A. Albertin

The Effect-Site Concentration of Remifentanil Blunting Cardiovascular Responses to Tracheal Intubation and Skin Incision During Bispectral Index-Guided Propofol Anesthesia

We sought to determine the effect-site concentration of remifentanil blunting sympathetic responses to tracheal intubation and skin incision during bispectral index (BIS)-guided propofol anesthesia. Forty-one ASA physical status I–II patients, aged 20–65 yr and undergoing major abdominal surgery, were randomly assigned to one of two groups: tracheal intubation (group TI, n = 20) or skin incision (group SI, n = 21). All patients received a target-controlled infusion of propofol of 4 &mgr;g/mL, which was then adjusted to maintain a BIS value ranging between 40 and 50. The effect-site concentration of remifentanil blocking the sympathetic responses to tracheal intubation and skin incision in 50% of cases (Ce50) was determined using an up-and-down sequential allocation method. The mean (95% confidence interval [CI]) Ce50 of remifentanil was 5.0 ng/mL for TI (95% CI, 4.7–5.4 ng/mL) and 2.1 ng/mL for SI (95% CI, 1.4–2.8 ng/mL). This study shows that effect-site concentrations of remifentanil of 5 ng/mL and 2 ng/mL are effective in blunting sympathetic responses to tracheal intubation and skin incision in 50% of patients when combined with a BIS-guided target controlled infusion of propofol.

A new posterior approach to the sciatic nerve block : A prospective, randomized comparison with the classic posterior approach

To evaluate the efficacy and acceptance of a new posterior subgluteus approach to the sciatic nerve, as compared with the classic posterior approach, 128 patients undergoing foot orthopedic procedures were randomly allocated to receive either the classic posterior sciatic nerve block (Group Labat, n = 64) or a modified subgluteus posterior approach (Group subgluteus, n = 64). All blocks were performed with the use of a nerve stimulator (stimulation frequency, 2 Hz; intensity, 1–0.5 mA). In Group subgluteus, a line was drawn from the greater trochanter to the ischial tuberosity; then, from the midpoint of this line, a second line was drawn perpendicularly and extended caudally for 4 cm. The end of this line represented the needle entry. In both groups, a proper sciatic stimulation was elicited at 0.5 mA; then 20 mL of 0.75% ropivacaine was injected. The time from needle insertion to successful sciatic nerve stimulation was 60 s (range, 10–180 s) with the Labat’s approach and 32 s (range, 5–120 s) with the new subgluteus approach (P = 0.0005). The depth of appropriate sciatic stimulation was 45 ± 13 mm (mean ± sd) after 2 (range, 1–7) needle redirections in Group subgluteus and 67 ± 12 mm after 4 (range, 1–10) needle redirections in Group Labat (P = 0.0001 and P = 0.00001, respectively). The failure rate was similar in both groups. Severe discomfort during the procedure was less frequent and acceptance better in Group subgluteus (5 patients [8%] and 60 patients [94%], respectively) than in Group Labat (20 patients [31%] and 49 patients [77%], respectively) (P = 0.0005 and P = 0.005, respectively). We conclude that this new subgluteus posterior approach to the sciatic nerve is an easy and reliable technique and can be considered an effective alternative to the more traditional Labat’s approach.

Randomized Comparison of Isoflurane and Sevoflurane for Laparoscopic Gastric Banding in Morbidly Obese Patients

