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.

14 Sep 12

Importance of intravenous fluid dose and composition in surgical ICU patients

Posted in Fluid management at 1:34 by Laci

By K Raghunathan, W McGee, T Higgins

Curr Opin Crit Care 2012;18:350-357

This review discusses the importance of intravenous fluid dose and composition in surgical ICU patients. On the basis of updated physiologic postulates, we suggest guidelines for the use of crystalloids and colloids. Goal-directed fluid therapy is advocated as a means for avoiding both hypovolemia and hypervolemia.

Recent findings
Integrity of the endothelial surface layer (ESL) and ‘volume context’ are key determinants of fluid disposition. During critical illness the ESL is compromised. Optimal resuscitation may be guided by functional measures of fluid responsiveness with some caveats. The best approach may be to use physiologically balanced crystalloids for hypovolemic resuscitation and colloids for euvolemic hemodynamic augmentation.

Summary
The routine replacement of unmeasured presumed fluid deficits is not appropriate. In critically ill patients, resuscitation with intravenous fluids should produce a demonstrable enhancement of perfusion. Individualized goal-directed therapy using functional hemodynamic parameters can optimize resuscitation and ‘deresuscitation’.

12 Sep 12

Perioperative morbidity: lessons from recent clinical trials

Posted in Anesthesia, Early goal directed therapy, Fluid management at 3:31 by Laci

By R Thiele, J Huffmyer, J Raphael, Jacob

Curr Opin Crit Care 2012;18:358-365

To identify the recent literature supporting the ability of anesthesiologists to impact morbidity and mortality outside of the immediate intraoperative period.

Recent findings
Hemodynamic management designed to optimize cardiac output and stroke volume can significantly lower the risk of perioperative morbidity, and, in some cases, mortality. The implications of the POISE trial, which upended the previously accumulating data in support of indiscriminate perioperative β-blockade by demonstrating worsened outcomes, were supported by high-quality, propensity-matched, prospectively collected data. Data supporting the safety of colloid use has been threatened by the retraction of 88 publications of a single author, as well as prospective, nonrandomized data, suggesting increased renal morbidity in critically ill patients receiving synthetic colloids. Large datasets continue to suggest an association between red blood cell transfusion and mortality. Analysis of the operating room strongly implicates anesthesia providers as a potential mechanism for bacterial contamination.

Summary
Anesthesiologists should consider implication of goal-directed therapy in high-risk surgical patients, adhere to the American College of Cardiology/American Heart Association guidelines with regard to perioperative β-blockade, critically assess the data to support their choice of synthetic colloids over crystalloids, explore all possible strategies for avoiding perioperative transfusion, and be cognizant of their potential contribution to perioperative infectious morbidity.

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