Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2000
Pediatric evaluation of the bispectral index (BIS) monitor and correlation of BIS with end-tidal sevoflurane concentration in infants and children.
The bispectral index (BIS) has been developed in adults and correlates well with clinical hypnotic effects of anesthetics. We investigated whether BIS reflects clinical markers of hypnosis and demonstrates agent dose-responsiveness in infants and children. In an observational arm of this study, BIS values in children undergoing general anesthesia were observed and compared with similar data collected previously in a study of adults. In a second arm of the study, a range of steady-state end-tidal concentrations of sevoflurane was administered and corresponding BIS documented. Data were examined for differences between infants (0-2 yr) and children (2-12 yr). No difference was seen in BIS values in children before induction, during maintenance, and on emergence compared with adult values. There was no difference in BIS between infants and children at similar clinical levels of anesthesia. In children and infants, BIS was inversely proportional to the end-tidal concentration of sevoflurane. The sevoflurane concentration for a BIS = 50 (95% confidence interval) was significantly different: 1. 55% (1.40-1.70) for infants versus 1.25% (1.12-1.37) for children. Although validation with specific behavioral end points was not possible, BIS correlated with clinical indicators of anesthesia in children as it did in adults: as depth of anesthesia increased, BIS diminished. BIS correlated with sevoflurane concentration in infants and children. The concentration-response difference between infants and children was consistent with data showing that minimum alveolar concentration is higher in children less than 1 yr of age. ⋯ The use of bispectral index (BIS) during general anesthesia improves the titration of anesthetics in adults. The data from this study suggest that the same equipment and method of electroencephalogram analysis may be applied to infants and children.
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Anesthesia and analgesia · Apr 2000
Meta AnalysisPrevention of pain on injection with propofol: a quantitative systematic review.
The best intervention to prevent pain on injection with propofol is unknown. We conducted a systematic literature search (Medline, Embase, Cochrane Library, bibliographies, hand searching, any language, up to September 1999) for full reports of randomized comparisons of analgesic interventions with placebo to prevent that pain. We analyzed data from 6264 patients (mostly adults) of 56 reports. On average, 70% of the patients reported pain on injection. Fifteen drugs, 12 physical measurements, and combinations were tested. With IV lidocaine 40 mg, given with a tourniquet 30 to 120 s before the injection of propofol, the number of patients needed to be treated (NNT) to prevent pain in one who would have had pain had they received placebo was 1.6. The closest to this came meperidine 40 mg with tourniquet (NNT 1.9) and metoclopramide 10 mg with tourniquet (NNT 2.2). With lidocaine mixed with propofol, the best NNT was 2.4; with IV alfentanil or fentanyl, it was 3 to 4. IV lidocaine before the injection of propofol was less analgesic. Temperature had no significant effect. There was a lack of data for all other interventions to allow meaningful conclusions. The diameter of venous catheters and speed of injection had no impact on pain. ⋯ IV lidocaine (0.5 mg/kg) should be given with a rubber tourniquet on the forearm, 30 to 120 s before the injection of propofol; lidocaine will prevent pain in approximately 60% of the patients treated in this manner.
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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
Randomized Controlled Trial Clinical TrialPostcesarean epidural morphine: a dose-response study.
The purpose of this study was to describe the dose-response relationship of epidural morphine for postcesarean analgesia for quality of analgesia and relation to the side effects of pruritus, nausea, and vomiting. Sixty term parturients undergoing nonurgent cesarean delivery were enrolled and randomized to receive a single dose of epidural morphine after delivery (0,1.25, 2.5, 3.75, or 5 mg). A patient-controlled analgesia (PCA) device provided free access to additional analgesics. PCA morphine use and the incidence and severity of side effects were recorded for 24 h. Data were analyzed with analysis of variance, Student's t-tests, and chi(2) analysis. Nonlinear regression was used to describe a dose-response curve. PCA use differed significantly among groups (P < 0.001); PCA use was significantly greater in Group 0 mg than Groups 2.5, 3.75, and 5 mg (P < 0.05). PCA use was also significantly greater in Group 1.25 mg than Groups 3.75 and 5 mg (P < 0.05). Pruritus scores were significantly higher in all groups given epidural morphine than the control group (0 mg) (P < 0.05), but did not differ among the treatment groups (1.25-5 mg), although pruritus scores were significantly higher in treatment groups than in the control (P < 0. 05). No relation was found between epidural morphine dose and incidence or severity of nausea and vomiting. We concluded that, for optimal analgesia, augmentation of epidural morphine with systemic analgesics or other epidural medications may be necessary. ⋯ Quality of analgesia increases as the dose of epidural morphine increases to at least 3.75 mg; increasing the dose further to 5 mg did not improve analgesia. Side effects were not dose related. For optimal analgesia, augmentation of epidural morphine with systemic analgesics or other epidural medications may be necessary.