Portuguese Version

Year:  2002  Vol. 68   Ed. 5 - (3º)

Artigo Original

Pages: 619 to 622

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Relationship between systemic hypertension and obstructive sleep apnea syndrome

Author(s): Fransérgio E.M. Cavallari 1,
Marcelo G.J. Leite1 1,
Paulo R.E. Mestriner1 1,
Luciano G.F. Couto1 1,
Denílson S. Fomin 2,
José A. A. Oliveira 3

Keywords: obstructive sleep apnea syndrome, systemic hypertension, polissonographyobstructive sleep apnea syndrome, systemic hypertension, polissonography

Abstract:
Systemic hypertension (SH) and Obstructive Sleep Apnea Syndrome (OSAS) are very prevalent diseases worldwide, and, although rising interest in medical community, they still are not completely elucidated on their mechanisms and physiopathology concerning to their complications. OSAS is being each time more related to cardiovascular diseases, specially SH, which is prevalent in OSAS patients. In our paper, we intend to evaluate the findings in presence of SH in OSAS patients. We studied a patient population of Snoring and Apnea Ambulatory in Ribeirão Preto Medical College of São Paulo University's Clinics Hospital, from February 1999 to February 2002, totalizing 42 patients, being 30 (71,42%) male and 12 (28,58%) female, ages ranging 21 to 77 years (m=45,3, pd=9,372706), all them with polissonography confirmed diagnosis of OSAS, divided into two groups, 21 patients each, first one with patients only diagnosed as OSAS (control), and the second with patients diagnosed as OSAS and SH. We compared Epworth, Snoring and Sleepiness scales in both groups, added to use of polissonography for objective study. We found not significant statiscal differences between groups comparing scales results, even SH/OSAS group having always major media results. When we evaluate objectively the patients, with polissonography, using RDI (respiratory disturbance index), there is significant statiscal difference (p=0,0326), with SH patients reaching major medias. Comparing proportion inside groups, there is predominance of moderated and severe apnea in SH/OSAS group, and mild apnea prevails on control group. Concluding, concomitance of SH and OSAS represents aggravator factor in apnea grade.

Introduction

Systemic hypertension (SH) is a high morbidity-mortality condition prevalent worldwide, however it can be successfully managed in most of the cases if early diagnosed and with patient compliance. It is a multi-factorial disease with some genetic/environmental-related factors, but its pathophysiology still remains unexplained1, 2.

Obstructive Sleep Apnea is also reported as a high morbidity condition among the population and the medical community has been increasing its interest in it, since its consequences remain unclear as well as the mechanisms that generate complications. 3

Snoring is a symptom in 90 to 95% of the patients with OSA, therefore it should be investigated4. The syndrome affects 9% of the male population from 30 to 60 years old, and 4% of the female population within the same age range5. The clinical picture of the disease may include hundreds of breathing pauses during sleep, with intense oxyhemoglobin desaturation, cardiac arrhythmia and day and night symptoms such as nocturia, morning headache, excessive sleepiness at daytime, decreased intellectual performance, and symptoms of depression, impotence and even personality changes. OSA is the most severe sleep breathing disorder.

OSA has been increasingly related to cardiovascular pathologies, especially high blood pressure, which is reported as the most prevalent morbidity cause among OSA patients before its diagnosis. 6 Currently, OSA has been studied as one of the hypertension-related factors in some patients, however a consensus on the issue has not been reached yet.

OBJETIVE

The objective of this study is to assess the implications of high blood pressure in patients with OSA (Obstructive Sleeping Apnea).

Material and Method

The population consisted of patients from the Snoring and Apnea Department of the Clinical Hospital, Medical School of Ribeirão Preto, University of Sao Paulo from February 1999 through February 2002 (42 patients), with 30 (71.42%) male and 12 (28.58%) female subjects, with ages ranging from 21 to 77 years (mean age 45.3, SD = 9.372706). All patients had OAS and diagnosis was confirmed by polysomnography.

Patients were divided in two groups of 21 patients, according to presence or absence of systemic hypertension. The criterion used was SBP (systolic blood pressure) above 140 and DBP (diastolic blood pressure) above 90 in at least three measurements, taken at different intervals, or less than three readings but followed by symptoms or extremely high values. 2

The groups of this study were evaluated both by subjective and objective criteria.

The subjective evaluation classified patients according to 3 sleepiness scales. 7,8,9:

 Epworth Scale that is a questionnaire with 8 questions rated from 0 to 3 according to sleepiness intensity. The addition of the scores of the 8 questions will result in a final score that will be high for higher sleepiness levels. Total score is 24 and the normal range is equal or lower than 6.
 Stanford Sleepiness Scale: is a sleepiness scale to assess sleepiness level during the day using a rating scale from 0 to 10.
 Stanford Snoring Scale: rates the intensity of the snoring in a scale from 0 to 10.

