A Comparison of SleepDisordered Respiration in ESRD Patients Receiving Hemodialysis and Peritoneal Dial ysis

N.K. Wadhwal, W.B. Mendelson2

Study Objective: To compare sleep-disordered respiration in ESRD patients receiving peritoneal dialysis and hemodialysis .

Design: Subjective and objective measures of sleep were recorded in two groups of ESRD patients receiving PD andHD.

Setting: Tertiary-referral university hospital

Patients and Methods: Fifteen PD patients ( 12 males, 3 females) and 15 HD patients ( 11 males, 4 females) were studiedfor two nights in the sleep laboratory.

Results: Ten of the 15 PD patients and 8 of the 15 HD patients reported multiple types of sleep difficulties (NS). In the PD group, seven described substantial difficulty initially going to sleep; ten were troubled by awakenings during the night, while seven sufferedfrom daytime sleepiness. In the HD group, seven described substantial difficulty initially going to sleep; eight were troubled by awakenings during the night. while five experienced daytime sleepiness.

No significant difference was observed in total sleep time , intermittent wake time, sleep latency, sleep efficiency, total disordered breathing events, minimum oxygen saturation and periodic leg movements between the PD and HD groups.

Sleep apnea was noted in 9 of 15 PD and 8 of 15 HD patients.

Conclusions: This study indicates that the incidence and severity of sleep apnea is similar in ESRD patients receiving chronic peritoneal dialysis and hemodialysis.

Key words

Peritoneal dialysis, hemodialysis, sleep apnea syndrome, respiration, oxygen saturation, oxygen desaturation

From:

Division of Nephrology and Hypertensionl, Dept. of Medicine, State University of New York at Stony Brook, and Dept. of Psychiatry and Sleep Disorders Center, State University of New York at Stony Brook.

Introduction

Descriptions of the uremic patient have traditionally included disturbed nocturnal sleep and daytime sleepiness (1-3). Polygraphic studies have reported diminished sleep efficiency, increased fragmentation and decreased slow-wave sleep (4-5). Whether hemodialysis improves these nonspecific sleep changes in the long term is not clear. The effects of chronic peritoneal dialysis (PD) on sleep have only begun to be explored. One study found that peritoneal dialysate contained both Factor S and Interleukin-l, which are thought to enhance sleep (6). This raises the possibility that PD patients might suffer poor sleep resulting from removal of natural sleep-promoting substances. Similarly, the bulk effect of large volumes of peritoneal dialysate on respiratory function during sleep continues to need further clarification. One recent study from this laboratory has indicated that the presence of dialysate has little effect on patients with normal respiration during sleep, but may result in greater arterial oxygen desaturation in patients with pre-existing sleep-disordered breathing (7). Insofar as 50-60 percent of HD and PD patients may have sleep-disordered breathing (7-8), such effects of PD on respiration are of some concern. Although case series are available for examining sleep and respiration in hemodialysis (8) and peritoneal dialysis patients (7), there have been no available data comparing the two groups. In principle, peritoneal dialysis might have different consequences than hemodialysis by removing putative sleep factors as described above, by removing a larger percentage of middle molecules which may be associated with disturbed sleep (9) or by having a different time course of altering blood pH. For these reasons in the present study we compared respiratory variables as well as subjective and objective measures of sleep in matched groups of HD and PD patients.

Patients and methods

Fifteen PD patients (12 males, 3 females; mean age 57.7 :t 4.0 years) and 15 HD patients (11 males, 4 females; mean age 56.3 :t 5.4 years) were studied for two nights in the sleep laboratory .Arterial blood gases were drawn at 9:00 P .M. on the study nights, in order to determine any possible relationship between waking blood gases and sleep-related respiration. Complete blood count, renal and hepatic profiles were drawn in the morning following the fust night.

In order to assess reported habitual sleep patterns, patients completed a Sleep Habit Questionnaire ( 1011 ). A Morning Sleep Questionnaire was administered upon awakening on both nights.

