Lidocaine pretreatment with tourniquet versus lidocaine-propofol admixture for attenuating propofol injection pain: a randomized controlled trial.

OBJECTIVE: Findings from studies investigating optimal techniques for attenuating propofol-related injection pain are inconsistent. In previous studies, lidocaine pretreatment using a tourniquet has been reported to be superior, inferior, or equivalent to a lidocaine-propofol admixture for reducing pain. This discordance could represent either no meaningful difference in the treatments or underlying methodological differences in the previous studies. We hypothesized that tourniquet-controlled pretreatment with lidocaine would be superior to lidocaine-propofol admixture for reducing propofol injection pain. METHODS: This randomized controlled trial compared 3 groups-a control group (saline pretreatment/saline admixture; n = 50), a pretreatment group (lidocaine pretreatment/saline admixture; n = 51), and an admixture group (saline pretreatment/lidocaine admixture; n = 50). The primary outcome was verbal pain score after injection. The incidence of pain on injection was explored as a secondary outcome. RESULTS: The median (interquartile range) verbal pain score after study solution injection were as follows-control group: 3 (0-6), pretreatment group: 0 (0-0), and admixture group: 0 (0-2). The pretreatment group had significantly lower pain scores when compared with the admixture group (P = 0.016), and both groups were superior to the control group. The pretreatment group had fewer subjects experiencing any injection pain than did the admixture group (20% vs. 44%, respectively; P = 0.024). CONCLUSIONS: Tourniquet-controlled pretreatment with lidocaine is statistically superior to admixing lidocaine with propofol for reducing propofol injection pain intensity, but the clinical importance of this small effect is questionable. However, pretreatment more effectively eliminates injection pain.

Respiratory and sleep effects of remifentanil in volunteers with moderate obstructive sleep apnea.

BACKGROUND: There is concern that opioid-based analgesia will worsen sleep-related respiratory insufficiency in patients with obstructive sleep apnea (OSA), resulting in serious morbidity or mortality. However, there are no studies that directly address the merit of this concern. Consequently, the authors designed this study as the first prospective, double-blind, placebo-controlled investigation of opioid pharmacology in patients with documented OSA. METHODS: Patients (n = 19) with moderate OSA documented by polysomnography (sleep study) were randomized to undergo an additional sleep study while receiving either a saline infusion or a remifentanil infusion (0.075 microg x kg x h). Sleep stages, apneas, hypopneas, and arterial hemoglobin oxygen saturation were continually recorded during saline or remifentanil infusion, and were compared with values obtained during the patients' earlier sleep study. RESULTS: Saline infusion had no effect on sleep or respiratory variables. In contrast, remifentanil increased Stage 1 sleep, markedly decreased rapid eye movement sleep, increased arousals from sleep, and decreased sleep efficiency. Remifentanil actually decreased the number of obstructive apneas, but markedly increased the number of central apneas. Arterial hemoglobin oxygen saturation was also significantly lower in OSA patients receiving remifentanil. CONCLUSIONS: The decrease in obstructive apneas likely resulted from the marked decrease in rapid eye movement sleep caused by remifentanil. Despite fewer obstructions, OSA was worse during remifentanil infusion because of a marked increase in the number of central apneas. These data suggest that caution is warranted when administering opioids to subjects with moderate OSA, but that the primary risk may be central apnea, not obstructive apnea.

Concurrent expansion of plasma volume and left ventricular end-diastolic volume in patients after rapid infusion of 5% albumin and lactated Ringer's solution.

STUDY OBJECTIVE: To examine the effects of plasma volume expansion on plasma volume, left ventricular end-diastolic volume (LVEDV), and cardiac index (CI) after rapid fluid infusion, as knowledge of the degree of concordance between plasma and cardiac preload expansion could optimize LVEDV expansion without administering excessive fluid. DESIGN: Randomized, double-blinded study. SETTING: Academic community hospital. PATIENTS: 20 patients undergoing elective coronary artery bypass surgery. INTERVENTIONS: Patients were administered either 5% albumin (5 mL/kg) or lactated Ringer's solution (25 mL/kg) over 30 minutes, just before incision. MEASUREMENTS: Serial measurements of plasma volume, LVEDV by transesophageal echocardiography, and CI were recorded. MAIN RESULTS: Albumin expanded plasma volume and LVEDV to a similar degree (11.3% and 13.2%). In contrast, lactated Ringer's solution increased plasma volume more than LVEDV (21.7% vs 14.4%; P = 0.0005). Increased LVEDV significantly but poorly correlated with increased CI (r(2) = 0.2, P < 0.0001) for both fluids. However, LVEDV expansion was brief and returned to baseline or less within 30 minutes for both fluids despite continued plasma volume expansion and increased CI. Correspondingly, rates of decline from peak expansion were significantly faster for LVEDV than plasma volume expansion for both albumin (-1.9% + 1.9%/min vs -0.1% + 0.1%/min; P = 0.0008) and lactated Ringer's (-1.1% + 0.8%/min vs -0.4% + 0.2%/min; P = 0.006). CONCLUSIONS: Intravenous fluids increased LVEDV to a lesser extent and duration than did plasma volume expansion. Monitoring of LVEDV was a poor guide for fluid administration to maximize CI.

