Manuel Carlos Martins Castro

Obstetric Outcome in Pregnant Women on Long-term Dialysis: A Case Series

BACKGROUND Although still uncommon, pregnancy frequency in women on maintenance hemodialysis therapy has increased in the past 20 years. Most published reports suggest that intensified hemodialysis regimens result in better pregnancy outcomes. The small number of patients investigated in all reported series is the main limitation of the available studies. STUDY DESIGN Retrospective case series. SETTING & PARTICIPANTS Data for all pregnancies that occurred in 1988-2008 in women undergoing maintenance hemodialysis (52 pregnancies) at the São Paulo University Medical School (São Paulo, Brazil). OUTCOMES & MEASUREMENTS We analyzed maternal and fetal outcomes of 52 pregnancies, as well as their relationship with various clinical, laboratory, and hemodialysis parameters, such as pre-eclampsia, pregnancy before or after dialysis therapy, hemodialysis dose, polyhydramnios, anemia, and predialysis serum urea level. In addition, logistic regression models for a composite adverse fetal outcome (perinatal death or extremely premature delivery) and linear regression models for birth weight were built. RESULTS 87% overall rate of successful delivery, with a mean gestational age of 32.7 +/- 3.1 weeks. Pre-eclampsia was associated with a poor prognosis compared with pregnancies without pre-eclampsia: a successful delivery rate of 60% versus 92.9% (P = 0.02), extremely premature delivery rate of 77.8% versus 3.3% (P < 0.001), lower gestational age (P < 0.001), and birth weight (P < 0.001). Patients with an adverse composite fetal outcome had a higher frequency of pre-eclampsia (P < 0.001), lower frequency of polyhydramnios (P = 0.03), lower third-trimester hematocrit (P = 0.03), and higher predialysis serum urea level (P = 0.03). The same results were seen for birth weight. LIMITATIONS Retrospective data analysis. The absence of creatinine clearance measurements did not allow evaluation of the impact of residual renal function on fetal outcome. CONCLUSIONS Outcomes of pregnancy in women undergoing hemodialysis often are good. Pre-eclampsia, third-trimester hematocrit, polyhydramnios, and predialysis serum urea level are important variables associated with fetal outcome and birth weight.

Effects of bone remodelling on calcium mass transfer during haemodialysis

BACKGROUND During haemodialysis, calcium balance can affect, or be affected by, mineral metabolism. However, when dialysate calcium concentration (d[Ca]) is chosen or kinetic models are employed to calculate calcium balance, bone remodelling is rarely considered. In this study, we examined whether bone remodelling affects calcium mass transfer during haemodialysis. METHODS We dialysed 23 patients using a d[Ca] of 1.0, 1.25, 1.5 or 1.75 mmol/L. Calcium mass transfer was measured and associated with remodelling bone factors. RESULTS Calcium balance varied widely depending on the d[Ca]. Calcium removal was -578 +/- 389, -468 +/- 563, +46 +/- 400 and +405 +/- 413 mg when a d[Ca] of 1.0, 1.25, 1.5 or 1.75 mmol/L was used, respectively (1.0 and 1.25 vs 1.5 and 1.75 mmol/L, P < 0.001; 1.5 vs 1.75 mmol/L, P < 0.05). Univariate analysis showed that calcium balance correlated with calcium gradient, parathyroid hormone (PTH), osteocalcin and dialysis vintage. Multivariate analysis revealed that calcium balance was dependent on calcium gradient, PTH and osteocalcin. CONCLUSIONS These results suggest that bone remodelling could affect calcium mass transfer during haemodialysis.

Pruritus in hemodialysis patients: The problem remains

Pruritus is still one of the most common and disturbing symptoms of end‐stage renal disease. The objective of this study is to analyze the prevalence of pruritus in hemodialysis patients and the possible factors implicated in its genesis. In a cross‐sectional study, 101 patients on hemodialysis at our center were screened for pruritus. The relationship of various factors with pruritus was evaluated. Of the 101 patients included, 31(30.7%) had pruritus at the time of examination. Patients with pruritus were significantly older than those without pruritus (P=0.0027). Pruritus tended to be more prevalent in patients undergoing dialysis 3 times a week than in those undergoing daily dialysis, but the difference did not reach statistical significance (P=0.0854). Lower transferrin saturation levels were found in patients with pruritus than in those without pruritus (P=0.0144). C‐reactive protein levels were significantly higher in patients with pruritus than in those without pruritus (P=0.0013). There was no significant difference between the groups in the levels of the other inflammatory biomarkers measured. However, there was a tendency toward a correlation between the levels of α‐1‐glycoprotein and the intensity of pruritus (P=0.0834). Our results suggest a possible relationship of the inflammatory response upregulation to pruritus. Additionally, there was a positive relationship between pruritus and iron deficiency, possibly associated with inflammatory elevation of hepcidin. A better understanding of the factors implicated in the genesis of pruritus related to end‐stage renal disease is crucial in the development of more effective treatments for this symptom.

