Andreas Pierratos

Improvement of Sleep Apnea in Patients with Chronic Renal Failure Who Undergo Nocturnal Hemodialysis

BACKGROUND Sleep apnea is common in patients with chronic renal failure and is not improved by either conventional hemodialysis or peritoneal dialysis. With nocturnal hemodialysis, patients undergo hemodialysis seven nights per week at home while sleeping. We hypothesized that nocturnal hemodialysis would correct sleep apnea in patients with chronic renal failure because of its greater effectiveness. METHODS Fourteen patients who were undergoing conventional hemodialysis for four hours on each of three days per week underwent overnight polysomnography. The patients were then switched to nocturnal hemodialysis for eight hours during each of six or seven nights a week. They underwent polysomnography again 6 to 15 months later on one night when they were undergoing nocturnal hemodialysis and on another night when they were not. RESULTS The mean (+/-SD) serum creatinine concentration was significantly lower during the period when the patients were undergoing nocturnal hemodialysis than during the period when they were undergoing conventional hemodialysis (3.9+/-1.1 vs. 12.8+/-3.2 mg per deciliter [342+/-101 vs. 1131+/-287 micromol per liter], P<0.001). The conversion from conventional hemodialysis to nocturnal hemodialysis was associated with a reduction in the frequency of apnea and hypopnea from 25+/-25 to 8+/-8 episodes per hour of sleep (P=0.03). This reduction occurred predominantly in seven patients with sleep apnea, in whom the frequency of episodes fell from 46+/-19 to 9+/-9 per hour (P= 0.006), accompanied by increases in the minimal oxygen saturation (from 89.2+/-1.8 to 94.1+/-1.6 percent, P=0.005), transcutaneous partial pressure of carbon dioxide (from 38.5+/-4.3 to 48.3+/-4.9 mm Hg, P=0.006), and serum bicarbonate concentration (from 23.2+/-1.8 to 27.8+/-0.8 mmol per liter, P<0.001). During the period when these seven patients were undergoing nocturnal hemodialysis, the apnea-hypopnea index measured on nights when they were not undergoing nocturnal hemodialysis was greater than that on nights when they were undergoing nocturnal hemodialysis, but it still remained lower than it had been during the period when they were undergoing conventional hemodialysis (P=0.05). CONCLUSIONS Nocturnal hemodialysis corrects sleep apnea associated with chronic renal failure.

The effects of frequent nocturnal home hemodialysis: the Frequent Hemodialysis Network Nocturnal Trial

Prior small studies have shown multiple benefits of frequent nocturnal hemodialysis compared to conventional three times per week treatments. To study this further, we randomized 87 patients to three times per week conventional hemodialysis or to nocturnal hemodialysis six times per week, all with single-use high-flux dialyzers. The 45 patients in the frequent nocturnal arm had a 1.82-fold higher mean weekly stdKt/V(urea), a 1.74-fold higher average number of treatments per week, and a 2.45-fold higher average weekly treatment time than the 42 patients in the conventional arm. We did not find a significant effect of nocturnal hemodialysis for either of the two coprimary outcomes (death or left ventricular mass (measured by MRI) with a hazard ratio of 0.68, or of death or RAND Physical Health Composite with a hazard ratio of 0.91). Possible explanations for the left ventricular mass result include limited sample size and patient characteristics. Secondary outcomes included cognitive performance, self-reported depression, laboratory markers of nutrition, mineral metabolism and anemia, blood pressure and rates of hospitalization, and vascular access interventions. Patients in the nocturnal arm had improved control of hyperphosphatemia and hypertension, but no significant benefit among the other main secondary outcomes. There was a trend for increased vascular access events in the nocturnal arm. Thus, we were unable to demonstrate a definitive benefit of more frequent nocturnal hemodialysis for either coprimary outcome.

