Sole use of dexmedetomidine has limited utility for conscious sedation during outpatient colonoscopy

BACKGROUND: This study evaluated the ability of dexmedetomidine to provide analgesia and sedation for outpatient colonoscopy, examining outcomes including cardiorespiratory variables, side effects, and discharge readiness. METHODS: Sixty-four patients were randomly assigned to one of three treatment regimens. In group D, patients received 1 microg/kg dexmedetomidine over 15 min followed by an infusion of 0.2 microg x kg x h. Group P received meperidine (1 mg/kg) with midazolam (0.05 mg/kg), and group F received fentanyl (0.1-0.2 mg intravenous) on demand. The assessment included measurements of heart rate, blood pressure, oxygen saturation, respiratory rate, quality of sedation/analgesia, and an evaluation of the recovery time. RESULTS: The study was terminated before the planned 90 patients had been recruited because of adverse events in group D. In all groups, negligible hemoglobin oxygen saturation and respiratory rate variations were observed. In group D, there was a significantly larger decrease in heart rate (to approximately 40 beats/min in 2 of 19 cases) and blood pressure (to less than 50% of the initial value in 4 of 19 patients). Supplemental fentanyl was required in 47% of patients receiving dexmedetomidine to achieve a satisfactory level of analgesia (vs. 42.8% of patients in group P and 79.2% of patients in group F). Vertigo (5 patients), nausea/vomiting (5 patients), and ventricular bigeminy (1 patient) were observed only in group D. Time to home readiness was longest in group D (85 +/- 74, 39 +/- 21, and 32 +/- 13 min in groups D, P and F, respectively; P = 0.007). CONCLUSIONS: The use of dexmedetomidine to provide analgesia/sedation for colonoscopy is limited by distressing side effects, pronounced hemodynamic instability, prolonged recovery, and a complicated administration regimen.     

Anesthesiologist-controlled versus patient-controlled propofol sedation for shockwave lithotripsy

PURPOSE: To compare anesthesiologist-controlled sedation (ACS) with patient-controlled sedation (PCS), with respect to propofol requirements, sedation, and recovery, in patients undergoing extracorporeal shockwave lithotripsy for urinary calculi. METHODS: Sixty-four patients were randomized, in this double-blind study, to receive propofol sedation according to one of two regimens: infusion of 200 microg.kg(-1) .min(-1) for ten minutes reduced thereafter to 50-150 microg.kg(-1) .min(-1) titrated by an anesthesiologist, according to patient response (group ACS), or propofol administered by patient-controlled analgesia (bolus dose 300 microg.kg(-1), lockout interval three minutes, no basal infusion), (group PCS). All patients received midazolam 10 microg.kg(-1) iv and fentanyl 1 microg.kg(-1) iv preoperatively, followed by fentanyl infused at a rate of 0.5 microg.kg(-1) .hr(-1) throughout the procedure. Sedation and analgesia were assessed using the A-line ARX index and visual analogue scale, respectively. Psychomotor recovery and readiness for recovery room discharge were assessed using the Trieger dot test and postanesthesia discharge score, respectively. Patient satisfaction was assessed on a seven-point scale (1-7). RESULTS: In comparison to group PCS, patients in group ACS received more propofol (398 +/- 162 mg vs 199 +/- 68 mg, P < 0.001), were more sedated (A-line ARX index: 35 +/- 16 vs 73 +/- 16, P < 0.001), experienced less pain (visual analogue scale: 0 +/- 0 vs 3 +/- 1, P < 0.001), and were more satisfied (median [Q1, Q3]: 7 [7, 7] vs 6 [6, 7], P < 0.001). In contrast, patients in group PCS had faster psychomotor recovery (Trieger dot test median [Q1, Q3]: 8 [4, 16] vs 16 [12, 26] dots missed, P = 0.002) and achieved postanesthesia discharge score >/=9 earlier (median [Q1, Q3]: 40 [35, 60] vs 88 [75, 100] min, P < 0.001) compared with group ACS. CONCLUSION: In comparison to PCS for patients undergoing extracorporeal shockwave lithotripsy, propofol/fentanyl ACS is associated with increased propofol administration, deeper sedation levels, and greater patient comfort. However, ACS is associated with slower recovery and a longer time to meet discharge criteria, when compared to PCS.     

Comparison of Remifentanil and Fentanyl in Patients Undergoing Craniotomy for Supratentorial Space-occupying Lesions

Background: Remifentanil hydrochloride is an ultra-short-acting, esterase-metabolized micro-opioid receptor agonist. This study compared the use of remifentanil or fentanyl during elective supratentorial craniotomy for space-occupying lesions.