Patients were objectively evaluated with a polysomnography exam, which is considered an essential test for both the qualitative and quantitative diagnosis of OAS and for assessing its severity. It provides the respiratory disturbance index (RDI), which counts apnea episodes (breathing stops during sleepiness higher than 10 seconds) and of hypoapnea (breathing stops lower than 10 seconds). The RDI is then applied to classify apnea as follows:

 Mild - from 5 to 15 episodes per hour
 Moderate - from 15 to 30 episodes/hour
 Severe - more than 30 episodes/hour.

Statistical analysis of our data was carried out with mean and standard deviation, and significance tests were performed with the software's Microsoft Excel® and Analyze-it®, using the ANOVA test.

Figure 1. Relation between patients with OAS and hypertensive patients with OAS



Figure 2. Relation between patients with OAS and hypertensive patients with OAS



Figure 3. Relation between patients with OAS and hypertensive patients with OAS



Figure 4. Relation between patients with OAS and hypertensive patients with OAS

Results

Sampling was divided in two groups with the same number of patients as mentioned before, and differences found in the analyses were classified as follows:

Figure 1 shows comparative charts between the average obtained in the Epworth scale in the two groups. There was a difference between the means, with higher levels among hypertensive patients against the control group. The application of statistical tests, however, did not show significant difference according to Table 1.

Similar results were obtained with the comparison of Stanford Snoring and Daytime Sleeping scales, in which hypertensive patients had in average higher levels than control group patients, but were not statistically significant. (Figures and Tables 2 and 3)

Figure 4 shows a chart with the comparison between the respiratory disturbance index (RDI) of the groups. (Table 4). In this case the analysis was statistically significant between the groups with hypertensive patients reporting higher RDI than the control group. Differentiated data of the patients with mild, moderate and severe apnea are reported in Table 6 showing that hypertensive patients had greater number of severe apnea.

Table 1



Table 2



Table 3



Table 4

Tukey 95% IC:-17.751 p/ -0.806 - Significant

Table 5

Discussion

There is not a well-defined explanation of the causing factors related to hypertension and OSA. Studies show a high prevalence of high blood pressure among patients with OSA before it is diagnosed, reinforcing the hypothesis of hypoxia in patients with apnea causing high blood pressure. Additional data show that there is increase of blood pressure (BP) in normotensive patients during the night simultaneously with oxyhemoglobin desaturation. These BP elevation decrease with NCPAP (Non-Continuous Positive Air Pressure) 10. Clinical trials suggested a role of bradykinin related to SH and OSA, and this provides evidences of altered vascular response in hypertensive patients with apnea. The change in the breathing pattern in OSA decreases internal chest pressure that facilitates venous return flow to the heart. The maximum response to bradykinin is decreased in hypertensive apnea patients, but it could be reversed after treatment with CPAP (Continuous Positive Air Pressure) 11.

Other pathologies could be related to OAS in addition to systemic hypertension, namely; angina, myocardium ischemia and cerebral vascular accidents, besides other simultaneous risk factors3,12. Obesity is highly related to systemic hypertension and obstructive sleeping apnea, since it is prevalent in both groups of patients.

The findings of this study showed that hypertensive patients, OSA patients included, had higher score in Epworth Scale, Stanford Snoring and Sleepiness Scales, however they were not statistically significant.

In terms of OAS severity evaluation, the values of RDI found in high blood pressure patients were significantly higher against that of the control group. The division of patients in groups of mild, moderate and severe apnea reported higher rates of severe patients among the hypertensive group than in the control group, which had a prevalence of mild apnea.

These data strengthened the relation between OSA and systemic hypertension, since apnea severity reported in high blood pressure patients was more intense. Otorhinolaryngologists should pay more attention to this group of patients that have higher risk of having OSA complications, especially because obstructive apnea is also a factor that affects cardiac output and vascular reactivity.

Conclusion

This study clearly showed a simultaneous prevalence of Systemic Hypertension and Obstructive Sleeping Apnea confirmed by polysomnography. However, subjective analysis did not show significant differences between the groups. Since the severity of obstructive apnea is related to hypertension, the immediate management of OAS should be an essential part of the treatment of apneic hypertensive patients, especially to prevent severe complications such as myocardium infarction and cerebral vascular accidents.

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1 Resident physician in Otorhinolaryngology, Hospital das Clínicas, Medical School of Ribeirão Preto, USP.
2 Master in Otorhinolaryngology, Medical School of Ribeirão Preto/USP; Assistant Physician, Hospital das Clínicas, Medical School of Ribeirão Preto, USP.
3 Faculty Professor, Head of the Discipline of Otorhinolaryngology, Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Medical School, Ribeirão Preto, USP.

Study conducted at the Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Medical School, Ribeirão Preto, University of São Paulo.

Address correspondence to: Departamento de Oftalmologia, Otorrinolaringologia e Cirurgia de Cabeça e Pescoço da Faculdade de Medicina de Ribeirão Preto.

Av. Bandeirantes, 3900 - Ribeirão Preto SP 14049-900 - Tel (55 16) 602-2863 - Fax (55 16) 602-2860

Article submitted on July 19, 2002. Article accepted on August 22, 2002

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