Predictive Modeling of Massive Transfusion Requirements During Liver Transplantation and Its Potential to Reduce Utilization of Blood Bank Resources.

BACKGROUND: Patients undergoing liver transplantation frequently but inconsistently require massive blood transfusion. The ability to predict massive transfusion (MT) could reduce the impact on blood bank resources through customization of the blood order schedule. Current predictive models of MT for blood product utilization during liver transplantation are not generally applicable to individual institutions owing to variability in patient population, intraoperative management, and definitions of MT. Moreover, existing models may be limited by not incorporating cirrhosis stage or thromboelastography (TEG) parameters. METHODS: This retrospective cohort study included all patients who underwent deceased-donor liver transplantation at the Johns Hopkins Hospital between 2010 and 2014. We defined MT as intraoperative transfusion of > 10 units of packed red blood cells (pRBCs) and developed a multivariable predictive model of MT that incorporated cirrhosis stage and TEG parameters. The accuracy of the model was assessed with the goodness-of-fit test, receiver operating characteristic analysis, and bootstrap resampling. The distribution of correct patient classification was then determined as we varied the model threshold for classifying MT. Finally, the potential impact of these predictions on blood bank resources was examined. RESULTS: Two hundred three patients were included in the study. Sixty (29.6%) patients met the definition for MT and received a median (interquartile range) of 19.0 (14.0-27.0) pRBC units intraoperatively compared with 4.0 units (1.0-6.0) for those who did not satisfy the criterion for MT. The multivariable model for predicting MT included Model for End-stage Liver Disease score, whether simultaneous liver and kidney transplant was performed, cirrhosis stage, hemoglobin concentration, platelet concentration, and TEG R interval and angle. This model demonstrated good calibration (Hosmer-Lemeshow goodness-of-fit test P = .45) and good discrimination (c statistic: 0.835; 95% confidence interval, 0.781-0.888). A probability cutoff threshold of 0.25 was found to misclassify only 4 of 100 patients as unlikely to experience MT, with the majority such misclassifications within 4 units of the working definition for MT. For this threshold, a preoperative blood ordering schedule that allocated 6 units of pRBCs for those unlikely to experience MT and 15 for those who were likely to experience MT would prevent unnecessary crossmatching of 338 units/100 transplants. CONCLUSIONS: When clinical and laboratory parameters are included, a model predicting intraoperative MT in patients undergoing liver transplantation is sufficiently accurate that its predictions could guide the blood order schedule for individual patients based on institutional data, thereby reducing the impact on blood bank resources. Ongoing evaluation of model accuracy and transfusion practices is required to ensure continuing performance of the predictive model.

Analgesic efficacy of ultrasound-guided regional anesthesia: a meta-analysis.

STUDY OBJECTIVE: To determine if the use of ultrasound guidance (vs non-ultrasound techniques) improves the success rate of nerve blocks. DESIGN: Meta-analysis of randomized controlled trials (RCTs) in the published literature. SETTING: University medical center. MEASUREMENTS: 16 RCTs of patients undergoing elective surgical procedures were studied. Patients underwent ultrasound-guided or non-ultrasound techniques (nerve stimulation, surface landmark) for peripheral nerve blocks. Success rates were measured. MAIN RESULTS: Ultrasound guidance (vs all non-ultrasound techniques) was associated with a significant increase in the success rate of nerve blocks [relative risk (RR) = 1.11 (95% confidence interval [CI]: 1.06 to 1.17, P < 0.0001]). When compared with nerve stimulator techniques only, ultrasound guidance was still associated with an increase in the success rate (RR = 1.11 [95% CI: 1.05 to 1.17, P = 0.0001]). For specific blocks, ultrasound guidance (vs all non-ultrasound) was associated with a significant increase in successful brachial plexus (all) nerve blocks (RR = 1.11 [95% CI: 1.05 to 1.20, P = 0.0001]), sciatic popliteal nerve block (RR = 1.22 [95% CI: 1.08 to 1.39, P = 0.002]) and brachial plexus axillary nerve block (RR = 1.13 [95% CI: 1.00 to 1.26, P = 0.05]) but not brachial plexus infraclavicular nerve block (RR = 1.25 [95% CI: 0.88 to 1.76, P = 0.22]). CONCLUSIONS: Ultrasound-guided peripheral nerve block is associated with an increased overall success rate when compared with nerve stimulation or other methods. Ultrasound-guided techniques also increase the success rate of some specific blocks.

Efficacy of bicarbonate in decreasing pain on intradermal injection of local anesthetics: a meta-analysis.

