CYCLICAL NOCTURNAL OXYGEN DESATURATION AND IMPACT ON ACTIVITIES OF DAILY LIVING IN ELDERLY PATIENTS

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1 JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY 2007, 58, Suppl 5, H. FROHNHOFEN 1, H.C. HEUER 1, N. PFUNDNER 1, G. ORTH 2 CYCLICAL NOCTURNAL OXYGEN DESATURATION AND IMPACT ON ACTIVITIES OF DAILY LIVING IN ELDERLY PATIENTS 1 Department of Geriatric Medicine, Kliniken-Essen-Mitte, Essen, Germany; 2 Department of Geriatric Medicine, Helios Klinikum, Schwelm, Germany It is well known, that sleep disordered breathing (SDB) is associated with functional impairment in stroke patients. In elderly non-stroke subjects this relation is unclear. We evaluated 539 elderly patients (median age was 81 years, range 41 to 100 years). We measured activities of daily living (ADL) with the Barthel-Index (BI, 0-100) on admission and discharge, excessive daytime sleepiness (EDS), and the nocturnal oxygen desaturation index (ODI). BI on admission was 54 ±33 in men and 55 ±31 in women (n.s.). More than 50% of the subjects had an ODI above 10/h. The mean BI on discharge was 65 ±31 in men and 67 ±29 in women (n.s.). With increasing SDB severity (quartiles of ODI), BI on admission decreased from 58 ±33 to 46 ±31 (P< 0.001) and BI on discharge decreased from 70 ±31 to 59 ±29 (P< 0.001). The frequency of EDS increased with increasing severity of SDB from 14.1% (first quartile of ODI) to 40.3% (forth quartile of ODI) (P< 0.001). In 330 subjects without EDS, BI on admission did not differ regarding ODI. BI on discharge decreased from 78 ±22 (first quartile of ODI) to 66 ±25 (forth quartile of ODI) (P<0.04). SDB and EDS have a negative and independent impact on activities of daily living in elderly non-stroke subjects. Regarding the high frequency of SDB in the elderly and the effect size on ADL further interventional studies are warranted. Key words: daily activity, elderl, sleep disorders breathing, functional impairmen INTRODUCTION Improving everyday function and activities of daily living (ADL) in the elderly is one the most important goals of geriatric medicine. Impairment in the activities of daily living lessens quality of life, is a burden to relatives and

2 186 increases the risk of nursing home placement (1). The identification and the management of modifiable risk factors for loss of function is of great importance. Several studies have documented that the prevalence of sleep disordered breathing (SDB) increases with age (2-5). There is also a high frequency of SDB in stroke patients (6-9). Moreover, in stroke patients SDB is associated with poor functional outcome (6, 8-10). The relationship between SDB and ADL in the elderly non-stroke subjects was not investigated. Thus we explored this relation in a random sample of elderly hospital admitted patients. MATERIAL AND METHODS Patients consecutively admitted to a geriatric unit were asked randomly to participate in the study. Two hundred and fifty three patients could not be included because of refusal or invalid data on oximetry, leaving 539 consenting patients. The median age was 81 years (range 41 to 100 years) and there were 35% men and 65% women. The institutional review committee approved the study. We collected the following data in all patients: age, gender, reason for admission, medical history, activities of daily living, nocturnal arterial oxygen saturation (SaO 2 ), medication and excessive daytime sleepiness. Patients were evaluated for nocturnal oxygen saturation in a stable period of their disease using continuous computerized overnight oximetry (Somnocheck, Fa. Weinmann). Computerized analysis of oximetry data was performed. A cyclical desaturation event was defined as a continuous drop of SaO 2 of at least 4% from baseline and a slope of at least 4% per minute. A rise of 4% above the nadir of a desaturation event signaled the end of that event. Recordings were collected from 10:00 p.m. to 6:00 a.m. Only registrations with a duration of at least 6 hours were analyzed. The mean overnight SaO 2, lowest SaO 2, and a total number of desaturation events were recorded. The oxigen desaturation index (ODI) was calculated by dividing the total number of desaturation events by the recording time. Patients were divided into four groups according to quartiles of ODI. Patients sleeping at inappropriate times or in inappropriate situations during the day were classified as suffering from excessive daytime sleepiness (EDS). The Barthel Index (BI), a common and widely used scale in geriatric medicine (11), was used to assess activities of daily living (ADL). BI encompasses 0 to 100 points with 0 points meaning maximal impairment and 100 points meaning no impairment in ADL. The BI was scored for all patients on admission and on discharge. Personnel scoring EDS or BI was blinded to the results of oximetry. The BI on admission and on discharge was compared regarding quartiles of ODI and the presence of EDS. The primary outcome was the relationship between SDB and ADL. RESULTS Five hundred thirty nine randomly selected patients were included into the study. The mean age of the 187 men was 79 ±9 years and the mean age of the 352 women was 82 ±7 years. The mean BI on admission was 54 ±33 in men and 55 ±31 in women (n.s.). The mean BI on discharge was 65 ±31 in men and 67 ±29 in women (n.s.). Since there were no gender differences in BI, the data were combined for futher analysis.

