Introduction
Obstructive sleep apnea if remains untreated can lead to excessive daytime sleepiness, diminished performance and overall poor quality of life. Factors that increase vulnerability of sleep apnea include age, male sex, obesity, family history, craniofacial abnormalities and certain health behaviors such as alcohol abuse and smoking.1 Obstructive sleep apnea syndrome is a potentially disabling condition in which disruptive snoring, repeated complete or partial collapse of upper airway occurs leading to nocturnal hypoxemia, frequent arousal and excessive daytime sleepiness. However, new research in biochemistry and genetics of this disorder lead us to its cure. Continuous positive airway pressure (CPAP) therapy remains the first line of treatment. Although its acceptance is low due to high cost and long term use, it leads to improvement in quality of life, improvement in metabolic derangements that occurs in OSA patients as well as prolongs the life with good compliance of therapy. 2, 3 Other options available are drugs, oral appliances and upper airway surgeries.2, 3 Apnea-Hypo apnea Index (AHI) is widely used for the diagnosis and assessment of severity of OSA. AHI refers to mean number of apneas or hypopneas per hour of sleep. AHI of >5 is suggestive of OSA.
Hypopnea is characterized by polysomnographic variables as any one of these.
Decrease in nasal airflow by >50% for >10 sec.
Decrease in nasal airflow by less than 50% with up to 4% fall in oxygen saturation.
Decrease in nasal airflow by less than 50% with electroencephalographic evidence of arousal.
Apnea is defined as complete cessation of nasal air flow for >10 seconds. 2
Polysomnography is considered “gold standard” for diagnosis, but it is not without limitations. It requires an overnight stay in a sleep laboratory staffed with qualified personnel that can collect and interpret complex physiological data. Obstructive sleep apnea prevalence varies in different population. In most of the studies it varies from 3-7%. 4 Prevalence of OSA in India is 7.5% in males and that of 4.5% in females. 5 All patients of COPD and bronchial asthma diagnosed as per guidelines and those fulfilling the criteria for diagnosis of obstructive sleep apnea were included in the study.
Previously diagnosed cases of COPD and bronchial asthma (as per guidelines) having symptoms of obstructive sleep apnea were also included in this study. This present study was planned to study assessing of severity of sleep apnea in obstructive airway diseases patients.
Material and Methods
The present study was conducted in the sleep laboratory of the Department of Pulmonary Medicine of a tertiary care hospital that caters to population of diverse groups. This was a prospective study carried over a period of 18 months. Institutional ethical committee approval was obtained for this study. Sample size estimation was done with expert statistician.
Patients after clinical examination and spirometry with post bronchodilator reversibility were categorized into bronchial asthma and COPD. Subsequently polysomnography was done of these patients to study the sleep pattern.
Exclusion criteria
Age < 13 yrs.
Patients having chronic lung diseases not satisfying guidelines for diagnosis of COPD, bronchial asthma and OSA
Patients admitted with life threatening conditions like acute respiratory failure, critical metabolic acidosis, altered sensorium, hypotension, left ventricular failure
Acute exacerbation of COPD/bronchial asthma, acute myocardial infarction, acute stroke
Uncooperative patients
Patients not giving consent
All the patients included in the study were interviewed for demographic data and detail history of their illness.
Diagnosis of COPD was based on Global Initiative for Obstructive Lung Disease guidelines i.e. cough with sputum production for most of the days in a year atleast 3 months for 2 consecutive years or dyspnea with history of exposure for risk factors (e.g. tobacco smoking), progressive breathlessness and spirometry showing FEV1/FVC less than 70% and FEV1 less than 80% predicted with poor bronchodilator reversibility (i.e. improvement in FEV1 <12% and 200ml). Also patients with mixed ventilator disorder were included in COPD patients, as all of them had poor bronchodilator response on Spirometry.6
COPD patients were further staged as mild, moderate, severe, very severe as per the GOLD guidelines.
The apnea-hypopnea index (AHI-the number of apneas plus hypopneas per hour of sleep) is the standard metric used to quantitate the severity of obstructive sleep apnea.7
Although the AHI has been proven to be superior metric when assessing the overall effect of OSA, it excludes the degree of oxygen desaturation, degree of hypoventilation, and total number of arousals. An AHI greater than 5 to 10 events per hour is indicative of OSA. The obstructive sleep apnea syndrome (OSAS) is said to be present when the AHI is greater than 5 to 10 events per hour and the patient has symptoms of excessive daytime somnolence, unrefreshing sleep, or chronic fatigue.
Diagnostic Criteria for Adult Obstructive Sleep Apnea
Results
Total 98 patients of COPD, bronchial asthma and obstructive sleep apnea who satisfied all the inclusion criteria attending a tertiary care centre were studied over a period of 18 months.
