Magnesium sulfate does not reduce postoperative analgesic requirements

BACKGROUND: Because magnesium blocks the N-methyl-D-aspartate receptor and its associated ion channels, it can prevent central sensitization caused by peripheral nociceptive stimulation. However, transport of magnesium from blood to cerebrospinal fluid (CSF) across the blood-brain barrier is limited in normal humans. The current study was designed to evaluate whether perioperative intravenous magnesium sulfate infusion affects postoperative pain. METHODS: Sixty patients undergoing abdominal hysterectomy received 50 mg/kg intravenous magnesium sulfate as a bolus dose followed by a continuous infusion of 15 mg x kg(-1) x h(-1) for 6 h (magnesium group) or the same volume of isotonic saline (control group). At the end of surgery, serum and CSF magnesium concentration were measured in both groups. The cumulative postoperative analgesic consumption was measured to assess the analgesic effect using a patient-controlled epidural analgesia device. Pain intensities at rest and during forced expiration were evaluated at 6, 24, 48, and 72 h postoperatively. RESULTS: At the end of surgery, patients in the magnesium group had significantly greater postoperative serum magnesium concentrations compared with both preoperative and control group values (P < 0.001). Despite significantly higher serum magnesium concentrations in the magnesium group, there was no significant difference in magnesium concentration measured in postoperative CSF. Cumulative postoperative analgesic doses were similar in both groups. However, there was observed an inverse relation between cumulative postoperative analgesic consumption and the CSF magnesium concentration in both groups. Visual analog pain scores at rest and during forced expiration were similar and less than 4 in both groups. CONCLUSIONS: Perioperative intravenous administration of magnesium sulfate did not increase CSF magnesium concentration and had no effects on postoperative pain. However, an inverse relation between cumulative postoperative analgesic consumption and the CSF magnesium concentration was observed. These results suggest that perioperative intravenous magnesium infusion may not be useful for preventing postoperative pain.     

Intravenous Magnesium Sulfate Administration Reduces Propofol Infusion Requirements during Maintenance of Propofol-N2O Anesthesia: Part I: Comparing Propofol Requirements According to Hemodynamic Responses: Part II: Comparing Bispectral Index in Control and Magnesium Groups

Background: The authors investigated whether an intravenous administration of magnesium sulfate reduces propofol infusion requirements during maintenance of propofol-N2O anesthesia.

Methods: Part I study: 54 patients undergoing total abdominal hysterectomy were randomly divided into two groups (n = 27 per group). The patients in the control group received 0.9% sodium chloride solution, whereas the patients in the magnesium group received magnesium (50 mg/kg as a bolus, then 8 mg [middle dot] kg-1 [middle dot] h-1). To maintain mean arterial blood pressure (MAP) and heart rate (HR) at baseline value, the propofol infusion rate was changed when the MAP or the HR changed. The amount of propofol infused excluding the bolus dosage was divided by patient's body weight and total infusion time. Part II study: Another 20 patients were randomly divided into two groups (n = 10 per group). When the MAP and HR had been maintained at baseline value and the propofol infusion rate had been maintained at 80 [mu]g [middle dot] kg-1 [middle dot] min-1 (magnesium group) and 160 [mu]g [middle dot] kg-1 [middle dot] min-1 (control group), bispectral index (BIS) values were measured.

Results: Part I: The mean propofol infusion rate in the magnesium group (81.81 +/- 13.09 [mu]g [middle dot] kg-1 [middle dot] min-1) was significantly less than in the control group (167.57 +/- 47.27). Part II: BIS values in the control group (40.70 +/- 3.89) were significantly less than those in the magnesium group (57.80 +/- 7.32).     