STUDY OBJECTIVE To compare the efficacy and recovery profile of sevoflurane and isoflurane as the main anesthetics for morbidly obese patients. DESIGN Randomized, blinded study. SETTING Inpatients. PATIENTS 30 ASA physical status II and III obese patients [body mass index (BMI) > 35 kg/m(2)] undergoing laparoscopic gastric banding for morbid obesity. INTERVENTIONS After standard intravenous induction of general anesthesia and tracheal intubation, anesthesia was maintained with either sevoflurane or isoflurane as the main anesthetics. The end-tidal concentrations of the volatile drugs were adjusted to maintain systolic arterial blood pressure within +/-20% from baseline values. When the surgeon started the skin suture, the end-tidal concentration of the inhalational drug was reduced to 0.5 minimum alveolar concentration in both groups. At the last skin suture, the inhalational drug was discontinued and the vaporizator was removed to allow blinded evaluation of the emergence times. MEASUREMENTS AND MAIN RESULTS No differences in anesthetic exposure, hemodynamic parameters, incidence of untoward events, or postoperative pain relief were reported between the two groups. Extubation, emergence, and response times were shorter after sevoflurane [6 min (3-15 min), 8 min (5-18 min), and 12 (6-25 min)] than isoflurane [10 min (6-26 min), 14 min (6-21 min), and 21 min (14-41 min)] (p = 0.001, p = 0.03, and p = 0.0005, respectively). The median time for postanesthesia care unit discharge was 15 minutes (25th-75th percentiles: 10-18 min) after sevoflurane and 27 minutes (25th-75th percentiles: 20-30 min) after isoflurane (p = 0.0005). CONCLUSIONS Sevoflurane provides a safe and effective intraoperative control of cardiovascular homeostasis in morbidly obese patients undergoing laparoscopic gastric banding, with the advantage of a faster recovery and earlier discharge from the postanesthesia care unit than isoflurane.

Effects of two target-controlled concentrations (1 and 3 ng/ml) of remifentanil on MAC(BAR) of sevoflurane.

BackgroundThe aim of this prospective, randomized, double-blind study was to determine the effects of two different target-controlled concentrations of remifentanil (1 and 3 ng/ml) on the sevoflurane requirement for blunting sympathetic responses after surgical incision (MACBAR). MethodsSeventy-four patients aged 20–50 yr, with American Society of Anesthesiologists physical status I, were anesthetized with propofol, cisatracurium, and sevoflurane with a mixture of 60% nitrous oxide in oxygen. Then, patients were randomly allocated to receive no remifentanil infusion (n = 27) or a target-controlled plasma concentration of 1 ng/ml (n = 27) or 3 ng/ml remifentanil (n = 20). Sympathetic responses to surgical incision (presence or absence of an increase in either heart rate or mean arterial blood pressure of 15% or more above the mean of the values measured during the 2 min before skin incision) were determined after a 20-min period of stable end-tidal sevoflurane and target-controlled remifentanil concentrations. Predetermined end-tidal sevoflurane concentrations and the MACBAR for each group were determined using an up-and-down sequential-allocation technique. ResultsThe MACBAR of sevoflurane was higher in the group receiving no remifentanil (2.8% [95% confidence interval: 2.5–3.0%]) as compared with patients of the groups receiving 1 ng/ml (1.1% [0.9–1.3%]; P = 0.012) and 3 ng/ml remifentanil (0.2% [0.1–0.3%]; P = 0.006). When considering a minimum anesthetic concentration (MAC) value in this age population and the contribution of 60% nitrous oxide (0.55 MAC), the combined MACBAR values, expressed as multiples of the MAC, were 1.95 MAC, 1.1 MAC, and 0.68 MAC, in the three groups, respectively. ConclusionA target-controlled concentration of 1 ng/ml remifentanil results in a 60% decrease in the MACBAR of sevoflurane combined with 60% nitrous oxide. Increasing the target concentration of remifentanil to 3 ng/ml produces a further 30% decrease in the MACBAR values of sevoflurane.

The effects of single or multiple injections on the volume of 0.5% ropivacaine required for femoral nerve blockade.

We compared the effects of using a single- or multiple-injection technique on the volume of 0.5% ropivacaine required to block the femoral nerve, in a prospective, randomized, blinded fashion in which 50 premedicated patients received a femoral nerve block with 0.5% ropivacaine by use of a nerve stimulator and either a single- (n = 25) or multiple- (n = 25) injection technique. Muscular twitches were elicited at ≤0.5 mA before anesthetic injection. The designated volume of local anesthetic was equally divided among contraction of the vastus medialis, vastus intermedius, and vastus lateralis for the multiple injections, or it was injected at the contraction of the vastus intermedius with motion of the patella for the single injection. The local anesthetic volumes were varied for consecutive patients by using an up-and-down staircase method; a blinded observer determined the adequacy of nerve blockade (loss of pinprick sensation in the medial, patellar, and lateral portions of the knee, with concomitant block of the quadriceps muscle) 20 min after injection. The mean (95% confidence interval) volume required for blocking the femoral nerve with the multiple-injection technique (14 [12–16] mL) was significantly smaller than that observed with the single injection (23 [20–26] mL) (P = 0.001). According to logistic regression analyses, the 95% effective volumes of ropivacaine required to block the femoral nerve within 20 min after injection were 29 and 21 mL with a single or multiple injection, respectively. We conclude that searching for multiple muscular twitches reduces the volume of 0.5% ropivacaine required to produce blockade of the femoral nerve.