Polysomnography using a Grass Model 7 polygraph with a paper speed of 10 mm/sec. and calibrated to 50 microvolts/1 0 mm was carried out using standard techniques, and provided measures of sleep architecture and respiration (12). Physiologic measures included nasal and oral thermistor channels, chest and abdominal respiratory movement (Respitrace-R), arterial oxygen saturation (earlobe oximetry), electrocardiogram, anterior tibialis electromyogram, electroencephalogram (leads: C3-A2 and OI-A2) and submental electromyogram. Disordered breathing events (DBEs) were comprised of central and obstructive apneas and hypopneas. Apneas were defined as events in which there was complete cessation of air flow in the nasal and oral thermistor channels for at least 10 seconds duration, accompanied by a drop of at least 5% in arterial oxygen saturation. Hypopneas comprised similar events in which air flow in the thermistor channels decreased to one-third or more of the basal level. Obstructive events were considered to be those in which there was evidence of paradoxical ventilatory movement detected from the chest and abdominal strain gauges. Among the parameters considered were the number and mean duration of each type of event in total, nonREM and REM sleep, as well as the average and absolute minimum arterial oxygen saturation. The total time spent in DBEs (apneas and hypopneas) was determined, and the percentage of this time spent in each type of DBE (obstructive or central) was calculated. Patients with a disordered breathing event index (number of apneas and/or hypopneas per hour of sleep) five or more were considered to have sleep apnea syndrome. All polysomnographic recordings were interpreted by one "blind" investigator.

Statistical methods included two-tailed Student's t-test and Fisher's exact probability test. A probability value of < 0.05 was taken as the level of significance. Data are reported as mean :t SEM.

Results
Demographic and laboratory data

Five patients in the PD group had diabetes mellitus, as did three patients in the HD group. Hematocrits were significantly (p<0.05) higher in PD patients (32.3 :t 2.2) in comparison to HD patients as a group (25.8 :t 1.2; Table I); this difference was not apparent when only those patients with sleep apnea were considered. There was no significant difference in the mean age, mean dry weight and mean duration of dailysis in PD and HD patients (Table I). The waking arterial blood gases were similar in both groups (Table II).

Subjective measures of sleep

Analysis of the Sleep Habit Questionnaire showed no significant differences between the two groups. Ten of the 15 PD patients and 8 of the 15 HD patients reported multiple types of sleep difficulties. In the PD group, seven described substantial difficulty initially going to sleep; ten were troubled by awakenings during the night, while seven were troubled by daytime sleepiness. In the HD group, seven described substantial difficulty initially going to sleep; eight were troubled by awakenings during the night, while five by daytime sleepiness.

Polysomnographic data

Although there was evidence of sleep disturbance in both groups, there were no significant differences in polygraphic measures between the HD and PD patients (Table II). PD patients fell asleep in 15.0 I 3.5 minutes and HD patients fell asleep in 12.2 I 2.5 minutes (NS). Their sleep efficiencies (total sleep time/total recording time in bed) were 72.8 I 3.6 percent and 74.3 I 3.1 percent in PD and HD group respectively. Waking time after sleep onset (a measure of sleep disturbance) was 104.5 I 14.7 and 89.1 I 12.8 minutes respectively (NS). There were no significant differences between any measures of sleep-related respiration between the two groups. The patients had substantial numbers of periodic leg movements (82 I 25 and 91 I 33) in the PD and HD groups respectively (NS).

Of the 15 PD patients, significant sleep apnea was found in nine, of which six were primarily obstructive. Eight of 15 patients in HD had sleep apnea, all primarily obstructive. Interestingly, the frequency of periodic leg movements and measures of sleep related respiration including the number, rate, type and duration of disordered breathing events and mean minimum arterial oxygen saturation did not significantly differ between the two groups. In the apneic patients as a group the mean percentage of total disordered breathing time comprised of obstructive events did not differ between the two groups, nor was there a difference in the distribution of events in nonREM and REM sleep.

There was no significant relationship between serum BUN, creatinine, or hematocrit, and waking arterial blood gases or sleep-related respiratory variabies, in either patient group as a whole or the subgroup of apneic patients.

Discussion

In summary , these data confirm previous reports (78,13) that 50-60 percent of ESRD patients have significant sleep apnea and indicate that there are not significant differences in sleep and sleep-related respiration between those receiving PD and HD. Although periodic leg movements frequently appear in ESRD patients (7,8,13), there was no difference in the total number of PLMs in the two dialysis groups. The only clinically significant difference between the two groups was the higher hematocrit in the PD patients; this difference was not apparent when those patients with sleep apnea in the two groups were compared. These data suggest that any differences in rate of change of pH or in percentage of solutes removed by the two methods of dialysis are not relevant to the subjective and objective measure of sleep in these patients.

Acknowledgment

The authors appreciate the excellent assistance of the dialysis staff (in-center and home-program): Ms. Joann Hallisey, Ms. Fran Weiner, Ms. Nancy Howell, Ms. Karen Martin, Mr .Jim Cullinan, Ms. Jeanne Dawson, Ms. Gail Holden, Ms. Denise Parsons, Ms. Belinda Rivera, Ms. Joan Hudson and Charlotte Slintak R.N.C.

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Corresponding author:
Nand K Wadhwa, MD, MRCP, Division of Nephrology and Hypertension, HSC, T-15, Room 020, Stony Brook, New York 11794-8152.