Effect of preoperative Mg sulfate infusion on serum cardiac troponin (cTn) in moderate preeclamptic undergoing elective cesarean section under spinal anesthesia

This study was designed to investigate and compare the effect of preoperative Mg sulfate infusion on serum cardiac troponin (cTn) in moderate preeclampsia undergoing elective cesarean section. A total of fifty parturients having moderate preeclampsia scheduled for elective cesarean section were included. They were randomly allocated into two equal groups 25 each, magnesium group (GMg) received preoperative magnesium sulfate infusion and control group (GC) then both received spinal anesthesia, serum troponin measured preoperative then at 6, 12 and 24 h postoperative. Mean arterial pressure and heart rate were also recorded. Baseline serum cardiac troponin was higher above normal and was comparable at the rest of times in both groups. Mean arterial pressure readings were significantly lower in GMg compared to GC at induction of spinal, skin incision and skin closure (P < 0.05) and were comparable at the rest of times. Serum cardiac troponin (cTn) levels were comparable in parturients received magnesium sulfate infusion preoperatively with those did not receive magnesium sulfate.     

Lack of Impact of Intravenous Lidocaine on Analgesia, Functional Recovery, and Nociceptive Pain Threshold after Total Hip Arthroplasty

Background: The analgesic effect of perioperative low doses of intravenous lidocaine has been demonstrated after abdominal surgery. This study aimed to evaluate whether a continuous intravenous low-dose lidocaine infusion reduced postoperative pain and modified nociceptive pain threshold after total hip arthroplasty.

Methods: Sixty patients participated in this randomized double-blinded study. Patients received lidocaine 1% (lidocaine group) with a 1.5 mg/kg-1 intravenous bolus in 10 min followed by a 1.5 mg [middle dot] kg-1 [middle dot] h-1 intravenous infusion or saline (control group). These regimens were started 30 min before surgical incision and stopped 1h after skin closure. Lidocaine blood concentrations were measured at the end of administration. In both groups, postoperative analgesia was provided exclusively by patient-controlled intravenous morphine. Pain scores, morphine consumption, and operative hip flexion were recorded over 48 h. In addition, pressure pain thresholds and the extent of hyperalgesia around surgical incision were systematically measured at 24 and 48 h.

Results: In comparison with the placebo, lidocaine did not induce any opioid-sparing effect during the first 24 h (median [25-75% interquartile range]; 17 mg [9-28] vs. 15 mg [8-23]; P = 0.54). There was no significant difference regarding the effects of lidocaine and placebo on pain score, pressure pain thresholds, extent in the area of hyperalgesia, and maximal degree of active hip flexion tolerated. Mean plasma lidocaine concentration was 2.1 +/- 0.4 [mu]g/ml.     

Effects of Perioperative Analgesic Technique on the Surgical Outcome and Duration of Rehabilitation after Major Knee Surgery

Background: Continuous passive motion after major knee surgery optimizes the functional prognosis but causes severe pain. The authors tested the hypothesis that postoperative analgesic techniques influence surgical outcome and the duration of convalescence.

Methods: Before standardized general anesthesia, 56 adult scheduled for major knee surgery were randomly assigned to one of three groups, each to receive a different postoperative analgesic technique for 72 h: continuous epidural infusion, continuous femoral block, or intravenous patient-controlled morphine (dose, 1 mg; lockout interval, 7 min; maximum dose, 30 mg/4 h). The first two techniques were performed using a solution of 1% lidocaine, 0.03 mg/ml morphine, and 2 [micro sign]g/ml clonidine administered at 0.1 ml [middle dot] kg-1 [middle dot] h-1. Pain was assessed at rest and during continuous passive motion using a visual analog scale. The early postoperative maximal amplitude of knee flexion was measured during continuous passive motion at 24 h and 48 h and compared with the target levels prescribed by the surgeon. To evaluate functional outcome, the maximal amplitudes were measured again on postoperative day 5, at hospital discharge (day 7), and at 1- and 3-month follow-up examinations. When the patients left the surgical ward, they were admitted to a rehabilitation center, where their length of stay depended on prospectively determined discharge criteria.

Results: The continuous epidural infusion and continuous femoral block groups showed significantly lower visual analog scale scores at rest and during continuous passive motion compared with the patient-controlled morphine group. The early postoperative knee mobilization levels in both continuous epidural infusion and continuous femoral block groups were significantly closer to the target levels prescribed by the surgeon than in the patient-controlled morphine group. On postoperative day 7, these values were 90 [degree sign] (60-100 [degree sign]) (median and 25th-27th percentiles) in the continuous epidural infusion group, 90 [degree sign] (60-100 [degree sign]) in the continuous femoral block group, and 80 [degree sign] (60-100 [degree sign]) in the patient-controlled morphine group (P < 0.05). The durations of stay in the rehabilitation center were significantly shorter: 37 days (range, 30-45 days) in the continuous epidural infusion group, 40 days (range, 31-60 days) in the continuous femoral block group, and 50 days (range, 30-80 days) in the patient-controlled morphine group (P < 0.05). Side effects were encountered more frequently in the continuous epidural infusion group.     

