Enhanced external counterpulsation: a new technique to augment renal function in liver cirrhosis

Advanced liver cirrhosis is characterized by cardiovascular changes, such as low arterial blood pressure, peripheral vasodilation and renal vasoconstriction. As a consequence, renal hypoperfusion, impaired diuresis and natriuresis and eventual hepatorenal syndrome may ensue. Previous studies using head-out water immersion to increase central blood volume have demonstrated the functional nature of the renal abnormalities. Enhanced external counterpulsation (EECP) is a new non-invasive cardiac assist device to augment diastolic blood pressure by electrocardiogram-triggered diastolic inflation and deflation of cuffs wrapped around the lower extremities. We investigated whether EECP would improve renal dysfunction of liver cirrhosis.

Twelve healthy controls and 19 patients with liver cirrhosis were observed during 2 h of baseline followed by 2 h of EECP. The following parameters of renal and cardiovascular function were measured: renal plasma flow by para-aminohippurate clearance, glomerular filtration rate (GFR) by inulin clearance, urine flow rate, urinary excretion rates of sodium and chloride, mean arterial blood pressure (MAP), renal vascular resistance (RVR) and plasma concentrations of renin, atrial natriuretic peptide (ANP), endothelin-1, antidiuretic hormone, epinephrine and N-epinephrine.

EECP was well tolerated by healthy controls and cirrhotic patients alike. EECP increased MAP (cirrhotic patients: from 74+/-18 to 88+/-20 mmHg, P<0.01; controls: from 89+/-8 to 94+/-5 mmHg, P = NS) and ANP (cirrhotic patients: from 23+/-18 to 30+/-20 ng/l, P<0.05; controls: from 11+/-4 to 16+/-5 ng/l, P<0.01). The plasma renin concentration decreased (cirrhotic patients: from 98+/-98 to 58+/-57 ng/l, P<0.01; controls: from 4.6+/-1.6 to 3.4+/-1.1 ng/l, P<0.01). This was associated with improvement of the urinary flow rate (cirrhotic patients: from 3.6+/-1.8 to 4.6+/-0.7 ml/min, P<0.05; controls: from 1.8+/-1.5 to 2.8+/-1.9 ml/min, P<0.05), as well as of the sodium and chloride excretion rates in both groups. However, in contrast to healthy controls, GFR and renal plasma flow in cirrhotic patients failed to rise significantly. Renal vascular resistance fell numerically in healthy controls (68+/-5 vs 55+/-4 mmHg . min/l; P = NS). In contrast, RVR showed a significant increase by approximately 20% in cirrhosis (67+/-4 vs 80+/-8 mmHg . min/l; P<0.05). Endothelin-1 levels fell in controls (0.38+/-0.42 vs 0.31+/-0.35; P<0.05), whereas they remained statistically unchanged in cirrhotic patients. Epinephrine, N-epinephrine and vasopressin were not altered by EECP in either group.

EECP is an effective procedure to augment renal excretory function in healthy volunteers as well as in patients with cirrhosis. In healthy volunteers, GFR and renal plasma flow increased during EECP. In contrast, these parameters remained unchanged in the patients and their renal vascular resistance increased during EECP. Therefore, EECP improves diuresis, but does not influence the vasoconstrictive dysregulation of the kidneys in liver cirrhosis.