Methods: Sixty-three adults gave written informed consent for this prospective, randomized, double-blind, multiple-center trial. Anesthesia was induced with thiopental, pancuronium, nitrous oxide/oxygen, and fentanyl (n = 32; 2 micro gram [center dot] kg [center dot] sup -1 min sup -1) or remifentanil (n = 31; 1 micro [center dot] kg sup -1 [center dot] min sup -1). After tracheal intubation, infusion rates were reduced to 0.03 micro gram [center dot] kg sup -1 [center dot] min sup -1 (fentanyl) or 0.2 micro gram [center dot] kg sup -1 [center dot] min sup -1 (remifentanil) and then adjusted to maintain anesthesia and stable hemodynamics. Isoflurane was given only after specified infusion rate increases had occurred. At the time of the first burr hole, intracranial pressure was measured in a subset of patients. At bone flap replacement either saline (fentanyl group) or remifentanil ([nearly equal] 0.2 micro gram [center dot] kg sup -1 [center dot] min sup -1) were infused until dressing completion. Hemodynamics and time to recovery were monitored for 60 min. Analgesic requirements and nausea and vomiting were observed for 24 h. Neurological examinations were performed before operation and on postoperative days 1 and 7.

Results: Induction hemodynamics were similar. Systolic blood pressure was greater in the patients receiving fentanyl after tracheal intubation (fentanyl = 127 +/- 18 mmHg; remifentanil = 113 +/- 18 mmHg; P = 0.004). Intracranial pressure (fentanyl = 14 +/- 13 mmHg; remifentanil = 13 +/- 10 mmHg) and cerebral perfusion pressure (fentanyl = 76 +/- 19 mmHg; remifentanil = 78 +/- 14 mmHg) were similar. Isoflurane use was greater in the patients who received fentanyl. Median time to tracheal extubation was similar (fentanyl = 4 min: range = -1 to 40 min; remifentanil = 5 min: range = 1 to 15 min). Seven patients receiving fentanyl and none receiving remifentanil required naloxone. Postoperative systolic blood pressure was greater (fentanyl = 134 +/- 16 mmHg; remifentanil = 147 +/- 15 mmHg; P = 0.001) and analgesics were required earlier in patients receiving remifentanil. Incidences of nausea and vomiting were similar.     

Epidural Clonidine Used as the Sole Analgesic Agent during and after Abdominal Surgery: A Dose-Response Study

Background: Many studies have shown the beneficial effect of epidural clonidine in postoperative pain management. In these studies, the patients received local anesthetics, opioids, or both in combination with clonidine. Due to the interactive potentiation of those drugs, the importance of the intrinsic analgesic properties of the alpha2 -adrenoceptor agonist is difficult to establish. The authors investigated the analgesic potency of epidural clonidine when used as the sole analgesic agent during and after major abdominal surgery.

Methods: Fifty young adult patients undergoing intestinal surgery under general anesthesia with propofol were studied. At induction, the patients received epidurally either an initial dose of 2 micro gram/kg clonidine followed by an infusion of 0.5 micro gram [center dot] kg-1 [center dot] h-1 (group 1, n = 10) or 4 micro gram/kg followed by 1 micro gram [center dot] kg-1 [center dot] h-1 (group 2, n = 20) or 8 micro gram [center dot] kg-1 [center dot] h-1 followed by an infusion of 2 micro gram [center dot] kg-1 [center dot] h-1 (group 3, n = 20). During the operation, increases in arterial blood pressure or heart rate that did not respond to a propofol bolus (0.5 mg/kg) were treated with a bolus of intravenous lidocaine (1 mg/kg). Three successive injections were allowed. When baseline values were not restored, opioids were added and the patient was removed from the study. After operation, the clonidine infusions were maintained for 12 h. During this period and at every 30 min, sedation scores and visual analog scale values at rest and at cough were noted. In case of subjective scores up to 5 cm at rest or up to 8 cm at cough, the patients were given access to a patient-controlled analgesia device that delivered epidural bupivacaine. The end point of the study was reached once the patient activated the analgesic delivery button.

Results: During surgery, 60% of patients in group 1 compared with 33% of patients in group 2 and only 5% of patients in group 3 were removed from the study protocol because of inadequate anesthesia (P < 0.05). After operation, epidural clonidine provided complete analgesia lasting 30 +/- 21 min in group 1 compared with 251 + 237 min in group 2 or 369 +/- 256 min in group 3 (P < 0.05 for group 1 vs. groups 2 and 3 and group 2 vs. group 3).     

Opioid-sparing Effects of a Low-dose Infusion of Naloxone in Patient-administered Morphine Sulfate

Background: A naloxone infusion is effective in reducing epidural and intrathecal opioid-related side effects. The use of naloxone infusion concomitant with intravenous morphine patient-controlled analgesia (PCA) has not been evaluated, probably because of an expected direct antagonism of the systemic opioid effect. The authors compared the incidence of morphine-related side effects and the quality of analgesia from two small doses of naloxone infusion.

