Leanne Clifford

Characterizing the Epidemiology of Perioperative Transfusion-associated Circulatory Overload

Background:Transfusion-associated circulatory overload (TACO) is a leading cause of transfusion-related fatalities, but its incidence and associated patient and transfusion characteristics are poorly understood. To inform surgical transfusion practice and to begin mitigating perioperative TACO, the authors aimed to define its epidemiology. Methods:In this retrospective cohort study, the medical records of adult patients undergoing noncardiac surgery with general anesthesia during 2004 or 2011 and receiving intraoperative transfusions were screened using an electronic algorithm for identification of TACO. Those patients who were screened as high probability for TACO underwent rigorous manual review. Univariate and multivariate analyses evaluated associations between patient and transfusion characteristics with TACO rates in a before-and-after study design. Results:A total of 2,162 and 1,908 patients met study criteria for 2004 and 2011, respectively. The incidence of TACO was 5.5% (119 of 2,162) in 2004 versus 3.0% (57 of 1,908) in 2011 (P < 0.001), with comparable rates for men (4.8% [98 of 2,023]) and women (3.8% [78 of 2,047]) (P = 0.09). Overall, vascular (12.1% [60 of 497]), transplant (8.8% [17 of 193]), and thoracic surgeries (7.2% [10 of 138]) carried the highest TACO rates. Obstetric and gynecologic patients had the lowest rate (1.4% [4 of 295]). The incidence of TACO increased with volume transfused, advancing age, and total intraoperative fluid balance (all P < 0.001). Conclusions:The incidence of perioperative TACO is similar to previous estimates in nonsurgical populations. There was a reduction in TACO rate between 2004 and 2011, with incidence patterns remaining comparable in subgroup analyses. Future efforts exploring risk factors for TACO may guide preventive or therapeutic interventions, helping to further mitigate this transfusion complication.

Characterizing the epidemiology of postoperative transfusion-related acute lung injury.

Background:Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related death in the United States; however, it remains poorly characterized in surgical populations. To better inform perioperative transfusion practice, and to help mitigate perioperative TRALI, the authors aimed to better define its epidemiology before and after TRALI mitigation strategies were introduced. Methods:This retrospective cohort study examined outcomes of adult patients undergoing noncardiac surgery with general anesthesia who received intraoperative transfusions during 2004 (n = 1,817) and 2011 (n = 1,562). The demographics and clinical characteristics of transfusion recipients, blood transfusion descriptors, and combined TRALI/possible TRALI incidence rates were evaluated. Univariate analyses were used to compare associations between patient characteristics, transfusion details, and TRALI mitigation strategies with TRALI/possible TRALI incidence rates in a before-and-after study design. Results:The incidence of TRALI/possible TRALI was 1.3% (23 of 1,613) in 2004 versus 1.4% (22 of 1,562) in 2011 (P = 0.72), with comparable overall rates in males versus females (1.4% [23 of 1,613] vs. 1.2% [22 of 1,766]) (P = 0.65). Overall, thoracic (3.0% [4 of 133]), vascular (2.7% [10 of 375]), and transplant surgeries (2.2% [4 of 178]) carried the highest rates of TRALI/possible TRALI. Obstetric and gynecologic surgical patients had no TRALI episodes. TRALI/possible TRALI incidence increased with larger volumes of blood product transfused (P < 0.001). Conclusions:Perioperative TRALI/possible TRALI is more common than previously reported and its risk increases with greater volumes of blood component therapies. No significant reduction in the combined incidence of TRALI/possible TRALI occurred between 2004 and 2011, despite the introduction of TRALI mitigation strategies. Future efforts to identify specific risk factors for TRALI/possible TRALI in surgical populations may reduce the burden of this life-threatening complication.

Electronic health record surveillance algorithms facilitate the detection of transfusion-related pulmonary complications

BACKGROUND: Transfusion‐related acute lung injury (TRALI) and transfusion‐associated circulatory overload (TACO) are leading causes of transfusion‐related mortality. Notably, poor syndrome recognition and underreporting likely result in an underestimate of their true attributable burden. We aimed to develop accurate electronic health record–based screening algorithms for improved detection of TRALI/transfused acute lung injury (ALI) and TACO.

Preoperative platelet transfusions and perioperative red blood cell requirements in patients with thrombocytopenia undergoing noncardiac surgery

Perioperative hemorrhage impacts patient outcomes and health care resource utilization, yet the risks of transfusion therapies are significant. In patients with preoperative thrombocytopenia, the effects of prophylactic preoperative platelet (PLT) transfusion on perioperative bleeding complications remain uncertain.