A comparison of intra-articular magnesium and/or morphine with bupivacaine for postoperative analgesia after arthroscopic knee surgery

Purpose

Both magnesium and morphine provide enhanced patient analgesia after arthroscopic knee surgery when administered separately via the intra-articular route. Magnesium sulfate amplifies the analgesic effect of morphine. This study was designed to compare the analgesic effects of intra-articular magnesium and morphine, with bupivacaine, when used separately and in combination.

Methods

Eighty patients undergoing arthroscopic menisectomy were randomized blindly into four intra-articular groups: group B+Mor+Mg received 20 ml 0.25% bupivacaine, morphine 2 mg, and magnesium 150 mg; group B+Mor received 20 ml 0.25% bupivacaine and morphine 2 mg; group B+Mg received 20 ml 0.25% bupivacaine and magnesium 150 mg; and group B received 20 ml 0.25% bupivacaine. Pain scores at rest and during movement, analgesic duration, and total analgesic consumption were recorded.

Results

Group B+Mor and group B+Mg patients had equally effective postoperative analgesia. Group B+Mor+Mg patients had significantly reduced visual analogue scale (VAS) values both at rest and during movement and significantly increased time to first postoperative analgesic request, as well as significantly reduced total analgesic consumption, compared with the other groups.

Conclusion

Intra-articular administration of magnesium sulfate or morphine, with bupivacaine, had comparable analgesic effects in the doses used. Their combination provided more effective postoperative analgesia than either drug alone.     

Comparison of Adenosine and Remifentanil Infusions as Adjuvants to Desflurane Anesthesia

Background: Because adenosine has been alleged to produce both anesthetic and analgesic sparing effects, a randomized, double-blinded study was designed to compare the perioperative effects of adenosine and remifentanil when administered as intravenous adjuvants during general anesthesia for major gynecologic procedures.

Methods: Thirty-two women were assigned randomly to one of two drug treatment groups. After premedication with 0.04 mg/kg intravenous midazolam, anesthesia was induced with 2 [micro sign]g/kg intravenous fentanyl, 1.5 mg/kg intravenous propofol, and 0.6 mg/kg intravenous rocuronium, and maintained with desflurane, 2%, and nitrous oxide, 65%, in oxygen. Before skin incision, an infusion of either remifentanil (0.02 [micro sign]g [middle dot] kg-1 [middle dot] min-1) or adenosine (25 [micro sign]g [middle dot] kg-1 [middle dot] min-1) was started and subsequently titrated to maintain systolic blood pressure, heart rate, or both within 10-15% of the preincision values.

Results: Adenosine and remifentanil infusions were effective anesthetic adjuvants during lower abdominal surgery. Use of adenosine (mean +/- SEM, 166 +/- 17 [micro sign]g [middle dot] kg-1 [middle dot] min-1) was associated with a significantly greater decrease in systolic blood pressure and higher heart rate values compared with remifentanil (mean +/- SEM, 0.2 +/- 0.03 [micro sign]g [middle dot] kg-1 [middle dot] min-1). Total postoperative opioid analgesic use was 45% and 27% lower in the adenosine group at 0-2 h and 2-24 h after surgery, respectively.     

