Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2000
Randomized Controlled Trial Clinical TrialThe effects of the single or multiple injection technique on the onset time of femoral nerve blocks with 0.75% ropivacaine.
We evaluated the effect of the injection technique on the onset time and efficacy of femoral nerve block performed with 0.75% ropivacaine. A total of 30 patients undergoing arthroscopic knee surgery were randomly allocated to receive femoral nerve blockade with 0.75% ropivacaine by using either a single injection (Single group, n = 15) or multiple injection (Multiple group, n = 15). Nerve blocks were placed by using a short-beveled, Teflon-coated, stimulating needle. The stimulation frequency was set at 2 Hz, and the intensity of stimulating current, initially set at 1 mA, was gradually decreased to <0.5 mA after each muscular twitch was observed. In the Single group, 12 mL of 0.75% ropivacaine was slowly injected, as soon as the first muscular twitch was observed. In the Multiple group, the stimulating needle was inserted and redirected, eliciting each of the following muscular twitches: contraction of vastus medialis, vastus intermedius, and vastus lateralis. At each muscular twitch, 4 mL of the study solution was injected. Placing the block required 4.2 +/- 1.7 min (median, 5 min; range, 2-8 min) in the Multiple group and 3.4 +/- 2.2 min (median, 3 min; range, 1-5 min) in the Single group (P = 0.02). Onset of nerve block (complete loss of pinprick sensation in the femoral nerve distribution with concomitant inability to elevate the leg from the operating table with the hip flexed) required 10 +/- 3.7 min in the Multiple group (median, 10 min; range, 5-20 min) and 30 +/- 11 min in the Single group (median, 30 min; range, 10-50 min) (P < 0.0005). Propofol sedation was never required to complete surgery; although 0.1 mg fentanyl at trocar insertion was required in two patients of the Multiple group (13%) and nine patients of the Single group (60%) (P = 0.02). We conclude that searching for multiple muscular twitches shortened the onset time and improved the quality of femoral nerve block performed with small volumes of 0.75% ropivacaine. ⋯ This prospective, randomized, blinded study was conducted to evaluate the effect of searching for multiple muscular twitches when performing femoral nerve block with small volumes of 0. 75% ropivacaine. Our results demonstrated that multiple injections markedly shortened the onset time and improved the quality of nerve blockade. This technique-related effect must be carefully considered when different clinical studies evaluating the use of new local anesthetic solutions for peripheral nerve blocks are compared.
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Anesthesia and analgesia · Jul 2000
Randomized Controlled Trial Clinical TrialKetorolac suppresses postoperative bladder spasms after pediatric ureteral reimplantation.
We evaluated the efficacy of ketorolac in suppressing postoperative bladder spasms after ureteroneocystostomy (ureteral reimplantation). Twenty-four pediatric patients undergoing intravesical ureteroneocystostomy were enrolled prospectively to receive either ketorolac or placebo via double-blinded randomization. Twelve patients in each group shared similar preoperative characteristics. All were maintained on an epidural infusion of bupivacaine (0.1%) with fentanyl (2 microg/mL) throughout the study. Patients were given either ketorolac (0.5 mg. kg(-1). dose(-1)) or placebo (equivalent volume saline) IV after surgery and every 6 h thereafter for 48 h. Parents were instructed to record bladder spasm episodes prospectively by using a standardized time-flow diary. Three patients (25%) in the ketorolac group experienced bladder spasms, compared with 10 patients (83%) in the placebo group (two-sided P < 0.05). The median severity score for the ketorolac group was 1.2 (mild = 1.0, severe = 3.0), compared with 2.6 for the placebo group (P = 0.003). We conclude that IV ketorolac reduces the frequency and severity of postoperative bladder spasms after intravesical ureteroneocystostomy. ⋯ We studied the efficacy of ketorolac, a prostaglandin synthesis inhibitor, in the treatment of bladder spasm after ureteroneocystostomy (antireflux operation). Patients were randomized in a double-blinded manner to receive either ketorolac or placebo after the surgery. We demonstrate that ketorolac reduces the frequency and severity of postoperative bladder spasm.
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Anesthesia and analgesia · Jul 2000
Randomized Controlled Trial Clinical TrialThe effect of timing of dexamethasone administration on its efficacy as a prophylactic antiemetic for postoperative nausea and vomiting.
