Marcello Marcondes

Intraperitoneal pressure and hernias in children on peritoneal dialysis

Abstract Abdominal wall hernias have been increasingly recognized in patients on continuous ambulatory peritoneal dialysis (CAPD). They are also more frequent in children than in adults. The aim of this study was to determine the influence of intraperitoneal pressure (IPP) on the development of hernias in children on CAPD, and if there was a difference between IPP in children and adults. We studied 14 children aged 11.2±3.2 years, body weight 31.1±9.4 kg, who had undergone CAPD for 16.2±14.4 months. Also, 10 adults were studied, aged 48±18 years, body weight 62.4±13.9 kg, on the CAPD program for 35±27 months. The IPP was measured via a column of dialysate in the peritoneal dialysis line, immediately before the drainage of the peritoneal cavity. The pressure was measured with the patients in the supine position, at the level of the umbilical cicatrix with the zero point located on the mean axillary line. IPP was measured at inspiration and at expiration, and the mean of these two measurements was calculated. The children were divided in two groups : group 1 (n=7) without hernias and group 2 (n=7) with hernias (5 umbilical and 2 inguinal). The IPP of all children was 9.5±2.9 cm H2O. The IPP was 8.1±2.6 and 10.9±2.6 cm H2O in groups 1 and 2, respectively (P=0.003). The instilled volume for test was similar in both groups. The IPP of the adults was 13.8±2.8 cm H2O, which was significantly greater than that of the children (P=0.001). In conclusion, hernia is a common complication in children on CAPD and its prevalence is affected by IPP. Other associated factors may be the presence of anatomically weak sites in the abdominal wall of the children, since IPP is lower in children than in adults.

Salt sensitivity in human essential hypertension: effect of renin-angiotensin and sympathetic nervous system blockade.

We studied the acute effect of oral captopril (25mg) and clonidine(300 micrograms) on blood pressure (BP) in patients with essential hypertension successively maintained on a low (LSD) and high (HSD) salt diet. Seven patients were salt sensitive (SS) and seven were salt resistant (SR). The maximal decrease in diastolic BP caused by captopril in patients on the LSD was greater in SS than SR individuals. Baseline urinary norepinephrine levels did not change from LSD to HSD (p greater than 0.05) in SS patients and decreased in SR patients (p less than 0.05). The maximal decrease in mean BP during the clonidine test was the same for both diets (p greater than 0.05) in SS patients and was lower (p less than 0.05) for the HSD in SR patients. SS patients on the HSD presented a higher decrease in systolic BP than SR patients (p less than 0.05) during the clonidine test. These data suggest overactivity of the renin-angiotensin system in SS patients on the LSD and of the sympathetic nervous system in SS patients on the HSD and that the clonidine test could be a good indicator for identifying SS and SR patients.

Outcome of acute renal failure associated with cardiac surgery in infants

OBJECTIVE To analyze the impact of acute renal failure (ARF) on the evolution of infants undergoing cardiac surgery. METHODS We assessed 15 infants undergoing cardiac surgery who developed (ARF). Their demographic, clinical and surgical data, and evolution were analyzed. RESULTS Their mean age was 4.4+/-4.0 months (8 days to 24 months). Twelve infants were males, and 4 patients already had ARF at surgery. The primary cause of ARF was immediate acute cardiac dysfunction in 10 infants, cardiac dysfunction associated with sepsis in 2 infants, and isolated sepsis in 3 infants. All children depended on mechanical ventilation during their postoperative period, 14 infants used vasoactive drugs, and 11 had an infectious process associated with ARF. Thirteen infants required dialytic treatment. Eleven infants developed oluguric ARF, and all had to undergo peritoneal dialysis; of the 4 patients with non-oliguric, 2 required dialysis, the main indication being hypervolemia. Of these 13 dialyzed infants, 4 died in the first 24 hours because of the severity of the underlying cardiac disease (mean urea level of 49+/-20 mg/dl). The mortality rate for the entire group was 60%, and it was higher among the patients with oliguria ARF (73% vs 25%, p<0. 001). The cause of death was acute cardiac dysfunction in 6 infants (early type-1 ARF) and sepsis in the 3 remaining infants (late type-2 ARF). CONCLUSION The mortality rate of ARF associated with cardiac surgery in infants was hight, being higher among children with oliguria; peritoneal dialysis was indicated due to clinically uncontrolled hypervolemia and not to the uremic hypercatabolic state.

