[Modification of the hemodynamic parameters and peripheral vascular flow in a porcine experimental of model of laparoscopic nephrectomy].

OBJECTIVES

It has been demonstrated that abdominal high-pressure and the use of CO2 pneumoperitoneum induce changes of the cardiovascular and respiratory systems, attributable to two factors: changes of the cardiac output (CO) and hypercarbia. Other modifications derived from these facts include changes of the systemic vascular resistances (SVR), blood pressure (BP), central venous pressure (CVP), vascular changes like modifications of the renal blood flow (RBF), carotid flow (CF), portal flow, and hepatic artery flow (HAF). Our objective is to analyze the hemodynamic modifications induced by pneumoperitoneum on renal blood flow, carotid flow, portal flow and hepatic artery flow in a porcine experimental model.

METHODS

We compared two groups of pigs: CONTROL group (n = 10) and LAPAROSCOPIC group (n = 10), undergoing open or laparoscopic nephrectomy respectively. In every case, catheters were inserted into the right external jugular vein and femoral artery and cardiac output, CVP, blood pressure and systemic vascular resistances (calculated as RVS = (BP/CVP)x 80/CO); these measurements were taken at the following times: baseline, 5, 30, 60 min. and postoperatively. Renal blood flow, carotid flow, portal flow and hepatic artery flow were registered by means of an electromagnetic probe around the vessel 30 minutes after the start of surgery.

RESULTS

Comparative analysis shows: an increase of cardiac output in the laparoscopic group, the difference which was maximal at 30 minutes (4.33 + 0.73 vs. 8 .54 + 1.26 l/min., p < 0.,001); a descent of the systemic vascular resistances (1118.81 + 302.52 vs. 663.37 + 81.45 dynes .s.cm5, p < 0.001) and an increase of blood pressure (66.5 + 11.52 vs. 80.25 + 2.49 mm Hg in the laparoscopic group. Flow analysis showed an increase of the carotid artery flow (125.73 + 41.69 vs. 291.7 + 51.52 ml/min., p < 0.001) and a decrease of portal flow (973.67 + 131.70 vs. 546.83 + 217.53 ml/min., p = 0.001) and hepatic artery flow (278.00 + 94.71 vs. 133.33 + 112.32 ml/min., p = 0.03) in the laparoscopic group. There were no significant differences in renal blood flow with the volume expansion used.

CONCLUSIONS

Laparoscopic nephrectomy conditions an increase of carotid flow, probably secondary to the increase of cardiac output, and also a diminishment of hepatic perfusion, both arterial and portal. Nevertheless, volume expansion and the limitation of intra-abdominal pressure to 12 mm Hg enable to maintain similar renal blood flow in both groups.