OBJECTIVE: Intradermal injection of local anesthetic often results in pain on injection due in part to the acidic pH of commercially prepared solutions, which are optimized to prolong shelf life. Although there are other possible explanations (eg, noxious properties of local anesthetics, pressure effect of infiltration), the etiology is most likely multifactorial. Although addition of bicarbonate to local anesthetics may decrease pain on intradermal injection, the extent of this analgesic effect is uncertain. We performed a meta-analysis of available trials investigating pain during intradermal injection of buffered local anesthetic preparations. METHODS: We searched the National Library of Medicine's PubMed database for all relevant articles published on the topic through November 2006. Inclusion criteria included double-blind, randomized controlled trials and use of a visual analog scale to measure pain on infiltration of local anesthetic buffered with sodium bicarbonate compared with that of unbuffered local anesthetic. Meta-analysis was performed using the Review Manager 4.2.7 (The Cochrane Collaboration, 2004). A random-effects model was used. RESULTS: Our search resulted in 86 abstracts, of which 12 articles met all inclusion criteria. Overall, there were 609 observations for buffered local anesthetic and 615 for unbuffered local anesthetic. Use of buffered local anesthetic resulted in a statistically lower weighted mean difference in visual analog scale of -1.17 (95% confidence interval, -1.68 to -0.67) compared with unbuffered local anesthetic. CONCLUSIONS: Our systematic review suggests that the use of buffered local anesthetics seems to be associated with a statistical decrease in pain of infiltration when compared with unbuffered local anesthetic.

Meta-analysis of the effect of extended-release epidural morphine versus intravenous patient-controlled analgesia on respiratory depression.

OBJECTIVE: Extended-release epidural morphine (EREM) is a single-dose, extended-release epidural morphine formulation intended to provide postoperative pain relief over a 48-hour period. There have been a few randomized controlled trials investigating the use and safety of EREM versus intravenous patient-controlled analgesia with opioids (IV-PCA); however, the adverse event of respiratory depression of this treatment is unclear. The authors have undertaken a meta-analysis to examine this issue. METHODS: A systematic literature search of the National Library of Medicine's PubMed database was conducted for terms related to EREM. Only randomized controlled trials, in the English language, assessing the rates of respiratory depression of EREM to IV-PCA were included for analysis. Data on pertinent study characteristics and relevant outcomes were extracted from accepted articles. Meta-analysis was performed using the Review Manager 4.2.7 (The Cochrane Collaboration, 2004). A random effects model was used. RESULTS: The authors' literature search yielded three articles which met all inclusion criteria. All studied doses of EREM were evaluated. Pooled estimates (odds ratio) were made for rates of adverse events of respiratory depression. Use of EREM was associated with significantly higher odds of respiratory depression compared to IV-PCA (odds ratio = 5.74; 95% confidence interval: 1.08, 30.54, p = 0.04). Even when examining only Food and Drug Administration approved dosages for EREM, the use of EREM was associated with significantly higher odds of respiratory depression when compared with IV-PCA (odds ratio = 5.80; 95% confidence interval: 1.05, 31.93, p = 0.04). CONCLUSIONS: Although perioperative single-dose epidural EREM (versus IV-PCA) was effective for postoperative pain relief for up to 48 hours, it is associated with significantly higher odds of respiratory depression. Further examination of the issue of respiratory depression of epidural EREM may be warranted.

Pregabalin as a treatment for painful diabetic peripheral neuropathy: a meta-analysis.

BACKGROUND AND OBJECTIVES: Painful diabetic peripheral neuropathy (DPN) is an increasingly prevalent disorder that is best managed through a multimodal approach. We examined the effects of pregabalin on pain control, sleep disturbance, and the patient's global impression of change (PGIC) for the treatment of this disorder. METHODS: Studies were identified using the National Library of Medicine's PubMed and EMBase databases (1966 to July 15, 2007). Inclusion criteria were randomized trials comparing pregabalin to placebo in the treatment of DPN for adult patients. A total of 13 abstracts were identified of which 3 met inclusion criteria. Data were collected from each article and results were recorded. Primary outcome was pain at the conclusion of the study. Secondary outcomes included number of patients with 50% reduction in mean pain score, PGIC ratings at endpoint, and adverse events. A random-effects model was used. RESULTS: The 3 studies yielded 728 total subjects from 5 centers, of which 476 received pregabalin (dose range 75 to 600 mg/day) and 252 received placebo. Pregabalin treatment was associated with a significant decrease in pain scores (weighted mean difference, 1.15), higher likelihood to achieve at least a 50% reduction in mean pain score (relative risk [RR], 4.05), and improved PGIC ratings (RR = 1.45). Pregabalin was associated with an increased risk of somnolence, dizziness, and edema. CONCLUSIONS: Pregabalin has significant effects on the pain associated with DPN as well as secondary endpoints that affect patients' quality of life.