Use of the NMDA antagonist magnesium sulfate during monitored anesthesia care for shockwave lithotripsy

PURPOSE: To assess whether intravenous magnesium sulfate infusion affects analgesic requirements during monitored anesthesia care (MAC) for shockwave lithotripsy (SWL). PATIENTS AND METHODS: Fifty patients in ASA class I or II undergoing SWL with MAC were randomized into two groups. Induction of MAC was produced by bolus doses of midazolam 0.03 mg/kg(-1) and fentanyl 0.5 microg/kg(-1) followed by intravenous infusion of midazolam 0.015 to 0.06 mg/kg(-1)/hr(-1) with fentanyl supplementation 0.2 microg/kg(-1). In addition, group I patients received magnesium sulfate 30 mg/kg(-1) intravenously as a bolus dose followed by a continuous infusion of 10 mg/kg(-1) /hr(-1) beginning 15 minutes before induction of sedation. The midazolam infusion rate and additional fentanyl doses were adjusted by verbal analog scale (VAS) measurements, observer assessment sedation score (OAA/S), and achieving a target bispectral index (BIS) in a range of 70 to 90. At the end of SWL, the total midazolam and total fentanyl consumptions were recorded, and the serum magnesium concentration was measured. RESULTS: Magnesium caused significant decreases in the total consumption of midazolam (P = 0.001) and fentanyl (P = 0.001). The VAS values at the 15th, 20th, and 25th minute in group I were significantly lower than in group II. In group I, hemodynamic and arterial oxygen parameters were better than in group II. CONCLUSION: A magnesium bolus and infusion can be utilized to reduce analgesic requirements under MAC during SWL.     

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).     

硫酸镁对吗啡病人自控静脉术后镇痛效果的影响

目的 评价硫酸镁对吗啡病人自控静脉术后镇痛效果的影响.方法 择期拟行上腹部手术病人印例,性别不限,年龄45～60岁,体重48～70 kg,ASA Ⅰ或Ⅱ级,随机分为吗啡组(M组)和硫酸镁复合吗啡组(MS组),每组30例.VAS评分≥3分时,术后行病人自控静脉镇痛,M组吗啡单次给药剂量为0.015 mg/kg,MS组单次给药剂量吗啡为0.015 mg/kg、硫酸镁为0.9 mg/kg.病人首次按压后4、8、16、24、48 h时记录镇痛药物用量.记录术后胃肠功能恢复时间.于麻醉前、术毕及镇痛结束时取静脉血,测定血清镁离子和钙离子浓度.结果 与M组比较,MS组镇痛药物用量减少,术后胃肠功能恢复时间缩短(P<0.05);与麻醉前比较,术毕及镇痛结束时两组血清镁离子浓度降低(P<0.05);与术毕时比较,镇痛结束时MS组血清镁离子浓度升高(P<0.05).两组各时点血清钙离子浓度比较差异无统计学意义(P>0.05).结论 硫酸镁可改善吗啡病人自控静脉术后镇痛的效果.     

Intrathecal vs intravenous magnesium as an adjuvant to bupivacaine spinal anesthesia for total hip arthroplasty

BackgroundThe aim of this study was to investigate the effect of intravenous infusion vs intrathecal magnesium sulfate during spinal anesthesia on postoperative pain, analgesic consumption, and intraoperative blood loss on patients undergoing total hip arthroplasty surgery.MethodsIn this prospective randomized controlled study, 75 adult patients, ASA physical status I and II scheduled for total hip arthroplasty, were included and randomized into three groups. Patients in Group I (control) received spinal anesthesia with hyperbaric bupivacaine and fentanyl. In Group II (IT Mg), 50 mg of magnesium sulfate was added to bupivacaine and fentanyl. In Group III (IV Mg), after induction of spinal anesthesia as in group I, a bolus dose of i.v. magnesium sulfate 40 mg kg^?1 was injected over 10 min, followed by continuous infusion of 15 mg kg^?1 h^?1 till the end of surgery. Arterial blood pressure, heart rate, electrocardiography, and O₂ saturation were continuously monitored. Onset, duration of sensory and motor block, and postoperative pain scores were assessed. Serum magnesium concentrations were checked before induction of anesthesia, immediately after surgery, at 6 h and 24 h after surgery. Total analgesic consumption and intraoperative blood loss were calculated.ResultsThere were no significant differences between the study groups in terms of onset time and maximum sensory level achieved, as well as onset and duration of motor block. Postoperative pain scores and 24 h analgesic consumption were lower in group II and III with insignificant differences between them. Intraoperative blood loss was significantly lower in group III. Postoperative Mg levels were higher in group III, without significant side effects.ConclusionsBoth i.v. infusion and intrathecal injection of Mg sulfate improved postoperative analgesia after total hip replacement. In addition, i.v. infusion of Mg sulfate reduced intraoperative blood loss.     

