[Effect of limited volume resuscitation on hemodynamic changes in pregnant rabbit with hemorrhagic shock]

To determine the effects of two fluid resuscitation strategies on the changes of hemodynamic variables, serum concentration of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in a clinically relevant model of uncontrolled hemorrhagic shock in pregnant rabbits.

Hemorrhagic shock was induced by bleeding via carotied artery, followed by transection of a medium vessel in gestational sac. Experimental design consisted of three phases, shock phase (0-30 min), prehospital phase (30-90 min) and hospital phase (90-180 min). Twenty pregnant rabbits were randomly divided into two groups (n=10 /group), aggressive fluid resuscitation group (PNL group) and limited volume resuscitation group (PLH group). In the shock phase, animals were hemorrhaged by blood withdrawal to mean arterial pressure (MAP) of 40-45 mm Hg (1 mm Hg=0.133 kPa) via carotid artery. In the prehospital phase, a medium vessel in the gestational sac was transected, then the animals in the PNL group and PLH group were resuscitated with 0.9% normal saline (NS) and shed blood to MAP of 80, 60 mm Hg respectively. In the hospital phase, bleeding was controlled by surgical intervention and all the animals were reinfused with shed blood and NS to MAP 80 mm Hg. Hemodynamic variables and respiration rate were monitored and blood samples were collected for TNF-alpha and IL-6 measurement, and finally subsequent volume resuscitation and survival rate were recorded.

(1) At 120 min, the respiration rate and heart rate in the animals assigned to PLH group was (66+/-16) bpm, (235+/-41) bpm respectively, which were significantly lower than those in PNL group (P<0.01), while MAP and central venous pressure in the PLH group was (80.4+/-7.2) mm Hg, (8.0+/-4.4) cm H2O, respectively, which were significantly higher than those in PNL group (P<0.01); (2) The serum concentration of TNF-alpha, IL-6 of all the animals were markedly increased after hemorrhagic shock, and peak at 24 min. The serum concentration of TNF-alpha, IL-6 in animals assigned to PLH group were (105+/-67) ng/L, (118+/-51) ng/L respectively, which were significantly lower than those in PNL group (P<0.01). The serum concentration of TNF-alpha, IL-6 in the animals assigned to PLH group were decreased to normal at 480 min; (3) The subsequent blood transfusion volume and NS resuscitation volume in PLH group in prehospital phase were (16.0+/-2.2) ml, (39.0+/-5.5) ml respectively, while those in hospital phase were (28.0+/-6.7) ml, (90.0+/-7.1) ml respectively, which were significantly lower than those in PNL group (P<0.05); (4) The 24 and 72 hours survival rate in the animals assigned to PLH group were 100%, 90% respectively; which were significantly higher than those in PNL group (P<0.01).

Limited volume resuscitation improves thermodynamic changes of pregnant rabbit, attenuates the increase of serum concentration of TNF-alpha, IL-6, and results in higher survival rate. Limited volume resuscitation is an ideal means for hemorrhagic shock resuscitation in pregnant rabbit.