Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2000
Randomized Controlled Trial Clinical TrialThe hemodynamic and adrenergic effects of perioperative dexmedetomidine infusion after vascular surgery.
We tested dexmedetomidine, an alpha(2) agonist that decreases heart rate, blood pressure, and plasma norepinephrine concentration, for its ability to attenuate stress responses during emergence from anesthesia after major vascular operations. Patients scheduled for vascular surgery received either dexmedetomidine (n = 22) or placebo (n = 19) IV beginning 20 min before the induction of anesthesia and continuing until 48 h after the end of surgery. All patients received standardized anesthesia. Heart rate and arterial blood pressure were kept within predetermined limits by varying anesthetic level and using vasoactive medications. Heart rate, arterial blood pressure, and inhaled anesthetic concentration were monitored continuously; additional measurements included plasma and urine catecholamines. During emergence from anesthesia, heart rate was slower with dexmedetomidine (73 +/- 11 bpm) than placebo (83 +/- 20 bpm) (P = 0.006), and the percentage of time the heart rate was within the predetermined hemodynamic limits was more frequent with dexmedetomidine (P < 0.05). Plasma norepinephrine levels increased only in the placebo group and were significantly lower for the dexmedetomidine group during the immediate postoperative period (P = 0.0002). We conclude that dexmedetomidine attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia. ⋯ The alpha(2) agonist, dexmedetomidine, attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia in vascular surgery patients.
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Anesthesia and analgesia · Apr 2000
Opioid substitution to improve the effectiveness of chronic noncancer pain control: a chart review.
We evaluated the efficacy and tolerability of opioids in the long-term management of chronic noncancer pain. This retrospective chart review included 86 outpatients who started receiving, between 1994 and 1998, long-acting opioids. For each patient, the number of different opioids used and the efficacy and tolerability of each opioid prescribed were noted. During a mean follow-up of 8.8 +/- 6.3 mo, the number of opioids used by each patient was 2.3 +/- 1.4. Patient diagnoses were: back pain (31), neuropathy (20), joint pain (13), visceral pain (7), reflex sympathetic dystrophy (7), headache (5), fibromyalgia (3). The first opioid prescribed was effective for 36% of patients, was stopped because of side effects in 30%, and was stopped for ineffectiveness in 34%. Of the remaining patients, the second opioid prescribed after the failure of the first was effective in 31%, the third in 40%, the fourth in 56%, and the fifth in 14%. There was one case of addiction and no case of tolerance. We conclude that if it is necessary to change the opioid prescription because of intolerable side effects or ineffectiveness, the cumulative percentage of efficacy increases with each new opioid tested. Failure of one opioid cannot predict the patient's response to another. ⋯ This study showed that if a patient receiving chronic opioid therapy experiences an intolerable side effect or if the drug is ineffective, changing to a different opioid may result in a lessening or elimination of the side effect and/or improved analgesia.
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Anesthesia and analgesia · Apr 2000
Randomized Controlled Trial Clinical TrialThe use of a ketamine-propofol combination during monitored anesthesia care.
Supplemental analgesics are commonly used to enhance analgesia and improve patient comfort during procedures performed under local anesthesia and sedation. Because the use of ketamine as an analgesic adjunct to propofol sedation has not been well established, we evaluated its impact on analgesia, sedation, and recovery after ambulatory surgery. One hundred female outpatients undergoing breast biopsy procedures under local anesthesia participated in this randomized, double-blinded, placebo-controlled study. After premedication with midazolam, 2 mg IV, patients received an infusion of a solution containing propofol (9.4 mg/mL) in combination with either placebo (saline) (Group 1) or ketamine, 0.94 mg/mL (Group 2), 1.88 mg/mL (Group 3), or 2.83 mg/mL (Group 4). The sedative infusion rate was varied to maintain a deep level of sedation (Observer Assessment of Alertness/Sedation score 4) and normal respiratory and hemodynamic functions. Sufentanil, 2.5 microg IV, "rescue" boluses were used as needed to treat patients' responses (if any) to local anesthetic infiltration or surgical stimulation. Ketamine produced a dose-dependent reduction in the "rescue" opioid requirements. However, there was an increase in postoperative nausea and vomiting, psychomimetic side effects, and delay in discharge times with the largest ketamine dosage (Group 4). The adjunctive use of ketamine during propofol sedation provides significant analgesia and minimizes the need for supplemental opioids. The combination of propofol (9.4 mg/mL)/ketamine (0.94-1.88 mg/mL) provides effective sedation/analgesia during monitored anesthesia care. ⋯ Ketamine, when used in subhypnotic dosages, may be an useful adjuvant to propofol sedation.
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Anesthesia and analgesia · Apr 2000
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of urapidil, clonidine, meperidine and placebo in preventing postanesthetic shivering.
This placebo-controlled study was performed to evaluate the efficacy of urapidil compared with clonidine and meperidine in preventing postanesthetic shivering, which is common after anesthesia administration and may be very distressing. We studied 120 patients undergoing elective abdominal or orthopedic surgery under standardized general anesthesia. After surgery, patients were randomly assigned to one of four groups (each group n = 30) using a double-blinded protocol: Group A received 0.2 mg/kg urapidil; Group B, 3 microg/kg clonidine; Group C, 0.4 mg/kg meperidine; and Group D, saline 0.9% as placebo. Postanesthetic shivering was scored by using a five-point scale. Clonidine and meperidine significantly reduced the incidence and the severity of shivering in comparison with placebo, whereas there were no significant differences between the urapidil and placebo groups. Both clonidine and meperidine caused a significantly prolonged emergence time (13.4 +/- 5.8 and 13. 3 +/- 5.0 min, respectively) compared with placebo (10.4 +/- 5.3 min) and urapidil (11.4 +/- 2.9 min). We confirmed that both clonidine and meperidine are effective in preventing postanesthetic shivering, whereas urapidil, in our setting and dosage, was not effective. Patients who received clonidine or meperidine had a prolonged emergence time. In the dosage used, urapidil seems to be unable to prevent postanesthetic shivering. ⋯ Shivering (irregular muscle activity) is common after surgery and anesthesia. This study compared urapidil (an antihypertensive drug) as a prophylaxis with two established antishivering drugs (meperidine and clonidine) and placebo. In the dosage used, we were unable to show a significant benefit of urapidil.
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The relationship between epidural analgesia and cesarean delivery remains controversial. Several studies have documented an association, although others have not. This inconsistency may result from an association between severe labor pain and dystocia. We hypothesized that dystocia causes severe labor pain, such that more epidural medication is required to maintain comfort. We examined the relationship between labor outcome and severe pain, defined by the number of supplemental epidural boluses. We retrospectively reviewed the anesthesia records of 4493 parturients who received small-dose labor epidural analgesia. An independent association was found between operative delivery and maternal age, body mass index, nulliparity, fetal weight, induction of labor, and the number of boluses required during labor. By using multivariate analysis, the odds ratio of cesarean delivery among women who required at least three boluses was 2.3 compared with those who required two boluses or less. No association was found between the concentration of bupivacaine in the epidural infusion and operative delivery. Because women with cesarean deliveries appeared to have more pain, degree of labor pain may be a confounding factor in studies examining epidural analgesia and outcome. ⋯ This is a retrospective observational study demonstrating an association between labor pain and cesarean delivery. Our results provide an alternative explanation of why epidural analgesia is associated with cesarean delivery.