Prophylactic plasma transfusion for surgical patients with abnormal preoperative coagulation tests: a single-institution propensity-adjusted cohort study

BACKGROUND Perioperative haemorrhage negatively affects patient outcomes and results in substantial consumption of health-care resources. Plasma transfusions are often administered to address abnormal preoperative coagulation tests, with the hope to mitigate bleeding complications. We aimed to assess the associations between preoperative plasma transfusion and bleeding complications in patients with elevated international normalised ratio (INR) undergoing non-cardiac surgery. METHODS We did an observational study in a consecutive sample of adult patients undergoing non-cardiac surgery with preoperative INR greater than or equal to 1·5. The exposure of interest was transfusion of preoperative plasma for elevated INR. The primary outcome was WHO grade 3 bleeding in the early perioperative period (from entry into the operating room until 24 h following exit from operating room). Hypotheses were tested with univariate and propensity-matched analyses. We did multiple sensitivity analyses to further evaluate the robustness of study findings. FINDINGS Between Jan 1, 2008, and Dec 31, 2011, we identified 1234 (8·4%) of 14 743 patients who had an INR of 1·5 or above and were included in this investigation. Of 1234 study participants, 139 (11%) received a preoperative plasma transfusion. WHO grade 3 bleeding occurred in 73 (53%) of 139 patients who received preoperative plasma compared with 350 (32%) of 1095 patients who did not (odds ratio [OR] 2·35, 95% CI 1·65-3·36; p<0·0001). Among the propensity-matched cohort, 65 (52%) of 125 plasma recipients had WHO grade 3 bleeding compared with 97 (40%) of 242 of those who did not receive preoperative plasma (OR 1·75, 95% CI 1·09-2·81; p=0·021). Results from multiple sensitivity analyses were qualitatively similar. INTERPRETATION Preoperative plasma transfusion for elevated international normalised ratios was associated with an increased frequency of perioperative bleeding complications. Findings were robust in the sensitivity analyses, suggestive that more conservative management of abnormal preoperative international normalised ratios is warranted. FUNDING Mayo Clinic, National Institutes of Health.

Brachial artery catheterization: An assessment of use patterns and associated complications

BACKGROUND:Although studies have compared safety and outcomes of radial artery cannulation with other arterial catheterization locations, there is insufficient information describing brachial artery catheterization. In this study, we characterized the perioperative use patterns and the complication rates associated with brachial arterial catheterization and compared these outcomes with radial artery catheterization. METHODS:We performed a retrospective analysis of adult patients (age ≥18 years) undergoing surgical procedures at an academic medical center from January 1, 2008, to December 31, 2011. An institutional database containing information on anesthetic care was queried to identify all brachial artery catheterizations. Baseline characteristics, details relating to the surgical and catheterization procedures, and catheter-related complications were collected and compared with a random sample of patients receiving radial artery catheterization. RESULTS:We identified 858 patients receiving brachial catheterization perioperatively. An additional 3432 patients receiving radial catheterization were identified. Patients receiving brachial catheterization were more often women, had a lower body mass index, had more comorbidities, and had longer anesthetic and catheterization durations. Three vascular complications were identified in the cohort receiving brachial artery catheterization compared with 1 patient with a peripheral neuropathy in the radial artery catheterization cohort (unadjusted complication incidence [95% confidence intervals] brachial artery catheterization, 0.35% [0.12%–1.02%] vs radial artery catheterization, 0.03% [0.005%–0.16%], respectively; P = 0.030; relative risk [95% confidence interval] = 12.0 [1.7–83.4]). There were no catheter-related bloodstream infections. CONCLUSIONS:We found that brachial artery catheterization is used in more medically complex patients and for longer duration than radial artery catheterizations. Although the limited number of adverse outcomes precluded statistical adjustments in this investigation, the observed differences in complication rates between cannulation methods suggest that brachial artery catheterization may be a suitable alternative to radial artery catheterization in patients with complex medical comorbidities.

