Biomedical subjects

R Minutolo

Publications and source records attributed to R Minutolo.

25 records · Page 2Linked to original sources

PubMed1995

Early effects of contrast media on renal hemodynamics and tubular function in chronic renal failure.

The pathophysiology and prevention of contrast media (CM)-induced nephropathy in chronic renal failure (CRF) are still ill defined. GFR, RPF, endothelin-1 (ET-1) levels, urinary sodium concentration, and fractional excretion of sodium were measured in CRF patients undergoing water diuresis in basal conditions and 20 to 120 min after an iv bolus of either the high-osmolar CM diatrizoate (D) or the low-osmolar CM iopamidol (I). The two CM induced an immediate and progressive decline of both GFR and RPF in the absence of hypovolemia, more pronounced in D (-36% at 120 min) than after I (-19% at 120 min; P < 0.05 versus D). Both CM determined a marked and steady increase of the fractional excretion of sodium. The natriuresis could not be totally ascribed to a CM-induced osmotic diuresis as because the urinary sodium concentration markedly increased. In two further groups of patients receiving D, we studied the effects of pretreatment with a single dose of either captopril or nifedipine. Both drugs, although not preventing the increase of natriuresis, partially antagonized D-induced renal hypoperfusion: GFR and RPF were equally reduced by 20% in D/captopril and D/nifedipine (P < 0.05 versus D). In unpretreated patients receiving either D or I, plasma ET-1 did not change but urinary levels increased; these changes were, however, dissociated from those observed in renal hemodynamics. Both plasma and urinary levels of ET-1 did not vary in pretreated groups. The 72-h follow-up evidenced a significant reduction of renal function only in the unpretreated D group. Therefore, the main findings after CM administration in CRF patients are: (1) an immediate GFR decline proportional to the osmolarity of CM and secondary to the renal hypoperfusion that is neither caused by hypovolemia nor mediated by ET-1, (2) an early tubular dysfunction at the level of the proximal nephron, and (3) a protective effect of single-dose pretreatment with either captopril or nifedipine on D-induced acute and short-term GFR changes.

Contrast Media↗

PubMed1994

Role of loop diuretics in chronic renal failure.

The natriuretic effects of furosemide and the long-acting loop diuretic torasemide have been compared in patients with chronic renal failure with and without nephrotic syndrome. In patients with chronic renal failure without nephrotic syndrome, furosemide and torasemide exerted similar natriuretic activity. In patients with chronic renal failure complicated by nephrotic syndrome, torasemide showed a greater natriuretic potency and a longer duration of action than furosemide.

Administration, Oral↗

PubMedDate not supplied

Diuretics in renal failure.

Fluid retention following reduction in the glomerular filtration rate causes extracellular fluid volume expansion that reduces tubular reabsorption by residual nephrons, thereby maintaining the external sodium balance. The price paid for this is salt-dependent hypertension. Thus, loop diuretics are the best treatment for uremic hypertension. Diuretics are also used in chronic renal failure to treat edema due to nephrotic syndrome and congestive heart failure (CHF). In nephrotics, edema is often refractory to diuretics because of low plasma protein, depletion of the intravascular compartment, decrease in the protein-bound fraction of the diuretic in peritubular blood, and increase in tubular fluid. Thus, higher doses are needed. In uremics with CHF the efficacy of diuretics may be hampered because of the reduced renal blood flow. The association of dopamine (1-1.5 microg/kg body weight/min) may overcome this resistance; improvement in cardiac function by dialysis ultrafiltration may also help. Diuretic resistance is sometimes observed; it may be overcome by the following procedures: in CHF by the use of digitalis and/or angiotensin-converting enzyme inhibitors; by substitution of an ineffective loop diuretic for another one; by using larger doses of diuretic; by intravenous infusion rather than bolus therapy, and by a combination of diuretics acting in different segments of the tubule: loop diuretic+thiazide+amiloride. Intravenous infusion of 20% albumin has also been suggested.

Chronic Disease↗

PubMedDate not supplied

[Acute and chronic effects of standard hemodialysis and soft hemodiafiltration on interdialytic serum phosphate levels].

