Anesthesia and analgesia
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Clinical TrialSimulation of an epidural test dose with intravenous epinephrine in sevoflurane-anesthetized children.
An epidural test dose containing small doses of epinephrine does not produce a reliable increase in heart rate (HR) in children under halothane anesthesia. Because sevoflurane is increasingly used in clinical practice, we designed the present study to determine the hemodynamic responses to, and efficacy of, a simulated IV test dose containing a small dose of epinephrine in sevoflurane-anesthetized children. Sixty ASA physical status I infants and children (4.1 +/- 2.5 yr) undergoing elective minor surgeries were studied during 1.0 minimum alveolar anesthetic concentration of sevoflurane and 60% nitrous oxide in oxygen. The patients were randomly assigned to receive either saline (n = 15), a test dose consisting of 1% lidocaine (0.1 mL/kg) with 1:200,000 epinephrine (0.5 microg/kg, n = 15), atropine 0.01 mg/kg followed 5 min later by saline (n = 15), or atropine followed by the test dose (n = 15) via a peripheral vein to simulate intravascular injection of the epidural test dose. HR and systolic blood pressure were recorded every 15 and 30 s, respectively. The test dose increased the HR from 15 to 60 s and from 15 to 90 s without and with atropine, respectively. Mean maximum increases in HR were similar with and without atropine (21 +/- 8 and 22 +/- 6 bpm, respectively). Of 15 children, 7 and 5 developed HR changes < 20 bpm after the test dose with and without atropine, respectively, whereas all children who received saline had an increase in HR < 20 bpm. No dysrhythmia occurred during the study. Our results indicate that an epidural test dose containing epinephrine is unreliable based on the conventional HR criterion (positive if > or = 20 bpm increase), but reliable on the modified HR criterion (positive if > or = 10 bpm increase) in children anesthetized with sevoflurane. I.v. atropine before the test dose injection did not improve the efficacy based on the conventional HR criterion. Because test doses of epinephrine-containing solution are used to determine whether an epidural catheter is intravascular, it is important to define the optimal test dose under sevoflurane anesthesia. ⋯ We found that during sevoflurane anesthesia in children, a heart rate increase > or = 10 bpm and a systolic blood pressure increase > or = 15 mm Hg, when preceded by atropine, may be reliable indicators for detecting intravascular injection.
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Anesthesia and analgesia · May 1998
Hydroxyethyl starch antibodies in humans: incidence and clinical relevance.
Hydroxyethyl starch (HES) is a plasma expander used for perioperative i.v. fluid management, as well as for resuscitation from trauma and shock. HES is very well tolerated, and the incidence of anaphylactic reactions is lower than with dextran or gelatin. Dextran anaphylaxis is caused by circulating dextran-reactive antibodies (ABs) of the immunoglobin G (IgG) class found in most adults. Histamine release from mast cells induces adverse reactions after gelatin infusion. The cause of adverse reactions due to HES is not yet clear. To investigate AB formation due to HES, we collected sera of 1004 patients at least 14 days after starch administration. Using a highly sensitive enzyme-linked immunoabsorbent assay technique, we found one patient with a low 1:10 titer of HES-reactive ABs (immunoglobin M [IgM] class). Despite repeated HES infusions, no clinical reaction could be detected in this patient. On the basis of a binomial distribution, a one-tailed confidence interval (99%) was used to calculate the percentage of the occurrence of ABs in general with maximum of 33 in 10,000 persons (IgM) and 23 in 10,000 persons (IgG). We suggest that HES-reactive ABs are extremely rare and that they do not necessarily induce anaphylaxis. Other mechanisms may be responsible for adverse reactions due to HES. ⋯ The frequency of antibody formation due to hydroxyethyl starch, a commonly used plasma expander, was prospectively investigated in 1004 patients. Only one patient showed transient antibody formation, which was not harmful to the patient. This low antigenicity could explain the excellent tolerance of hydroxyethyl starch compared with other plasma expanders.
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Clinical TrialPremedication with fentanyl and midazolam decreases the reliability of intravenous lidocaine test dose.