Does continuous sciatic nerve block improve postoperative analgesia and early rehabilitation after total knee arthroplasty?: A prospective, randomized, double-blinded study

Introduction: The aim of this prospective, randomized, double-blind study was to evaluate whether continuous sciatic nerve block can improve postoperative pain relief and early rehabilitation compared with single-injection sciatic nerve block in patients undergoing total knee arthroplasty (TKA) and lumbar plexus block. Methods: After ethical committee approval and written informed consent, 38 patients with ASA physical status I to II were enrolled. The first group received continuous sciatic and continuous lumbar plexus blocks (group regional or R, n = 19), whereas the second group received a single sciatic nerve block followed by saline infusion through the sciatic catheter and continuous lumbar plexus block (group control or C, n = 19). We assessed morphine consumption, scores for visual analog scale for pain at rest (VASr), and during continuous passive motion (VASi during CPM) for 48 hours postoperatively. Effectiveness of early ambulation was also evaluated. Results: Scores for VASr and VASi during CPM, as well as morphine consumption, were significantly higher in group C than in group R (P < 0.01). Moreover, patients in group R showed earlier rehabilitation with more effective ambulation (P < 0.05). Conclusions: Continuous sciatic nerve block improves analgesia, decreases morphine request, and improves early rehabilitation compared with single-injection sciatic nerve block in patients undergoing TKA and lumbar plexus block.

No adjustment vs. adjustment formula as input weight for propofol target-controlled infusion in morbidly obese patients.

Background and objective The purpose of this prospective, randomized, double-blind study was to determine the predictive performance of target-controlled infusions of propofol in morbidly obese patients using the ‘Marsh’ pharmacokinetic parameter set. Methods Twenty-four patients (ASA II or III, age 25–62 years, BMI 35.5–61.7) were randomly allocated to receive propofol target-controlled infusion based on a weight adjustment formula (group adjusted) or without adjustment [group total body weight (TBW)]. Anaesthesia was induced by a propofol-targeted concentration of 6 μg ml−1 that was subsequently adapted to maintain stable bispectral index values ranging between 40 and 50. Arterial blood samples were collected before the start of the infusion and every 15 min thereafter to determine the predictive performances. Results There were no statistically significant differences between the groups with regard to performance errors, divergence and wobble. Results are presented as median (interquartiles). Median performance error and median absolute performance error were −31.7 (−35.9, −19.4) and 31.7% (20.2, 35.9) for group adjusted and −16.3 (−26.3, 2.2) and 20.6% (14.8, 26.9) for group TBW, respectively. Wobble median value was 7.4% (3.8, 8.4) for group adjusted and 8.2% (7.0, 9.6) for group TBW. As for wobble and divergence, no statistically significant differences were found between groups. Conclusion Weight adjustment causes a clinically unacceptable performance bias, which is not corrected when TBW is used as an input to the ‘Marsh’ model. It is, therefore, advisable to administer propofol to morbidly obese patients by titration to targeted processed-EEG values.

