Thierry Hannedouche

Laparoscopy: An Alternative to Surgery in Patients Treated with Continuous Ambulatory Peritoneal Dialysis

Fifteen laparoscopic abdominal operations were performed in 14 patients treated by continuous ambulatory peritoneal dialysis for chronic renal failure. Celioscopic exploration of the abdomen and subsequent operation displayed several advantages specific to the method: identification of the etiology of scrotal dialysate outflow was achieved in 4 cases, peritoneal dialysis catheter salvage during laparoscopic cholecystectomy in 1 case, abdominal exploration during occurrence of peritonitis in 3 cases, and catheter dysfunction or abdominal examination before catheter implantation in 7 cases. The laparoscopic procedure allows early resumption of peritoneal dialysis after surgery, hence avoiding the need for transient hemodialysis. Nevertheless, it seemed unable to offer a salvage capability of infected catheters through extensive abdominal washing. Laparoscopy has been reported to decrease postoperative pain and disorders of ventilation, allowing for rapid recovery of social and professional activities following this minimal invasive surgical technique. Laparoscopy is a novel technique which enables precise diagnosis and surgical operations in patients treated by continuous ambulatory peritoneal dialysis.

Erythropoietin Increases Blood Pressure in Normotensive and Hypertensive Rats

Treatment with recombinant human erythropoietin (rHuEPO) successfully reverses anemia in uremic patients. Of major concern, however, are blood pressure increases during rHuEPO therapy, observed particularly in patients with a history of hypertension. The present study was designed to determine whether high-dose rHuEPO elevates blood pressure in nonuremic rats, and if so, whether preexisting hypertension enhances this response. We examined blood pressure responses to high (100 IU/kg) and very high (200 IU/kg) doses of rHuEPO or placebo, given subcutaneously every other day for 3 weeks to male spontaneously hypertensive rats (SHR) and their normotensive genetic controls (Wistar-Kyoto rats, WKY). The high and very high doses of rHuEPO stimulated equivalent increases in hematocrit, and this increase was always larger in SHR than in WKY. In contrast to the pattern of hematocrit changes, blood pressure did not change following high-dose rHuEPO but was elevated in both strains after the very high dose of the drug. Although the rise in blood pressure tended to be greater in SHR than in WKY, this difference was not significant. The data indicate that very high-dose rHuEPO raises blood pressure comparably in normotensive and hypertensive rats and this increase is relatively independent of the increase in hematocrit.

Renal abnormalities in normotensive insulin-dependent diabetic offspring of hypertensive parents.

To assess the effects of genetic predisposition of essential hypertension on early renal function in recent insulin-dependent diabetics, we studied inulin, para-aminohippuric, sodium, and lithium clearances in 69 unselected diabetics with (n = 20) and without (n = 49) a family history of essential hypertension. Despite similar metabolic control, glomerular filtration rate and mean arterial pressure were significantly higher in diabetics with than in those without a family history of hypertension. However, no difference was found between the two groups regarding renal vascular resistance, sodium excretion, or fractional proximal and distal sodium reabsorption. Renal responses to acute captopril (75 mg) administration were evaluated in 27 patients (six with family history of hypertension). Captopril decreased filtration fraction and mean arterial pressure similarly in both groups, whereas glomerular filtration rate and renal vascular resistance decreased more dramatically in diabetics with family history of hypertension. These findings indirectly suggest an abnormal response to angiotensin of vascular tone in recent diabetics with familial predisposition to hypertension. Renal response to acute nicardipine (2.5 mg i.v.) administration was analyzed in 24 patients (five with family history of hypertension). In both groups, nicardipine similarly decreased mean arterial pressure and renal vascular resistance and induced a marked natriuretic effect due to a predominant reduction in proximal reabsorption of sodium. However, the increase in sodium excretion was twofold to threefold more pronounced in diabetics with a family history of hypertension. Whether these early renal abnormalities may contribute to the risk of diabetic nephropathy, as suggested by retrospective studies, remains to be determined.

Renal response to angiotensin after short-term angiotensin converting enzyme inhibition.

In 13 normotensive subjects on a normal sodium diet, we studied hormonal, blood pressure, and renal vascular changes and dextran sieving profiles induced by infusion of exogenous angiotensin II (Ang II) (5 ng.kg-1.min-1). during baseline conditions and after 5 days of administration of the angiotensin converting enzyme inhibitor cilazapril. Cilazapril induced a renal vasodilative effect without affecting supine blood pressure and glomerular filtration rate. Fractional dextran clearances were significantly decreased for dextran of effective radius ranging from 3.0 to 4.0 nm. This shift was primarily related to an increase in glomerular capillary plasma flow, because no change was observed in the transcapillary glomerular pressure gradient, the ultrafiltration coefficient, or the membrane parameters. Ang II elicited a slight pressor response accompanied by hormonal, antinatriuretic, and renal hemodynamic changes that were similar during and before short-term angiotensin converting enzyme inhibition. Dextran sieving curves were unchanged by a low dose of Ang II. However, the transcapillary glomerular pressure gradient and the ultrafiltration coefficient were computed to increase by 19.4% and to decrease by 44.2%, respectively, whereas membrane parameters were unaffected. When superimposed onto short-term angiotensin converting enzyme inhibition, glomerular response to this unique dose of Ang II was similar to that induced by Ang II alone. These findings indirectly suggest that most, if not all, of the renal effects of cilazapril are mediated through suppression of Ang II formation.

Sclerostin: a new biomarker of interest in nephrology

Sclerostin is an osteocyte-specific glycoprotein secreted by the osteocyte and involved in the regulation of bone mass. High sclerostin levels are associated with osteoporosis, whereas low sclerostin levels are correlated with higher bone mineral density. It seems interesting to investigate a potential association between sclerostin levels and vascular calcifications since sclerostin is considered as a potent inhibitor of bone formation. In chronic kidney disease, serum sclerostin levels rise as renal function declines. Preliminary studies show a positive association between serum sclerostin and vascular calcification, but the link between sclerostin and survival of patients remains unclear in the absence of large-scale studies.