3 Patients were admitted for cardiovascular diseases (27%), pneumonia (5%), obstructive pulmonary diseases (5%), pain syndromes (10%), dementia (40%), and other diseases (13%). Diagnoses causing hospital admission were distributed equally among the quartiles of ODI. Characteristics of subjects including comorbid conditions regarding quartiles of ODI are demonstrated in Table 1. BI differed significantly among quartiles of ODI. The increase of SDB severity was significantly associated with a decrease in BI. This association appeared in BI on both admission and discharge. There was no significant difference between BI on admission in the first quartile of ODI and BI on discharge in the forth quartile of ODI. The frequency of comorbid conditions like heart disease, hypertension, atrial fibrillation, dementia, diabetes, dementia, and the intensity of treatment for hypertension increased significantly with the severity of SDB. There were no significant differences in the prescription of hypnotics among the quartiles of ODI. The mean overnight oxygen saturation was 93.7 ±2.2% in men and 93.2 ±3.0% in women (n.s.). The mean ODI was 17.8 ±17/h in men and 15 ±16/h in women (P<0.02) and the mean minimum oxygen saturation was 81 ±6% in men and 80 ±8% in women (n.s.). 187 Table 1. Characteristics of subjects, comorbid conditions and quartiles of oxygen desaturation index (ODI). Quartiles of ODI 1 st 2 nd 3 rd 4 th Number of subjects (n) P value Age (yr ±SD) 79 ±9 81 ±7 82 ±7 82 ±7 <0.05 Length of stay (days ±SD) 18 ±14 17 ±11 19 ±11 23 ±17 <0.05 BI on admission 58 ±33 58 ±31 54 ±31 46 ±31 <0.001 BI on discharge 70 ±31 71 ±26 65 ±30 59 ±29 <0.001 Number of comorbid conditions n (%) n (%) n (%) n (%) Heart failure 22 (16) 26 (19) 31 (23) 50 (38) Hypertension 116 (85) 113 (84) 124 (92) 126 (93) <0.05 Myocardial Infarction 15 (11) 20 (15) 28 (21) 31 (23) <0.05 Atrial fibrillation14 (11) 19 (14) 35 (26) 33 (25) <0.01 COPD 23 (17) 20 (15) 26 (19) 25 (19) Dementia 36 (26) 36 (26) 54 (40) 45 (34) <0.01 Depression33 (24) 37 (28) 31 (23) 31 (23) Diabetes mellitus 35 (26) 36 (26) 42 (31) 58 (44) <0.05 Hypnotics 39 (29) 39 (29) 35 (2) 27 (20) Antihypertensives >2 26 (19) 33 (25) 40 (30) 58 (44) <0.01

4 188 Table 2. Data on nocturnal oximetry and quartiles of ODI. Quartiles of ODI 1 st 2 nd 3 rd 4 th Number of subjects (n) P value ODI 4% (events/h) 2 ±1 6 ±2 6 ±4 40 ±14 Mean SaO 2 (%) 94 ±2 9 ±24 93 ±2 92 ±4 <0.001 Minimum SaO 2 (%) 86 ±4 82 ±5 79 ±7 74 ±9 <0.001 EDS (events/%) <0.001 Fig. 1. Barthel Index and Quartiles of ODI. There was an inverse, significant association between the quartiles of ODI and BI. Data on nocturnal pulse oximetry regarding quartiles of ODI appear in Table 2. In 266 subjects the ODI was below 10/h and in 268 subjects it exceeded 10/h. The mean BI on admission was 59 ±32 for subjects with ODI below 10/h and 50 ±31 for the group with ODI above 10/h (P<0.002). The mean BIs on discharge were 71 ±29 and 63 ±30 for each patient group, respectively (P<0.001). One hundred thirty three subjects (25%) suffered from excessive daytime sleepiness. The frequency of EDS increased significantly with increasing severity of SDB. The proportion of subjects suffering from EDS increased from 14.1% to 40.3% with increasing quartiles of ODI (P<0.001).