Reversal of Neuromuscular Blockade and Simultaneous Increase in Plasma Rocuronium Concentration after the Intravenous Infusion of the Novel Reversal Agent Org 25969

Background: The purpose of this study was to determine the changes in the plasma concentration of rocuronium and the reversal of its neuromuscular blockade after the intravenous infusion of Org 25969, the novel neuromuscular block-reversal agent, in anesthetized guinea pigs.

Methods: Rocuronium was infused for 1 h at a rate of 12-19 nmol[middle dot]kg-1[middle dot]min-1 to produce a steady-state 90% neuromuscular block. After 30 min, a concomitant infusion of either the reversal agent Org 25969 at a rate of 50 nmol[middle dot]kg-1[middle dot]min-1 or an infusion of an equivalent volume of saline was started. The time course of plasma concentrations of rocuronium was determined by use of liquid chromatography-mass spectrometry/mass spectrometry.

Results: In both treatment groups, a steady-state plasma concentration of rocuronium was obtained after 30 min. In the saline-treated group, the plasma concentration of rocuronium and depth of block remained constant. In the Org 25969 group, neuromuscular block was reversed while the rocuronium infusion was ongoing. Simultaneously, an increase in the total plasma concentration of rocuronium (free and complexed) was observed, even though the infusion rate of rocuronium was not changed. Compared with the saline-treated group, a small increase in the postmortem bladder concentration of rocuronium was detected.     

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).     

A comparative study between amiodarone and magnesium sulfate as antiarrhythmic agents for prophylaxis against atrial fibrillation following lobectomy

Purpose

Atrial fibrillations are common after thoracic surgery. Amiodarone and magnesium sulfate have been used for the management of atrial fibrillation following cardiac and non-cardiac surgery. However, to our knowledge, comparisons of both drugs with each other and with a control group in relation to the prevention of AF following lung surgery have not been performed. Our primary aim in this study was to prospectively evaluate the prophylactic effects of magnesium sulfate and amiodarone used separately and compare them with a control group analyzed retrospectively during and following lobectomy surgeries.

Patients and methods

The prophylactic value of amiodarone (group A; 219 patients) administered as an intravenous infusion (15 mg/kg for 48 h postoperatively) after a loading dose (5 mg/kg) was compared with magnesium sulfate (group M; 219 patients) administered intravenously as a loading dose (80 mg/kg magnesium sulfate over 30 min preoperatively) and then as an intravenous infusion (8 mg/kg/h for 48 h) in 438 patients undergoing lobectomy. These two groups were compared with a control group of 219 patients who were analyzed retrospectively.

Results

The results showed significantly lower incidences of AF in groups A and M when compared with group C (P < 0.05). There was no significant difference between the amiodarone and magnesium sulfate groups. However, the incidence of postoperative AF was lower in the amiodarone group, where only 21 (10 %) patients developed AF in comparison to 27 (12.5 %) patients in the magnesium sulfate group. Group C showed a higher incidence, 44 (20.5 %) patients, when compared with both groups. In addition, there were significant differences between the three groups concerning intensive care unit (ICU) and total hospital stays (P < 0.05).

Conclusion

Our study showed that during the intra- and postoperative periods, both amiodarone and magnesium sulfate are effective at preventing the incidence of atrial fibrillation following lung resection surgery in comparison to the control group.     

Comparison of magnesium sulfate with opioid and NSAIDs on postoperative pain management after coronary artery bypass surgery

