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We measured the time it takes to reach the desired inspired anesthetic concentration using the Primus (Drägerwerk, AG, Lübeck, Germany) and the Avance (GE Datex-Ohmeda, Munich, Germany) anesthesia machines with toddler and newborn ventilation settings. The time to reach 95% of inspired target sevoflurane concentration was measured during wash-in from 0 to 6 vol% sevoflurane and during wash-out from 6 to 0 vol% with fresh gas flows equal to 1 and 2 times the minute ventilation. The Avance was faster than the Primus (65 seconds [95% confidence interval (CI): 55 to 78] vs 310 seconds [95% CI: 261 to 359]) at 1.5 L/min fresh gas flow, tidal volume of 50 mL, and 30 breaths/min. Times were shorter by the same magnitude at higher fresh gas flows and higher minute ventilation rates. The effect of doubling fresh gas flow was variable and less than expected. The Primus is slower during newborn than toddler ventilation, whereas the Avance's response time was the same for newborn and toddler ventilation. Our data confirm that the time to reach the target-inspired anesthetic concentration depends on breathing circuit volume, fresh gas flow, and minute ventilation.

Background: Although it has been reported that an increase in skin temperature indicates block success with higher specificity and sensibility than skin sensitivity to pinprick and cold, the methodology previously used computer-assisted infrared thermography, a technique that is expensive and requires substantial personnel training. In this prospective observational study, we evaluated whether a simple infrared thermometer can reliably predict block effectiveness after infraclavicular brachial plexus blockade., Methods: Thirty consecutive patients undergoing upper limb surgery under infraclavicular block were enrolled. From the end of the local anesthetic injection, skin temperature was measured in all four major nerve distribution areas, and the sensory block onset (using cold and pinprick with 0 = no sensation to 2 = normal) were evaluated every 5 min for 30 min. A successful block was defined as the absence of sensation to cold (swab soaked with alcohol) and pinprick (needle) with a score of "0" within 30 min after the injection in the 4 major nerve distribution areas (radial, ulnar, median and musculocutaneous). Skin temperature measurements were performed using a noncontact temperature probe., Results: One-hundred-twenty nerves (30 patients, 4 nerves per patient) were anesthetized. Twenty-five patients had a successful block. Four patients required supplementation for block failure. General anesthesia was performed in one patient. Skin temperature variation was not different among different nerves. There was a statistically significant increase in cutaneous temperature after nerve block compared to the same skin area before the procedure (P < 0.0001 from T5 to T30). Average temperature variations in blocked versus unblocked nerves at the same time were significantly different (P < 0.05 at T5 then P < 0.0001 from T10 to T30). When temperature in a specific sensory territory increased 1 degree C or more, at 5 and 10 min, the specific nerve was blocked (the score was "0"). Thus, when temperature changes in all 4 nerves were noted at 5 and 10 min, the block was successful at 30 min. No change in temperature in the contralateral arm or in the core temperature was observed., Conclusion: Skin temperature assessment with an infrared thermometer is a reliable, simple and early indicator of a successful nerve block.

Background: Spinal anesthesia in elderly patients is frequently associated with significant technical difficulties. Thus, we compared the classical midline approach to the paramedian approach to perform continuous spinal anesthesia (CSA)., Methods: We prospectively studied 40 patients aged >75 yr who underwent open surgical repair of a hip fracture. These patients were randomly allocated to one of two groups: Group M: midline approach, and Group PM: paramedian approach. Patients were positioned in the lateral decubitus to receive CSA at L4-5 level. CSA was considered successful if cerebrospinal fluid was obtained through the needle. In case of initial failure in either approach, the same approach was repeated by the same operator. If two attempts were unsuccessful, the other anatomical approach was used by the same operator. If both approaches failed, a staff anesthesiologist performed a final attempt. In case of failure or insufficient block, the patient received general anesthesia., Results: The success rate after the first attempt was 85% (17) for Group PM and 45% (9) for Group M (P = 0.02). All catheters were successfully introduced. No patient required general anesthesia. Vascular puncture after needle puncture was observed in six patients in Group M versus 0 in Group PM (P = 0.03), but none were of clinical consequence. No other clinically significant complications were observed., Conclusion: In summary, after the initial attempt, the paramedian approach is associated with an increased success rate, compared with the midline approach, during the performance of CSA in elderly patients.

