A 49-year-old man on maintenance hemodialysis, diagnosed with severe OSA was treated successfully with bilevel pressure therapy dropping his ESS score from 20 down to 6.

By Daniel B. Carlsen

Occasionally, a patient is studied via nocturnal polysomnography and either the diagnosis or the result of therapeutic intervention produces more questions, and outlines needed areas of further investigation on a larger scale. This case report involves a dialysis patient who was diagnosed with severe obstructive sleep apnea (OSA) and successfully treated with nasal continuous positive airway pressure (NCPAP). This article is not intended to identify specific trends in the area of sleep disorders within the hemodialysis patient population; however, it does highlight the need for more data about dialysis patient sleep quality, and reinforces the possibility that sleep disorders among that group are more widespread than commonly thought.

The National Kidney Foundation (NKF) reports that more than 378,000 Americans suffer from chronic kidney failure and need maintenance hemodialysis or peritoneal dialysis to survive.¹ The NKF further reveals that diabetes is apparently the leading cause of kidney failure, followed by hypertension. Dialysis procedures simulate normal kidney function at intervals of daily, nightly, or two to three times per week. These procedures accomplish the removal of excess body water; removal of waste products such as blood urea, nitrogen, and creatinine; normalization of blood pH; and normalization of electrolytes such as potassium, sodium, and calcium.

A literature search on the topics of dialysis and sleep disorders yields remarkably little information and existing research; however, statistical data is emerging from smaller samples of studied dialysis patients. Most noteworthy is the suggestion that OSA may occur within at least 60% of end-stage renal disease (ESRD) patients.² This provokes the question of whether OSA is underdiagnosed within the dialysis patient population.

OSA is not the only sleep disorder identified more frequently within the dialysis group. A German study of 69 ESRD patients treated with hemodialysis reveals that 67% complained of sleep disorders in general.³ Chief complaints within this group include periodic leg movement syndrome (PLMS), restless legs syndrome (RLS), insomnia, snoring, and sleep apnea. Additionally, in a study of 694 Italian maintenance hemodialysis patients, 45% complained of insomnia, defined either by delayed sleep onset or by nighttime waking.⁴

Poor sleep quality is common among dialysis patients and is associated with lower health-related quality of life.⁵ If OSA is one of the more prevalent sleep disorders within the dialysis patient population, perhaps screening for OSA ought to become a routine portion of case management of these patients.⁶

Case History
A 49-year-old male, on maintenance hemodialysis for the past year and a half, was referred by his nephrologist to the Methodist Hospital Sleep Disorders Center, Park Nicollet Health Services, St Louis Park, Minn, on April 17, 2003, for evaluation of snoring, witnessed apneas, and excessive daytime sleepiness.

Medical history for the patient included ESRD secondary to hypertension, congestive heart failure, and chronic obstructive pulmonary disease. The patient had currently smoked a half pack per day. He also complained of intermittent problems with vomiting, dyspepsia, dyspnea on exertion, and decreased energy.

The patient revealed that he had felt fatigued over the past 25 years. In addition, dialysis personnel had told him that he fell asleep every time he was on dialysis, snoring loudly, making loud growling noises, and disturbing other dialysis patients with his sounds and thrashing about. The patient also reported that he never seemed to get a good night’s sleep and that he slept excessively, sleeping after each dialysis treatment and also after every meal. Daytime sleepiness was also interfering with his work as a CPA. The patient stated that he was fired from his job because he fell asleep at work and was unable to arrive at work before noon.

Results
Diagnostic nocturnal polysomnography (PSG) showed severe OSA syndrome with a high respiratory disturbance index (RDI = 103) and severe oxygen desaturations, with a low SaO2 of 51% during the baseline portion of the study. NCPAP was then initiated and the patient was titrated from 5 cm water pressure to 12 cm with heated humidity. Mouth leaks and continued desaturations during rapid eye movement (REM) sleep were present at the higher pressures, so CPAP was switched to bilevel therapy for better ventilation. Bilevel pressures were titrated to 13 cm inspiratory pressure and 9 cm expiratory pressure with good compliance. All obstructive respiratory events were abolished at this level.

Once the patient was placed on NCPAP, he had significant improvement with consolidated sleep and a great deal of REM and slow wave rebounding. He demonstrated 90% sleep efficiency and 44% REM time over four REM periods. One REM period was two and a half hours long. During his follow-up visit, the patient reported that the night of his PSG study was the best night’s sleep he could recall ever having.

After using bilevel pressure therapy at home for 2 weeks, the patient was resurveyed using both the Epworth Sleepiness Scale (ESS)⁷ and the Functional Outcomes of Sleep Questionnaire (FOSQ).⁸ The FOSQ is a quality-of-life questionnaire designed specifically for people with sleep disorders. Increasing FOSQ scores theoretically indicate improving quality of life. The dialysis patient’s ESS score had dropped from a pre-PSG level of 20 down to 6. His FOSQ score almost doubled, rising from 56 before PAP therapy to 103, 2 weeks after initiating therapy at home.

