The Correlation Studies Between Kidney Hemodynamic Changes And Acute Kidney Injury Of CPB By The CDFI

Objective Cardio pulmonary bypass (CPB) surgery is often complicated by different degrees of kidney injuries. The complicating cases with acute kidney injury (AKI) shall be treated via dialysis, while some of the cases to the most severe extent even come to death. As a non-invasive physical examination means, Color Doppler Ultrasound was being widely adopted for its own superiority over other means in the diagnosis of kidney diseases. By technical means of Color Doppler Ultrasound and based on renal biochemical detection index, the study was carried out to explore the possible relationship between renal hemodynamic changes and renal dysfunction after CPB surgery.Methods 31 cases with heart diseases were involved, who were fully informed of the study intention in advance and gave consent to being studied. Prior to the operation and 1h,2h,4h,8h,16h and 24h after the operation, Color Doppler Flow Imaging (CDFI) was adopted to monitor 3-level renal blood flow dynamics of renal portal master renal artery, renal sinus segment artery and renal interlobar artery between bilateral vertebral margin of leaf, and measure the artery Peak Systolic Velocity (PSV), End Diastolic Velocity (EDV), Mean Velocity (MNV), Pulsatility Index (PI) and Resistance Index (RI). Meanwhile, biochemical technology was adopted to detect the renal function at various time points, including Blood Urea Nitrogen (Urea), Uric Acid (UA) and Creatinine (Crea). With reference to AKI diagnostic criteria i.e. within 48h Crea value increased by 26.4umol/L or by 150% to 200%, these cases for the study are grouped as Non-AKI (N=17) and AKI (n=14). SPSS 17.0 statistical software was used to collect and deal with the data available. For each case studied, left and right renal artery blood flow parameter were summed up and averaged, and the average value was taken as the renal flow parameter. T-test was conducted to compare between AKI group and Non-AKI group and the parameter P<0.05 obtained refers to the difference of statistical significance. The relationship between various index of renal blood flow and renal function was analyzed by linear correlation and linear regression, coefficient r and linear regression equation were calculated. The parameter P<0.05 obtained refers to difference of statistical significance. Results (1) General information, ①the age and weight of Non-AKI group was 40.52 ± 19.64 years and 53.59 ± 20.64 kg, the age and Weight of AKI group was 44.86 ± 18.94 years and 50.21 ± 17.65 kg, there were no statistically significant differences (P>0.05). ②Aortic clamping time, CPB time and Operative time, in the Non- AKI group vs the AKI group, were 0.84±0.45 (h) vs 1.35±0.54 (h),1.08±0.50 (h) vs 1.76±0.61 (h) and 3.23±0.26 (h) vs 4.23±0.55 (h), there were statistically significant differences between the Non- AKI group and the AKI group (P<0.05). (2) Renal function, ①preoperative Urea, UA and Crea, in the Non- AKI group vs the AKI group, were 5.55±1.87 (mmol/L) vs 5.16±1.54 (mmol/L),327.06±91.50 (umol/L) vs 358.43±147.37 (umol/L) and 50.07±17.13 (umol/L) vs 53.76±27.55(umol/L), there were no statistically significant differences (P> 0.05), ②In the postoperative group of Non-AKI group, postoperative 24h Urea than the preoperative was7.81±3.23 (mmol/L) vs5.55±1.87 (mmol/L), there was a significant difference (P<0.05), but there was no significant differences in UA and Crea; ③In the postoperative group of AKI group:postoperative 16h and 24h Crea were 122.30±77.57 (umol/L),155.74±116.27 (umol/L), postoperative 8h,16h,24h Urea were 10.81±4.42 (mmol/L),10.08±5.31 (mmol/L),13.58±8.90 (mmol/L), compared with the preoperative Urea and Crea, there were statistically significant differences (P<0.05).