Key result
Low-trigger red-cell transfusion during vascular surgery resulted in a numerically higher mean intraoperative cardiac output compared to a high-trigger strategy (mean difference 0.36 L/min; P=0.092).
Why the study?
During vascular surgery, restricted red-cell transfusion reduces frontal lobe oxygen saturation, and it was unknown whether an inadequate increase in cardiac output following haemodilution explains this reduction.
Does a restrictive red-cell transfusion trigger increase cardiac output in patients undergoing elective vascular surgery?
RCT (n=46)
randomized
Does a restrictive red-cell transfusion trigger increase cardiac output in patients undergoing elective vascular surgery?
Effect estimate: Mean difference 0.36 L/min (95% CI -0.05 to 0.78)
p-value: p=.092
A restrictive transfusion trigger in vascular surgery leads to an expected compensatory increase in cardiac output, suggesting that limited cardiac capacity does not explain the associated decrease in cerebral oxygen saturation.
Background During vascular surgery, restricted red‐cell transfusion reduces frontal lobe oxygen (ScO 2 ) saturation as determined by near‐infrared spectroscopy. We evaluated whether inadequate increase in cardiac output (CO) following haemodilution explains reduction in ScO 2 . Methods This is a post‐hoc analysis of data from the Transfusion in Vascular surgery (TV) Trial where patients were randomized on haemoglobin drop below 9.7 g/dL to red‐cell transfusion at haemoglobin below 8.0 (low‐trigger) vs 9.7 g/dL (high‐trigger). Fluid administration was guided by optimizing stroke volume. We compared mean intraoperative levels of CO, haemoglobin, oxygen delivery, and CO at nadir ScO 2 with linear regression adjusted for age, operation type and baseline. Data for 46 patients randomized before end of surgery were included for analysis. Results The low‐trigger resulted in a 7.1% lower mean intraoperative haemoglobin level (mean difference, −0.74 g/dL; P < .001) and reduced volume of red‐cell transfused (median [inter‐quartile range], 0 [0‐300] vs 450 mL [300‐675]; P < .001) compared with the high‐trigger group. Mean CO during surgery was numerically 7.3% higher in the low‐trigger compared with the high‐trigger group (mean difference, 0.36 L/min; 95% confidence interval (CI.95), −0.05 to 0.78; P = .092; n = 42). At the nadir ScO 2 ‐level, CO was 11.9% higher in the low‐trigger group (mean difference, 0.58 L/min; CI.95, 0.10‐1.07; P = .024). No difference in oxygen delivery was detected between trial groups (MD, 1.39 dL O2 /min; CI.95, −6.16 to 8.93; P = .721). Conclusion Vascular surgical patients exposed to restrictive RBC transfusion elicit the expected increase in CO making it unlikely that their potentially limited cardiac capacity explains the associated ScO 2 decrease.
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Møller et al. (2020) conducted an RCT in elective vascular surgery (n=46). low-trigger red-cell transfusion vs. high-trigger red-cell transfusion (haemoglobin below 9.7 g/dL) was evaluated on mean intraoperative levels of cardiac output (Mean difference 0.36 L/min, 95% CI -0.05 to 0.78, p=.092). Low-trigger red-cell transfusion during vascular surgery resulted in a numerically higher mean intraoperative cardiac output compared to a high-trigger strategy (mean difference 0.36 L/min; P=0.092).
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