Short-Term Blood Pressure, Noradrenergic, and Vascular Effects of Nocturnal Home Hemodialysis

Abstract—Long-term nocturnal hemodialysis, which uses longer and more frequent sessions than conventional hemodialysis, lowers clinic blood pressure and left ventricular mass. We tested the hypotheses that short-term nocturnal hemodialysis would (1) reduce ambulatory blood pressure; (2) cause peripheral vasodilation; (3) lower plasma norepinephrine concentration; and (4) improve the arterial response to reactive hyperemia (a marker of endothelium-dependent vasodilation). We studied 18 consecutive patients (age, 41±2; [mean±SEM]) before and 1 and 2 months after conversion from conventional (three 4-hour sessions per week) to nocturnal (six 8-hour sessions per week) hemodialysis. As the dialysis dose per session (Kt/V) increased from 1.24±0.06 to 2.04±0.08 after 2 months (P =0.02), symptomatic hypotension developed and most antihypertensive medications were withdrawn. Nocturnal hemodialysis nonetheless lowered 24-hour mean arterial pressure (from 102±3 to 90±2 mm Hg after 2 months; P =0.01), total peripheral resistance (from 1967±235 to 1499±191 dyne · s · cm−5; P <0.01) and plasma norepinephrine (from 2.66±0.4 to 1.96±0.2 nmol; P =0.04). Endothelium-dependent vasodilation could not be elicited during conventional hemodialysis (−2.7±1.8%) but was restored (+8.0±1.0%; P =0.001) after 2 months of nocturnal hemodialysis. The brachial artery response to nitroglycerin also improved (from 6.9±2.8 to 15.7±1.6%; P <0.05). Nocturnal hemodialysis had no effect on weight or on stroke volume. Rapid reversal of these markers of adverse cardiovascular events with more intense hemodialysis may translate into improved outcome in this high-risk group of patients.

Intensive Hemodialysis Associates with Improved Survival Compared with Conventional Hemodialysis

Patients undergoing conventional maintenance hemodialysis typically receive three sessions per week, each lasting 2.5-5.5 hours. Recently, the use of more intensive hemodialysis (>5.5 hours, three to seven times per week) has increased, but the effects of these regimens on survival are uncertain. We conducted a retrospective cohort study to examine whether intensive hemodialysis associates with better survival than conventional hemodialysis. We identified 420 patients in the International Quotidian Dialysis Registry who received intensive home hemodialysis in France, the United States, and Canada between January 2000 and August 2010. We matched 338 of these patients to 1388 patients in the Dialysis Outcomes and Practice Patterns Study who received in-center conventional hemodialysis during the same time period by country, ESRD duration, and propensity score. The intensive hemodialysis group received a mean (SD) 4.8 (1.1) sessions per week with a mean treatment time of 7.4 (0.87) hours per session; the conventional group received three sessions per week with a mean treatment time of 3.9 (0.32) hours per session. During 3008 patient-years of follow-up, 45 (13%) of 338 patients receiving intensive hemodialysis died compared with 293 (21%) of 1388 patients receiving conventional hemodialysis (6.1 versus 10.5 deaths per 100 person-years; hazard ratio, 0.55 [95% confidence interval, 0.34-0.87]). The strength and direction of the observed association between intensive hemodialysis and improved survival were consistent across all prespecified subgroups and sensitivity analyses. In conclusion, there is a strong association between intensive home hemodialysis and improved survival, but whether this relationship is causal remains unknown.

Survival among nocturnal home haemodialysis patients compared to kidney transplant recipients

BACKGROUND Kidney transplantation is the gold standard renal replacement therapy. Nocturnal haemodialysis (NHD) is an intensive dialysis modality (6-8 h/session, 3-7 sessions/week) associated with a significant improvement of clinical and biochemical parameters compared to conventional dialysis. To date, no studies have compared survival in patients treated with NHD and kidney transplantation. METHODS Using data from two regional NHD programmes and the USRDS from 1994 to 2006, we performed a matched cohort study comparing survival between NHD and deceased and living donor kidney transplantation (DTX and LTX) by randomly matching NHD patients to transplant recipients in a 1:3:3 ratio. The independent association of treatment modality with survival was determined using Cox multivariate regression. RESULTS The total study population consisted of 177 NHD patients matched to 1062 DTX and LTX recipients (total 1239 patients) followed for a maximum of 12.4 years. During the follow-up period, the proportion of deaths among NHD, DTX and LTX patients was 14.7%, 14.3% and 8.5%, respectively (P = 0.006). We found no difference in the adjusted survival between NHD and DTX (HR 0.87, 95% CI 0.50-1.51; NHD reference group), while LTX survival was better (HR 0.51, 95% CI 0.28-0.91). CONCLUSIONS These results indicate that NHD and DTX survival is comparable, and suggest that this intensive dialysis modality may be a bridge to transplantation or even a suitable alternative in the absence of LTX in the current era of growing transplant waiting lists and organ shortage.

