To study the profile of various sleep related breathing disorders in patients with overlap syndrome and its therapeutic implications

SUMMARY

Background-Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA)

represent two of the most prevalent chronic respiratory disorders in clinical practice, the

coexistence of which is referred to as the overlap syndrome. López-Acevedo et al. reported that

overlap syndrome occurs in 10–20% of patients with OSA. A recent comprehensive review

indicates that the two disorders coexist in approximately 1% of adults. Thus overlap syndrome is

not uncommon. There is paucity of literature on the profile of Sleep related breathing disorders

(SRBD) in overlap syndrome. There are no consensus guidelines to positive airway pressure

(PAP) titration in overlap syndrome.

Methods- The study was conducted in the department of Pulmonary, Critical care and Sleep

medicine, Safdarjung hospital from December 2015 to April 2017 in patients presenting with

COPD and history suggestive of sleep disordered breathing. It was a prospective observational

study. A minimum of 30 patients were to be included in the study as a sample size of

convenience. In view of absence of any large prospective trial on this field of research and also

considering average annual rate of patients with overlap syndrome as 30, this study was a pilot

study with minimum sample size of 30.

Results- All patients presenting to Respiratory department with history suggestive of COPD

underwent a post bronchodilator spirometry to confirm the diagnosis and were be classified

according to GOLD staging as well as Groups A to D according to severity, symptoms and

exacerbations. History regarding excessive daytime sleepiness, snoring, early morning headache,

lethargy and fatigue was taken and Epworth sleepiness score was calculated. Those found to

have an AHI more than 5/hour in the diagnostic part were labelled as overlap syndrome. Thirty

seven such patients were included in the study. The underlying sociodemographic profile of the

patients was suggestive of a predominant male and middle aged population. Most of the patients

(81%) had moderate to severe obstruction in spirometry and only around 5% had mild

obstruction on classifying into COPD groups. On evaluation of the profile of sleep disordered

breathing found in these patients, it was seen that only around half of the patients had pure

obstructive sleep apnea with no hypoventilation. Around 35.1% of the patients had associated

hypoventilation with OSA. Around 5.4% patients had cheynes stokes breathing (hypocapnic

central sleep apnea) and rest had OSA with central sleep apnea along with hypoventilation. Pure

OSA group was easily titrated by OSA titration guidelines of AASM and were easily corrected

by CPAP therapy. OSA with hypoventilation group were mostly severe COPD with hypercapnia,

they required Bilevel PAP titration to correct rise in co2 to awake levels. Transcutaneous CO2

monitoring was done to document hypoventilation Patients with hypoventilation and central

sleep apnea needed a back up rate for correction and were given bilevel PAP with S/T mode for

correction. Patients with cheyne stokes breathing were elderly hypertensive patients with

congestive heart failure who were corrected by PAP and optimisationof medical therapy for heart

failure. Our study also did not demonstrate any correlation with degree of obstruction and AHI.

So, we divided our patients into 4 groups on the basis of severity of the two underlying diseasesmild-

moderate COPD with mild-moderate OSAHS, mild-moderate COPD with severe OSAHS,

severe COPD with mild-moderate OSAHS, severe COPD with severe OSAHS and analysed

their symptoms, examination, ABG and polysomnography charecteristics. Most of the

charecteristics like age ,sex, smoking history, Epworth sleepiness score were well distributed

among these groups with ANNOVA analysis showing p value >0.05. Pulmonary hypertension

and evidence of cor-pulmonale was highly evident in the severe COPD groups and systemic

hypertension was present in 5/7 patients in severe COPD and severe OSA group. However, the

comorbidties distribution was not statistically significant.

These findings also give us clinical hints as to when to suspect which profile of SDB when

considering a patient for PSG titration so that appropriate titration can be done and various

modes of PAP therapy can be appropriately advised. There are currently no defined guidelines

for titration of such overlap patients. In view of overlap disease not being uncommon, and the

titration issues discussed above, further large scale studies are required to evaluate titration of

such patients and formulating guidelines for the same.

CONCLUSIONS AND RECOMMENDATIONS

1. Overlap syndrome is defined as overlap of OSA with COPD, however it can present with

varied sleep-disordered breathing profiles. Only around half of the patients have pure

OSA which can be titrated according to AASM guidelines.

2. These profiles include OSA, hypoventilation, cheyne-stokes breathing and central sleep

apnea

3. Evaluation of the above mentioned profiles is necessary to treat such patients

appropriately as various PAP types and devices may be required for correction of the

same