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Low vs. high hemoglobin trigger for Transfusion in Vascular surgery (TV): a randomized clinical feasibility trial

Anders Møller, Henning B. Nielsen, Jørn Wetterslev, Ole B. Pedersen, Dorthe Hellemann, Per Winkel, Klaus V. Marcussen, Benedicte G.U. Ramsing, Anette Mortensen, Janus C. Jakobsen and Saeid Shahidi

Key points

  • Perioperative restriction of red-cells significantly lowered hemoglobin levels, red-cell units transfused, and cerebral tissue oxygenation.

  • Explorative outcomes indicated harm with the low transfusion trigger and warrants further trials to establish whether such strategy is safe.

Abstract

Current guidelines advocate to limit red-cell transfusion during surgery, but the feasibility and safety of such strategy remains unclear as the majority of evidence is based on postoperative stable patients. We assessed the effects of a protocol aiming to restrict red-cell transfusion throughout hospitalization for vascular surgery. Fifty-eight patients scheduled for lower limb-bypass or open abdominal aortic aneurysm repair were randomized upon hemoglobin drop below 9.7g/dL to a low-trigger (hemoglobin<8.0 g/dL) vs. high-trigger (hemoglobin<9.7 g/dL) for red-cell transfusion. Intraoperative oxygen desaturation in cerebral- and muscle tissue was assessed by near-infrared spectroscopy. An explorative outcome included data on death and major vascular complications from a nationwide registry. The primary outcome, mean hemoglobin within 15 days of surgery, was significantly lower in the low-trigger group: 9.46 g/dL vs. 10.33 g/dL in the high-trigger group (mean difference, 0.87g/dL; P=0.022; longitudinal analysis) as were units of red-cells transfused (median [interquartile range(IQR)], 1 [0-2] vs. 3 [2-6]; P=0.0015). While the duration and magnitude of cerebral oxygen desaturation from baseline increased in the low-trigger group (median [IQR], 421 minutes*% [42-888] vs. 127 [11-331]; P=0.0036), muscle oxygenation was unaffected. The low-trigger associated to a higher rate of death or major vascular complications: 19/29 vs. 8/29 (hazard ratio, 3.20; P=0.006) and fewer days alive outside hospital within 90 days (median [IQR], 76 [67-82] vs. 82 [76-84] days; P=0.049). In conclusion, a perioperative protocol restricting red-cell transfusion successfully separated hemoglobin levels and red-cell units transfused. Exploratory outcomes suggested potential harm with the low-trigger and warrants further trials in vascular surgery before such strategy is universally adopted. (ClinicalTrials.gov identifier NCT02465125).

  • Submitted October 12, 2018.
  • Accepted March 4, 2019.