Arteriovenous fistula cannulation by buttonhole technique using dull needle

INTRODUCTION: Cannulation of arteriovenous fistula (AVF) may be performed by the following techniques: area puncture, rope ladder, or buttonhole. The ideal technique has not yet been established. OBJECTIVE: To assess the complications and difficulties of introducing the buttonhole (BH) technique for cannulation of AVF created with a native vein in a dialysis unit. METHODS: Sixteen patients (mean age, 57 ± 14 years) undergoing hemodialysis for 63 ± 38 months were changed to BH AVF cannulation. In the phase of track formation cannulations were performed with sharp needles and, in the maintenance phase, with blunt needles. In both phases, patients were assessed for pain intensity on a 0 to 10 scale. RESULTS: The number of HD sessions required for the track formation was 9.5 ± 1.5 and the number of sessions during the maintenance phase was 29.7 ± 0.8 per patient. During the 152 HD for the track formation, no significant complications occurred. During the 475 HD sessions using the BH technique and a blunt needle, the complications were as follows: resistance to cannulation (7.6%); cannulation using a sharp needle due to cannulator choice (5.7%); change from a blunt to a sharp needle during cannulation (4.2%); and local bleeding (0.8%). One patient required antibiotic therapy. The median pain intensity reported by the patients was four during the track formation, and two during cannulation with a blunt needle. The Kt/V values before and after changing the cannulation technique did not differ (1.48 ± 0.27 and 1.48 ± 0.23). CONCLUSION: The introduction of the BH technique with a blunt needle is technically easy, has few complications, reduces pain, and does not induce change in dialysis dose.

Obstructive sleep apnea in patients on conventional and short daily hemodialysis.

Obstructive sleep apnea (OSA) is common among patients on maintenance hemodialysis. However, the factors associated with the origin of OSA as well as the cardiovascular consequences in this population are not completely understood. We evaluated, by standard overnight polysomnography, 24-hour ambulatory blood pressure (BP) monitoring and echocardiography in 30 patients (14 males, age 34 ± 11 years, BMI 23.2 ± 5.2) – 15 on short daily hemodialysis (SDH) and 15 matched patients on conventional hemodialysis (CHD). The hemodialysis dose (standard Kt/V) was higher in patients on SDH than on CHD (p = 0.001). OSA (apnea-hypopnea index >5 events/h) was present in 13 patients (43%). Patients with OSA were predominantly males (77 vs. 44%), presented a higher BMI (25.5 ± 6.2 vs. 21.5 ± 3.6), a larger neck circumference (38 ± 1 vs. 34 ± 1 cm) and a lower Kt/V (2.6 ± 0.3 vs. 2.2 ± 0.1) than patients with no OSA (p < 0.05). Neck circumference and lower Kt/V were independently associated with OSA on multivariate analysis. No patient with Kt/V >2.5 (n = 10) presented OSA. On the other hand, hypertensive patients with OSA needed more BP control pills (p = 0.03). Despite similar BP control, patients with OSA presented a higher interventricular septum thickness (11.5 ± 0.5 vs. 9.9 ± 0.3 mm; p = 0.011). In conclusion, among patients on maintenance hemodialysis, the traditional risk factors for OSA are present and interact with hemodialysis efficiency. Among these patients, OSA is associated with difficult BP control and heart remodeling suggesting that OSA may contribute to poor cardiovascular outcome.

Characterization of acid-base status in maintenance hemodialysis: physicochemical approach

Acidosis is a common and deleterious aspect of maintenance dialysis. Traditionally, it is considered to be an elevated anion gap acidosis caused by the inability to excrete nonvolatile anions. Stewart’s approach made it possible to identify real determinants of the acid-base status and allowed quantification of the components of these disturbances, especially the unmeasured anions. We performed a cross-sectional study to identify and quantify each component of acidosis in hemodialysis maintenance patients. Sixty-four maintenance hemodialysis patients and 14 controls were enrolled in this study. Gasometrical and biochemical analysis were performed before the midweek dialysis session. Quantitative physicochemical analysis was carried out using the Stewart methodology. Hemodialysis patients were found to have mild acidemia (mean pH: 7.33 ± 0.06 versus 7.41 ± 0.05) secondary to metabolic acidosis (serum bicarbonate: 18.8 ± 0.26 versus 25.2 ± 0.48 mEq/l). The metabolic acidosis was due to retention of unmeasured anions (6.5 ± 0.29 versus 3.1 ± 0.62 mEq/l), hyperchloremia (105.1 ± 0.5 versus 101.8 ± 0.7 mEq/l), and hyperphosphatemia (5.90 ± 0.19 versus 3.66 ± 0.14 mg/dl). Compared with control values, the unmeasured anions and hyperchloremia had a similar acidifying effect (3.4 and 3.3 mEq/l), corresponding to almost 90% of the metabolic acidosis. Unmeasured anions and hyperchloremia are important components of acidosis in maintenance hemodialysis, in addition to phosphorus. Future studies to determine the etiology and consequences of hyperchloremic acidosis are warranted.

