Prolonged controlled hemorrhagic shock in a swine model: Is there a role for mechanical circulatory assistance?

Outcomes of mechanical circulatory assistance during hemorrhagic shock were evaluated in a swine model. Pigs were bled to a mean arterial pressure of 35 mm Hg (group 1, n = 3) or 40 mm Hg (group 11, n = 5; group III, n = 5), maintained there for 30 minutes, and then resuscitated with fluids alone (groups I and 11) or fluids plus mechanical circulatory assistance (group 111). Mean blood loss was greater in group I than in groups 11 or III (1,037 +/- 212 vs. 862 +/- 387 ml vs. 681 +/- 117 ml, respectively; I vs. III, p < 0.05) and survival was shorter (230 +/- 25.5 min vs. 709 251 min vs. 662 428 min, respectively; I vs. 11 or III, p < 0.05). Cardiac arrhythmia caused death in most cases. Mean biochemical parameters increased progressively in all cases. Left anterior descending coronary artery flow stayed relatively constant in group 11 but increased in group Ill. Superior mesenteric artery flow returned to baseline in group 11 but increased in group III. Cardiac output was similar in groups 11 and Ill, but SGOT levels significantly differed (750 +/- 135 U/L vs. 359 +/- 157 U/L; p < 0.005). These results suggest that the swine model will be useful for studying ways to improve outcomes after prolonged hemorrhagic shock.