Preoperative use of enoxaparin increases the risk of postoperative bleeding and re-exploration in cardiac surgery patients.

OBJECTIVE: The purpose of this study was to investigate if the preoperative use of new platelet inhibitors and low-molecular-weight heparins may contribute to bleeding after cardiac surgery. DESIGN: Retrospective data review. SETTING: University teaching hospital. PARTICIPANTS: One hundred eleven patients divided in 5 groups. INTERVENTIONS: Patients were grouped according to preoperative antithrombotic regimen: group 1, control, no agents (n=55); group 2, clopidogrel (n=9); group 3, enoxaparin (n=17); group 4, any GP IIb/IIIa inhibitor (n=14); and group 5, any drug combination (n=15). Data included cumulative mediastinal chest tube drainage, allogeneic blood transfusions, total blood donor exposures, and re-exploration. MEASUREMENTS AND MAIN RESULTS: Use of any drug (groups 2-5) resulted in greater total blood transfusions and donor exposure (p=0.0003) than control, especially red cells (p=0.002) and platelets (p=0.006). A greater percentage of patients on enoxaparin required mediastinal re-exploration for nonsurgical bleeding versus control (3/17 v 0/55, p=0.001). The use of enoxaparin was associated with significantly higher chest tube output after the first 24 hours postoperatively (p=0.048). CONCLUSION: Newer antithrombotic agents were associated with greater transfusion rates and total donor exposures. Enoxaparin use was associated with greater overall blood loss and with higher incidence of mediastinal re-exploration. The relative risk-benefit ratio of reduced periprocedure morbidity versus increased bleeding complications has yet to be determined.

Parasternal block and local anesthetic infiltration with levobupivacaine after cardiac surgery with desflurane: the effect on postoperative pain, pulmonary function, and tracheal extubation times.

Early tracheal extubation has become common after cardiac surgery. Anesthetic techniques designed to achieve this goal can make immediate postoperative analgesia challenging. We conducted this randomized, placebo-controlled, double-blind study to investigate the effect of a parasternal block on postoperative analgesia, respiratory function, and extubation times. We enrolled 20 patients having cardiac surgery via median sternotomy; 17 patients completed the study. A de-sflurane-based, small-dose opioid anesthetic was used. Before sternal wire placement, the surgeons performed the parasternal block and local anesthetic infiltration of sternotomy and tube sites with either 54 mL of saline placebo or 54 mL of 0.25% levobupivacaine with 1:400,000 epinephrine. Effects on pain and respiratory function were studied over 24 h. Patients in the levobupivacaine group used significantly less morphine in the first 4 h after surgery (20.8 +/- 6.2 mg versus 33.2 +/- 10.9 mg in the placebo group; P=0.013); they also had better oxygenation at the time of extubation. Four of nine in the placebo group needed rescue pain medication, versus none of eight in the levobupivacaine group (P=0.08). Peak serum levobupivacaine concentrations were below potentially toxic levels in all patients (0.64 +/- 0.43 microg/mL; range, 0.24-1.64 microg/mL). Parasternal block and local anesthetic infiltration of the sternotomy wound and mediastinal tube sites with levobupivacaine can be a useful analgesic adjunct for patients who are expected to undergo early tracheal extubation after cardiac surgery.

Spinal 2-chloroprocaine: a dose-ranging study and the effect of added epinephrine.

UNLABELLED: With the availability of preservative- and antioxidant-free 2-chloroprocaine (2-CP), there may be an acceptable short-acting alternative to lidocaine for spinal anesthesia. We examined the safety, dose-response characteristics, and effects of epinephrine with spinal 2-CP. Six volunteers per group were randomized to receive 30, 45, or 60 mg of spinal 2-CP with and without epinephrine. Intensity and duration of sensory and motor blockade were assessed. When 11 of the 18 volunteers complained of vague, nonspecific flu-like symptoms, breaking of the blind revealed that all spinal anesthetics associated with the flu-like symptoms contained epinephrine. There were no complaints of flu-like symptoms in the volunteers who received 2-CP without epinephrine. No further spinal anesthetics containing epinephrine were administered, resulting in 29 anesthetics (11 with epinephrine, 18 without epinephrine.) Plain 2-CP demonstrated a dose-dependent increase in peak block height and duration of effect at all variables except time to 2-segment regression and time to regression to T10. Time to complete sensory regression with plain 2-CP was 98 +/- 20, 116 +/- 15, and 132 +/- 23 min, respectively. 2-CP with epinephrine produced times to complete sensory regression of 153 +/- 25, 162 +/- 33, and 148 +/- 29 min, respectively. Preservative and antioxidant free 2-CP can be used effectively for spinal anesthesia in doses of 30-60 mg. Epinephrine is not recommended as an adjunct because of the frequent incidence of side effects. IMPLICATIONS: Hyperbaric spinal 2-chloroprocaine is effective and has an anesthetic profile appropriate for use in the surgical outpatient over the dose range of 30-60 mg without signs of transient neurologic symptoms. The addition of epinephrine is not recommended because of the frequent incidence of side effects.

