Continuous resuscitation after hemorrhage and acute fluid replacement improves cardiovascular responses

Background. Although acute fluid replacement after trauma and severe hemorr hage remains the cornerstone in the management of trauma victims, it remain s unknown whether continuous resuscitation after trauma-hemorrhage and acut e fluid replacement produces salutary effects on cardiovascular function an d reduces proinflammatory release. Methods. Adult male mts underwent laparotomy lie, soft tissue trauma) and w ere bled to and maintained at a mean arterial pressure of 40 mm Hg until 40 % of the shed blood volume was returned in the form of Ringer's lactate (RL ). The animals were then resuscitated with 4 times the volume of shed blood with RL for 60 minutes, followed by continuous resuscitation with RL at 5 mL/h/kg for 48 hours after the acute fluid replacement. At 45 hours after h emorrhage, mean arterial pressure cardiac output, and left ventricular cont ractility parameters, such as the maximal rates of ventricular pressure inc rease (+dP/dt(max)) and decrease (-dP/dt(max)), were determined, Microvascu lar blood flow in the intestine and kidney was assessed by laser Doppler fl owmetry. In addition, plasma levels of TNF-alpha were assayed by enzyme-lin ked immunosorbent assay. Results. The mean arterial pressure and cardiac output were decreased by 34 % and 18%, respectively, at 48 hours after hemorrhage and acute resuscitati on. Continuous resuscitation, however, markedly improved these parameters. Similarly, +dP/dt(max) and -dP/dt(max) decreased significantly after hemorr hage and acute fluid replacement but was restored to sham values after cont inuous resuscitation. Microvascular blood flow in the gut and kidneys was d ecreased after hemorrhage and acute resuscitation by 34% and 35%, respectiv ely. However, Intestinal and renal perfusion was maintained at the sham lev els at 48 hours after continuous resuscitation. In addition, the upregulate d TNF-alpha after acute resuscitation alone was reduced after continuous re suscitation, Conclusions, Continuous resuscitation after acute fluid replacement appears to be a useful approach for restoring and maintaining cardiovascular funct ion and organ perfusion after trauma and severe hemorrhage.