Methods: Sixty patients classified as American Society of Anesthesiologists physical status 1, 2, or 3 who were scheduled for total abdominal hysterectomies were enrolled in the study. Patients received a standardized general anesthetic. In the postanesthetic care unit, patients received morphine as a PCA. They were randomized to receive either 0.25 micro gram [center dot] kg sup -1 [center dot] h sup -1 naloxone (low dose), 1 micro gram [center dot] kg sup -1 [center dot] h sup -1 (high dose), or saline (placebo) as a continuous infusion. Verbal rating scores for pain, nausea, vomiting, and pruritus; sedation scores; requests for antiemetic; and morphine use were recorded for 24 h. Blood pressure, respiratory rate, and oxyhemoglobin saturation were also monitored.

Results: Sixty patients completed the study. Both naloxone doses were equally effective in reducing the incidence of nausea, vomiting, and pruritus compared with placebo (P < 0.05 by the chi-squared test). There was no difference in the verbal rating scores for pain between the groups. The cumulative morphine use was the lowest in the low-dose group (42.3 +/- 24.1 mg; means +/- SD) compared with the placebo (59.1 +/- 27.4 mg) and high-dose groups (64.7 +/- 33.0 mg) at 24 h (P < 0.05 by analysis of variance). There was no incidence of respiratory depression (< 8 breaths/min) and no difference in sedation scores, antiemetic use, respiratory rate, and hemodynamic parameters among the groups.     

Potentiation of Mivacurium Blockade by Low Dose of Pancuronium: A Pharmacokinetic Study

Background: Mivacurium is potentiated by pancuronium to a much greater extent than other relaxants. In a previous investigation we suggested that this potentiation could be due to the ability of pancuronium to inhibit plasma cholinesterase activity, but we did not measure plasma concentrations of mivacurium. In the current study we performed a pharmacokinetic analysis by measuring the plasma concentration of mivacurium when preceded by administration of a low dose of pancuronium.

Methods: After induction of general anesthesia with propofol and fentanyl and orotracheal intubation, 10 patients (pancuronium-mivacurium group) received 15 [mu]g/kg pancuronium followed 3 min later by 0.1 mg/kg mivacurium, whereas 10 other patients (mivacurium group) received saline followed by 0.13 mg/kg mivacurium 3 min later. Plasma cholinesterase activity was measured before and 3 and 30 min after pancuronium dosing in the pancuronium-mivacurium group and was measured before and after administration of saline in the mivacurium group. Arterial plasma concentrations of mivacurium and its metabolites were measured at 0.5, 1, 1.5, 2, 4, 10, 20, and 30 min after injection. Neuromuscular blockade was assessed by mechanomyography.

Results: Plasma cholinesterase activity decreased by 26% in the pancuronium-mivacurium group 3 min after injection of pancuronium (P < 0.01) and returned to baseline values 30 min later; however, no significant variation was observed in the mivacurium group. The clearances of the two most active isomers (Cis-Trans and Trans-Trans) were lower in the pancuronium-mivacurium group (17.6 +/- 5.1, 14.7 +/- 5.3 ml [middle dot] min-1[middle dot] kg-1, respectively) than in the mivacurium group (32.4 +/- 20.2, 24.8 +/- 13.5 ml [middle dot] min-1[middle dot] kg-1;P < 0.05).     

Intravenous Regional Anesthesia Using Lidocaine and Clonidine

Background: Clonidine has been added to local anesthetic regimens for various peripheral nerve blocks, resulting in prolonged anesthesia and analgesia. The authors postulated that using clonidine as a component of intravenous regional anesthesia (IVRA) would enhance postoperative analgesia.

Methods: Forty-five patients undergoing ambulatory hand surgery received IVRA with lidocaine, 0.5%, and were assigned randomly and blindly to three groups. The control group received intravenous saline, the intravenous clonidine group received 1 [mu]g/kg clonidine intravenously, and the IVRA clonidine group received 1 [mu]g/kg clonidine as part of the IVRA solution. After their operations, the patients' pain and sedation scores and analgesic use were recorded.

Results: Patients in the IVRA clonidine group had a significantly longer period of subjective comfort when they required no analgesics (median [range]) for 460 min (215-1,440 min), compared with 115 min (14-390 min) for the control group and 125 min (17-295 min) for the intravenous clonidine group (P < 0.0001). The patients who received IVRA with clonidine reported significantly lower pain scores 1 and 2 h after tourniquet deflation compared with the other groups, and they required no fentanyl in the postanesthesia care unit. They also required fewer analgesic tablets (325 mg acetaminophen with 30 mg codeine) in the first 24 h (2 +/- 1, mean +/- SD) compared with the other two groups, 5 +/- 1 tablets (control) and 4 +/- 2 tablets (intravenous clonidine) (P < 0.0001). No significant postoperative sedation, hypotension, or bradycardia developed in any of the patients.     