INTRODUCTION: The dialytic management of hyper-phosphoremia, which is inadequate because of insufficient intra-dialytic removal of phosphate (P), is further limited by PDR-P, i.e. the significant increase in serum P levels during the early postdialytic period. Patients and methods. To investigate the effects of enhanced P removal by haemodiafiltration on the inter-dialytic phosphoremia, we studied 12 uremic patients that were switched, with cross-over randomised modality, to a single session of standard hemodialysis (HD) and hemodiafiltration (HDF) (Acute Study). Blood samples were obtained before the treatment, at the end (T0), after 30, 60, 90 and 120 minutes, and at 24, 48 and 68 hours. During both dialytic treatments the whole effluent dialysate was collected to evaluate the intradialytic removal of P. Thereafter, patients were randomised to receive either HD or HDF for three months, in the presence of constantly similar Kt/V, food intake and dose of phosphate binder (Chronic Study). RESULTS: Acute Study. Compared to HD, P removal in HDF was about 44% greater in the presence of identical predialytic P levels (6.0+/-0.2 and 5.9+/-0.4 mg/dl) and Kt/V (1.35+/-0.06 and 1.34+/-0.05); however, the inter-dialytic decline of serum P levels did not differ (-50+/-3% versus -42+/-3%, p=0.098). In HDF, PDR-P was faster (30 min versus 90 min) and better (at T120: +69+/-6% versus +31+/-4%, p<0.001). The higher P levels were maintained throughout the inter-dialytic period whereas Ca x P changed in parallel. Chronic Study. During the three months, pre-dialytic serum P diminished in HDF (from 5.8+/-0.2 to 4.4+/-0.3 mg/dl, p<0.05), while it remained unchanged in HD. A similar pattern of changes was detected in Ca x P. CONCLUSIONS: Enhancement of P removal, acutely amplifies the extent of PDR-P, but allows better control of Ca-P homeostasis in the medium term. This effect is likely to be dependent on the enhanced mobilisation of phosphate from a deep compartment.

Adult↗

PubMedDate not supplied

[Daily nutrient intake in hemodialysis].

BACKGROUND: Although there is a higher nutrient requirement, food intake in haemodialysis patients is often inadequate. Protein nitrogen appearance (PNA) indirectly estimates the mean protein intake during the short interdialysis period, but it does not measure the daily nutrient intake, which is generally unknown. We carried out a longitudinal study aimed at estimating the daily nutrient intake and its relationship with the nutritional status of haemodialysis patients. METHODS: We selected 28 haemodialysis patients with adequate nutritional status and no evidence of risk-factor for malnutrition. Patients were treated with biocompatible membranes, low-flux and high bicarbonate dialysis, Kt/V > 1.2, PNA > 1.1 g/kg/day and erythropoietin. We measured every four months daily PNA, protein and calorie intake (DPI, DCI) as well as weight gain (WG) during an entire week for one-year. The nutritional status was assessed by biochemical and BIA markers. RESULTS: Twenty seven subjects (8 F, 19 M; age 57.1 +- 2.7 yeas; dialysis age 105 +- 13 months) completed the trial. The mean interdialytic PNA did not change in both long- and short-interdialysis periods, resulting in the "normal" range (> 1.1 g/kg/day); however, daily levels of protein and calorie intake were significantly reduced on the third day during the long interdialysis interval. Eight patients showed time-averaged values of DPI and DCI lower than 0.8 g/kg/day and 25 Kcal/kg/day, respectively, on the third day (LOW group), values that were associated with similar changes in WG. Such a highly reduced nutrient intake during the third interdialysis day was associated with a normal PNA value (1.23 +- 0.05 g/kg/day vs 1.30 +- 0.06 in CON, NS) when measured during the short interdialysis period (S), just as it is in clinical practice; in contrast, when the PNA value was measured during the long interdialysis period it was found to be significantly reduced (1.07 +- 0.08 g/kg/day vs 1.37 +- 0.06 in CON, p < 0.05 and vs S, p < 0.05). During the study, the body weight progressively decreased from 68.0 +- 5.5 to 65.8 +- 5.9 kg (p < 0.05) in the LOW group, due to the decrease in lean body mass, as suggested by the reduction in serum creatinine (9.2 +- 1.1 vs 8.1 +- 0.7 mg/dL, p < 0.05), creatinine generation (835 +- 155 vs 723 +- 106 mg/die, p < 0.05) and serum albumin (3.96 +- 0.07 vs 3.66 +- 0.06 g/dL, p < 0.05). Moreover, reactance and phase angle declined in the LOW group (from 54 +- 4 to 44 +- 3 ohms, p < 0.05 and 5.5 +- 0.3 to 4.5 +- 0.3 degrees, p < 0.05, respectively). At the end of the study the nutritional status in the LOW group was reduced as compared to the CON group. CONCLUSIONS: In stable, well-nourished haemodialysis patients, in absence of known risk factors for malnutrition, the daily nutrient intake is variable and progressively reduce during the interdialytic interval. The measurement of interdialytic PNA, as is done in clinical practice, does not enable the discovery of such abnormal eating behaviour; the low daily nutrient intake, on the contrary, can be evidenced by the daily measurement of either PNA or weight gain, and it can also be inferred by the reduced PNA during the long interdialytic period. Finally, the persistent reduction in nutrient intake below the threshold of 0.8 g/kg/day of proteins and 25 Kcal/kg/day one day a week, is capable of inducing body protein wasting and moderate impairment of the nutritional status.

