Anesthesia and analgesia
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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 Clinical TrialThe effect of epinephrine on small-dose hyperbaric bupivacaine spinal anesthesia: clinical implications for ambulatory surgery.
The effect of adding epinephrine to small doses of spinal bupivacaine on the duration of sensory motor block has not been carefully investigated. Twelve volunteers underwent hyperbaric bupivacaine spinal anesthesia (7.5 mg) with and without epinephrine (0.2 mg) in a randomized, double-blind, cross-over fashion. Sensory block was assessed with pinprick, transcutaneous electrical stimulation (TES) equivalent to surgical stimulation (at umbilicus, pubis, knee, and ankle), and tolerance of a pneumatic thigh tourniquet. Motor block was assessed with isometric force dynamometry. Discharge criteria were defined as return of pinprick sensation to dermatome S2, ability to ambulate, and ability to urinate. Extent of sensory block to pinprick over time was unaffected by the addition of epinephrine. However, epinephrine prolonged tolerance of TES at the pubis, knee, and ankle (33-48 min, P < 0.05) and of thigh tourniquet (30 min, P < 0.01). Motor block was prolonged by epinephrine at the quadriceps and gastrocnemius muscles (by 23 and 51 min, respectively, P < 0.002). Achievement of discharge criteria was prolonged by 48 min by the addition of epinephrine (P < 0.01). Thus, epinephrine may prolong surgical anesthesia for lower abdominal and lower extremity surgery and delay time until patients achieve discharge criteria. ⋯ Using a cross-over study design, 12 volunteers underwent bupivacaine spinal anesthesia with and without epinephrine. This study suggests that adding epinephrine to bupivacaine may prolong surgical anesthesia and also delay patients' discharge.
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Clinical TrialClearance of morphine in postoperative infants during intravenous infusion: the influence of age and surgery.
We analyzed morphine clearance values in infants receiving the drug by continuous i.v. infusion for analgesia after surgery, because we found lower steady-state morphine concentrations than we expected from our previous studies. Infants received morphine after a loading dose of 0.05 mg/kg and continuous infusion calculated to reach a steady-state concentration of 20 ng/mL. Blood was sampled twice on Postoperative Day 1 at times separated by at least 2 h, and morphine and morphine-6-glucuronide (M-6-G) concentrations were determined by high-performance liquid chromatography. Clearance of morphine was calculated as infusion rate divided by the steady-state morphine concentration. Morphine given to 26 infants by continuous i.v. infusion after major noncardiac surgery has rapidly increasing clearance values, from a median value of 9.2 mL x min(-1) x kg(-1) in infants 1-7 days old, 25.3 in infants 31-90 days old, and 31.0 in infants 91-180 days old to 48.9 in infants 180-380 days old. Adult clearance values are reached by 1 mo of age, more quickly than in infants of the same age previously studied who received morphine after cardiac surgeries. M-6-G was measured in all infants. The ratio of M-6-G to morphine concentrations was 1.9-2.1 in these infants, which is lower than ratios reported in older infants or adults by others, but higher than those reported in newborns. Infants with normal cardiovascular systems undergoing surgery clear morphine more efficiently than infants of the same age undergoing cardiac surgery. ⋯ Morphine removal from the body is slow in newborns but increases to reach adult values in the first months of life. Calculating the clearance of morphine from blood samples drawn during continuous i.v. infusions after surgery shows that this maturation occurs more quickly in infants undergoing noncardiac surgery (by 1-3 mo of age) than in those receiving morphine after cardiac surgery (by 6-12 mo of age).
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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.