Temperature control and recovery of bowel function after laparoscopic or laparotomic colorectal surgery in patients receiving combined epidural/general anesthesia and postoperative epidural analgesia

UNLABELLED We compared the effects of a laparoscopic (n = 23) versus laparotomic (n = 21) technique for major abdominal surgery on temperature control in 44 patients undergoing colorectal surgery during a combined epidural/general anesthesia. A thoracic epidural block up to T4 was induced with 6-10 mL of 0.75% ropivacaine; general anesthesia was induced with thiopental, fentanyl, and atracurium IV and maintained with isoflurane. Core temperature was measured with a bladder probe and recorded every 15 min after the induction. In both groups, core temperature decreased to 35.2 degrees C (range, 34 degrees C-36 degrees C) at the end of surgery. After surgery, normothermia returned after 75 min (60-120 min) in the Laparoscopy group and 60 min (45-180 min) in the Laparotomy group (P = 0.56). No differences in postanesthesia care unit discharge time were reported between the two groups. The degree of pain during coughing was smaller after laparoscopy than laparotomy from the 24th to the 72nd observation times (P < 0.01). Morphine consumption was 22 mg (2-65 mg) in the Laparotomy group and 5 mg (0-45 mg) in the Laparoscopy group (P = 0.02). The time to first flatus was shorter after laparoscopy (24 h [16-72 h]) than laparotomy (72 h [26-96 h]) (P = 0.0005), and the first intake of clear liquid occurred after 48 h (24-72 h) in the Laparoscopy group and after 96 h (90-96 h) in the Laparotomy group (P = 0.0005). Although laparoscopic surgery provides positive effects on the degree of postoperative pain and recovery of bowel function, the reduction in heat loss produced by minimizing bowel exposure with laparoscopic surgery does not compensate for the anesthesia-related effects on temperature control, and active patient warming must also be used with laparoscopic techniques. IMPLICATIONS This prospective, randomized, controlled study demonstrates that laparoscopic colorectal surgery results in less postoperative pain and earlier recovery of bowel function than conventional laparotomy but does not reduce the risk for perioperative hypothermia. Accordingly, active warming must be provided to patients also during laparoscopic procedures.

Fentanyl does not improve the nerve block characteristics of axillary brachial plexus anaesthesia performed with ropivacaine

Background: The aim of this prospective, randomized, double‐blind study was to evaluate the effects of adding 1 μg · kg−1 fentanyl to ropivacaine 7.5 mg · ml−1 for axillary brachial plexus anaesthesia.

A comparison of remifentanil and Sufentanil as adjuvants during sevoflurane anesthesia with epidural analgesia for upper abdominal surgery : Effects on postoperative recovery and respiratory function

UNLABELLED We compared the recovery profile and postoperative SpO(2) after the administration of general anesthesia with either sevoflurane-remifentanil or sevoflurane-sufentanil in 30 healthy patients undergoing upper abdominal surgery. They were randomly allocated to receive general anesthesia with sevoflurane and small doses of either remifentanil (n = 15) or sufentanil (n = 15), followed by postoperative epidural analgesia. The median sevoflurane minimum alveolar anesthetic concentration-hour was 2.3 (1.2-6.3) in group Remifentanil and 2.6 (1.4-5.2) in group Sufentanil (P: = 0.39), while the median consumption of remifentanil was 1.3 mg (0.7-3.4 mg) and sufentanil 0.09 mg (0.05-0.6 mg). Tracheal extubation required 10 min (6-18 min) with remifentanil and 14 min (8-24 min) with sufentanil (P: = 0.05); however, no differences in time to discharge from the recovery area were reported (24 min [12-75 min] with remifentanil and 30 min [12-135 min] with sufentanil; P: = 0. 35). From the first to seventh hour after surgery, SpO(2) was decreased more in the sufentanil than in the remifentanil group (P: = 0.001), and seven patients in the sufentanil group showed at least one episode with SpO(2) < or = 90% for more than 1 min (P: = 0.006) (median: 1 episode; range: 0-17 episodes; P: = 0.003). When added to sevoflurane, remifentanil is as effective as sufentanil during the intraoperative period, but provides shorter time to tracheal extubation and fewer effects on postoperative SpO(2) in the first 7 h after surgery. IMPLICATIONS In this double-blinded study, we evaluated the effects of adding small infusions of either remifentanil or sufentanil to sevoflurane in combination with postoperative epidural analgesia for upper abdominal surgery. We demonstrated that remifentanil is as effective as sufentanil during the intraoperative period, but that it provides shorter time to extubation and fewer effects on postoperative SpO(2) in the first 7 h after surgery.