OBJECTIVE: This study measured the effectiveness of magnesium sulfate during and after coronary artery bypass grafting (CABG) on postoperative pain and respiratory functions, and compared it with 2 other well-known and widely used analgesic agents: codeine and diclofenac, a nonsteroidal anti-inflammatory drug (NSAID). DESIGN: Prospective unblinded study. Setting: Single institution. PARTICIPANTS: Patients undergoing CABG. INTERVENTIONS: Patients were divided into 3 groups. In group A (n = 50), intraoperative magnesium sulfate, 2 g/70 kg, was infused intravenously and was continued during the first 3 days postoperatively. In group B (n = 50), codeine, 60 mg/70 kg, was given orally 4 times a day for 3 days. In group C (n = 50), diclofenac sodium, 75 mg, was given orally twice a day for 3 days. MAIN RESULTS: On the first postoperative day the visual analog scale (VAS) score was greater than 5 in all groups. On the second day the VAS score was greater than 5 in groups B and C, and was less than 5 in group A. On the third day the VAS score was less than 5 in all groups. During the first 2 postoperative days the need for morphine was significantly less in group A than in the other 2 groups. Preoperative respiratory function tests (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and FEV1/FVC) were similar in each group. The FEV1, FVC, and FEV1/FVC values on the postoperative first, second, and third days were significantly higher in group A. CONCLUSIONS: Magnesium sulfate can be a beneficial adjuvant therapy for pain after CABG. In this respect, especially in patients with respiratory problems or intolerance to NSAIDs, magnesium sulfate can be a better choice than NSAIDs and opioids.     

Sevoflurane Increases Lumbar Cerebrospinal Fluid Pressure in Normocapnic Patients Undergoing Transsphenoidal Hypophysectomy

Background: The data on the effect of sevoflurane on intracranial pressure in humans are still limited and inconclusive. The authors hypothesized that sevoflurane would increase intracranial pressure as compared to propofol.

Methods: In 20 patients with no evidence of mass effect undergoing transsphenoidal hypophysectomy, anesthesia was induced with intravenous fentanyl and propofol and maintained with 70% nitrous oxide in oxygen and a continuous propofol infusion, 100 [micro sign]g [middle dot] kg-1 [middle dot] min-1. The authors assigned patients to two groups randomized to receive only continued propofol infusion (n = 10) or sevoflurane (n = 10) for 20 min. During the 20-min study period, each patient in the sevoflurane group received, in random order, two concentrations (0.5 times the minimum alveolar concentration [MAC] and 1.0 MAC end-tidal) of sevoflurane for 10 min each. The authors continuously monitored lumbar cerebrospinal fluid (CSF) pressure, blood pressure, heart rate, and anesthetic concentrations.

Results: Lumbar CSF pressure increased by 2 +/- 2 mmHg (mean +/- SD) with both 0.5 MAC and 1 MAC of sevoflurane. Cerebral perfusion pressure decreased by 11 +/- 5 mmHg with 0.5 MAC and by 15 +/- 4 mmHg with 1.0 MAC of sevoflurane. Systolic blood pressure decreased with both concentrations of sevoflurane. To maintain blood pressure within predetermined limits (within +/- 20% of baseline value), phenylephrine was administered to 5 of 10 patients in the sevoflurane group (range = 50-300 [micro sign]g) and no patients in the propofol group. Lumbar CSF pressure, cerebral perfusion pressure, and systolic blood pressure did not change in the propofol group.     

Prophylactic effect of magnesium infusion against postoperative atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is a common complication of cardiac operation. For the development of postoperative AF, various risk factors have been identified over the years. In a recent study, it was detected that low serum magnesium levels was an independent predictor of AF after coronary artery bypass grafting (CABG). The purpose of this study was to assess the prophylactic effect of intravenous magnesium infusion on postoperative AF. METHODS: A total of 62 consecutive patients who had elective, first time cardiac operation on cardiopulmonary bypass were prospectively categorized to 2 group. In the treatment group, 30 patients received 8.3 mmol of magnesium sulfate in 100 ml of saline solution that was administered over 4 hours, preoperatively, just after admission in the ICU, and at the postoperative day 1, 2, 3, and 4. RESULTS: Postoperative AF occurred in 3/30 (10.0%) patients in the treatment group and in 14/32 (43.8%) patients in the control group (p<0.01). The arrhythmia developed on the 2.9 postoperative day on average. The postoperative length of hospital stay was significantly shortened in the treatment group (15.9 +/- 4.0 days) than that in the control group (20.5 +/- 7.0, p < 0.01). CONCLUSION: Our findings indicate that magnesium sulfate infusion is effective for the prophylaxis of post operative AF.     

