Effects of different fluid resuscitation program on renal function in swine during shock stage of severe burn

Objective To explore the effects of different fluid resuscitation program on renal function in swine during shock stage of severe burn. Methods Twenty-four Guangxi Bama miniature swine were inflicted with 40% total body surface area on the back, and then they were divided into four groups according to the random number table, with 6 swine in each group. At post injury hour (PIH) 2, swine in succinylated gelatin group (S), hydroxyethyl starch group (H), and allogeneic plasma group (A) were respectively resuscitated with succinylated gelatin, hydroxyethyl starch 130/0.4, and plasma according to burn shock " domestic general" resuscitation formula, and swine in Parkland group (P) were resuscitated with lactated Ringer′s solution according to Parkland formula. Hemodynamic indexes including heart rate, blood pressure, urine volume, pulmonary capillary wedge pressure, and central venous pressure before injury, at the first and second PIH 24 were recorded. The volume of resuscitation fluid was calculated at the first and second PIH 24. Blood and urine samples were collected before injury and at PIH 4, 8, 24, and 48, and then serum creatinine and urea nitrogen were detected by automatic biochemical analyzer, urine microalbumin and urine creatinine were detected by automated urine analyzer and the ratio of which was calculated. The renal tissue of swine in each group was obtained at PIH 48, and the pathologic changes were observed by optical microscopy and electron microscope. Data were processed with analysis of variance of repeated measurement, one-way analysis of variance, and LSD test. Results (1) The hemodynamic indexes of swine in each group were similar before injury and at the first and second PIH 24 (with P values above 0.05). Compared with those before injury, except that the heart rate of swine in group A had no significant change at the first PIH 24 (P>0.05), the heart rate of swine in each group was significantly increased at the first and second PIH 24 (with P values below 0.01); except that the systolic blood pressure of swine in group P was significantly increased at the first and second PIH 24 (P<0.05 or P<0.01), there were no significant changes of systolic blood pressure and diastolic blood pressure of swine in each group at the first and second PIH 24 (with P values above 0.05); except that urine volume of swine in groups S and A was significantly decreased at the first PIH 24 (P<0.05 or P<0.01), there were no significant change of urine volume of swine in each group at the first and second PIH 24 (with P values above 0.05); pulmonary capillary wedge pressure and central venous pressure of swine in each group were significantly increased at the first and second PIH 24 (P<0.05 or P<0.01). (2) Compared with that in group A, the volume of resuscitation fluid of swine in groups S and H had no significant change in the first and second PIH 24 (with P values above 0.05), while it was significantly increased in group P in the first PIH 24 and significantly decreased in the second PIH 24 (with P values below 0.05). (3) Compared with those in group A, except that serum creatinine of swine in group H was significantly increased at PIH 24 and significantly increased in group P at PIH 4, 8, 24, and 48, urea nitrogen of swine in group P was significantly decreased at PIH 4 and 8 and significantly increased at PIH 48, the ratio of urine microalbumin to urine creatinine of swine in group P was significantly increased at PIH 8, 24, and 48 (P<0.05 or P<0.01), serum creatinine, urea nitrogen, and the ratio of urine microalbumin to urine creatinine of swine in each group had no significant change at each time point (with P values above 0.05). Serum creatinine of swine in group P was (125±16) μmol/L at PIH 24, which was significantly higher than that before injury [(75±13) μmol/L, P<0.05]. Urea nitrogen of swine in group S was (2.90±1.17) μmol/L at PIH 48, which was significantly lower than that before injury [(4.60±0.47) μmol/L, P<0.05]; urea nitrogen of swine in group H was (4.82±0.82) μmol/L at PIH 4, which was significantly higher than that before injury [(3.80±0.73) μmol/L, P<0.05]; urea nitrogen values of swine in group A were respectively (4.80±0.33), (4.92±0.35), and (2.60±0.27) μmol/L at PIH 4, 8, and 48, while those at PIH 4, 8 were significantly higher and at PIH 48 was significantly lower than the value before injury [(3.93±0.32) μmol/L, with P values below 0.01]. The ratios of urine microalbumin to urine creatinine of swine in group P were respectively (106.7±16.4) and (171.6±36.9) mg/mmol at PIH 24 and 48, which were significantly higher than the ratio before injury [(59.0±3.0) mg/mmol, with P values below 0.01]. The serum creatinine, urea nitrogen, and the ratio of urine microalbumin to urine creatinine of swine in each group at the other time points were similar to those before injury (with P values above 0.05). (4) The renal tissue of swine in the four groups had no obvious pathological change. Conclusions According to the renal function results, fluid resuscitation with electrolyte and colloids are better than with lactated Ringer′s solution in swine during shock stage of burn injury, while natural colloids and succinylated gelatin have similar effects, and both are superior to hydroxyethyl starch 130/0.4.