Dietary Proteins↗

PubMedDate not supplied

Management of hypertension in chronic kidney disease: the Italian multicentric study.

BACKGROUND: Guidelines have indicated the achievement of blood pressure target (BP <130/80 mmHg) as a priority in the conservative treatment of chronic kidney disease (CKD), but the current implementation of these recommendations in clinical practice is unknown. METHODS: We assessed control rates, treatment and clinical correlates of hypertension in 1201 adult non-dialyzed CKD patients followed up by a nephrologist for at least 6 months. RESULTS: Estimated glomerular filtration rate (GFR) was 32 (SD 15) mL/min/1.73 m2. BP target was not achieved in 88% of patients (95% confidence interval (95% CI): 86-90%). In 84% of patients, BP levels were also above the target at the first visit to the nephrology unit 4.5 yrs previously. The risk of not achieving BP target during the nephro-logy follow-up was associated with older age (odds ratio (OR): 1.24, 95% CI 1.06-1.45, p=0.008), diabetes (OR: 2.25, 95% CI 1.20-4.20, p=0.011), and the duration of hypertension (OR: 1.13, 95% CI 1.02-1.24, p=0.016). Among patients with uncontrolled BP, about 70% received multidrug antihypertensive therapy including renin-angiotensin system (RAS) inhibitors; conversely, diuretic treatment was prescribed in a minority of patients (37%), and at insufficient doses in half the cases, despite the insufficient implementation of a low salt diet (18%). CONCLUSIONS: BP target was not reached in most CKD patients routinely seen in the renal clinics. The main barrier to guideline implementation is possibly the inadequate treatment of extracellular volume expansion despite the large prevalence of factors, such as older age and diabetes, which further enhance the intrinsic BP salt sensitivity of CKD.

Aged↗

PubMedDate not supplied

[Hypertension in patients on hemodialysis: the role of salt intake].

In the 1960s, about 10% of hemodialysis (HD) patients had hypertension; the current percentage of hypertensive patients has risen to 70-75%. The scarce implementation of low-salt diets and the increment of dialysate sodium concentration aimed at ameliorating treatment tolerability are the main causes of the currently poor hypertension control. Considerable sodium intake activates a vicious circle: an increase in serum osmolarity, greater thirst and greater water intake, high inter-dialytic weight gains, need for large ultrafiltration rates, more frequent episodes of intradialytic hypotension, failure to achieve dry weight, progressive extra-cellular volume (ECV) expansion, and finally, blood pressure (BP) increase. Therefore, many studies have pointed out the importance of a low-salt diet in HD; it has been proven that the normalization of BP and ECV overload with a low-salt diet is associated with left ventricular hypertrophy regression and diastolic dysfunction improvement. Preparing meals with fresh foods, using spices, avoiding salt when cooking, and drastically limiting salty foods reduce dietary sodium down to about 6 g/day. Sodium intake during inter-dialytic periods can easily be assessed by measuring the changes in serum sodium concentration and in body weight.

Diet, Sodium-Restricted↗