02 Oct 12

Lipid emulsion infusion: resuscitation for local anesthetic and other drug overdose

Posted in Regional anaesthesia, Resuscitation at 1:07 by Laci

By G L Weinberg

Anesthesiology 2012;117:180–187

IT seems implausible that an injection of a simple, off-the-shelf, intravenous nutritional solution could be acutely life-saving for a patient with severe drug overdose. But dozens of published case reports support this observation, first made more than a decade ago in a rodent model of bupivacaine toxicity. It is even more surprising that such a simple formulation can rapidly reverse severe clinical toxicity from a variety of vastly disparate medications with distinct pharmacodynamics and mechanisms of action. This review will focus on the clinical application of lipid emulsion therapy in resuscitation from drug-related toxicity and will provide an introduction to the development of the method, guidelines for its use, and insights into potential controversies and future applications.

Background
Weinberg et al. first showed in 1998 that an infusion of a soybean oil emulsion normally used as a total parenteral nutrition solution could prevent (by pretreatment) or improve resuscitation from cardiovascular collapse caused by severe bupivacaine overdose in the intact, anesthetized rat. Subsequent studies from the same laboratory confirmed these findings in isolated rat heart and anesthetized dog. Under the latter experimental model, return of spontaneous circulation after a bupivacaine challenge occurred in all animals receiving lipid, but in none of the saline controls. This study was accompanied by an editorial asking whether lipid might be the long-sought “silver bullet” for local anesthetic systemic toxicity (LAST). Since then, the effectiveness of lipid emulsion infusion in reversing LAST has been confirmed in other laboratories and by systematic analysis4 in the clinical setting, as well.

18 Sep 12

The beneficial effect of transversus abdominis plane block after laparoscopic cholecystectomy in day-case surgery

Posted in Anesthesia, Regional anaesthesia at 0:47 by Laci

By P Petersen, P Stjernholm, V Kristiansen, H Torup, E Hansen, A Mitchell, A Moeller, J Rosenberg, J Dahl and O Mathiesen

Anesth Anal, 2012;115:527-533

Laparoscopic cholecystectomy is associated with postoperative pain of moderate intensity in the early postoperative period. Recent randomized trials have demonstrated the efficacy of transversus abdominis plane (TAP) block in providing postoperative analgesia after abdominal surgery. We hypothesized that a TAP block may reduce pain while coughing and at rest for the first 24 postoperative hours, opioid consumption, and opioid side effects in patients undergoing laparoscopic cholecystectomy in day-case surgery.

Methods
In this randomized, double-blind study, 80 patients undergoing laparoscopic cholecystectomy in our day-case surgery unit were allocated to receive either bilateral ultrasound-guided posterior TAP blocks (20 mL 0.5% ropivacaine) or placebo blocks. Postoperative pain treatment consisted of oral acetaminophen 1000 mg × 4, oral ibuprofen 400 mg × 3, IV morphine (0–2 hours postoperatively), and oral ketobemidone (2–24 hours postoperatively). The primary outcome was postoperative pain scores while coughing calculated as area under the curve for the first 24 postoperative hours (AUC/24 h). Secondary outcomes were pain scores at rest (AUC/24 h), opioid consumption, and side effects. Patients were assessed 0, 2, 4, 6, 8, and 24 hours postoperatively. Group-wise comparisons of visual analog scale (VAS) pain (AUC/24 h) were performed with the 2-sample t test. Morphine and ketobemidone consumption were compared with the Mann-Whitney test for unpaired data. Categorical data were analyzed using the χ2 test.

Results
The primary outcome variable, VAS pain scores while coughing (AUC/24 h), was significantly reduced in the TAP versus the placebo group (P = 0.04); group TAP: 26 mm (SD 13) (weighted average level) versus group placebo: 34 (18) (95% confidence interval): 0.5–15 mm). VAS pain scores at rest (AUC/24 h) showed no significant difference between groups. Median morphine consumption (0–2 hours postoperatively) was 7.5 mg (interquartile range: 5–10 mg) in the placebo group compared with 5 mg (interquartile range: 0–5 mg) in the TAP group (P < 0.001). The odds ratio of a random patient in group TAP having less morphine consumption than a random patient in group placebo was P (group TAP < group placebo) = 0.26 (confidence interval: 0.15, 0.37) where 0.5 represents no difference between groups. There were no between-group differences in total ketobemidone consumption, levels of nausea and sedation, number of patients vomiting, or consumption of ondansetron.

Conclusions
TAP block after laparoscopic cholecystectomy may have some beneficial effect in reducing pain while coughing and on opioid requirements, but this effect is probably rather small.

11 Jan 12

Comparison of intermediate vs subcutaneous cervical plexus block for carotid endarterectomy

Posted in Anesthesia, Regional anaesthesia at 1:45 by Laci

By  S K Ramachandran, P Picton, A Shanks, P Dorje and J Pandit

Br. J. Anaesth 2011;107:157-163

Carotid endarterectomy surgery can be performed under regional anaesthesia alone or under general anaesthesia. However, there are several types of regional block available and reported complication rates after superficial cervical plexus blocks are significantly lower than deep blocks. It is not known if subcutaneous and intermediate blocks are equally effective, although anatomical evidence suggests that the latter (where the injectate diffuses below the deep cervical fascia) might provide superior quality of intraoperative anaesthesia.

Methods
Forty-four patients were randomized to receive either subcutaneous or intermediate cervical plexus blocks for carotid endarterectomy. The primary endpoint was supplemental lidocaine requirement during surgery. Secondary outcome measures included: total amount of fentanyl administered during surgery, recall of pain scores during surgery, complications, and patient and surgeon satisfaction.

Results
There was no statistically significant difference for median (range) lidocaine supplementation between the subcutaneous and intermediate groups 65 (20–170) mg vs 85 (30–345) mg, respectively; P=0.31. There were no statistical differences in the secondary outcome measures and no major complications during the study.

Conclusions
Intermediate and subcutaneous cervical plexus blocks are equally effective for carotid endarterectomy. This study adds to the body of evidence supporting the safe use of superficial blocks for this type of surgery.

03 Apr 11

ASRA: practice advisory on local anesthetic systemic toxicity

Posted in Regional anaesthesia at 1:01 by Laci

By J Neal, C Bernards, J Butterworth, G Di Gregorio, K Drasner, M Hejtmanek, M Mulroy, R Rosenquist, G Weinberg

Reg Anesth Pain Med 2010;35:152-161

The American Society of Regional Anesthesia and Pain Medicine Practice Advisory on Local Anesthetic Systemic Toxicity assimilates and summarizes current knowledge regarding the prevention, diagnosis, and treatment of this potentially fatal complication. It offers evidence-based and/or expert opinion-based recommendations for all physicians and advanced practitioners who routinely administer local anesthetics in potentially toxic doses. The advisory does not address issues related to local anesthetic-related neurotoxicity, allergy, or methemoglobinemia. Recommendations are based primarily on animal and human experimental trials, case series, and case reports. When objective evidence is lacking or incomplete, recommendations are supplemented by expert opinion from the Practice Advisory Panel plus input from other experts, medical specialty groups, and open forum. Specific recommendations are offered for the prevention, diagnosis, and treatment of local anesthetic systemic toxicity.

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