Warming blood products for transfusion to neonates: In vitro assessments

Blood products may be transfused into neonates at temperatures at or below room temperature. The benefits and risks of warming blood to 37°C are not defined in this population or with the equipment used in neonates. Physiologic warming might enhance product effectiveness or decrease transfusion-associated hypothermia.

We utilized an in vitro model of neonatal transfusions, with a syringe pump, blood tubing, and 24-gauge catheter and compared current practice (cold products) vs an inline blood warmer. Transfusions were performed rapidly (30 minutes) and slower (120 minutes) to model emergent vs routine situations. We tested red blood cells, fresh-frozen plasma, apheresis platelets (PLTs), and cold-stored low-titer group O whole blood. We used infrared detectors and inline probes to measure temperatures at the origin and at the simulated patient. We assessed warmer-induced damage by measuring plasma hemoglobin and hematocrit (seeking hemolysis), fibrinogen (seeking activation of coagulation), and PLT count and TEG-MA (seeking PLT destruction or dysfunction).

The cold-stored products were 4.2 ± 1.0°C (mean ± SD) at the origin and 21.5 ± 0.1°C at the patient. With the inline warmer, products were 37.8 ± 0.6°C at the warmer and 32.6 ± 1.7°C at the patient during a 30-minute infusion, but were 34.5 ± 2.1 with a foil sheath covering the terminal tubing. We found no warmer-induced damage using any metric.

In simulated neonatal intensive care unit (NICU) transfusions, an inline blood warmer can deliver blood products at near-physiologic temperatures with no detected damage. We suggest in vivo testing of warmed NICU transfusions, assessing product effectiveness and hypothermia risk reduction.