Regional anesthesia for outpatient surgery.

In summary, regional techniques offer significant advantages in the outpatient setting. They can avoid the side effects of nausea, vomiting, and pain that frequently delay discharge or cause admission. They can also provide prolonged analgesia as well as offer, with the use of continuous catheters, the promise of a pain-free perioperative period. The choice of drugs must be carefully adjusted, especially with neuraxial techniques. Despite frequently requiring some additional time at the outset, regional techniques have consistently been shown to provide competitive discharge times and costs when compared with general anesthesia. They deserve a prominent place in outpatient surgery.

Suprascapular nerve block prolongs analgesia after nonarthroscopic shoulder surgery but does not improve outcome.

UNLABELLED: Suprascapular nerve block (SSNB) reportedly improves analgesia and 24-h outcomes after arthroscopic shoulder surgery performed under general anesthesia. In this study, we assessed the analgesic and clinical outcome efficacy of SSNB as an adjunct to interscalene brachial plexus block (ISB) for ambulatory nonarthroscopic shoulder surgery. Fifty patients were randomized to receive either a SSNB or sham injection as part of a standardized ISB-general anesthesia regimen. Time to first significant pain (the primary outcome measure) was significantly delayed in the SSNB group (594 +/- 369 min versus 375 +/- 273 min, respectively; P = 0.02). There were no other differences between groups with regard to postanesthesia recovery unit measures, 24-h assessment of pain, supplemental analgesic use, or quality of life outcomes. We conclude that adjunctive SSNB adds minimal value to a primary ISB anesthetic for nonarthroscopic shoulder surgery. IMPLICATIONS: When used as an adjunct to an interscalene block combined with general anesthesia, suprascapular nerve block with bupivacaine moderately prolongs analgesia without improving other outcome measures after ambulatory nonarthroscopic shoulder surgery.

"See one, do one, teach one, have one": a novel variation on regional anesthesia training.

INTRODUCTION: Is it possible to determine the number of nerve blocks needed for residents to become competent in regional anesthesia? Several studies have focused on this question, and the Residency Review Committee (RRC) for Anesthesiology has now defined a "minimum clinical experience" for some aspects of regional anesthesia training. In our experience, personally being a regional block recipient can also serve to enhance training. METHODS: Many residents at Virginia Mason Medical Center have received regional anesthetics as volunteers in research projects. We designed questionnaires to define their perceptions in both performing and receiving regional anesthesia. RESULTS: Twenty-one residents were recipients of a total of 72 regional anesthetic procedures. Many residents' comments focused on the discomfort of local anesthesia infiltration, the value of sedation, a better appreciation of the patients' perspectives, and improved preoperative consultation. Residents experiencing paresthesias were more likely to consider paresthesias as bad (P =.0098). CONCLUSION: The lessons learned from personally receiving a regional anesthetic are invaluable and can improve the quality of training, as well as the relationship between anesthesiologist and patient.

Hyperbaric spinal levobupivacaine: a comparison to racemic bupivacaine in volunteers.

UNLABELLED: Levobupivacaine is the isolated S-enantiomer of bupivacaine and may be a favorable alternative to spinal bupivacaine. However, its clinical efficacy relative to bupivacaine and its dose-response characteristics, in spinal anesthesia, must first be known. This double-blinded, randomized, cross-over study was designed to compare the clinical efficacy of hyperbaric levobupivacaine and bupivacaine for spinal anesthesia. Eighteen healthy volunteers were randomized into three equal groups to receive two spinal anesthetics, one with bupivacaine and the other with levobupivacaine, of equal-milligram doses (4, 8, or 12 mg). We assessed blockade quality and duration with pinprick, transcutaneous electrical stimulation, thigh tourniquet, abdominal and quadriceps muscle strength, modified Bromage scale, and time until achievement of discharge criteria. Sensory and motor block were similar between the same doses of levobupivacaine and bupivacaine (P > 0.56 to 0.86). For example, in the 12-mg groups of levobupivacaine versus bupivacaine, mean duration of tolerance to transcutaneous electrical stimulation at T12 was 100 min for both. The duration of motor block at the quadriceps was 71 versus 73 min, and time until achievement of discharge criteria was 164 min for both. Hyperbaric spinal levobupivacaine has equivalent clinical efficacy to racemic bupivacaine for spinal anesthesia in doses from 4 to 12 mg. IMPLICATIONS: Hyperbaric spinal levobupivacaine has equivalent clinical efficacy to hyperbaric spinal bupivacaine over the 4-12-mg ranges.