With the help of a proforma data was meticulously collected and entered in the MS EXCEL spreadsheet and analyzed. On analysis of the data following observations and results were found in the present study. Patients included in the present study were divided after spirometry as per post bronchodilator FEV1 reversibility as, those with asthma (>12% or 200 ml reversibility in FEV1) and those with COPD (<12% or 200 ml reversibility in FEV1)
Amongst total 98 patients, 67(68.37%) were of COPD and 31(31.63%) were of bronchial asthma. Majority of patients having COPD were in the age group of 45-54 years and 55-64 years, 52.23% and 23.88% respectively. Majority of patients having bronchial asthma were in the age group of 35-44 years 51.62%. Amongst COPD patients 51(76.12%) were males and 16(23.88%) were females, male to female ratio in COPD was 3.19:1. Amongst patients with asthma 18(58.06%) were males and 13(41.94%) were females, with male to female ratio of 1.39:1.
In the total study population of 98 patients 69(70.41%) were males and 29(29.59%) were females.
Table 1
Showing active smoking in study population
|
Disease(n) |
Smokers |
Nonsmokers |
Total |
|
COPD (n=67) |
55(82.09%) |
12(17.91%) |
67(100%) |
|
Asthma (n=31) |
10(32.26%) |
21(67.74%) |
31(100%) |
55 (82.09%) amongst 67 patients with COPD were smokers and 12 (17.91%) were non smokers, smokers to nonsmokers ratio was 4.58:1. In asthma 10 (32.26%) patients were smokers and 21(67.74%) patients were non-smokers. In COPD patients bidi smoking was common seen in 48(87.27%) patients, than cigarette smoking seen in 07(12.73%) patients and among asthmatic patients, 08 were bidi smokers and 02 were cigarette smokers. Not in the above table is history of chullah smoke exposure among the nonsmoker COPD patients, found in 08 patients, and in total asthmatic patients it was found in 05 patients.
Body mass index was normal [BMI 18.5-24.99] in 53(54.08%) patients, 18(18.37%) patients were overweight [BMI 25-29.99] amongst this group, obesity [BMI >30] was found in 27(27.55%) patients having COPD and bronchial asthma.
Table 2
Showing most common symptoms of obstructive airway diseases in the study population
|
Symptoms |
COPD (n=67) |
Asthma (n=31) |
|
Breathlessness |
55 (82.09%) |
27 (87.10%) |
|
Cough |
41 (61.19%) |
24 (77.42%) |
|
Chest tightness |
31 (46.26%) |
13 (41.94%) |
|
Wheeze |
18 (26.87%) |
26 (83.87%) |
Amongst patients with COPD, breathlessness was the most common symptom seen in 55(82.09%) patients, followed by cough in 41(61.19%) patients, chest tightness in 31(46.26%) patients and wheeze in 18(26.87%) patients. In patients having bronchial asthma, breathlessness was the most common symptom seen in 27(87.10%) patients, followed by wheeze in 26(83.87%) patients, cough in 24(77.42%) patients and chest tightness in 13(41.94%) patients.
Table 3
Showing most common symptoms of obstructive sleep apnea in the study population
Most common symptom of OSA in study population was snoring, present in 62(63.26%) patients, excessive daytime sleepiness in 30(30.61%), nocturnal awakening in 28(28.57%) and memory loss, personality changes in 02(2.04%) patients. Amongst patients with OSA, snoring was seen in 20(76.92%), excessive daytime sleepiness in 16(61.54%), nocturnal awakening in 12(46.15%) and memory loss and personality change in 01(3.85%) patients.
Table 4
Showing distribution in patients with COPD as per stages of severity, according to GOLD guidelines (n=67)
|
Severity |
Total |
Percentage |
|
Mild |
11 |
16.42% |
|
Moderate |
26 |
38.80% |
|
Severe |
22 |
32.84% |
|
Very severe |
08 |
11.94% |
|
Total |
67 |
100% |
Amongst patients with COPD, 11(16.42%) had mild COPD, 26(38.80%) had moderate COPD, 22(32.84%) had severe COPD and 08(11.94%) patients had very severe COPD.
Table 5
Showing distribution of patients having bronchial asthma as per per stages of severity, according to GINA guidelines (n=31)
|
Severity |
Total |
Percentage |
|
Intermittent |
04 |
12.90% |
|
Mild persistent |
06 |
19.36% |
|
Moderate |
12 |
38.71% |
|
Severe |
09 |
29.03 |
|
Total |
31 |
100% |
38.71% and 29.03% that is 12 and 09 out of 31 patients had moderate and severe asthma respectively. Again 19.36% and 12.90% that is 06 and 04 patients had mild persistent and intermittent asthma respectively.
