Active internal re-warming using a centrifugal pump and heat exchanger following haemorrhagic shock, surgical trauma and hypothermia in a porcine model

SummaryBackgroundThe centrifugal vortex blood pump (CVBP) using heparin-bonded circuitry allows re-warming of hypothermic trauma patients without anticoagulation. Study objectives were to confirm efficacy, and to characterise the physiology of CVBP re-warming in a porcine model.MethodsSixteen pigs were randomised to conventional or CVBP re-warming. They were bled to a mean arterial pressure of 30 mmHg and cooled to 29 °C. A physiological analysis was recorded during resuscitation to normo-tension and re-warming back to 37 °C.ResultsCVBP animals re-warmed significantly faster: 85.0 + 16.4 min versus 217.4 + 49.3 min (p < 0.0001). Activated clotting time was significantly elevated in both groups at 29 °C with a marked trend to normalise faster in CVBP pigs. The peak cardiac index (CI) was significantly lower (1.14 + 0.68 versus 4.83 + 1.50 L/(min m2)), while the systemic vascular resistance (SVR) was significantly higher (4239.9 + 1173.0 versus 1472.6 + 451.2 dyn × S × m2/cm5) with CVBP (p < 0.001).ConclusionCVBP is simple and very effective at re-warming hypothermic animals and may also reverse coagulopathy more quickly. Physiological derangements of elevated SVR and diminished CI require further study to elaborate underlying aetiology, and define optimal re-warming strategies.