Patient supplemented epidural analgesia after major abdominal surgery with bupivacaine/fentanyl or ropivacaine/fentanyl

PURPOSE: To compare analgesic efficacy and occurrence of motor block and other side effects during patient supplemented epidural analgesia (PSEA) with either ropivacaine/fentanyl or bupivacaine/fentanyl mixtures. METHODS: In a prospective, randomized, double-blind study, 32 ASAI-III patients undergoing major abdominal surgery received an epidural catheter at the T8- T10, followed by integrated general epidural anesthesia. Postoperative epidural analgesia was provided using a patient controlled pump with either ropivacaine 0.2%/2 microg x ml(-1) fentanyl (group Ropivacaine, n = 16) or bupivacaine 0.125%/2 microg x ml(-1) fentanyl (group Bupivacaine, n = 16) [background infusion 4-6 ml x hr(-1), 1.5 ml Incremental Doses and 20 min lock out]. Verbal pain rating score, number of incremental doses, consumption of epidural analgesic solution and rescue analgesics, sedation (four-point scale), and pulse oximetry were recorded by a blind observer for 48 hr after surgery. RESULTS: No differences in pain relief, motor block, degree of sedation, pulse oximetry and other side effects were observed between the two groups. The number of incremental doses and the volume of analgesic solution infused epidurally were higher in patients receiving the bupivacaine/fentanyl mixture (10 [0-52] I.D. and 236 [204-340] ml) than in patients receiving the ropivacaine/fentanyl solution (5 [0-50] I.D. and 208 [148-260] ml) (P = 0.03 and P = 0.05, respectively). CONCLUSION: Using a ropivacaine 0.2%/2 microg x ml(-1) fentanyl mixture for patient supplemented epidural analgesia after major abdominal surgery provided similar successful pain relief as bupivacaine 0.125%/2 microg x ml(-1) fentanyl, but patients receiving bupivacaine/fentanyl requested more supplemental.     

A comparison of the sedative, hemodynamic, and respiratory effects of dexmedetomidine and propofol in children undergoing magnetic resonance imaging

We compared the sedative, hemodynamic, and respiratory effects of dexmedetomidine and propofol in children undergoing magnetic resonance imaging procedures. Sixty children were randomly distributed into two groups: The dexmedetomidine (D) group received 1 microg/kg initial dose followed by continuous infusion of 0.5 microg.kg(-1).h(-1) and a propofol group (P) received 3 mg/kg initial dose followed by a continuous infusion of 100 microg.kg(-1).min(-1). Inadequate sedation was defined as difficulty in completing the procedure because of the child's movement during magnetic resonance imaging. Mean arterial pressure (MAP), heart rate, peripheral oxygen saturation, and respiratory rate (RR) were recorded during the study. The onset of sedation, recovery, and discharge time were significantly shorter in group P than in group D. MAP, heart rate, and RR decreased during sedation from the baseline values in both groups. MAP and RR were significantly lower in group P than in group D during sedation. Desaturation was observed in four children of group P. Dexmedetomidine and propofol provided adequate sedation in most of the children. We conclude that although propofol provided faster anesthetic induction and recovery times, it caused hypotension and desaturation. Thus, dexmedetomidine could be an alternative reliable sedative drug to propofol in selected patients.     

Intraoperative infusion of dexmedetomidine reduces perioperative analgesic requirements

PURPOSE: This prospective, randomized, double-blind study was designed to assess whether intraoperative infusion of dexmedetomidine provides effective postoperative analgesia. Postoperative pain scores and morphine consumption were compared in a treated group and a placebo group, both of which received patient-controlled morphine after total abdominal hysterectomy. METHODS: Fifty women were randomly assigned to two groups. Group D (n = 25) received a loading dose of dexmedetomidine 1 mug.kg(-1) iv during induction of anesthesia, followed by a continuous infusion at a rate of 0.5 mug.kg(-1).hr(-1) throughout the operation. Group P (n = 25) received a volume-matched bolus and infusion of placebo (0.9% saline). For each case, heart rate, peripheral oxygen saturation, and systolic and diastolic blood pressure were recorded intraoperatively and for 48 hr postoperatively. Patients used a patient-controlled analgesia device to receive bolus doses of morphine after surgery. Total morphine consumption, pain scores, and sedation scores were recorded for the first 48 hr (two hours in the postanesthesia care unit and 46 hr on the ward). RESULTS: The groups were similar with respect to mean times to extubation of the trachea. Pain and sedation scores were also similar between groups at all corresponding times throughout the 48-hr period of observation. Group D patients consumed significantly less morphine in the postanesthesia care unit and on the ward (P < 0.05 and P < 0.01, respectively). Fewer patients in Group D experienced itching or nausea/vomiting (P < 0.05). CONCLUSION: Continuous iv dexmedetomidine during abdominal surgery provides effective postoperative analgesia, and reduces postoperative morphine requirements without increasing the incidence of side effects.     

