INCREASED INTRAABDOMINAL PRESSURE DURING PNEUMOPERITONEUM STIMULATES ENDOTHELIN RELEASE IN A CANINE MODEL

Prolonged pneumoperitoneum during laparoscopic surgery has been associ ated with oliguria in clinical experimental studies. Although the path ophysiology of this oliguria is thought to be renal parenchymal and ve nous compression, the role of the potent vasoconstrictor endothelin (E T) has not been studied. The purpose of this study was to investigate the effect of pneumoperitoneum on endothelin release and renal functio n in a canine model, Two groups of dogs were studied during pneumoperi toneum (Group 1, N = 7) or isolated left renal vein compression (Group 2, N = 6), Urine and plasma samples were collected for urine output, glomerular filtration rate (GFR), urine sodium, and plasma endothelin measurements. In Group 1, GFR fell significantly (p < 0.05) by 49% fro m a control of 0.88 +/- 0.12 mL/min per gram of kidney weight, Urine v olume fell by 79% (p < 0.05) from a control value of 0.014 +/- 0.003 m L/min/gkw, Sodium excretion was decreased by 88%, Sodium reabsorption was significantly enhanced during pneumoperitoneum (99.56 +/- 0.15% v 98.44 +/- 0.25%), Arterial plasma ET concentrations were elevated by 8 % during the first 20 minutes of pneumoperitoneum (30.8 +/- 3.6 v 33.3 +/- 3.4 pg/mL; p < 0.05), In Group 2, left renal vein compression res ulted in a 31% decrease (p < 0.05) in GFR in the left kidney and a 25% decrease in the right kidney, Urine volume fell by 67% in the left ki dney and 40% in the right. Renal venous ET concentrations also increas ed after renal vein compression. Although the mechanism by which oligu ria occurs during pneumoperitoneum is not fully understood, the ET con centration was elevated. Because ET can decrease RBF, GFR, and sodium excretion, it may contribute to the oliguria observed during long peri ods of pneumoperitoneum.