INTRODUCTION

A large number of adult patients who have sleep disorders present daytime sleepiness as the main symptom. These are, for example, patients who have obstructive sleep apnea syndrome (OSAS), disorders of periodical limbic movement, narcolepsy and idiopathic hypersomnia8.

OSAS is caused by recurrent episodes of obstruction of upper airways during sleep, causing reduction of respiratory flow (hypoapnea) or interruption of flow (apnea); it may be purely obstructive, leading to increased central respiratory effort and interruption of respiratory movements, or mixed, when the central component coexists with the obstructive one. During sleep, there are still repetitive episodes of snoring and night microawakenings. Excessive daytime sleepiness is a typical manifestation due to interruption and poor quality of night sleep. Patients normally present restless sleep, respiratory difficulty and innumerous microawakenings associated with body movement2.

Obesity is frequently associated with the syndrome, but we also find non-obese patients with the same pathology, showing that there are other etiological factors involve. Patients are normally not aware of the problem, nor of its severity. Pathophysiology is complex and not fully understood yet. It is accepted that stability and patency of upper airways depend on flaccidity of oropharynx and action of abductor muscles, which are normally activated rhythmically during inspiration. Airways are subject to a collapse if the force produced by its muscles exceeds the negative pressure generated by the inspiration activity of the diaphragm and intercoastal muscles. It may happen if suction pressure is excessively high or when dilation forces of muscles are not enough to compensate suction2, 3.

It is also known that cardiopulmonary repercussions of severe obstructive apnea, such as pulmonary hypertension, cor pulmonale and cardiorespiratory failure leading to hypoxemia and hypercapnia, are severe and quite common manifestations, frequently underdiagnosed in the syndrome3,12. In order to try to measure daytime sleepiness, a number of scales and methods have been created, such as the test of multiple sleep latency, test of wake maintenance, sleepiness scale of Stanford, and daytime sleepiness scale by Epworth; the latter is the most widely used and reliable8.

OBJECTIVE

Once established the importance of assessing daytime sleepiness for the diagnosis of OSAS and the relation with cardiorespiratory pathologies, we used daytime sleepiness scale by Epworth and the sleepiness scale by Stanford to assess patients affected by different types of chronic cardiac pathologies in order to determine the incidence of daytime sleepiness in these patients.

MATERIAL AND METHOD

We evaluated 27 in-patients of Cardiology at Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo (HCFMRRUSP), divided in 19 men and 8 women, ages ranging from 17 to 81 years, all of them with chronic cardiac pathologies. We evaluated them concerning the presence of daytime sleepiness and the presence of signs and symptoms suggestive of OSAS. Patients were evaluated by the scales of Epworth and Stanford, which aim at measuring daytime sleepiness, and by snoring scale that measures audibility of snoring. We also calculated body mass index (BMI) to check overweight in the patients.

RESULTS

Out of 27 assessed patients, 22 reported daytime sleepiness by Stanford scale, representing 81.48% of the total. Forty point seventy-four percent (40.74%) of the cases presented index equal or higher than 12 in Epworth scale, suggesting the presence of daytime sleepiness, among which 81.81 % had clinical manifestations suggestive of OSAS and 63.63%, BMI higher than 25, indicating overweight. Among the patients that had index below 12 in Epworth scale (59.26% of the total), 50% had clinical presentation suggestive of OSAS and 37.5% had BMI above 25.

Snoring was reported as a complaint by 19 patients (70.37% of the total), and it was classified as severe or very severe by 33.33% of the subjects.

The most frequent cardiac pathologies were coronary diseases (59.26%), valvulopathy (18.52%), myocardiopathy (14.81%), severe hypertension (3.7%) and arrhythmia (3.7%) (Table 1).

DISCUSSION

According to Epworth scale, an index higher than 12 suggests the need for further investigation of apnea and above 16 it is strongly indicative of moderate to severe apnea6,8,11. This concept has been used as a way of screening subjects who have higher likelihood of OSAS treated in the Ambulatory of Snoring and Sleep at HCFMRP-USR Based on that, we indicate polysomnography

Cardiopulmonary diseases may be aggravated, caused or even triggered by OSAS1,5,14. Long-term studies have shown that hypertensive apnea patients have lower pressure levels after installation of CPAP, which does not happen with normal pressure patients. Therefore, if apnea is resolved successfully in hypertensive patients, the dose of antihypertensive medication should be reviewed14,15. Cardiopulmonary pathologies are so prevalent in subjects with moderate to severe apnea that a complete assessment is necessary in most patients, especially if a surgical procedure is indicated. Arterial blood hypertension has been identified in about 50% of the apnea patients, pulmonary hypertension in 10 to 20%, in addition to cardiac arrhythmia that is also very prevalent4,7,9,10,13,14.





The fact that we found 40.74% of patients with daytime sleepiness in Epworth scale and 81.48% in Stanford scale among studied cardiac patients shows its great incidence in this group of patients, reinforcing the idea that there is a high proportion of apnea patients among cardiopathy patients. Such a diagnosis would only be reached by polysomnography, an objective exam that would confirm our findings.

Obesity is no pre-requisite for OSAS. Nevertheless, its prevalence among apnea patients is very high. It is also known that body mass index (BMI) is based on weight in kilograms, divided by the square of the height in meters, and the value above 25 is considered overweight and above 27 is correlated with a progressive increase of mortality. It has also been defined that weight loss improves severity of apnea and that its gain is normally followed by worsening of symptoms14.

We found 48.15 % of patients with overweight in the studied group and 63.63 % of them had daytime sleepiness, but 37.5 % did not have it. This fact confirmed the correlation between obesity and OSAS. The finding of 70.37% of patients with snoring complaints emphasizes the important role of the otorhinolaryngologist in the assessment of these patients.

CONCLUSIONS

Obstructive sleep apnea syndrome is considered moderately prevalent, presenting daytime sleepiness as an important clinical manifestation. Its relation with chronic cardiac pathologies remains a topic for discussion. The fact that we found a large percentage of patients with daytime sleepiness who had cardiopathies does not irrefutably confirm its relation with OSAS, but it claims for further investigation of these patients, aiming at diagnosing potential apnea in patients with cardiac pathologies.

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* Resident Physician of Otorhinolaryngology at Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo (USP).
** Assistant Physician of Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto. Master in Otorhinolaryngology at Faculdade de Medicina de Ribeirão Preto, USP.
*** Faculty Professor and Head of the Department of Ophthalmology and Otorhinolaryngology at Faculdade de Medicina de Ribeirão Preto, USP.

Study conducted at the Department of Ophthalmology and Otorhinolaryngology, Faculdade de Medicina de Ribeirão Preto, Universidaie de São Paulo.
Address for correspondence: Prof Jose Ant6nio A. de Oliveira. Departamento de Oftalmologia a Otorrinolaringologia da Faculdade de Medicina de Ribeirão Preto.
Avenida Bandeirantes, 3900 - 14049-900 Ribeirão Preto (SP) - Tel: (55 16) 602-3000 - Fax: (55 16) 633-1586.
Article submitted on August 4, 2000. Article accepted on September 14, 2000.