A Phase I, Two-center Study of the Pharmacokinetics and Pharmacodynamics of Dexmedetomidine in Children

Background: To investigate dexmedetomidine in children, the authors performed an open-label study of the pharmacokinetics and pharmacodynamics of dexmedetomidine.

Methods: Thirty-six children were assigned to three groups; 24 received dexmedetomidine and 12 received no drug. Three doses of dexmedetomidine, 2, 4, and 6 [mu]g [middle dot] kg-1 [middle dot] h-1, were infused for 10 min. Cardiorespiratory responses and sedation were recorded for 24 h. Plasma concentrations of dexmedetomidine were collected for 24 h and analyzed. Pharmacokinetic variables were determined using nonlinear mixed effects modeling (NONMEM program). Cardiorespiratory responses were analyzed.

Results: Thirty-six children completed the study. There was an apparent difference in the pharmacokinetics between Canadian and South African children. The derived volumes and clearances in the Canadian children were V1 = 0.81 l/kg, V2 = 1.0 l/kg, Cl1 (systemic clearance) = 0.013 l [middle dot] kg-1 [middle dot] min-1, Cl2 = 0.030 l [middle dot] kg-1 [middle dot] min-1. The intersubject variabilities for V1, V2, and Cl1 were 45%, 38%, and 22%, respectively. Plasma concentrations in South African children were 29% less than in Canadian children. The volumes and clearances in the South African children were 29% larger. The terminal half-life was 110 min (1.8 h). Median absolute prediction error for the two-compartment mammillary model was 18%. Heart rate and systolic blood pressure decreased with time and with increasing doses of dexmedetomidine. Respiratory rate and oxygen saturation (in air) were maintained. Sedation was transient.     

Dexmedetomidine Increases the Cocaine Seizure Threshold in Rats

Background: Central [alpha] adrenoceptors have been demonstrated to play an important role in the control of seizure activity; moreover, [alpha]2 adrenoceptors have been linked to electroencephalogram changes associated with cocaine. The purpose of this study was to determine if dexmedetomidine, a highly selective [alpha]2-adrenoceptor agonist, alters the threshold for cocaine-induced seizure activity in rats.

Methods: Sprague-Dawley rats received a cocaine infusion (1.25 mg [middle dot] kg-1 [middle dot] min-1) followed 15 min later by the coinfusion of either dexmedetomidine (20-[mu]g/kg intravenous bolus followed by an infusion of 1 [mu]g [middle dot] kg-1 [middle dot] min-1, CD group, n = 8) or an equal volume of saline (CS group, n = 8). Dexmedetomidine or saline were coinfused with cocaine until the onset of cocaine-induced seizures. Dopamine concentrations in the nucleus accumbens were measured by microdialysis paired with chromatography. To determine if changes in extracellular dopamine were related to the seizures, dopamine (1 [mu]m) was continuously delivered to the nucleus accumbens in a separate group (DACD group, n = 6) via retrograde microdialysis. These rats then received an intravenous cocaine infusion followed by dexmedetomidine in the same manner as the CD group.

Results: Dexmedetomidine significantly increased the dose of cocaine necessary to produce seizures. Seizures occurred at 25.0 +/- 7.7 and 49.3 +/- 14.8 min in CS and CD, respectively (P < 0.001). The ratio of the percent increase in accumbal dopamine to the cocaine dose at the onset of seizure activity was significantly lower in CD, 39.9 +/- 16.5, compared to CS, 82.2 +/- 46.5 (P = 0.04). Intraaccumbal administration of dopamine prevented the effects of dexmedetomidine on the cocaine seizure threshold.     

Double-blind, Randomized Comparison of Ondansetron and Intraoperative Propofol to Prevent Postoperative Nausea And Vomiting

Background: Breast surgery is associated with a high incidence of postoperative nausea and vomiting. Propofol and prophylactic administration of ondansetron are associated with a lower incidence of postoperative nausea and vomiting. To date no comparison of these two drugs has been reported. A randomized study was done to compare the efficacy of ondansetron and intraoperative propofol given in various regimens.

