[Influence on kidney after resuscitation of heart arrest due to hypothermia induced by 4 centigrade normal saline in pig].

OBJECTIVE

To assess the effects of hypothermia state induced by 4 centigrade normal saline (NS) on kidney after successful cardiopulmonary resuscitation (CPR) in pig.

METHODS

After the induction of a 4-minute ventricular fibrillation (VF) in pigs, standard CPR was performed, and then the surviving pigs were divided into two groups: hypothermia group (n=5) with 4 centigrade NS continuous infusion at the speed of 1.33 ml×kg(-1)×min(-1) for 22 minutes, and then the speed was slowed down to 10 ml×kg(-1)×min(-1) and maintaining for 4 hours; the normal temperature group (n=5) with infusion of NS of normal temperature with the same speed as that of the hypothermia group. The hemodynamic parameters and oxygen metabolism were monitored before CA and also at different time points after recovery of spontaneous circulation (ROSC). Blood samples were collected to determine the serum urea nitrogen (BUN) and creatinine (Cr). The animals were sacrificed, and the kidneys were collected to determine the ATPase activity, as well as the histological changes with both light and electron microscopy at 24 hours after ROSC.

RESULTS

Continuous infusion of 4 centigrade NS could lower the central temperature by no more than 1.5 centigrade, with a little lowering of cardiac output, without obvious changes in heart rate, mean arterial pressure and coronary perfusion pressure, but the oxygen extraction rate was decreased compared with that of the normal temperature group. Serum BUN and Cr at 2 hours and 4 hours of ROSC in the normal temperature group were higher than those before CA (BUN: 3.80±0.79 mmol/L, 4.12±0.85 mmol/L vs. 3.11±0.48 mmol/L; Cr: 94.43±18.25 μmol/L, 94.15±14.03 μmol/L vs. 79.70±16.03 μmol/L, all P<0.05), and the levels in hypothermia group showed no significant changes compared with those of normal temperature group. The activities of renal Na (+)-K(+)-ATPase and Ca(2+)-ATPase at 24 hours after ROSC in the hypothermia group were lower than those in the normal temperature group, but without significant difference (1.278±0.664 μmol×mg(-1)×h(-1) vs. 3.190±0.789 μmol×mg(-1)×h(-1), 1.727±0.772 μmol×mg(-1)×h(-1) vs. 2.630±0.816 μmol×mg(-1)×h(-1), both P>0.05). Compared with the normal temperature group, there were less cellular edema, necrosis and inflammatory cells infiltration in the hypothermia group, and the mitochondria appeared normal.

CONCLUSION

4 centigrade NS continuous infusion after CPR could quickly create a hypothermia state, and the hemodynamics and oxygen metabolism were maintained, thus protecting the kidney.