Discussion
Although the ESS and FOSQ are both subjective measures of sleepiness and quality of life, respectively, the improved scores on both scales seem to corroborate the patient’s own testimonial that his energy level improved, he slept better at home, and he did not need to sleep while undergoing dialysis any more. He stated that he used to fall asleep on dialysis and would not wake up until he was done with his treatment. Dialysis staff confirmed this change in his behavior. The patient also enthusiastically reported that one day, about a week and a half after using PAP at home, he was awake for 24 hours surfing the Internet.

This case of successful intervention to rescue sleep quality in a dialysis patient seems to indicate that PAP can potentially work as well in that group as it does within the general population; however, other concerns remain regarding sleep disorders in the dialysis patient population, and the cure or resolution of those disorders. These concerns require further study and analysis before accurate, generalized conclusions can be drawn and standards of practice changed.

First, if OSA indeed occurs at least 60% of the time within the dialysis population, then perhaps nephrologists and other medical practitioners need to consider interviewing and screening all kidney patients for potential sleep disorders. According to the NKF, more than 20 million Americans (one in nine adults) have chronic kidney disease.1 How many of these will convert to actual kidney failure is unknown; however, the NKF also reports that diabetes is clearly the leading cause of chronic kidney failure. About 44% of all new cases of kidney failure are due to diabetes. Also per the NKF, poorly controlled high blood pressure is the second leading cause of chronic kidney failure in the United States, accounting for about 35% of all cases. Is it possible that treating sleep disorders like OSA in patients with chronic kidney disease may reduce the occurrence of kidney failure by potentially reducing blood pressure and improving prognoses in diabetic patients?

Second, there are questions about dialysis patient compliance with NCPAP or bilevel therapy for OSA and sleep-disordered breathing (SDB), in general. Is it feasible or practical to prescribe PAP therapies for dialysis patients if they are noncompliant with their dialysis regimens? Some dialysis patients do not monitor their fluid intake or restrict their intake of high potassium foods very well, for example. Delivery of adequate dialysis requires patient compliance. So, if patients do not follow these prescribed instructions for dialysis, will they also be noncompliant with PAP therapies?⁹ That is, will some dialysis patients be better candidates for PAP than others?

Third, there is some evidence that large volumes of fluid exchanged during nocturnal peritoneal dialysis may exacerbate OSA in patients who have it.2 Is OSA really worsened by high volume nocturnal peritoneal dialysis, or is this anecdotal and statistically insignificant information? Further, even if OSA is worsened, can it still be corrected to achieve normal or near normal RDI in these patients? If it cannot be corrected as well in peritoneal dialysis patients, does this mean that hemodialysis is a better option for ESRD patients with OSA? In addition, if large volume peritoneal dialysis worsens apnea, does accumulating and carrying large volumes of excess body water between hemodialysis treatments have a similar effect on severity of OSA in those patients?

Fourth, if at least 60% of dialysis patients have OSA, what percentage actually have symptoms from the broader category of SDB, which includes hypopneas, snore arousals, and other respiratory-related arousals (RERAs)—not just apneas or pauses in breathing? Unless OSA is defined to include RERAs and hypopneas, then the category that should be explored is more appropriately SDB instead of simply OSA.

Fifth, the underlying causes of the higher frequency and potentially the severity of sleep disorders of the dialysis patient need to be identified and explained. For example, in addition to potential body water volumetric influences on SDB, what is the relationship between uremic and/or diabetic neuropathies and SDB in dialysis patients? Also, what is the relationship between neuropathies and other sleep disorders such as RLS and PLMS? What impact do neuropathies have on sleep disorders in the nondialysis patient?

Conclusion
Where dialysis patients and their potential sleep disorders are concerned, it would seem that there are often more questions than answers. However, this case report about a dialysis patient, diagnosed with severe OSA and successfully treated with nasal bilevel pressure therapy, supports the idea that some sleep disorders can be identified and resolved in dialysis patients just as well as they can be within the general population.

At this time, a comparison of symptomatology and resolution of those symptoms needs to be done between sleep disorders of dialysis patients and those of the general population. Also, it seems that the broader category of SDB vs OSA needs to be examined and trends redetermined. Further, the possibility that a certain volume of excess body water may exacerbate OSA makes the typical practice of using body mass index (BMI) to predict OSA potentially less relevant in dialysis patients, especially if their ideal or “dry” weight is used in the BMI calculation. In addition, compliance with PAP therapies may be more problematic in some dialysis patients. Finally, it appears that sleep disorders are more frequent and sometimes more severe in dialysis patients. The underlying causes of this phenomenon need to be explained and the process of diagnosis and prescription adjusted accordingly, when identifying and resolving sleep disorders in dialysis patients.

Probably the most important concern, however, is to include screening of all dialysis patients for sleep disorders. To guard against underdiagnosing OSA and SDB, and other sleep disorders, this is a clinical imperative. The patient in this case study may have had OSA for 20 or 30 years or more. The patient related that he remembered being excessively sleepy at times, even in elementary school. In his case, his condition was not discovered until his kidneys had already failed and he was undergoing hemodialysis three times per week. Perhaps the imperative need is to screen all patients for sleep disorders, but this may be especially true for dialysis patients.

Daniel B. Carlsen is a polysomnographic technologist for Park Nicollet Health Services in St Louis Park, Minn. Carlsen had a decade of clinical dialysis experience before joining the community of sleep specialists.

References
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