Risk Factors and Clinical Outcomes Associated with Perioperative Transfusion-associated Circulatory Overload

Background: Transfusion-associated circulatory overload remains underappreciated in the perioperative environment. The authors aimed to characterize risk factors for perioperative transfusion-associated circulatory overload and better understand its impact on patient-important outcomes. Methods: In this case–control study, 163 adults undergoing noncardiac surgery who developed perioperative transfusion-associated circulatory overload were matched with 726 transfused controls who did not develop respiratory complications. Univariate and multivariable logistic regression analyses were used to evaluate potential risk factors for transfusion-associated circulatory overload. The need for postoperative mechanical ventilation, lengths of intensive care unit and hospital stay, and mortality were compared. Results: For this cohort, the mean age was 71 yr and 56% were men. Multivariable analysis revealed the following independent predictors of transfusion-associated circulatory overload: emergency surgery, chronic kidney disease, left ventricular dysfunction, previous &bgr;-adrenergic receptor antagonist use, isolated fresh frozen plasma transfusion (vs. isolated erythrocyte transfusion), mixed product transfusion (vs. isolated erythrocyte transfusion), and increasing intraoperative fluid administration. Patients who developed transfusion-associated circulatory overload were more likely to require postoperative mechanical ventilation (73 vs. 33%; P < 0.001) and experienced prolonged intensive care unit (11.1 vs. 6.5 days; P < 0.001) and hospital lengths of stay (19.9 vs. 9.6 days; P < 0.001). Survival was significantly reduced (P < 0.001) in transfusion recipients who developed transfusion-associated circulatory overload (1-yr survival 72 vs. 84%). Conclusions: Perioperative transfusion-associated circulatory overload was associated with a protracted hospital course and increased mortality. Efforts to minimize the incidence of transfusion-associated circulatory overload should focus on the judicious use of intraoperative blood transfusions and nonsanguineous fluid therapies, particularly in patients with chronic kidney disease, left ventricular dysfunction, chronic &bgr;-blocker therapy, and those requiring emergency surgery.

Ensemble learning approaches to predicting complications of blood transfusion

Of the 21 million blood components transfused in the United States during 2011, approximately 1 in 414 resulted in complication [1]. Two complications in particular, transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO), are especially concerning. These two alone accounted for 62% of reported transfusion-related fatalities in 2013 [2]. We have previously developed a set of machine learning base models for predicting the likelihood of these adverse reactions, with a goal towards better informing the clinician prior to a transfusion decision. Here we describe recent work incorporating ensemble learning approaches to predicting TACO/TRALI. In particular we describe combining base models via majority voting, stacking of model sets with varying diversity, as well as a resampling/boosting combination algorithm called RUSBoost. We find that while the performance of many models is very good, the ensemble models do not yield significantly better performance in terms of AUC.

Predicting Adverse Reactions to Blood Transfusion

In 2011 approximately 21 million blood components were transfused in the United States, with roughly 1 in 414 causing an adverse reaction [1]. Two adverse reactions in particular, transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO), accounted for 62% of reported transfusion-related fatalities in 2013 [2]. We describe newly developed models for predicting the likelihood of these adverse reactions, with a goal towards better informing the clinician prior to a transfusion decision. Our models include both traditional logistic regression as well as modern machine learning techniques, and incorporate over sampling methods to deal with severe class imbalance. We focus on a minimal set of predictors in order to maximize potential application. Results from 8 models demonstrate AUCs ranging from 0.72 to 0.84, with sensitivities tunable by threshold choice across ranges up to 0.93. Many of the models rank the same predictors amongst the most important, perhaps yielding insight into the mechanisms underlying TRALI and TACO. These models are currently being implemented in a Clinical Decision Support System [3] in perioperative environments at Mayo Clinic.

A Clinical Decision Support System for Preventing Adverse Reactions to Blood Transfusion

During 2011 approximately 21 million blood components were transfused in the United States, with roughly 1 in 414 resulting in complication. For Americans, the two leading causes of transfusion-related death are the respiratory complications Transfusion-related acute lung injury (TRALI) and Transfusion-associated circulatory overload (TACO). Each of these complications results in significantly longer ICU and hospital stays as well as significantly greater rates of mortality. We have developed a set of machine learning models for predicting the likelihood of these adverse reactions in surgical populations. Here we describe deploying these models into a perioperative critical care environment via a continuous monitoring and alerting clinical decision support system. The goal of this system, which directly integrates our suite of machine learning models running in the R statistical environment into a traditional health information system, is to improve transfusion-related outcomes in the perioperative environment. By identifying high-risk patients prior to transfusion, the clinical team may be able to choose a more appropriate therapy or therapeutic course. Identifying high-risk patients for increased observation after transfusion may also allow for a more timely intervention, thereby potentially improving care delivery and resulting patient outcome. An early prototype of this system is currently running in two Mayo Clinic perioperative environments.