A PORCINE MODEL FOR RENAL HEMODYNAMIC-STUDY DURING LAPAROSCOPY

Laser Doppler flowmetry (LDF) is a sensitive method for the measuremen t of microvascular blood flow in tissue. The method has been found use ful for estimating skin, liver, or gastrointestinal blood flow. Whethe r it can be applied laparoscopically and whether it is able to measure the intraparenchymal blood flow of an intraabdominal organ is still u nknown. In a pilot study, 6 pigs received a laparotomy for placement o f a 19-gauge LDF needle probe into the renal parenchyma. Three differe nt locations of the lower pole kidney were chosen for the blood flow m easurement. The reliability of using the instrument to measure the ren al tissue blood flow was assessed by comparison of the results of rena l arterial blood flow obtained from a well-established methodology-ult rasonic Doppler flowmetry. Recordings were taken following (a) intrave nous administration of 0.005 mg/kg norepinephrine, (b) manual compress ion of the suprarenal aorta, and (c) intravenous injection of a lethal dose of phenobarbital (50 mg/kg). Measurements of LDF were possible i n all kidney units. The renal tissue perfusion detected by LDF correla ted excellently with the renal arterial blood how under different rena l perfusion pressures. The feasibility of using LDF probe to measure t he renal tissue perfusion in a laparoscopic model was then assessed in 15 pigs. Under pneumoperitoneum, the right kidneys were approached tr ansperitoneally with the animal in the decubitus position. A total of three trocars were used. The peritoneum and Gerota's fascia were incis ed and the LDF needle probe was manipulated and inserted by an endofor ceps into the renal tissue via a 5-mm trocar. The insertion of the LDF needle probe was technically feasible in all 15 kidney units, and the depth of insertion could be adjusted un der direct vision. Baseline v alues for the renal cortical and renal medullary blood flow were 50.1 +/- 17.7 and 8.8 +/- 3.3 ml/min/100 g tissue, respectively. Spatial va riations of the LDF measurements averaged 6%, and temporal variations over 15 min averaged 5%. Four additional hemodynamic parameters were s imultaneously recorded, including left carotid artery blood flow, aort ic blood pressure, inferior vena caval pressure, and intraabdominal pr essure. It appears that systemic and renal hemodynamic parameters can be monitored reliably and continuously in the porcine model. This meth od allows further information concerning hemodynamic changes and safet y of laparoscopy to be obtained. (C) 1996 Academic Press, Inc.