Background: We evaluated the potential role of an euctectic mixture of local anesthetic (EMLA) cream application before performing midhumeral block., Methods: Sixty patients undergoing surgery distal to the elbow amenable to a humeral block were prospectively recruited for the study. The patients were randomly allocated to 1 of 3 groups: Group E: topical EMLA cream 60 min before block plus 2 mL IV normal saline 5 min before procedure; Group P: topical sham cream plus 2 mL IV normal saline, and Group S: topical sham cream plus 0.1 microg/kg of sufentanil in 2 mL solution IV. Pain experienced during skin puncture, and overall pain for the whole procedure were rated using a 100-mm visual analog scale (0: no pain to 100: worst pain)., Results: Patients in Group E experienced less pain compared with those in Groups P and S (5 +/- 3 mm vs 33 +/- 20 mm and 30 +/- 18 mm, respectively, P < 0.0001). The pain experienced throughout the complete humeral block was more substantial in Group P than in Group E (P = 0.01)., Conclusion: The patients who received EMLA cream had less pain with needle puncture as well as throughout the performance of humeral block.

Background: There is great variability in the need for morphine in the postoperative period. We performed a pharmacokinetic-pharmacodynamic study considering the potential effect of the two main metabolites of morphine., Methods: Fifty patients with moderate to severe pain received morphine as an IV titration, followed by IM administration postoperatively. The plasma concentration of morphine, morphine-6-glucuronide (M-6-G), morphine-3-glucuronide (M-3-G), and pain intensity were measured at frequent intervals. Pharmacokinetic and pharmacodynamic fitting was performed with the software NONMEM., Results: The pharmacokinetics were largely predictable. M-6-G and M-3-G clearances were markedly decreased in patients with renal failure. The pharmacodynamics was less predictable, with an important interindividual variability. M-6-G was 7.8 times more potent than morphine, but the average time to peak concentration in the effect compartment after a bolus injection of morphine was 4.25 h for M-6-G, when compared to 0.33 h for morphine. M-3-G showed mild inhibition of the analgesic properties of morphine and of M-6-G. The time to M-3-G peak concentration in the effect compartment after a bolus injection of morphine was 10 h., Conclusions: M-6-G is a potent opioid agonist and M-3-G a mild opioid antagonist. Both are poorly excreted in patients with renal failure. However, the metabolism of morphine was rapid when compared to the transfer of metabolites through the blood-brain barrier, which appears to be the limiting process. Because poor analgesia due to M-3-G's effect may occur in some patients after 1 or 2 days, a switch to other molecules should be considered.

Background: In this prospective study we compared the success of the infraclavicular brachial plexus block using double-stimulation in regard to the second nerve response elicited with neurostimulation., Methods: Six-hundred-twenty-eight patients undergoing emergency upper limb surgery using infraclavicular brachial plexus block were included in this study. The musculocutaneous nerve was initially blocked and the groups were then evaluated according to the second nerve located, which was radial in 54%, median in 35%, and ulnar in 11% of patients. Blocks were performed using lidocaine 1.5% with 1/400,000 epinephrine 40 mL in all cases. The block was assessed every 5 min for 30 min after completion of the block., Results: The success rate was 96% for the radial response group, 89% for the median response group, and 90% for the ulnar response group (P < 0.05). Time to perform the block and the onset time were not significantly different among groups. No serious complications were observed., Conclusion: We conclude that having initially located and blocked the musculocutaneous nerve, subsequent injection on a radial response resulted in a slightly more reliable success rate than injection with an ulnar or median response.

Aging and disease may make elderly patients particularly susceptible to hypotension during spinal anesthesia. We compared the hemodynamic effect of continuous spinal anesthesia (CSA) and small dose single injection spinal anesthesia (SA) regarding the incidence of hypotension. Seventy-four patients aged >75 yr undergoing surgical repair of hip fracture were randomized into 2 groups of 37 patients each. Group CSA received a continuous spinal anesthetic with a titration of 2.5 mg boluses every 15 min of isobaric bupivacaine, while group SA received a single injection spinal anesthetic with 7.5 mg of isobaric bupivacaine. The overall variations in noninvasive automated arterial blood pressure were not statistically significantly different in the 2 groups at baseline and after CSA or SA (not significant). In the SA group, 68% of patients experienced at least one episode of hypotension (decrease in systolic arterial blood pressure greater than 20% of baseline value) versus 31% of patients in the CSA group (P = 0.005). In the SA group, 51% of patients experienced at least one episode of severe hypotension (decrease in systolic arterial blood pressure more than 30% of baseline value) versus 8% of patients in the CSA group (P < 0.0001). In the CSA group, 4.5 +/- 2 mg of ephedrine was injected versus 11 +/- 2 mg in the SA group (P = 0.005). In the CSA group, 5 mg (2.5-10) of anesthetic solution was required versus 7.5 mg in the SA group (P < 0.0001). We conclude that, in elderly patients undergoing hip fracture repair, CSA provides fewer episodes of hypotension and severe hypotension compared with a single intrathecal injection of 7.5 mg bupivacaine.