Seasonal variation of blood pressure in maintenance hemodialysis

CONTEXT Seasonal variation in arterial blood pressure has been reported in studies with hypertensive and normotensive subjects. However, the influence of seasonal change on blood pressure of hemodialysis patients has not been reported. OBJECTIVE To investigate the seasonal variation of blood pressure in Brazil, a tropical country, in patients on hemodialysis. DESIGN Prospective, cohort study. SETTING Dialysis unit of a tertiary medical center (a teaching hospital of the University of São Paulo School of Medicine, São Paulo). PATIENTS Sixteen patients with chronic renal failure undergoing hemodialysis. OUTCOMES Blood pressure, body weight, and ambient temperature were evaluated during 6 hemodialysis sessions carried out on 13 days during the four seasons. RESULTS The diastolic blood pressure was lower in summer than in fall and winter (95 +/- 8 vs 107 +/- 10 and 101 +/- 10 mmHg, respectively; p < 0.05). The same was observed with mean blood pressure (116 +/- 8 vs 130 +/- 11 and 124 +/- 9 mmHg, respectively; p < 0.01). On the other hand, the ambient temperature was higher in summer than in fall and winter (23.0 +/- 1.6 vs 19.5 +/- 3.0 and 15.8 +/- 1.9 degrees C, respectively; p < 0.01). CONCLUSIONS We concluded that for patients with chronic renal failure the blood pressure has a seasonal variation with higher pressures in fall and winter than in summer. Thus, further studies are needed to elucidate the impact of this observation on the adjustment of antihypertensive treatment and on morbidity and mortality in maintenance dialysis patients.

Long-Lasting Inhibition of Angiotensin Response in Rats by Depot Administration of Octanoyl-[Leu8]-Angiotensin II

Depot administration of a lipophilic angiotensin II (AII) antagonist was tested for obtaining prolonged inhibition of the pressor response to AII in rats. Intramuscular injections of 1.5 or 5.0 mg of octanoyl‐[Leu8]AII (oct‐LAII), in oil solution produced the same degree of AII inhibition either 6 h or 24 h after the injection. The inhibition was comparable to that expected from the continuous intravenous infusion of oct‐LAII at the rate of 1.2 μg kg−1 min−1. The prolonged effect of intramuscular injections of oct‐LAII in oil solution may be useful for chronic studies of physiopathological states involving the renin‐angiotensin‐aldosterone system.

The role of experimental aluminum intoxication in allogeneic immunoresponse

To evaluate the immunological properties of aluminum (Al) in experimental Al intoxication in rats, we performed heart transplantation and in vitro experiments. Lewis (Lew) rats were intoxicated with intraperitoneal injections of AlCl3. Heart transplants were performed using Brown-Norway (BN) rats as donors. Isotransplants and normal Lew were used as controls. No differences in survival were observed. Unidirectional mixed lymphocyte cultures (MLC) and Concanavalin A (Con A)-stimulated cultures were prepared using spleen cells from normal and Al-intoxicated Lew rats. No differences were found in unidirectional MLC. Intoxicated cells showed a less intense response to Con A than did normal cells. In conclusion, we could not detect an immunosuppressive role of Al intoxication in experimental cardiac transplantation or in MLC. However, the depressed Con A blastogenic response of Al-intoxicated cells may reflect an immunological role yet to be defined.

Late evaluation of glomerular filtration rate, proteinuria, and urinary acidification after acute tubular necrosis

Fourteen patients were studied 2 to 36 months after acute tubular necrosis. It was observed that 43% of the patients had decreased glomerular filtration rate. These patients were older and had lower urinary excretion of ammonium and titratable acidity. Proteinuria greater than 150 mg/day, without reaching a nephrotic level, was found in 92% of the patients. The presence of oliguria, the demand of dialysis, and the acute tubular necrosis etiology were not statistically different among the patients who recovered their glomerular filtration rate either totally or partially.

Progressive Hypervolemia Despite Hypoproteinemia and Massive Edema Formation in Rats with Nephrotoxic Serum Nephritis

Blood volume and whole kidney and single nephron function were evaluated 2 and 10 days after nephrotoxic serum nephritis (NSN) induction in Wistar rats. Progressive proteinuria, hypervolemia and edema were observed in NSN rats. Sodium retention was associated with a progressive depression of single nephron glomerular filtration rate and elevated fractional tubular reabsorption rates. Since hypervolemia rather than hypovolemia was observed in this study, edema formation must have been a consequence of intrarenal rather than extrarenal phenomena.

GLYCOSURIA IN GLOMERULAR DISEASES : HISTOPATHOLOGY AND CLINICAL CORRELATIONS

There are doubts about the presence of glycosuria and the progress of glomerular disease. Some reports suggest that glycosuria could be an index of a more severe tubulointerstitial lesion. We investigated the presence of glycosuria in 60 patients with primary glomerular diseases: 17 patients (28%) had glycosuria and 43 patients (72%) were glycosuria free. The two groups were similar in age, arterial pressure and sex. Serum creatinine was higher in patients with glycosuria (2.0 +/- 1.7 vs 1.3 +/- 0.9 mg/dl, P < 0.05). The protein excretion rate was 7.5 +/- 3.7 vs 5.3 +/- 4.2 g/day (P > 0.05) in patients with and without glycosuria, respectively, while serum albumin was lower in patients with glycosuria (1.7 +/- 0.6 vs 2.7 +/- 1.0 g/dl, P < 0.05). Several histological forms were present in the group with glycosuria, with membraneous glomerulonephritis being the most frequent. Histological evidence of tubular atrophy and interstitial fibrosis prevailed in patients with glycosuria, suggesting a poor prognosis for these patients. We may conclude that the presence of glycosuria in patients with glomerular disease is associated with more pronounced tubular atrophy and interstitial fibrosis and therefore imply a poorer prognosis.