Comparative efficacy of fluid resuscitation strategies in a rat model of traumatic cardiac arrest.

BACKGROUND

Traumatic cardiac arrest (TCA) has a high mortality, and its pathophysiology differs markedly from non-traumatic arrest. Although blood transfusion is pivotal for hypovolemia, prehospital storage and transport are challenging, making fluid resuscitation common yet its impact unclear. We established a rat TCA model combining hemorrhage and asphyxia to examine the efficacy of different fluids on outcomes.

METHODS

Rats underwent graded hemorrhage (0-40%) to assess shock/arrest. Then a combined TCA model with the same blood loss followed by asphyxia was used to identify the lethal threshold. Cardiopulmonary resuscitation (CPR) started 5 min after arrest. In the 30% hemorrhage + asphyxia model, after the return of spontaneous circulation (ROSC), animals received normal saline (NS), lactated Ringer's solution (LR), hydroxyethyl starch (HES) or whole blood (WB). Hemodynamics, 96‑hour survival and tissue injury were then assessed.

RESULTS

Hemorrhage exceeding 30% induced shock in 86% and over 40% caused arrest in 71%. All TCA animals achieved ROSC with CPR, but 96‑hour survival was 14% and 0% at 30% and 40% hemorrhage. In the lethal threshold model (30% hemorrhage + asphyxia), survival was 90% (WB), 80% (HES), 60% (LR) and 30% (NS), respectively. WB and HES improved hemodynamics and reduced tissue injury versus NS, except for blood pressure in HES. LR showed no hemodynamic benefit and modest tissue protection.

CONCLUSIONS

In this model, fluid resuscitation is needed when hemorrhage exceeds 30%. WB yields the best outcomes; HES is comparably effective but with lower blood pressure. LR and NS do not improve outcomes but prolong survival.