Methods: Study participants included 89 women classified as American Society of Anesthesiologists physical status 1 or 2 who were scheduled for major breast surgery. Patients were randomly assigned to one of four groups. Group O received 4 mg ondansetron in 10 ml 0.9% saline and groups PI, PIP, and PP received 10 ml 0.9% saline before anesthesia induction. Group O received thiopental, isoflurane, nitrous oxide-oxygen, and fentanyl for anesthesia. Group PI received propofol, isoflurane, nitrous oxide-oxygen, and fentanyl. Group PIP received propofol, isoflurane, nitrous oxide-oxygen, and fentanyl. Thirty minutes before expected skin closure, isoflurane was discontinued and 50 to 150 micro gram [centered dot] kg sup -1 [centered dot] min sup -1 propofol was given intravenously to maintain anesthesia. Group PP received propofol for induction and maintenance of anesthesia, nitrous oxide-oxygen, and fentanyl. Postoperative pain relief was provided with morphine administered by a patient-controlled analgesia pump. The incidence of nausea and vomiting, requests for rescue antiemetic and sedation, pain scores, and hemodynamic data were recorded for 24 h.

Results: Within 6 h of surgery, groups O and PP had a lower incidence of nausea compared with groups PI and PIP (P < 0.05). Fewer patients in group PP (19%) vomited during the 24-h period compared with groups O (48%), PI (64%), and PIP (52%) (P < 0.05). The incidence of antiemetic use was also less in group PP (P < 0.05). Patients in group PP had lower sedation scores at 30 min and at 1 h (P < 0.05). There were no differences among the groups in pain scores, blood pressure, heart rate, respiratory rate, and incidence of pruritus.     

Dexmedetomidine in combination with morphine PCA provides superior analgesia for shockwave lithotripsy

PURPOSE: To compare the analgesic effects of dexmedetomidine/morphine with those of tramadol/midazolam in patients undergoing extracorporeal shockwave lithotripsy (ESWL) for urinary calculi. METHODS: Sixty patients were randomized to receive either dexmedetomidine 1 micro g*kg(-1) iv followed by 0.5 micro g*kg(-1)*hr(-1) infusion together with morphine patient-controlled analgesia [(PCA); 2 mg bolus, five minutes lockout, 2 mg*hr(-1) infusion; (Group DEX)], or tramadol 1.5 mg*kg(-1) pre-mixed with midazolam 30 micro g*kg(-1) iv followed by tramadol PCA [20 mg bolus, five minute lockout, 20 mg*hr(-1) infusion; (Group TRA)]. Pain was assessed at baseline and every 15 min thereafter. Patients' and urologist's satisfaction with analgesia and sedation were determined on a seven-point scale ranging from 1 (extremely dissatisfied) to 7 (extremely satisfied). Patient's discharge time was also documented. RESULTS: Visual analogue scale scores over time were consistently lower in Group DEX compared with Group TRA (P = 0.001). Patients' satisfaction with analgesia (5 +/- 1 vs 4 +/- 2, P = 0.012) and with sedation (6 +/- 1 vs 5 +/- 1, P = 0.020), and urologist's satisfaction (6 +/- 1 vs 4 +/- 2, P = 0.001) were all higher amongst Group DEX patients compared with Group TRA. There was no difference between discharge times of patients in Group DEX compared with those in Group TRA [85 (60,115) min vs 65 (40,95) min, P = 0.069]. CONCLUSION: Dexmedetomidine in combination with morphine PCA provided better analgesia for ESWL and was associated with higher patients' and urologist's satisfaction when compared with a tramadol/midazolam PCA combination.     

A Comparison of Remifentanil and Morphine Sulfate for Acute Postoperative Analgesia after Total Intravenous Anesthesia with Remifentanil and Propofol

Background: The transition from remifentanil intraoperative anesthesia to postoperative analgesia must be planned carefully due to the short duration of action (3-10 min) of remifentanil hydrochloride, a potent, esterase-metabolized micro-opioid agonist. This study compared the efficacy and safety of transition regimens using remifentanil or morphine sulfate for immediate postoperative pain relief in patients who had surgery under general anesthesia with remifentanil/propofol.

Methods: One hundred fifty patients who had received open-label remifentanil and propofol for intraoperative anesthesia participated in this multicenter, double-blind, double-dummy study and were randomly assigned to either the remifentanil (R) group or the morphine sulfate (M) group. Twenty minutes before the anticipated end of surgery, the propofol infusion was decreased by 50%, and patients received either a placebo bolus (R group) or a bolus of 0.15 mg/kg morphine (M group). At the end of surgery, the propofol and remifentanil maintenance infusions were discontinued and the analgesic infusion was started: either 0.1 micro gram [center dot] kg sup -1 [center dot] min sup -1 remifentanil (R group) or placebo analgesic infusion (M group). During the 25 min after tracheal extubation, remifentanil titrations in increments of 0.025 micro gram [center dot] kg sup -1 [center dot] min sup -1 and placebo boluses (R group), or 2 mg intravenous morphine boluses and placebo rate increases (M group) were administered as necessary at 5-min intervals to control pain. Patients received the 0.075 mg/kg intravenous morphine bolus (R group) or placebo (M group) at 25 and 30 min after extubation, and the analgesic infusion was discontinued at 35 min. From 35 to 65 minutes after extubation, both groups received 2-6 mg open-label morphine analgesia every 5 min as needed.