Successful Pregnancies on Nocturnal Home Hemodialysis

BACKGROUND AND OBJECTIVES Women of childbearing age on conventional hemodialysis (CHD) have decreased fertility when compared with the general population. Even in women who conceived, maternal morbidity and fetal mortality remained elevated. We hypothesized that nocturnal hemodialysis (NHD) (3 to 6 sessions per week, 6 to 8 h per treatment), by augmenting uremic clearance, leads to a more hospitable maternal environment and therefore superior outcomes in fertility and pregnancy compared with CHD. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS This is a descriptive cohort study of all female patients achieving pregnancy and delivering a live infant while on NHD at the University Health Network, St. Michaels Hospital, and Humber River Regional Hospital from 2001 to 2006 in Toronto, Canada. Our primary objective was to describe maternal and fetal outcomes in addition to the changes in biochemical parameters after conception in our cohort. RESULTS Our cohort included five patients (age range, 31 to 37 yr) who had seven pregnancies while on NHD and delivered six live infants. All had previously been on CHD, but none conceived during that time. In all patients, the amount of hemodialysis was increased (from a weekly mean of 36 +/- 10 to 48 +/- 5 h; P < 0.01) after pregnancy was diagnosed. Mean predialysis blood urea and mean arterial BP were maintained within normal physiological parameters. The mean gestational age of the cohort was 36.2 +/- 3 wk and the mean birth weight was 2417.5 +/- 657 g. The maternal and fetal complications observed in the cohort included intrauterine growth restriction or small for gestational age (n = 2), preterm delivery (<32 wk) (n = 1), and shortened cervix threatened labor (n = 1). Anemia was accentuated during pregnancy, and intravenous iron and erythropoietin requirements were increased. To maintain normal physiological indices for plasma phosphate, an augmented dialysate phosphate supplementation regimen was required. CONCLUSIONS NHD may allow for improved fertility. Delivering a live infant at a mature gestational age is feasible for patients on NHD. Our cohort tended to have fewer maternal and fetal complications compared with historical controls. Hemoglobin and phosphate levels must be monitored with treatment adjusted accordingly.

Continuous Ambulatory Peritoneal Dialysis in Diabetics with End-Stage Renal Disease

Twenty diabetics with end-stage renal disease who had never previously received dialysis treatment were treated with continuous ambulatory peritoneal dialysis for periods of two to 36 months (average, 14.5). Intraperitoneal administration of insulin achieved good control of blood sugar. Even though creatinine clearance decreased significantly (P = 0.001), control of blood urea nitrogen and serum creatinine was adequate. Hemoglobin and serum albumin levels increased significantly (P = 0.005 and 0.04, respectively). Similarly, there was a significant increase in serum triglycerides and alkaline phosphatase (P = 0.02 and 0.05). Blood pressure became normal without medications in all but one of the patients. Retinopathy, neuropathy, and osteodystrophy remained unchanged. Peritonitis developed once in every 20.6 patient-months--a rate similar to that observed in nondiabetics. The calculated survival rate was 93 per cent at one year; the calculated rate of continuation on ambulatory peritoneal dialysis was 87 per cent. We conclude that continuous ambulatory dialysis with intraperitoneal administration of insulin is a good alternative treatment for diabetics with end-stage renal disease.

