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Techniques for blood loss estimation in major non-cardiac surgery: a systematic review and meta-analysis
Tran A, Heuser J, Ramsay T, McIsaac DM, Martel G
Canadian journal of anaesthesia = Journal canadien d'anesthesie. 2020
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Editor's Choice
Abstract
PURPOSE Estimated blood loss (EBL) is an important tool in clinical decision-making and surgical outcomes research. It guides perioperative transfusion practice and serves as a key predictor of short-term perioperative risks and long-term oncologic outcomes. Despite its widespread clinical and research use, there is no gold standard for blood loss estimation. We sought to systematically review and compare techniques for intraoperative blood loss estimation in major non-cardiac surgery with the objective of informing clinical estimation and research standards. SOURCE A structured search strategy was applied to Ovid Medline, Embase, and Cochrane Library databases from inception to March 2020, to identify studies comparing methods of intraoperative blood loss in adult patients undergoing major non-cardiac surgery. We summarized agreement between groups of pairwise comparisons as visual estimation vs formula estimation, visual estimation vs other, and formula estimation vs other. For each of these comparisons, we described tendencies for higher or lower EBL values, consistency of findings, pooled mean differences, standard deviations, and confidence intervals. PRINCIPLE FINDINGS We included 26 studies involving 3,297 patients in this review. We found that visual estimation is the most frequently studied technique. In addition, visual techniques tended to provide lower EBL values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses likely due to sample size limitations. When accounting for the contextual mean blood loss, similar case-to-case variation exists for all estimation techniques. CONCLUSIONS We found that significant case-by-case variation exists for all methods of blood loss evaluation and that there is significant disagreement between techniques. Given the importance placed on EBL, particularly for perioperative prognostication models, clinicians should consider the universal adoption of a practical and reproducible method for blood loss evaluation. TRIAL REGISTRATION PROSPERO (CRD42015029439); registered: 18 November 2015.PROSPERO (CRD42015029439); registered: 18 November 2015.
PICO Summary
Population
Adult patients undergoing major non-cardiac surgery (26 studies, n= 3,297).
Intervention
Visual estimation of blood loss.
Comparison
Formula estimation of blood loss, and other tecnniques for estimating blood loss.
Outcome
Visual estimation was the most frequently studied technique. Visual techniques tended to provide lower estimated blood loss values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses. When accounting for the contextual mean blood loss, similar case-to-case variation existed for all estimation techniques.
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Liberal Versus Restrictive Red Blood Cell Transfusion Thresholds in Hematopoietic Cell Transplantation: A Randomized, Open Label, Phase III, Noninferiority Trial
Tay J, Allan DS, Chatelain E, Coyle D, Elemary M, Fulford A, Petrcich W, Ramsay T, Walker I, Xenocostas A, et al
Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2020;:Jco1901836
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Editor's Choice
Abstract
PURPOSE Evidence regarding red blood cell (RBC) transfusion practices and their impact on hematopoietic cell transplantation (HCT) outcomes are poorly understood. PATIENTS AND METHODS We performed a noninferiority randomized controlled trial in four different centers that evaluated patients with hematologic malignancies requiring HCT who were randomly assigned to either a restrictive (hemoglobin [Hb] threshold < 70 g/L) or liberal (Hb threshold < 90 g/L) RBC transfusion strategy between day 0 and day 100. The noninferiority margin corresponds to a 12% absolute difference between groups in Functional Assessment of Cancer Therapy-Bone Marrow Transplant (FACT-BMT) score relative to baseline. The primary outcome was health-related quality of life (HRQOL) measured by FACT-BMT score at day 100. Additional end points were collected: HRQOL by FACT-BMT score at baseline and at days 7, 14, 28, 60, and 100; transplantation-related mortality; length of hospital stay; intensive care unit admissions; acute graft-versus-host disease; Bearman toxicity score; sinusoidal obstruction syndrome; serious infections; WHO Bleeding Scale; transfusion requirements; and reactions to therapy. RESULTS A total of 300 patients were randomly assigned to either restrictive-strategy or liberal-strategy treatment groups between 2011 and 2016 at four Canadian adult HCT centers. After HCT, mean pre-transfusion Hb levels were 70.9 g/L in the restrictive-strategy group and 84.6 g/L in the liberal-strategy group (P < .0001). The number of RBC units transfused was lower in the restrictive-strategy group than in the liberal-strategy group (mean, 2.73 units [standard deviation, 4.81 units] v 5.02 units [standard deviation, 6.13 units]; P = .0004). After adjusting for transfusion type and baseline FACT-BMT score, the restrictive-strategy group had a higher FACT-BMT score at day 100 (difference of 1.6 points; 95% CI, -2.5 to 5.6 points), which was noninferior compared with that of the liberal-strategy group. There were no significant differences in clinical outcomes between the transfusion strategies. CONCLUSION In patients undergoing HCT, the use of a restrictive RBC transfusion strategy threshold of 70 g/L was as effective as a threshold of 90 g/L and resulted in similar HRQOL and HCT outcomes with fewer transfusions.
PICO Summary
Population
Patients with haematologic malignancies requiring haematopoietic cell transplantation (HCT) across four Canadian HCT centres, (n=300).
Intervention
Restrictive red blood cell transfusion (RBC) strategy (haemoglobin [Hb] threshold < 70 g/L), (n= 150).
Comparison
Liberal RBC transfusion strategy (Hb threshold < 90 g/L), (n= 150).
Outcome
After HCT, mean pre-transfusion Hb levels were 70.9 g/L in the restrictive-strategy group and 84.6 g/L in the liberal-strategy group. The number of RBC units transfused was lower in the restrictive-strategy group than in the liberal-strategy group (mean, 2.73 units vs. 5.02 units). After adjusting for transfusion type and baseline Functional Assessment of Cancer Therapy-Bone Marrow Transplant (FACT-BMT) score, the restrictive-strategy group had a higher FACT-BMT score at day 100 (difference of 1.6 points), which was non-inferior compared with that of the liberal-strategy group. There were no significant differences in clinical outcomes between the transfusion strategies.