Effect of intraoperative magnesium sulphate infusion on pain relief after laparoscopic cholecystectomy

Introduction: The aim of the study is to evaluate the analgesic efficiency of perioperative magnesium sulphate infusion in patients undergoing laparoscopic cholecystectomy (LC). Methods: In a randomized, double‐blind trial study, 83 patients were divided into two groups. Group MT received 50 mg/kg i.v. magnesium sulphate in 100 ml of 0.9% normal saline and Group T received the same volume of isotonic saline during the intraoperative period. The cumulative post‐operative tramadol consumption was measured to assess the analgesic effect using a patient‐controlled analgesia device. Pain intensities at rest and while coughing were evaluated at 0, 2, 4, 8, 12, and 24 h post‐operatively. Results: The pain scores in Group MT were significantly lower than Group T at 0, 4, and 12 h post‐operatively. The average of visual analogue scale at rest and during cough during 24 h post‐operatively was found to be statistically significant between groups. The total dose of tramadol the 24‐h period in Group MT and Group T was found to be 281.34±90.82 and 317.46±129.59, respectively. Conclusion: Per‐operative 50 mg/kg magnesium sulphate infusion is effective in reducing post‐operative pain in patients undergoing LC.     

Effects of the intravenous administration of magnesium sulfate on corrected serum calcium level and nephrogenous cyclic AMP excretion in normal human subjects

Summary The effect of intravenous magnesium sulfate infusion on corrected serum calcium level and parathyroid function assessed by determination of nephrogenous cAMP (NcAMP) excretion were studied in normal human subjects. Significant hypermagnesemia induced by the magnesium sulfate infusion for 120 minutes was accompanied by a gradual and progressive decrease in the corrected serum calcium level. NcAMP excretion fell rapidly, reaching a nadir between 60 and 120 minutes after the infusion began, and after that rose above the baseline excretion. Urinary calcium excretion gradually increased, reaching a peak between 120 and 180 minutes after the infusion began and then gradually decreased. Since magnesium was given as the sulfate, it is not clear whether these changes were attributable to magnesium or sulfate or both. As a control study, we performed intravenous sodium sulfate infusion. The sodium sulfate infusion caused slight hypocalcemia, slight hypercalciuria, and a significant increase in NcAMP excretion. These findings indicate that the hypocalcemia and the hypercalciuria caused by the magnesium sulfate infusion is mainly due to the effect of magnesium, and that the decrease in NcAMP excretion during the infusion is due to the effect of magnesium alone. We conclude that the hypocalcemia caused by the magnesium sulfate infusion is mainly due to the renal calcium loss, and that the inhibition of parathyroid function caused by hypermagnesemia may be only partially involved in the early phase of this hypocalcemia.     

The Anabolic Effect of Epidural Blockade Requires Energy and Substrate Supply

Background: The authors examined the hypothesis that continuous thoracic epidural blockade with local anesthetic and opioid, in contrast to patient-controlled intravenous analgesia with morphine, stimulates postoperative whole body protein synthesis during combined provision of energy (4 mg [middle dot] kg-1 [middle dot] min-1 glucose) and amino acids (0.02 ml [middle dot] kg-1 [middle dot] min-1 Travasol(TM) 10%, equivalent to approximately 2.9 g [middle dot] kg-1 [middle dot] day-1).

Methods: Sixteen patients were randomly assigned to undergo a 6-h stable isotope infusion study (3 h fasted, 3 h feeding) on the second day after colorectal surgery performed with or without perioperative epidural blockade. Protein synthesis, breakdown and oxidation, glucose production, and clearance were measured by l-[1-13C]leucine and [6,6-2H2]glucose.

Results: Epidural blockade did not affect protein and glucose metabolism in the fasted state. Parenteral alimentation decreased endogenous protein breakdown and glucose production to the same extent in both groups. Administration of glucose and amino acids was associated with an increase in whole body protein synthesis that was modified by the type of analgesia, i.e., protein synthesis increased by 13% in the epidural group (from 93.3 +/- 16.6 to 104.5 +/- 11.1 [mu]mol [middle dot] kg-1 [middle dot] h-1) and by 4% in the patient-controlled analgesia group (from 90.0 +/- 27.1 to 92.9 +/- 14.8 [mu]mol [middle dot] kg-1 [middle dot] h-1;P = 0.054).