We evaluated the timing effect of a 10-mg IV administration of dexamethasone on its efficacy as a prophylactic antiemetic on postoperative nausea and vomiting (PONV). One hundred twenty women (n = 40 in each of three groups) undergoing abdominal total hysterectomy under general anesthesia were enrolled in this randomized, double-blinded, placebo-controlled study. Group 1 received dexamethasone before the induction of anesthesia, Group 2 received dexamethasone at the end of anesthesia, and Group 3 received placebo (saline). The incidence of PONV was evaluated. During the postoperative period of 0-2 h, patients in Group 1 reported a less frequent incidence of PONV (15%) than those in Groups 2 and 3 (45% and 53%, respectively). Patients in Group 1 also requested less rescue antiemetic (8%) than those in Groups 2 and 3 (30% and 35%, respectively). During the postoperative period of 2-24 h, patients in both Groups 1 and 2 reported less frequent incidences of PONV (25% and 28%) and requested fewer rescue antiemetics (13% and 15%) than those in Group 3 (55% and 38%, respectively). In conclusion, the prophylactic IV administration of dexamethasone immediately before the induction, rather than at the end of anesthesia, was more effective in preventing PONV. ⋯ We evaluated the effect of timing of dexamethasone administration on its efficacy as a prophylactic antiemetic on postoperative nausea and vomiting. We found that dexamethasone, when given immediately before the induction of anesthesia, was more effective than when given at the end of anesthesia.
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Anesthesia and analgesia · Jul 2000
Randomized Controlled Trial Comparative Study Clinical TrialCerebral hemodynamic response to the introduction of desflurane: A comparison with sevoflurane.
Rapid increases in the inspired concentration of desflurane cause transient increases in heart rate and blood pressure. Desflurane also impairs cerebral autoregulation at clinical concentrations. Sevoflurane does not share these hemodynamic side effects. We compared the cerebral and systemic hemodynamic responses to the introduction of desflurane or sevoflurane after the induction of anesthesia with propofol. Twenty healthy adult patients scheduled for nonneurological surgery were recruited. After the induction of anesthesia with propofol, either desflurane or sevoflurane (n = 10 per group) was introduced at 7.2% or 2.2%, respectively, and increased to 10.8% or 3.3%, respectively, 2 min later. Middle cerebral artery blood flow velocity was measured continuously by using a 2-MHz transcranial Doppler ultrasound probe. Heart rate and blood pressure were recorded at 1-min intervals during the 12-min study period. Those patients receiving desflurane had significantly greater middle cerebral artery blood flow velocities, heart rates, and blood pressures than those receiving sevoflurane (P < 0.01). ⋯ The introduction of desflurane after the induction of anesthesia leads to significant disturbances in cerebral and systemic hemodynamics suggesting loss of cerebral autoregulation and cerebral hyperemia. This may have implications for patients undergoing anesthesia for intracranial surgery.
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Anesthesia and analgesia · Jul 2000
Randomized Controlled Trial Clinical TrialNitrous oxide prevents movement during orotracheal intubation without affecting BIS value.
We sought to determine whether the addition of nitrous oxide (N(2)O) to an anesthetic with propofol and remifentanil modifies the bispectral index (BIS) during the induction of anesthesia and orotracheal intubation. Thirty ASA physical status I or II patients were randomly allocated to receive either 50% air in oxygen (control group) or 60%-70% N(2)O in oxygen (N(2)O group) that was commenced via a mask simultaneously with the induction of anesthesia. Anesthesia was performed in all the patients with IV propofol at the target effect compartment site concentration of 4 microg/mL throughout the study. A target-controlled infusion (TCI) of remifentanil was initiated 3 min after the TCI of propofol and maintained at the effect-site concentration of 4 ng/mL until the end of the study. After loss of consciousness, and before the administration of vecuronium 0.1 mg/kg, a tourniquet was applied to one arm and inflated to a value more than the systolic blood pressure. An examiner, blinded to the presence of N(2)O, sought to detect any gross movement within the first minute after tracheal intubation, which was performed 10 min after remifentanil TCI began. Inspired and expired oxygen, N(2)O, and carbon dioxide were continuously monitored. A BIS value was generated every 10 s. Arterial blood pressure and heart rate (HR) were measured noninvasively every minute. Measures of mean arterial pressure (MAP), HR, and BIS were obtained before the induction, before the start of the remifentanil TCI, before laryngoscopy, and 5 min after intubation. No significant intergroup differences were seen in BIS, HR, and MAP throughout the study. Maximum changes in BIS, HR, and MAP with intubation were significant (P < 0.01) for both groups but comparable. Six patients in the control group and none in the N(2)O group moved after intubation (P < 0.05). ⋯ We demonstrated that 0.6 minimal alveolar concentration of nitrous oxide combined with a potent anesthetic and an opioid prevents movement after orotracheal intubation without affecting the bispectral index. This demonstrates that the bispectral index is not a useful neurophysiologic variable to monitor the level of anesthesia when nitrous oxide is added to a general anesthetic regimen using propofol and remifentanil.