Anesthesia and analgesia
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialThe effect of clonidine or midazolam premedication on perioperative responses during ketamine anesthesia.
The use of ketamine as a sole anesthetic induces marked central sympathetic stimulation, causing increased heart rate, blood pressure (BP), and oxygen consumption (VO2). Both alpha 2-agonists and benzodiazepines have been used to attenuate these potentially harmful ketamine-induced responses. This double-blind, randomized, placebo-controlled study was designed to compare the perioperative metabolic, hemodynamic, and sympathoadrenal responses to IM clonidine (2 micrograms/kg) and midazolam (70 micrograms/kg) premedication during ketamine anesthesia. VO2 was measured continuously using indirect calorimetry in 30 ASA physical status I patients. The patients received ketamine, mivacurium, and fentanyl for the induction of anesthesia. Anesthesia was maintained using a ketamine infusion and fentanyl boluses i.v. Preoperatively, both VO2 and BP decreased significantly after the administration clonidine and midazolam compared with placebo (P < 0.01). Intraoperatively, VO2 was higher in the midazolam group than in the placebo and clonidine groups (P < 0.05). Postoperatively, there were no significant differences in BP and VO2, although they stayed at lower level in the clonidine group during the whole postoperative period. Clonidine decreased pre- and postoperative plasma catecholamine concentrations (P < 0.05). Our results indicate that a midazolam-ketamine combination may induce potentially harmful metabolic stimulation, whereas the sympatholytic effects of clonidine on ketamine-anesthetized patients may be beneficial, as perioperative VO2 was decreased. ⋯ Ketamine causes sympathetic stimulation with an ensuing increase in oxygen consumption. Anticipating that clonidine might attenuate this response, we measured oxygen consumption in patients undergoing surgery during ketamine anesthesia. Patients treated with a clonidine-ketamine combination had lower intra- and postoperative oxygen consumption than those treated with a midazolam-ketamine combination.
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialThe effect of preoperative dexamethasone on the immediate and delayed postoperative morbidity in children undergoing adenotonsillectomy.
In this prospective, randomized, double-blind, placebo-controlled study, we examined the effect of preoperative dexamethasone on postoperative nausea and vomiting (PONV) and 24-h recovery in children undergoing tonsillectomy. One hundred thirty children, 2-12 yr of age, ASA physical status I or II, completed the study. All children received oral midazolam 0.5-0.6 mg/kg preoperatively. Anesthesia was induced with halothane and nitrous oxide in 60% oxygen and maintained with nitrous oxide and isoflurane. Intubation was facilitated by mivacurium 0.2 mg/kg. Each child received fentanyl 1 microgram/kg i.v. before initiation of surgery, as well as dexamethasone 1 mg/kg (maximal dose 25 mg) (steroid group) or an equal volume of saline (control group). Intraoperative fluids were standardized to 25-30 mL/kg lactated Ringer's solution. All tonsillectomies were performed under the supervision of one attending surgeon using an electrodissection technique. Postoperatively, fentanyl and acetaminophen with codeine elixir were administered as needed for pain. Rescue antiemetics were administered when a child experienced two episodes of retching and/or vomiting. Before home discharge, the incidence of PONV, need for rescue antiemetics, quality or oral intake, and analgesic requirements did not differ between groups. However, during the 24 h after discharge, more patients in the control group experienced PONV (62% vs 24% in the steroid group) and complained of poor oral intake. Additionally, more children in the control group (8% vs 0% in the steroid group) returned to the hospital for the management of PONV and/or poor oral intake. The preoperative administration of dexamethasone significantly decreased the incidence of PONV over the 24 h after home discharge in these children. ⋯ In this double blind, placebo-controlled study, we examined the efficacy of a single large dose (1 mg/kg; maximal dose 25 mg) of preoperative dexamethasone on posttonsillectomy postoperative nausea and vomiting (PONV) in children 2-12 yr of age undergoing tonsillectomy. Compared with placebo, dexamethasone significantly decreased the incidence of PONV in the 24 h after discharge, improved oral intake, decreased the frequency of parental phone calls, and resulted in no hospital returns for the management of PONV and/or poor oral intake.
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialPeripheral nerve blocks improve analgesia after total knee replacement surgery.