Prevention of hypertension attenuates albuminuria and renal expression of fibronectin in diabetic spontaneously hypertensive rats.

Background/Aim: The aim of this study was to evaluate the effect of preventing hypertension on renal disease in a model of genetic hypertension and diabetes. Methods:Four-week-old spontaneously hypertensive rats (SHR) with streptozotocin-induced diabetes were randomized for no treatment, or for treatment with captopril, losartan or triple therapy (hydrochlorothiazide, reserpine and hydralazine) for 16 weeks. Results: Increase in systolic blood pressure was equally prevented by captopril (128 ± 3 mm Hg), losartan (128 ± 2) and triple therapy (129 ± 2, p < 0.0001). Albuminuria was similarly reduced by captopril (499 (404–659)), losartan (622 (470–976)) and triple therapy (479 (362–600) µg/24 h (p < 0.0001)). Renal fibronectin expression increased in diabetic SHR (125 ± 13 densitometric unit) as compared to the controls (51 ± 9, p < 0.0001), and decreased (p < 0.0001 vs. diabetic SHR) with captopril (32 ± 8), losartan (27 ± 4) and triple therapy (35 ± 6). Conclusion: The prevention of hypertension in diabetic SHR by captopril, losartan or triple therapy was equally efficacious in impeding increase of albuminuria and the expression of renal fibronectin. Under these conditions, tight blood pressure control was the main determinant in attenuating nephropathy.

The perception of sleep quality in kidney transplant patients during the first year of transplantation

OBJECTIVE: Poor sleep quality is one of the factors that adversely affects patient quality of life after kidney transplantation, and sleep disorders represent a significant cardiovascular risk factor. The objective of this study was to investigate the prevalence of changes in sleep quality and their outcomes in kidney transplant recipients and analyze the variables affecting sleep quality in the first years after renal transplantation. METHODS: Kidney transplant recipients were evaluated at two time points after a successful transplantation: between three and six months (Phase 1) and between 12 and 15 months (Phase 2). The following tools were used for assessment: the Pittsburgh Sleep Quality Index; the quality of life questionnaire Short-Form-36; the Hospital Anxiety and Depression scale; the Karnofsky scale; and assessments of social and demographic data. The prevalence of poor sleep was 36.7% in Phase 1 and 38.3% in Phase 2 of the study. RESULTS: There were no significant differences between patients with and without changes in sleep quality between the two phases. We found no changes in sleep patterns throughout the study. Both the physical and mental health scores worsened from Phase 1 to Phase 2. CONCLUSION: Sleep quality in kidney transplant recipients did not change during the first year after a successful renal transplantation.

Reprocessing high-flux polysulfone dialyzers does not negatively impact solute removal in short-daily online hemodiafiltration

There are no studies evaluating the impact of dialyzer reprocessing on solute removal in short‐daily online hemodiafiltration (OL‐HDF). Our aim was to evaluate the impact of dialyzer reuse on solute removal in daily OL‐HDF and compare with that in high‐flux short‐daily hemodialysis (SDH). Fourteen patients undergoing a SDH program were included. Pre‐dialysis and post‐dialysis blood samples and effluent dialysate were collected in the 1st, 7th, and 13th dialyzer uses in SDH sessions and in daily OL‐HDF sessions. Directly quantified small solute (urea, phosphorus, creatinine, and uric acid) total mass removal (TMDQ) and clearance (KDQ) were similar when the 1st, 7th, and 13th dialyzer SDH uses were compared with the 1st, 7th, and 13th daily OL‐HDF uses. TMDQ and KDQ of small solutes were similar among analyzed dialyzer uses in SDH sessions and in daily OL‐HDF sessions. β2‐Microglobulin TMDQ and KDQ were statistically higher in daily OL‐HDF dialyzer uses than in the respective SDH uses. There was no difference in β2‐microglobulin TMDQ and KDQ among dialyzer uses in daily OL‐HDF sessions or in SDH sessions. In daily OL‐HDF, albumin loss was significantly different among dialyzer uses (P < 0.001), being lower in the 7th and 13th dialyzer uses than in the first use. Dialyzer reprocessing did not impair solute extraction in daily OL‐HDF. β2‐Microglobulin removal was greater in daily OL‐HDF than in SDH sessions, without significant differences in other solutes extraction. There was a significant reduction in intradialytic albumin loss with dialyzer reprocessing in daily OL‐HDF sessions.

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.