Enhanced chemo-responsiveness in patients with sleep apnoea and end-stage renal disease

Although sleep apnoea is very common in patients with end-stage renal disease, the physiological mechanisms for this association have not yet been determined. The current authors hypothesised that altered respiratory chemo-responsiveness may play an important role. In total, 58 patients receiving treatment with chronic dialysis were recruited for overnight polysomnography. A modified Read rebreathing technique, which is used to assess basal ventilation, ventilatory sensitivity and threshold, was completed before and after overnight polysomnography. Patients were divided into apnoeic (n = 38; apnoea/hypopnoea index (AHI) 35±22 events·h-1) and nonapnoeic (n = 20; AHI 3±3 events·h-1) groups, with the presence of sleep apnoea defined as an AHI >10 events·h-1. While basal ventilation and the ventilatory recruitment threshold were similar between groups, ventilatory sensitivity during isoxic hypoxia (partial pressure of oxygen (PO2) 6.65 kPa) and hyperoxia (PO2 19.95 kPa) was significantly greater in apnoeic patients. Overnight changes in chemoreflex responsiveness were similar between groups. In conclusion, these data indicate that the responsiveness of both the central and peripheral chemoreflexes is augmented in patients with sleep apnoea and end-stage renal disease. Since increased ventilatory sensitivity to hypercapnia destabilises respiratory control, the current authors suggest this contributes to the pathogenesis of sleep apnoea in this patient population.

Intensive Hemodialysis Associates with Improved Pregnancy Outcomes: A Canadian and United States Cohort Comparison

Pregnancy is rare in women with ESRD and when it occurs, it is often accompanied by significant maternal and fetal morbidity and even mortality. Preliminary data from the Toronto Nocturnal Hemodialysis Program suggested that increased clearance of uremic toxins by intensified hemodialysis improves pregnancy outcomes, but small numbers and the absence of a comparator group limited widespread applicability of these findings. We compared pregnancy outcomes from 22 pregnancies in the Toronto Pregnancy and Kidney Disease Clinic and Registry (2000-2013) with outcomes from 70 pregnancies in the American Registry for Pregnancy in Dialysis Patients (1990-2011). The primary outcome was the live birth rate and secondary outcomes included gestational age and birth weight. The live birth rate in the Canadian cohort (86.4%) was significantly higher than the rate in the American cohort (61.4%; P=0.03). Among patients with established ESRD, the median duration of pregnancy in the more intensively dialyzed Toronto cohort was 36 weeks (interquartile range, 32-37) compared with 27 weeks (interquartile range, 21-35) in the American cohort (P=0.002). Furthermore, a dose response between dialysis intensity and pregnancy outcomes emerged, with live birth rates of 48% in women dialyzed ≤20 hours per week and 85% in women dialyzed >36 hours per week (P=0.02), with a longer gestational age and greater infant birth weight for women dialyzed more intensively. Pregnancy complications were few and manageable. We conclude that pregnancy may be safe and feasible in women with ESRD receiving intensive hemodialysis.

Effects of frequent hemodialysis on measures of CKD mineral and bone disorder.

More frequent hemodialysis sessions and longer session lengths may offer improved phosphorus control. We analyzed data from the Frequent Hemodialysis Network Daily and Nocturnal Trials to examine the effects of treatment assignment on predialysis serum phosphorus and on prescribed dose of phosphorus binder, expressed relative to calcium carbonate on a weight basis. In the Daily Trial, with prescribed session lengths of 1.5-2.75 hours six times per week, assignment to frequent hemodialysis associated with both a 0.46 mg/dl decrease (95% confidence interval [95% CI], 0.13-0.78 mg/dl) in mean serum phosphorus and a 1.35 g/d reduction (95% CI, 0.20-2.50 g/d) in equivalent phosphorus binder dose at month 12 compared with assignment to conventional hemodialysis. In the Nocturnal Trial, with prescribed session lengths of 6-8 hours six times per week, assignment to frequent hemodialysis associated with a 1.24 mg/dl decrease (95% CI, 0.68-1.79 mg/dl) in mean serum phosphorus compared with assignment to conventional hemodialysis. Among patients assigned to the group receiving six sessions per week, 73% did not require phosphorus binders at month 12 compared with only 8% of patients assigned to sessions three times per week (P<0.001). At month 12, 42% of patients on nocturnal hemodialysis required the addition of phosphorus into the dialysate to prevent hypophosphatemia. Frequent hemodialysis did not have major effects on calcium or parathyroid hormone concentrations in either trial. In conclusion, frequent hemodialysis facilitates control of hyperphosphatemia and extended session lengths could allow more liberal diets and freedom from phosphorus binders.