Table 6
Showing presence of obstructive sleep apnea in COPD and bronchial asthma
|
|
Without OSA |
With OSA |
Total |
|
COPD |
50 (74.63%) |
17 (25.37%) |
67 |
|
Asthma |
22 (70.97%) |
09 (29.03%) |
31 |
|
Total |
72 (73.47%) |
26 (26.53%) |
100 |
17(25.37%) patients of COPD were found to have obstructive sleep apnea and 09 (29.03%) patients of asthma had obstructive sleep apnea.
Table 7
Age distribution in OSA patients (n=26)
Among 26 patients of OSA 20 patients (76.92%) were in the age group of more than 45 years suggesting that OSA is more prevalent in middle and elderly patients of the study population.
Table 8
Showing correlation of smoking and obstructive sleep apnea (n=26)
|
|
COPD with OSA |
Asthma with OSA |
Total |
|
Smokers |
14 |
02 |
16 (61.54%) |
|
Non-smokers |
03 |
07 |
10 (38.46%) |
|
Total |
17 |
09 |
26 (100%) |
Out of 26 patients of OSA, 16(61.54%) were smokers of which 14 patients had COPD and 02 patients had bronchial asthma. 10(38.46%) patients were non smokers.
Table 9
Showing correlation of obesity and obstructive sleep apnea (n=26)
Out of 26 patients of obstructive sleep apnea 19 patients (73.08%) had mild to severe obesity, 06 patients (23.08%) were overweight and only 01 patient (3.85%) was having normal body mass index. It was observed that obesity is risk factor for the development of obstructive sleep apnea in the study population.
Table 10
Obstructive sleep apnea in COPD patients (n=17)
|
|
Mild COPD |
Moderate COPD |
Severe COPD |
Very severe COPD |
|
Mild OSA |
00 |
05 |
00 |
00 |
|
Moderate OSA |
00 |
01 |
07 |
02 |
|
Severe OSA |
00 |
00 |
01 |
01 |
|
Total |
00 (0%) |
06(35.29%) |
08(47.06%) |
03(17.65%) |
Out of 17 patients of obstructive sleep apnea 08(47.06%) patients had severe COPD, 06(35.29%) patients had moderate COPD and 03(17.65%) patients had very severe COPD.
Table 11
Showing comparison of spirometric, ABG and polysomnographic parameters of patients having COPD and overlap syndrome
Patients of overlap syndrome were having higher BMI (32.61 ±4.23) than that of COPD alone (24.65 ±3.99). Patients with overlap syndrome were having more severe hypercapnia (mean PaCO2 48.88 ±0.017) than that of COPD alone (mean PaCO2 46.02 ±0.03). They were having more severe hypoxemia (mean PaO2 69.65 ±0.012) than that of COPD alone (mean PaO2 72.16 ±0.025).
Patients with overlap syndrome were having more severe nocturnal desaturation (mean 85.35% ±0.022) than COPD alone (mean 92.48% ±0.015). Mean FEV1 of patients having overlap syndrome was 43.47% ±14.31 versus 55.34% ±17.81 in patients of COPD alone.
Table 12
Showing correlation of severity of obstructive sleep apnea with severity of bronchial asthma (n=9)
|
|
Mild asthma (FEV1 ≥ 80%) |
Moderate asthma (FEV1 60-80%) |
Severe asthma (FEV1 <60%) |
|
Mild OSA |
02 |
00 |
00 |
|
Moderate OSA |
00 |
02 |
02 |
|
Severe OSA |
00 |
01 |
02 |
|
Total |
02 (22.22%) |
03 (33.33%) |
04 (44.44%) |
Out of 09 patients of obstructive sleep apnea 04(44.44%) had severe asthma, 03(33.33%) patients had moderate asthma and 02 patients (22.22%) had mild asthma. This suggests that severity of asthma is one of the predictor of severity of OSA in patients of bronchial asthma.
It was also observed that in patients having severe OSA, 07 out of 09 patients had more severe grade of bronchial asthma.(FEV1 <80%)
Correlation coefficient was -0.527 as calculated with scatter diagram showed negative linear correlation of AHI with % FEV1 of predicted of Asthma patients.
Discussion
In the study population risk factors that were observed for the development of OSA were middle to elderly age (>45 years), male sex, obesity, smoking, and ear nose throat (ENT) pathologies (nasal polyps). These are the same factors that are responsible for the development of OSA in general population. As observed in table no. 2 in the present study amongst patients having COPD, breathlessness was the commonest symptom seen in 55 (82.09%) patients, followed by cough in 41 (61.19%) patients, chest tightness in 31 (46.26%) patients and wheeze in 18 (26.87%) patients.
