Effect of anesthetics and diuretics on Doppler measurements of intrarenal resistive index in dogs

lntrarenal resistive index (RI) was determined in normal, sedated and diuretic kidneys. The mean RI values of normal dogs were $0.64{\pm}0.03$ without statistically significant difference between left and right kidney. Interrenal RI difference (${\Delta}RI$) was $0.03{\pm}0.01$. No significant relationship was found between mean intrarenal RI versus body weight. The mean intrarenal RI values after administration of acepromazine, xylazine, thiopental, and ketamine were $0.66{\pm}0.03$, $0.64{\pm}0.03$, $0.56{\pm}0.05$, and $0.50{\pm}0.05$, respectively. After administration of acepromazine or xylazine, a significant change of the RI was not found. But, a significant decrease of the RI following thiopental or ketamine administration could be observed as compared with the normal RI. The mean intrarenal RI values were $0.63{\pm}0.06$ and $0.62{\pm}0.04$ at 10 minutes and 30 minutes after injection of furosemide, respectively. No significant change of intrarenal RI was found after administration of furosemide. But, mannitol significantly decreased mean intrarenal RI to $0.57{\pm}0.02$ and $0.58{\pm}0.03$ at 30 minutes and 60 minutes, respectively. Based on the obtained results, values of 0.72 and 0.05 may be proposed as the reasonable upper limits of RI and ${\Delta}RI$ of normal average. Acepromazine or xylazine are recommended as anesthetics for renal diseases because they have less effect on the RI. Further study using mannitol injection to increase ${\Delta}RI$ may be suggested in unilateral urinary tract obstruction since mannitol more effectively changed mean RI than furosemide.