Total knee replacement (TKR) produces severe postoperative pain. Peripheral nerve blocks can be used as analgesic adjuncts for TKR, but the efficacy of femoral nerve blocks alone is controversial. The sciatic nerve innervates posterior regions of the knee; thus, performance of both sciatic and femoral nerve blocks may be necessary to improve analgesia after TKR. We performed this study to determine whether peripheral nerve blocks improve analgesia after TKR. In a randomized, double-blind fashion, 36 patients undergoing TKR received either femoral, sciatic-femoral, or sham nerve blocks after a standardized spinal anesthetic. Further postoperative analgesia was provided by patient-controlled i.v. morphine and ketorolac. Pain at rest and with physical therapy, morphine use, nausea, pruritus, sedation, and patient satisfaction were assessed. Patients receiving peripheral nerve blocks reported better analgesia at rest for at least 8 h after transfer to the hospital ward (P < 0.05). Morphine use was decreased by approximately 50% in the peripheral nerve block groups until the second postoperative day (P < 0.02). Side effect profiles and patient satisfaction were similar between groups. We conclude that femoral nerve blocks improve analgesia and decrease morphine use after TKR. The addition of a sciatic nerve block to the femoral nerve block did not further improve analgesic efficacy. ⋯ Performance of femoral nerve blocks improves analgesia and decreases the need for morphine after total knee replacement surgery. The addition of a sciatic nerve block to the femoral nerve block does not provide additional benefits.
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Anesthesia and analgesia · Jul 1998
Randomized Controlled Trial Clinical TrialEffects of intravenous patient-controlled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty.
In this study, we assessed the influence of three analgesic techniques on postoperative knee rehabilitation after total knee arthroplasty (TKA). Forty-five patients scheduled for elective TKA under general anesthesia were randomly divided into three groups. Postoperative analgesia was provided with i.v. patient-controlled analgesia (PCA) with morphine in Group A, continuous 3-in-1 block in Group B, and epidural analgesia in Group C. Immediately after surgery, the three groups started identical physical therapy regimens. Pain scores, supplemental analgesia, side effects, degree of maximal knee flexion, day of first walk, and duration of hospital stay were recorded. Patients in Groups B and C reported significantly lower pain scores than those in Group A. Supplemental analgesia was comparable in the three groups. Compared with Groups A and C, a significantly lower incidence of side effects was noted in Group B. Significantly better knee flexion (until 6 wk after surgery), faster ambulation, and shorter hospital stay were noted in Groups B and C. However, these benefits did not affect outcome at 3 mo. We conclude that, after TKA, continuous 3-in-1 block and epidural analgesia provide better pain relief and faster knee rehabilitation than i.v. PCA with morphine. Because it induces fewer side effects, continuous 3-in-1 block should be considered the technique of choice. ⋯ In this study, we determined that, after total knee arthroplasty, loco-regional analgesic techniques (epidural analgesia or continuous 3-in-1 block) provide better pain relief and faster postoperative knee rehabilitation than i.v. patient-controlled analgesia with morphine. Because it causes fewer side effects than epidural analgesia, continuous 3-in-1 block is the technique of choice.
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Anesthesia and analgesia · Jul 1998
Clinical TrialEpidural labor analgesia and the incidence of cesarean delivery for dystocia.
We performed this retrospective study to examine the changes in cesarean delivery rates associated with the establishment of a labor epidural service. In April 1993, St. Louis Regional Medical Center established an on-demand labor epidural service. We obtained demographic data for all patients and reviewed the operative records of all patients undergoing cesarean section who delivered 12 mo before and 16 mo after the start of the labor epidural service. We compared labor epidural rates and total and nulliparous dystocia cesarean delivery rates before and after the epidural service started and among patients who did and did not receive labor epidural analgesia when it was available. Included were 3195 patients who delivered before and 3733 patients who delivered after epidural analgesia became available. Labor epidural rates were 1.2% vs 29.4% for the Before group versus the After group (P < 0.001). Total (9.1% vs 9.7%) and nulliparous dystocia (5.7% vs 6.4%) cesarean delivery rates did not significantly change with the availability of epidural analgesia. However, the total (11.6% vs 8.8%; P = 0.009) and dystocia (8.0% vs 1.0%; P = 0.001) cesarean delivery rates were higher among patients who received epidural analgesia when it was available. We conclude that epidural labor analgesia is associated with, but does not cause, cesarean delivery for dystocia. ⋯ Increased epidural analgesia use did not change the overall dystocia cesarean delivery rate, although dystocia was more common among women who chose an epidural analgesia. Consequently, limiting epidural availability will not affect cesarean delivery rates. The evidence does not support advising patients that epidural labor analgesia increases the risk of cesarean delivery.