This correlates with the study done by Kessler in the population of France on 2441 patients found that breathlessness (72.8%) was the commonest symptom in COPD followed by cough (58.7%).8 Our findings are also comparable with the study done by Kesten in COPD patients in California on 2678 patients in the year 2005 found that dyspnea was the commonest symptom (71%) in COPD followed by cough (19%).9
As observed in table no. 6 in patients having bronchial asthma, breathlessness was the most common symptom seen in 27(87.10%) patients, followed by wheeze in 26(83.87%) patients, cough in 24(77.42%) patients and chest tightness in 13(41.94%) patients. This correlates with the text mentioned in Crofton and Douglas that breathlessness is the most common symptom in bronchial asthma.(6) In the study done by Sistek et al., on 9651 patients in Swiss published in the year 2001 found that wheezing (94.4%) was the commonest symptom in bronchial asthma followed by exertional dyspnea (82%).10
As observed in table no. 8 in the present study amongst patients with COPD, 11(16.42%) had mild COPD, 26(38.80%) had moderate COPD, 22(32.84%) had severe COPD and 08 (11.94%) patients had very severe COPD.
Table 14
|
Severity |
Present study |
Seemungal et al., 11 |
Hoogendoorn et al., 12 |
Joshi et al., 13 |
|
Mild |
16.42% |
5.3% |
27% |
30% |
|
Moderate |
38.80% |
43% |
55% |
37% |
|
Severe |
32.84% |
35.1% |
15% |
33% |
|
Very severe |
11.94% |
15.9% |
03% |
0% |
|
Population |
67 |
720 |
- |
268 |
Present study findings correlates with Seemungal et al., and Harrinarine et al., study where most of the patients had moderate to severe disease. 11 As observed in Table no. 9 in the present study, 38.71% and 29.03% that is 12 and 09 out of 31 patients had moderate and severe asthma respectively. Again 19.36% and 12.90% that is 06 and 04 patients had mild persistent and intermittent asthma respectively.
In the study done by Gothi et al., on patients of bronchial asthma in Mumbai on 268 patients in the year 2001 found that 42% patients had mild asthma, 35% patients had moderate asthma and 22% patients had severe asthma. 13
Polysomnography was used to study the presence of obstructive sleep apnea and to study the sleep pattern in the study population. As observed in table no. 11 and 18, mean age for patients of OSA was 53.46 years (SD ±12.53), and among total 26 patients of OSA, 20 patients (76.92%) were in the age group of more than 45 years suggesting that OSA is more prevalent in middle and elderly patients of the study population.4, 14 These findings correlate with following studies.
Along with advances in healthcare technologies found us more rationale.15, 16
Table 15
|
Study done |
Mean age |
|
In the present study |
Mean age was 49.20 years SD ±2.43 |
|
Joaquin Duran, Santialo Esnaola, Ramon Rubio and Angeles Iztueta, done in the population of Spain on 442 patients in year 1993-97 17 |
Mean age for men was 52 years and that of women was 47.4 years |
|
Surendra kumar Sharma, Saket Kumpawat, Amit Banga and Ashish Goel, study done in the population of Delhi on 150 patients in year 2003-05 18 |
Mean age in patients with OSA was 46.7 ±9.3 years |
|
Emmanuel Weitzenblum, multicentric study done in OSA patients of France on 30 patients published in 2007 19 |
Mean age in overlap group was 58 years |
Limitations of this study
This is an observational study i.e. conclusions that are drawn are merely results of observations.
Confounding parameters of OSA were not dealt with in depth as it was beyond the scope of the study. And sleep parameters like stages of sleep were not compared with age matched population.
Due to resource limited setup we could not go into the details of risk factors in patients of OSA and put forward only the observations.
Large, long term, prospective, randomized controlled studies are necessary to more fully evaluate CPAP and asthma outcomes.
Large, long term, prospective, randomized controlled studies are necessary to study sleep pattern changes among obstructive airway disease patients, to study the effect of CPAP on sleep architecture.
Strength of this study
COPD and asthma remains a major public health problem and has considerable morbidity and mortality. Prevalence of OSA and overlap syndrome is also on a rise. These diseases were affecting quality of sleep and hence quality of life. In the present study, polysomnography was used to find sleep disturbance and OSA in study population. Polysomnography was also used to find out correlation between OSA and patients having COPD and asthma in resource limited settings. Use of auto-CPAP was found to be effective in OSA patients.
Conclusions
From this study, we may conclude that risk factors that were observed in patients having OSA were age more than 45, male sex, obesity, smoking, nasal polyp. 19 (73.08%) patients (out of 26 OSA patients) had mild to severe obesity suggesting that obesity is risk factor for the development of obstructive sleep apnea in the present study. In patients with overlap syndrome had more severe hypercapnia (mean PaCO2 48.88 ±0.017), and nocturnal desaturation (mean 85.35% ±0.022) Patients having moderate COPD had severe OSA. Patients having severe asthma had severe OSA with correlation coefficient R = -0.527 with p value <0.001 meaning negative linear correlation between AHI and %FEV1 of predicted of Asthma patients.
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