(3)The master renal artery Doppler parameters: ①PI, RI, PSV, EDV, MNV, in the preoperative of Non-AKI group vs in the preoperative of AKI group:were 1.37±0.38 vs 1.56±0.30,0.70±0.07 vs 0.73±0.07,2.00±20.14 (cm/s) vs 65.91±23.12 (cm/s),21.39±6.64 (cm/s) vs 16.63±4.44 (cm/s),32.65±8.46 (cm/s) vs 33.68±8.50 (cm/s), there were no statistically significant differences between the two groups(P>0.05), ②In the postoperative group of non-AKI group: postoperative 1hPI, RI, PSV were 2.00±0.69,0.76±0.10,87.81±36.10 (cm/s), postoperative 2h PI were 1.77±0.67, postoperative 4h PI was 1.84±0.66, postoperative 8h PI, RI, EDV were 1.88±0.71,0.75±0.09,16.45±5.60 (cm/s) postoperative 16h PI, RI were 1.79±0.51,0.75±0.08, there were significant differences in the PI, RI, EDV, PSV, compared with the preoperative(P<0.05). ③In the postoperative group of AKI group:postoperative 1h PI, RI were 1.94±0.54,0.79±0.03, postoperative 2h group PI, RI, EDV were 1.72±0.27, 0.78±0.07,24.26±5.17(cm/s), postoperative 4h PI was 2.14±1.07, postoperative 8h PI, RI were 1.99±0.89,0.78±0.08, postoperative 16h PI, RI were 2.07±0.75, 0.79±0.06, compared with the preoperative, there were statistically significant differences(P<0.05). (4) Renal segmental artery blood flow Doppler parameters:①PI, RI, PSV, EDV, MNV in the preoperative of Non-AKI group vs in the preoperative of AKI group were 1.29±0.27 vs 1.30±0.20,0.69±0.06 vs 0.69±0.06,44.34±13.51(cm/s) vs 37.60±11.35(cm/s),13.57±3.6(cm/s) vs 11.44±4.07 (cm/s),23.84±6.26 (cm/s) vs 21.64±5.20(cm/s), there were no statistically significant differences(P>0.05),②In the postoperative group of non-AKI group:postoperative 1h PI, RI, PSV were 1.81±0.66,0.75±0.08, 60.92±30.45(cm/s), postoperative 2h group PI, PSV, MNV were 1.75±0.80, 56.66±27.60(cm/s),29.23±6.89(cm/s), postoperative 4h group PI was 1.69±0.65, postoperative 8h group PI, RI, EDV were 1.67±0.54,0.73±0.08, 11.29±3.53 (cm/s), postoperative 16h group PI, RI were 1.55±0.45,0.72±0.07, compared with the preoperative, there were statistically significant differences(P<0.05).③the postoperative group of AKI group:postoperative 1h group PI, RI, PSV were 1.82±0.64,0.78±0.07,61.13±28.93, postoperative 2h group PI, RI were 1.71±0.35,0.77±0.08, postoperative 4h group PI, RI were 1.81±0.68,0.76±0.09, postoperative 16h group PI, RI were 1.56±0.44, 0.75±0.05, compared with the preoperative,there were statistically significant differences(P<0.05). (5) The Renal interlobar artery blood flow Doppler parameters:①PI, RI, PSV, EDV and MNV,in the preoperative of Non-AKI group vs in the preoperative of AKI group, were 1.18±0.21 vs 1.10±0.14, 0.66±0.05 vs 0.65±0.05,23.87±6.75 (cm/s) vs 20.40±4.93 (cm/s),7.68±1.88 (cm/s) vs 7.05±2.04 (cm/s),13.92±3.93 (cm/s) vs 13.81±2.65(cm/s), there were no statistically significant differences (P>0.05), ②In the postoperative group of non- AKI group:postoperative 1h PI, RI were 1.54±0.49,0.71±0.07, postoperative 2h group PI, PSV, MNV were 1.56±0.65,33.55±10.96 (cm/s), 21.85±3.46 (cm/s), postoperative 4h group PI, RI were 1.50±0.49,0.71±0.11, postoperative 8h group PI, RI were 1.51±0.45,0.72±0.07, postoperative 16h group PI, PSV were 1.57±0.93,28.68±10.58(cm/s), postoperative 24h group PI, PSV, MNV were 1.40±0.38,29.50±7.00(cm/s),18.24±4.42(cm/s), compared with the preoperative, there were statistically significant differences(P<0.05). ③the postoperative group of AKI group:postoperative 1h group PI, RI, PSV were 1.67±0.63,0.71±0.09,27.06±8.94(cm/s), compared with the preoperative, there were statistically significant differences(P<0.05). postoperative 2h group PI, RI, PSV were 1.55±0.25,0.73±0.07,26.51±2.47 (cm/s), compared with the preoperative, there were statistically significant differences(P< 0.05). postoperative 4h group PI, RI were 1.44±0.44,0.72±0.10, compared with the preoperative, there were statistically significant differences(P< 0.05). postoperative 8h group PI was 1.50±0.63, compared with the preoperative,there were statistically significant differences(P<0.05). postoperative 16h group PI, RI were 1.69±0.51,0.73±0.07, compared with the preoperative, there were statistically significant differences(P<0.05). postoperative 24h group PI, RI were 1.58±0.41,0.71±0.08, compared with the preoperative, there were statistically significant differences(P<0.05). (6) the straight line regression analysis of Renal function and renal blood flow doppler parameters:The linear correlation analysis:①The master renal artery:PI, RI and Urea was positively correlated (r=0.468,0.366, P<0.05), EDV, MNV and Urea was negatively