Results: Successful analgesia, defined as no or mild pain with adequate respiration (respiratory rate [RR] >or= to 8 breaths/min and pulse oximetry >or= to 90%), was achieved in more patients in the R group than in the M group (58% vs. 33%, respectively) at 25 min after extubation (P < 0.05). The median remifentanil rate for successful analgesia was 0.125 micro gram [center dot] kg sup -1 [center dot] min sup -1 (range, 0.05-0.23 micro gram [center dot] kg sup -1 [center dot] min sup -1), and the median number of 2-mg morphine boluses used was 2 (range, 0-5 boluses). At 35 min after extubation, >or= to 74% of patients in both groups experienced moderate to severe pain. Median recovery times from the end of surgery were similar between groups. Transient respiratory depression, apnea, or both were the most frequent adverse events (14% for the R group vs. 6% for the M group; P > 0.05).     

The effect of hemispheric synchronization on intraoperative analgesia

In this double-blinded randomized study, we sought to confirm that patients undergoing general anesthesia who were exposed to a hemispheric synchronization (Hemi-Sync) musical recording during surgery had a smaller analgesia requirement, as was suggested in a previous study. Bispectral index monitoring was used to adjust depth of hypnosis, and hemodynamic variables were used to determine analgesia administration. Consented patients underwent either laparoscopic bariatric or one-level lumbar disk surgery. After endotracheal intubation and application of headphones, baseline heart rate and arterial blood pressure were established. Isoflurane was titrated to maintain sedation on the basis of a target bispectral index range of 40-60, and 25-microg increments of fentanyl were administered in response to increases in heart rate and systolic arterial blood pressure. Bariatric patients who listened to Hemi-Sync required one-third less fentanyl than the control group (mean [SD]: 0.015 [0.01] vs 0.024 microg.kg(-1).min(-1) [0.01]) (P = 0.009). It is interesting to note that lumbar patients in the experimental and control groups required similar amounts of fentanyl (0.012 [0.01] vs 0.015 microg.kg(-1).min(-1) [0.01]). End-tidal isoflurane concentration was similar for Hemi-Sync and blank-tape patients (bariatric, 0.74% (0.14) vs 0.77% (0.21); lumbar, 0.36% [0.16] vs 0.39% [0.12]). The bariatric patients in this study demonstrated that Hemi-Sync may be an innovative intraoperative supplement to analgesia. IMPLICATIONS: The purpose of this study was to determine the decrease in analgesia requirement for patients listening to hemispheric synchronization (musical tones) while under general anesthesia. We demonstrated that bariatric patients who listened to hemispheric synchronization had a smaller analgesia requirement than those who listened to a blank tape.     

右美托咪定复合芬太尼用于痔术后自控镇痛

目的：探讨右美托咪啶复合芬太尼在痔手术后行自控镇痛的效果。方法：100例痔术后患者随机双盲分为F组（芬太尼8μg/mL,PCA）和FD组（芬太尼8μg/mL复合右美托咪啶4μg/mL,PCA）行自控镇痛。观察24 h内PCA自控追加要求,疼痛强度,患者情绪变化以及PCA相关的不良事件的记录。结果：FD组在术后0～48 h内显著降低芬太尼需要量,从术后第4 h开始显著降低疼痛级别;FD组焦虑情绪和血浆皮质醇浓度较F组显著降低。结论：右美托咪定复合芬太尼行静脉自控镇痛可显著节约芬太尼用量,减少恶心发生率,无过度镇静和不良的血流动力学变化。     

Remifentanil versus Morphine Analgesia and Sedation for Mechanically Ventilated Critically Ill Patients: A Randomized Double Blind Study

Background: The rapid onset and offset of action of remifentanil could make it quickly adjustable to the required level of sedation in critically ill patients. The authors hypothesized that the efficacy of a remifentanil-based regimen was greater than that of a morphine-based regimen.

Methods: Forty intent-to-treat patients were randomly allocated to receive a blinded infusion of either remifentanil 0.15 [mu]g[middle dot]kg-1[middle dot]min-1 or morphine 0.75 [mu]g[middle dot]kg-1[middle dot]min-1. The opioid infusion was titrated, in the first intent, to achieve optimal sedation defined as Sedation Agitation scale of 4. A midazolam open-label infusion was started if additional sedation was required.

