The effect of peritoneovenous shunting on catecholamine metabolism in patients with hepatic ascites

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Abstract
The elevated catecholamine levels in cirrhotic patients with ascites have been proposed to be due to sympathetic overactivity secondary either to reduced intravascular volume or to an underlying cardiovascular abnormality such as reduced pressor responsiveness. Furthermore, these elevated catecholamine levels have been proposed to be involved in the pathogenesis of salt and water retention. Therefore, the effect of peritoneovenous shunting on the circulating levels and renal excretion of catecholamines were studied in six patients with massive refractive ascites preoperative within the first 8 hr postoperative and by 2 weeks postoperative under metabolic conditions. The recirculation of ascites into the intravascular compartment resulted perioperatively in significant rises in cardiac output (p = 0.001), para-amino-hippurate clearance (p = 0.08), creatinine clearance, diuresis (p = 0.05) and natriuresis (p = 0.06). Systemic blood pressure remained unchanged while systemic vascular resistance decreased (p < 0.05). Preoperative circulating levels of free catecholamine were highly elevated, and renal vein concentrations were about 25% higher than renal arterial levels. Peri-operatively, there was little change in circulating catecholamine levels or distribution of renal blood flow although renal artery and vein concentrations tended to equalize. In contrast by 2 weeks postoperatively, free catecholamine levels had fallen to within the normal ranges: mean norepinephrine from 1,477.6 ± 194.6 to 395 ± 62.9 pg per ml (p < 0.05); epinephrine from 276 ± 74.2 to 65.7 ± 15.0 pg per ml (p < 0.02), and dopamine from 325.6 ± 175.2 to 47.9 ± 5.3 pg per ml. There was little change in circulating conjugated catecholamine levels, either urinary excretion or clearance of catecholamines, except epinephrine clearance which rose significantly (p < 0.05). Despite the normalization of circulating free catecholamine levels, the patients tended to remain hypotensive with a low peripheral vascular resistance. The return of circulating free catecholamine levels to normal following reexpansion of the intravascular volume by peritoneovenous shunting are in favor of their being elevated in response to vascular underfilling.