5 189 Three hundred thirty three subjects did not suffer from EDS during the whole stay in hospital. These subjects had a mean ODI of 15 ±16/h. BI on admission and discharge was 60 ±29 and 73 ±24, respectively. The mean BI on admission and discharge decreased when ODI increased, but only the differences in BI on discharge reached significance. The mean BI on admission was 65 ±24 for the first quartile of ODI and 56 ±27 for the forth quartile of ODI (n.s.). The mean BI on discharge was 78 ±22 for the first quartile of ODI and 66 ±25 for the forth quartile of ODI (P<0.04). In 181 subjects without EDS, ODI was below 10/h and in 149 subjects ODI exceeded 10/h. The mean BI on admission was 66 ±29 for subjects with ODI below 10/h (n=181) and 61 ±30 and for the group with an ODI over 10/h (n=149) (n.s.). The mean BI on discharge was 79 ±23 and 72 ±26 for each patient group respectivly (P< 0.02). DISCUSSION In the present study we found that among a large sample of randomly selected elderly subjects, SDB was associated with functional impairment. Increasing severity of SDB was significantly associated with a decline in activities of daily living. Several studies described such an association in stroke patients (6, 8, 9). Our study extends the existing knowledge, since we found a similar association in elderly non-stroke subjects. Excessive daytime sleepiness is a well known consequence of SDB in the elderly (2, 5, 12). The frequency of EDS increased with increasing severity of SDB. EDS and ODI were closely correlated and both had an impact on BI. An analysis of the relationship between BI and ODI in subjects without EDS revealed an independent impact of ODI on BI. Several studies showed that subjects with an ODI of 10/h or more had a higher rate of persistent functional impairment (6, 7). Such a cut-off value also seems to be reasonable in our sample since it is significantly associated with a lower BI and a higher frequency of EDS. However, this cut-off value needs further validation in a prospective study. The size effect of SDB on ADL can be estimated comparing the differences in BI between the first and the forth quartile of ODI. This difference is comparable with the size effect, thrombolytic therapy has on BI in subjects with acute stroke (13). This study confirms earlier findings that the frequency of SDB is high in elderly subjects (2, 5). The high frequency of SDB in our sample and its considerable impact on ADL underscore the clinical importance of SDB. Further studies are warranted to prove whether treatment of SDB in elderly subjects suffering from SDB will improve activities of daily living and that treatment is cost effective. Then, an extensive search for, and treatment of, SDB in the elderly would be justified. SDB was also associated with several comorbidities. The prevalence of heart failure, myocardial infarction, atrial fibrillation, dementia, and arterial

6 190 hypertension increased with SDB severity. Blood pressure measurements showed non significant differences between ODI quartiles but the medication necessary to control for hypertension increased significantly with SDB severity. These findings are in accord with the findings from younger patient groups showing a close relationship between SDB and cardiovascular disease (14-16). We investigated prospectively a large sample of subjects avoiding rigorous selection criteria. Thus, our results are transferable to a large group of elderly subjects with a high rate of comorbid conditions and in need for hospital treatment. There are some shortcomings of our study. Unattended pulse oximetry does not allow to determine sleep. The real degree of SDB may thus be underestimated. Pulse oximetry does not allow to distinguish different forms of SDB like obstructive sleep apnea or periodic breathing (14) and other reasons for EDS like periodic limb movement disorders or parasomnias also frequent in the elderly remain undetected (17). But pulse oximetry is a valid technique with a high rate of acceptance among elderly subjects (17). It is a useful and valid tool for screening for SDB. Since we intended to investigate a large sample of subjects and tried to minimize refusal rate, we applied pulse oximetry alone. Pulse oximetry detects intermittent nighttime hypoxemia. Intermittent nighttime hypoxemia is one of the most serious consequences of SDB (19). Pulse oximetry gives reasonable results for SDB even in a high prevalence sample like elderly subjects (19). Moderate forms of SDB or SDB without hypoxemia are easily overlooked with pulse oximetry alone. But clinical consequences of untreated moderate SDB in elderly subjects is far from clear. Further studies are needed to define the effort required for diagnosing and treating SDB in frail elderly subjects. Activities of daily living are of pivotal importance for elderly subjects. ADL determine self esteem, quality of life, and independence. Avoiding a decline in ADL is a very important goal of geriatric medicine. Intermittent nighttime hypoxemia and EDS are independent risk factors for impairment in ADL in elderly subjects. Screening elderly subjects for SDB is warranted. The results of this study strongly indicate that SDB is associated with impairment in ADL in elderly subjects. Trials of treatment for SDB associated with reduced ADL should be undertaken. REFERENCES 1. Diehr P, Williamson J, Patrick DL, Bild DE, Burke GL. Patterns of self-rated health in older adults before and after sentinel health events. J Am Geriatr Soc 2001; 49: Philip P, Dealberto MJ, Dartigues JF, Guilleminault C, Bioulac B. Prevalence and correlates of nocturnal deasturations in a sample of elderly people. J Sleep Res 1997; 6: Kaplan GA, Haan MN, Wallace RB. Understanding changing risk factor associations with increasing age in adults. Annu Rev Public Health 1999; 20: Carskadon MA, Dement WC. Respiration during sleep in the aged human. J Gerontol 1981; 36:

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In 1994, the American Sleep Disorders Association

In 1994, the American Sleep Disorders Association Unreliability of Automatic Scoring of MESAM 4 in Assessing Patients With Complicated Obstructive Sleep Apnea Syndrome* Fabio Cirignotta, MD; Susanna Mondini, MD; Roberto Gerardi, MD Barbara Mostacci, MD;