This study was performed to determine whether premedication with midazolam and fentanyl prevents reliable detection of an i.v. lidocaine test dose. Thirty ASA physical status I or II patients received either 3 mL of saline or 1.5 mg of midazolam (1.5 mL) plus 75 microg of fentanyl (1.5 mL) i.v. in a randomized, double-blind fashion. Five minutes later, lidocaine 1 mg/kg was injected i.v. At 1.5 min before and every minute after lidocaine administration, each subject was questioned regarding the presence of four symptoms of systemic lidocaine toxicity. Any new tinnitus, perioral numbness, metallic taste, or light-headedness within 5 min after lidocaine administration was considered a positive response. All 15 patients in the saline group (100% sensitivity) had a positive response to i.v. lidocaine, but only 9 of 15 patients in the sedation group had a positive response (60% sensitivity; P = 0.017). We conclude that midazolam and fentanyl premedication decreases the reliability of subjective detection of i.v. lidocaine. ⋯ Anesthesiologists often rely on subjective symptoms to prevent local anesthetic toxicity while performing regional anesthesia. Sedatives are often administered during the administration of regional anesthesia. This study demonstrates that typical sedation decreases the reliability of detection of local anesthetic toxicity by subjective symptoms.
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of patient-controlled analgesia with lornoxicam versus morphine in patients undergoing lumbar disk surgery.
The analgesic efficacy and tolerability of lornoxicam (Xefo; Nycomed Pharma A/S, Roskilde, Denmark), a new nonsteroidal antiinflammatory drug, was compared with that of morphine in a double-blind, randomized, parallel-group study of 96 patients with at least moderate pain after lumbar microsurgical discectomy. Both drugs were administered i.v. via a patient-controlled analgesia (PCA) for up to 24 h postoperatively. Efficacy was assessed by comparing mean hourly pain intensity differences, mean hourly pain relief, and total pain relief (TOTPAR) values derived from a 5-point verbal rating scores of pain intensity and pain relief at several time points over 24 h. Of 79 patients included in a per-protocol analysis, statistically significant equivalence of lornoxicam and morphine was shown by TOTPAR values of 31.6 and 28.9, respectively (P = 0.048). Trends toward slightly faster onset of analgesia with morphine and slightly greater PCA demands with lornoxicam were observed initially, which may partly have been due to a higher baseline pain intensity in the lornoxicam group. Lornoxicam caused fewer adverse events than morphine (21.7% vs 38.0% of patients, respectively), most of which were mild or moderate in severity. These results suggest that lornoxicam is an alternative to morphine when administered by PCA for the treatment of moderate to severe postoperative pain. ⋯ After surgery for lumbar disk disease, patients obtained statistically equivalent pain relief with lornoxicam and morphine when administered by patient-controlled analgesia. However, lornoxicam was associated with a lower incidence of adverse events. This study suggests that lornoxicam provides an alternative to morphine for the treatment of postoperative pain.
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Comparative Study Clinical TrialPatient-controlled versus anesthesiologist-controlled conscious sedation with propofol for dental treatment in anxious patients.
In a randomized, cross-over study, we prospectively compared the efficacy and quality of two methods to achieve conscious sedation with propofol in 11 unpremedicated, anxious dental patients. Each patient underwent two dental procedures, one that was conducted under target-controlled infusion (TCI) by the anesthesiologist (ACS), and the other that used patient-controlled sedation (PCS). The initial target concentration in the ACS mode was 2.5 microg/mL, which was manipulated in both directions until the desired clinical end point was achieved. In the PCS mode, a 4-mg bolus of propofol (10 mg/mL) was delivered at each activation of the machine, infused over 7 s without a lockout interval. The anxious dental patients could induce and maintain conscious sedation with the PCS settings. The mean (range) venous blood propofol concentrations were not significantly different with either mode: ACS 1.8 (0.8-2.7) microg/mL and PCS 1.2 (0.2-2.5) microg/mL. The level of patient satisfaction, quality of sedation, and treatability were not different for either mode of sedation. The intensity of amnesia for intraoperative events was related to the blood concentrations achieved. In the ACS mode, one patient became unresponsive (sedation level 4) immediately after the start of sedation. No adverse cardiorespiratory effects resulted from either mode of propofol sedation. Five patients expressed a strong preference for PCS, and three would prefer ACS in the future. The results of the present study suggest that with these PCS settings, a satisfactory level of conscious sedation and a high level of patient satisfaction was achieved. ⋯ In a randomized, cross-over study, the blood propofol concentrations necessary to achieve conscious sedation in anxious dental patients using a target-controlled infusion conducted by the anesthesiologist versus patient-controlled sedation were not different. With the patient-controlled sedation settings, a satisfactory level of conscious sedation and a high level of patient satisfaction were achieved.