Results: The mean percentage hours of optimal sedation was significantly longer in the remifentanil group (78.3 +/- 6.2) than in the morphine group (66.5 +/- 8.5). This was achieved with less frequent infusion rate adjustments (0.34 +/- 0.25 changes/h) than in the morphine group (0.42 +/- 0.22 changes/h). The mean duration of mechanical ventilation and extubation time were significantly longer in the morphine group (18.1 +/- 3.4 h, 73 +/- 7 min) than in the remifentanil group (14.1 +/- 2.8 h, 17 +/- 6 min), respectively. Remifentanil mean infusion rate was 0.13 +/- 0.03 [mu]g[middle dot]kg-1[middle dot]min-1, whereas morphine mean infusion rate was 0.68 +/- 0.28 [mu]g[middle dot]kg-1[middle dot]min-1. More subjects in the morphine group (9 of 20) than in the remifentanil group (6 of 20) required midazolam. The incidence of adverse events was low and comparable across the two treatment groups.     

帕瑞昔布钠复合吗啡与地佐辛复合氟比洛芬酯用于结肠癌患者术后镇痛效果比较

目的比较帕瑞昔布钠复合吗啡与氟比洛芬酯复合地佐辛用于结肠癌手术患者自控静脉镇痛（PCIA）的效果,探讨合适的镇痛方案。 方法选择ASAⅠ-Ⅱ择期行结肠癌手术的患者90例,随机分为帕瑞昔布钠组（P组）、地佐辛组（D组）和芬太尼组（F组）,每组各30例。3组患者均采用气管内插管全身麻醉,术后行PCIA。PCIA设置背景剂量2ml/h,按压剂量2ml/次,锁定时间15min。P组于气管插管前静脉注射帕瑞昔布钠40mg,并于术后12、24、36、48 h静注帕瑞昔布钠40mg,PCIA使用吗啡20 mg+0.9%氯化钠溶液至100ml;D组于气管插管前静脉注射地佐辛5mg,PCIA使用地佐辛30 mg+氟比洛芬酯200mg+0.9%氯化钠溶液至100 ml;F组PCIA使用芬太尼1.0mg+0.9%氯化钠溶液至100 ml。观察3组患者术后30min（T_30min）、2h（T_2h）、4h（T_4h）、12h（T_12h）、24h（T_24h）、48h（T_48h）VAS镇痛评分、Ramsay镇静评分及不良反应的情况;术后48h记录PCIA泵按压次数及患者总体满意度。 结果P组及D组在T_30min-T_12h时点VAS评分显著低于F组（P﹤0.05）;T_30min-T_4h时点,P组Ramsay评分显著低于D组和F组（P﹤0.05）;术后48h内P组、D组患者头晕发生率显著低于F组（P﹤0.05）。 结论帕瑞昔布钠复合吗啡、地佐辛复合氟比洛芬酯用于结肠癌患者术后的镇痛效果确切,不良反应发生率低。     

Effects of dexmedetomidine in morbidly obese patients undergoing laparoscopic gastric bypass

BACKGROUND: Obese patients may be sensitive to the respiratory depressant effect of opioid analgesics. Alternative methods for analgesia may be beneficial for management of bariatric surgery. We evaluated the effect of dexmedetomidine on anesthetic requirements during surgery, hemodynamic, recovery profile and morphine use in the postoperative period. METHODS: Eighty adult patients scheduled for elective laparoscopic Roux-en-Y gastric bypass surgery were randomly assigned to one of two study groups; Group D (40 patients) received dexmedetomidine (0.8-microg/kg bolus, 0,4 microg kg(-1) h) and Group P (40 patients) received normal saline (placebo) in the same volume and rate. Intraoperative and postoperative mean blood pressure and heart rate were recorded. The total amount of intraoperative fentanyl and propofol required to maintain anesthesia were measured. Recovery profile, pain score and total amount of morphine used via patient controlled analgesia (PCA) were assessed. RESULTS: During surgery, dexmedetomidine decreased the total amount of intraoperative fentanyl and propofol required for maintenance of anesthesia compared to placebo. Patients who received dexmedetomidine showed significant decrease of intraoperative and postoperative mean blood pressure, heart rate. In the postoperative period, dexmedetomidine decreased pain scores and PCA morphine use significantly and showed better recovery profile as compared to the placebo Group. There was no difference in the incidence of postoperative nausea and vomiting (PONV) between both groups. CONCLUSION: The intraoperative infusion of dexmedetomidine decreased the total amount of propofol and fentanyl required to maintain anesthesia, offered better control of intraoperative and postoperative hemodynamics, decreased postoperative pain level, decreased the total amount of morphine used and showed better recovery profile compared with placebo.