Impact of 1- and 2-unit red blood cell transfusions on continuously monitored vital signs: a longitudinal study

We measured trends in continuous vital sign parameters and hemoglobin concentration in adult patients before and after 1- and 2-unit red cell (RBC) transfusions.

A multi-center longitudinal study of 72 patients connected to a remote continuous monitoring service transfused 1 or 2 RBC units. Primary outcome was changes in heart rate (HR), respiratory rate (RR), and oxygen saturation (SpO₂), and secondary outcome was changes in hemoglobin concentration.

Fifty-one patients received 1 RBC unit, 21 received 2 units. During the 10-hour pre-single-unit transfusion period, there were no clinically meaningful trends in HR (0.05, 95% CI, -0.36 to 0.46), RR (0.13, 95% CI, 0.02 to 0.25), or SpO₂ (0.08%, 95% CI, -0.02 to 0.18). There were no clinically meaningful differences in trends in the 24-hour period post-single-unit RBC transfusion when compared to the pre-transfusion trend (HR: 0.03, 95% CI, -0.44 to 0.51; RR: -0.09, 95% CI, -0.22 to 0.05; SpO₂: -0.15%, 95% CI, -0.27 to -0.02). The mean hourly hemoglobin trend 48 hours pre-single-unit transfusion was -0.07 g/dL (95% CI, -0.09 to -0.05) and 0.08 g/dL (95% CI, 0.05 g/dL to 0.10 g/dL) in the 48 hours post transfusion when compared to the pre-transfusion trend. Similar results were observed pre- and post-double-unit RBC transfusion.

Despite hemoglobin concentration declines pre-single and double-unit RBC transfusion, and expected increases post-transfusion, there were no clinically meaningful trends in vital signs in the 10 hours before single- or double-unit transfusion or changes in trend in vital signs 24 hours post-transfusion.