Unlabelled: Most upper arm regional anesthesia techniques are successful and differences in efficacy should not dictate the choice of technique. In the present study, we compared humeral block (HB) and infraclavicular brachial plexus block (ICB) using anesthetic time (i.e., duration of the procedure + onset time) as the primary outcome measure. The block was successful when a complete sensory block was obtained in the four major nerves of the arm, and the time to complete block was recorded. Patients undergoing orthopedic surgery of the upper limb were included in a prospective randomized study and received ICB (group I, n = 60 patients) or HB (group H, n = 60 patients). Total anesthetic time was 19.5 min (95% confidence interval [CI], 17.4-21.6 min) for ICB and 20.8 min (95% CI, 18.7--22.9 min) for HB (not significant). Time to perform the block was 4.5 min (95% CI, 4-5 min) for ICB and 9.8 min (95% CI, 8.9--10.7 min) for HB (P < 0.05). The onset time was 15 min (95% CI, 13-17 min) for ICB and 11 min (95% CI, 9--13 min) for HB (P < 0.05). The success rate was 92% for ICB and 95% for HB (not significant). One self-limited vascular puncture was made in each group. HB had a faster onset time but ICB using a double-stimulation technique was faster to perform. Anesthetic time was similar with the two techniques., Implications: We have compared infraclavicular brachial plexus block (ICB) with humeral block. Efficacy and anesthetic time were not significantly different, although time to perform the block was shorter with the ICB.

Infraclavicular brachial plexus block is used less than other techniques of regional anesthesia for upper-limb surgery. We describe a modified coracoid approach to the infraclavicular brachial plexus using a double-stimulation technique and assess its efficacy. Patients undergoing orthopedic surgery of the upper limb were included in this prospective study. The landmarks used were the coracoid process and the clavicle. The needle was inserted in the direction of the top of the axillary fossa (in relation to the axillary artery), with an angle of 45 degrees. Using nerve stimulation, the musculocutaneous nerve was identified first and blocked with 10 mL of 1.5% lidocaine with 1:400,000 epinephrine. The needle was then withdrawn and redirected posteriorly and medially. The radial, ulnar, or median nerve was then blocked. The block was tested every 5 min for 30 min. The overall success rate, i.e., adequate sensory block in the 4 major nerve distributions at 30 min, was 92%, and 6% of the patients required supplementation. Five patients required general anesthesia. No major complications were observed. This modified infraclavicular brachial plexus block using a double-stimulation technique was easy to perform, had frequent success, and was safe in this cohort.

Lysophosphatidic acid (LPA), platelet-activating factor (PAF), and thromboxane A(2) are proinflammatory lipid mediators that activate surface receptors on platelets, producing increased intracellular calcium, which is necessary for aggregation. We investigated propofol's effect on platelet aggregation and intracellular calcium mobilization caused by these three agonists. Platelets from human volunteers were incubated in buffers containing LPA (1 microM), U46619 (thromboxane A(2) analog; 1 microM), or PAF (10 nM). Propofol emulsion or 2,6-diisopropylphenol (propofol without fat emulsion) dissolved in ethanol was added to achieve concentrations of propofol used clinically: 5 or 10 microg/mL. After 2 min, aggregation or intracellular calcium concentrations were measured with optical techniques. Propofol emulsion and propofol in ethanol produced similar inhibition of platelet aggregation induced by LPA, PAF, and U46619 in a dose-dependent fashion. LPA, PAF, and U46619 each caused significant increases in intracellular calcium that were not modified by propofol. Because propofol does not significantly alter intracellular calcium increases caused by receptor activation, inhibition appears to act distal to platelet receptors, inositol phosphate 3, and phospholipase C. Because the three lipid mediators play a key role in inflammation, their inhibition by propofol might be clinically important.

Unlabelled: To improve the incidence of block of the posterior femoral cutaneous nerve (PFCN) when using an anterior approach as described recently, we hypothesized that the distance between the inguinal line and the puncture site depends on the patient's height. A preliminary radiological study performed in 13 patients established a formula describing the relationships between the patient's height and the puncture site "S." A line was drawn between the anterior iliac spine and the superior angle of the pubic tubercle (inguinal line) and another line from the midpoint of the inguinal line to the puncture site "S." "S" was calculated from the midpoint of the inguinal line as "S" = (height in cm--100)/10. A prospective study was conducted in 53 patients. Results are presented as median (range, 0.25-0.75). Two minutes were required to locate the sciatic nerve at a depth of 12 cm (10.5-13.0 cm). Complete sciatic and PFCN blocks were observed in 92% of the patients. We conclude that consideration should be given to the patient's height when the sciatic nerve is blocked using an anterior approach. This technique seems to improve the success of block of the PFCN, essential to tolerate a thigh tourniquet., Implications: This prospective but noncomparative work was performed to evaluate a new anterior technique of sciatic block, an adaptation of the anatomic landmarks described by Chelly and Delaunay, to patient height.