partial pressure increased 8 +/- 3 mm Hg, from 63 +/- 12 to 71 +/- 9 mm Hg. Although epidural anesthesia increased tissue oxygenation significantly with and without general anesthesia, the magnitude of this increase might be of marginal clinical importance in regard to surgical wound infections. ⋯ Epidural anesthesia significantly increased subcutaneous tissue oxygenation in the thigh both with and without general anesthesia. Although each increase was statistically significant, previous work suggests that the magnitude of these changes is unlikely to markedly reduce the risk of surgical wound infection.
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Anesthesia and analgesia · Jun 2003
Randomized Controlled Trial Clinical TrialEffect-site concentration of propofol for recovery of consciousness is virtually independent of fentanyl effect-site concentration.
Fentanyl reduces the amount of propofol necessary to prevent responses to surgical stimuli. However, opioids have relatively little effect on consciousness. We, therefore, tested the hypothesis that fentanyl minimally alters the effect-site concentration of propofol associated with awakening. Fifty women having gynecologic laparotomy with propofol anesthesia were randomly allocated into the following target effect-site fentanyl concentrations: 0.8, 1.0, 1.4, 2.0, and 3.0 ng/mL. Fentanyl was continued at the designated rate through the initial postoperative phase. The propofol effect-site concentration associated with eye opening in response to verbal command was regarded as the awakening concentration. The estimated propofol effect-site concentrations at awakening did not differ significantly among the groups and were 1.9 +/- 0.5 micro g/mL with a fentanyl effect-site concentration of 0.8 ng/mL; 1.6 +/- 0.4 micro g/mL with 1.0 ng/mL of fentanyl; 1.6 +/- 0.2 micro g/mL with 1.4 ng/mL of fentanyl; 1.7 +/- 0.4 micro g/mL with 2.0 ng/mL of fentanyl; and 1.6 +/- 0.34 micro g/mL with 3.0 ng/mL of fentanyl (mean +/- SD). Seventy percent of the subjects in the 0.8 ng/mL fentanyl group spontaneously complained of pain, whereas none of the patients in the 2 or 3 ng/mL groups did. Five (56%) of 9 women in the 3 ng/mL group had a postoperative respiratory rate <6 breaths/min. Heart rate in one of these women decreased to <40 bpm. These data suggest that the optimal fentanyl effect-site concentration in patients recovering from gynecologic laparoscopy is between 1.4 and 2.0 ng/mL. ⋯ The effect-site concentration for propofol at awakening was virtually independent of the fentanyl effect-site concentration over the range of 0.8 to 3.0 ng/mL; however, 0.8 ng/mL of fentanyl was associated with inadequate postoperative analgesia, and 3.0 ng/mL of fentanyl was associated with respiratory toxicity. The optimal postoperative fentanyl effect-site concentration during recovery from propofol general anesthesia for laparotomy thus appears to be near 2 ng/mL.
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Anesthesia and analgesia · Jun 2003
Randomized Controlled Trial Clinical TrialSympathetic and vascular consequences from remifentanil in humans.
We explored the possible mechanisms of hypotension during the administration of sedation-analgesia doses of remifentanil in young (ASA physical status I) volunteers (n = 24). Cardiorespiratory and sympathetic variables were collected at baseline and at plasma concentrations of remifentanil (2 and 4 ng/mL). Monitoring included electrocardiogram, heart rate (HR), direct blood pressure, muscle sympathetic nerve activity, and forearm blood flow (FBF). A cold pressor test (1-min hand immersion in ice water) quantified analgesia effectiveness (visual analog scale, 0-100). Visual analog scale to the cold pressor test (62 at baseline) decreased to 27 and 18 during remifentanil infusions. Respiratory rate decreased and end-tidal carbon dioxide (ETCO(2)) increased with increasing doses of remifentanil; HR, direct blood pressure, muscle sympathetic nerve activity, SpO(2) remained unchanged, but FBF increased compared with placebo. In a second study (n = 7), timed respiration was used to maintain ETCO(2) during remifentanil, but FBF still increased. In a third study (n = 11), direct effects of remifentanil on vascular tone were determined with progressive infusions from 1 to 100 micro g/h into the brachial artery; FBF increased significantly from 3.5 to 4.3 mL/min per 100 mL of tissue (approximately 13%-18% increase). Sedative doses of remifentanil resulted in analgesia but no changes in neurocirculatory end-points except FBF. Direct effects of remifentanil on regional vascular tone may play a role in promoting hypotension. ⋯ Remifentanil occasionally has been associated with hypotension, the mechanism of which is unclear. This study found that remifentanil directly causes the forearm arterial vasculature to dilate.
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Anesthesia and analgesia · Jun 2003
Comparative Study Clinical TrialAcute intravascular volume expansion with rapidly administered crystalloid or colloid in the setting of moderate hypovolemia.
Although the distribution of various crystalloid and colloid solutions at equilibrium has been well established, the acute peak expansion of intravascular volume that can be achieved with the rapid administration of crystalloid or colloid is unknown. We studied eight healthy male subjects in a two-part crossover trial designed to assess the maximal increase in intravascular volume achieved with 1000 mL of lactated Ringer's solution compared with the same volume of 6% Hetastarch. Subjects were made moderately hypovolemic by the withdrawal of 900 mL of blood, and then the crystalloid or colloid solution was rapidly infused over 5-7 min. Serial dilution of hematocrit was measured every 5 min for 30 min to determine changes in blood volume. Peak expansion of intravascular volume with lactated Ringer's solution was 630 +/- 127 mL, occurring immediately the rapid infusion was complete, whereas the peak expansion of intravascular volume with 6% Hetastarch was 1123 +/- 116 mL and occurred 5 min after the completion of the fluid infusion. The results were significantly different (P < 0.001). These results would suggest that even for very short periods of time, rapid infusion of colloid significantly more effectively increases blood volume and, by inference, cardiac output than the same volume of crystalloid, even if the crystalloid is administered very rapidly. ⋯ Under conditions of moderate hypovolemia, the maximal acute intravascular volume expansion with the rapid infusion of 1000 mL of lactated Ringer's solution is slightly more than half that achieved with the same volume of 6% Hetastarch.