correlated (r=-0.423,-0.392, P<0.05), PSV and Urea was no significant correlation (r=-0.108, P>0.05), PI, RI and UA was positively correlated (r=0.526,0.375, P<0.05), EDV and UA was negatively correlated (r=-0.442, P<0.05), PSV, MNV and UA was no significant correlation (r=-0.022,-0.237, P>0.05), PI, RI and Crea was positively correlated (r=0.435,0.251, P<0.05), EDV and Crea was negatively correlated (r=-0.288, P<0.05), PSV, MNV and Crea was no significant correlation (r=0.085,-0.182, P>0.05);② the renal segmental arteries:PI, RI and Urea was positively correlated (r=0.376,0.353, P<0.05), EDV and Urea was negatively correlated (r=-0.332, P<0.05), PSV, MNV and Urea was no significant correlation(r=0.171,-0.031, P>0.05), PI,RI and UA was positively correlated (r=0.490,0.368, P<0.05), EDV and UA was negatively correlated (r=-0.353, P<0.05), PSV, MNV and UA was no significant correlation ((r=0.124,-0.124, P>0.05), PI, RI and Crea was positively correlated (r=0.401,0.351, P<0.05), EDV and Crea was negatively correlated (r=-0.254, P<0.05), PSV, MNV and Crea was no significant correlation (r=-0.025,-0.018, P>0.05),③the renal interlobar arteries:PI, RI and Urea was positively correlated (r=0.671,0.498, P<0.05), EDV and Urea was negatively correlated (r=-0.239, P<0.05), PSV, MNV and Urea no significant correlation(r=0.086,-0.098, P>0.05), PI, RI and UA was positively correlated (r=0.630,0.447, P<0.05), EDV and UA was negatively correlated (r=-0.298, P<0.05), PSV, MNV and UA was no significant correlation (r=-0.050,-0.189, P>0.05), PI, RI and Crea was positively correlated (r=0.670,0.488, P<0.05), EDV and Crea was negatively correlated (r=-0.190, P<0.05),PSV, EDV, MNV and Crea was no significant correlation (r=0.116,-0.174,-0.131, P>0.05)。The Linear regression analysis:①Each group to Urea as a variable y, to master renal artery of PI, RI, EDV, MNV as the independent variable x, for linear regression analysis, linear regression equation: y=2.651 x+2.637, y=11.267 x-0.962, y=-0.185 x+10.935, y=-0.104 x+9.983, to master renal segmental arteries of PI, RI, EDV as the independent variable x, for linear regression analysis, linear regression equation: y=2.415 x+3.345, y=16.456x-4.561, y=-0.199x+9.912, to master renal interlobar arteries of PI, RI, EDV as the independent variable x, for linear regression analysis, linear regression equation:y=5.518 x-0.47, y=26.532 x-10.743, y=-0.278 x+9.469;②Each group to UA as a variable y, to master renal artery of PI, RI, EDV as the independent variable x, for linear regression analysis, linear regression equation:y=119.090 x+170.316, y=438.641 x+47.428, y=-7.782x+528.953, to master renal segmental arteries of PI, RI, EDV as the independent variable x, for linear regression analysis, linear regression equation:y=130.250 x+164.379, y=674.643 x-115.342, y=-8.339x+482.795, to master renal interlobar arteries of PI, RI, EDV as the independent variable x, for linear regression analysis, linear regression equation: y=213.775 x+66.325, y=882.34 x-242.285, y=-12.793 x+458.041; ③Each group to Crea as a variable y,to master renal artery of PI, RI, EDV as the independent variable x, for linear regression analysis, linear regression equation: y=26.708 x+17.917,y=93.352-2.557, y=-1.362x+90.018, to master renal segmental arteries of PI,RI,EDV as the independent variable x, for linear regression analysis, linear regression equation:y=29.597 x+17.835, y=194.390x-74.440, y=-1.76x+87.74, to master renal interlobar arteries of PI, RI, EDV as the independent variable x, for linear regression analysis, linear regression equation:y=70.024 x-31.775, y=327.283 x-157.482, y=-3.022x+85.520. Conclusion (1) There was a correlation between acute renal dysfunction and intraoperative aortic clamping time, turnaround time, surgery time in Cardiopulmonary bypass heart surgery. (2) Renal artery, renal segmental arteries, renal interlobar artery PI and RI were positively correlated with Urea, UA and Crea. (3) Renal artery, renal segmental arteries and renal interlobar artery EDV were negatively correlated with Urea, UA and Crea. (4) Changes in renal function could be reflected soon by index of renal blood flow PI, RI and EDV.