Scholarly article on topic 'Assessment of carotid artery wall in patients with OSA syndrome and the effect of CPAP on its thickness'

Assessment of carotid artery wall in patients with OSA syndrome and the effect of CPAP on its thickness Academic research paper on "Clinical medicine"

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Abstract of research paper on Clinical medicine, author of scientific article — Mohammed A. Agha, Rehab M. Habib

Abstract Background In patients with Obstructive sleep apnea (OSA), the risks of fatal and non-fatal cardiovascular diseases and coronary artery disease are increased and measuring carotid intima-media thickness (CIMT) can assess these complications. Aim Studying the effect of OSA syndrome in the carotid artery wall thickness as an indicator to cardiovascular complications, and the effect of CPAP on these changes. Subjects and methods Polysomnography (PSG) was done for 45 patients; 29 patients of them proved to have OSA, and 10 obese subjects with normal PSG were included as a control group. All of them had ultrasonographic assessment of CIMT. 17 patients with OSA used CPAP overnight for 6months and the CIMT was remeasured. Results 29 were diagnosed with OSA (12 severe, 9 moderate and 8 mild OSA). There was a highly significant difference (p <0.01) in CIMT between patient and control groups, and also between severe and mild OSA patients with non-significant difference (p >0.05) between severe and moderate OSA. Regarding the different risk factors predispose to atherosclerosis, only factors related to OSA syndrome were correlated with CIMT. There was a highly significant reduction (p <0.01) in CIMT after six months of CPAP usage. Conclusions CIMT as a marker of atherosclerosis is significantly increased in patients with OSA and the use of CPAP in those patients is very important not only for improving sleep efficiency but also for reducing cardiovascular complications associated with OSAS.

Academic research paper on topic "Assessment of carotid artery wall in patients with OSA syndrome and the effect of CPAP on its thickness"

Egyptian Journal of Chest Diseases and Tuberculosis (2014) 63, 155-160

The Egyptian Society of Chest Diseases and Tuberculosis Egyptian Journal of Chest Diseases and Tuberculosis

www.elsevier.com/locate/ejcdt www.sciencedirect.com

ORIGINAL ARTICLE

Assessment of carotid artery wall in patients with OSA syndrome and the effect of CPAP on its thickness

Mohammed A. Agha a *, Rehab M. Habib b

a Chest Departments, Faculty of Medicine, Menoufiya University, Egypt b Radiology Departments, Faculty of Medicine, Menoufiya University, Egypt

Received 6 October 2013; accepted 9 October 2013 Available online 5 November 2013

KEYWORDS

Obstructive sleep apnea; Intima-media thickness; Polysomnography

Abstract Background: In patients with Obstructive sleep apnea (OSA), the risks of fatal and nonfatal cardiovascular diseases and coronary artery disease are increased and measuring carotid intima-media thickness (CIMT) can assess these complications.

Aim: Studying the effect of OSA syndrome in the carotid artery wall thickness as an indicator to cardiovascular complications, and the effect of CPAP on these changes.

Subjects and methods: Polysomnography (PSG) was done for 45 patients; 29 patients of them proved to have OSA, and 10 obese subjects with normal PSG were included as a control group. All of them had ultrasonographic assessment of CIMT. 17 patients with OSA used CPAP overnight for 6 months and the CIMT was remeasured.

Results: 29 were diagnosed with OSA (12 severe, 9 moderate and 8 mild OSA). There was a highly significant difference (p < 0.01) in CIMT between patient and control groups, and also between severe and mild OSA patients with non-significant difference (p > 0.05) between severe and moderate OSA. Regarding the different risk factors predispose to atherosclerosis, only factors related to OSA syndrome were correlated with CIMT. There was a highly significant reduction (p < 0.01) in CIMT after six months of CPAP usage.

Conclusions: CIMT as a marker of atherosclerosis is significantly increased in patients with OSA and the use of CPAP in those patients is very important not only for improving sleep efficiency but also for reducing cardiovascular complications associated with OSAS.

© 2013 The Egyptian Society of Chest Diseases and Tuberculosis. Production and hosting by Elsevier

B.V. All rights reserved.

* Corresponding author. Mobile: +20 1004774422. E-mail address: drmohammedagha@yahoo.com (M.A. Agha). Peer review under responsibility of The Egyptian Society of Chest Diseases and Tuberculosis.

Introduction

Obstructive sleep apnea is characterized by recurrent collapse of the pharyngeal airway during sleep, resulting in reduction (hypopnea) or complete cessation (apnea) of airflow despite the ongoing breathing efforts. These disruptions to breathing lead to intermittent hypercapnia and hypoxemia and surges of sympathetic activation. Loud snoring is a typical feature

0422-7638 © 2013 The Egyptian Society of Chest Diseases and Tuberculosis. Production and hosting by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016Zj.ejcdt.2013.10.006

of OSA and in most cases the culmination of a respiratory event is associated with a brief awakening from sleep (arousal). These events result in fragmented sleep as the patient oscillates between wakefulness and sleep. In severe cases respiratory events can occur more than 100 times per hour and typically each event last 20-40 s [1,2]. These events may include any combination of obstructive apnea, hypopnea, or respiratory effort-related arousals [3]. The stress caused by recurrent episodes of apnea results in increased levels of endogenous endothelin-1 a long-lasting vasoconstrictor. Blood pressure and endothelin-1 concentrations were increased after 4 h of untreated obstructive apneas, and decreased after 5 h of continuous positive airway pressure (CPAP) treatment [4]. In contrast, nitric oxide, which is a known vasodilator, has been reported to be reduced in patients with obstructive sleep apnea syndrome (OSAS). The increased endothelin and reduced nitric oxide levels have been reported to reverse with the use of CPAP [5]. Moreover, It has been suggested that endothe-lium-dependent vascular dysfunction in patients with OSAS plays a role in the development of atherosclerosis. Vascular endothelial growth factor (VEGF), a hypoxia-sensitive glyco-protein that stimulates neoangiogenesis is associated with vascular remodeling and its levels are closely correlated with the degree of nocturnal oxygen desaturation [6]. Vascular remodeling may cause an increase in the arterial blood pressure. It has been reported that amelioration of nocturnal hypoxia by CPAP is associated with a decrease in the serum levels of VEGF [7]. In patients with OSAS, the risk of fatal and nonfatal cardiovascular diseases and coronary artery disease is increased. A parallel increase in the severity of OSAS and the cardiovascular events has also been described. OSAS is often associated with cardiovascular risk factors, such as diabetes mellitus, hyperlipidemia and obesity [8]. Untreated OSAS is also associated with dysglycemia, systemic inflammation, endothelial dysfunction, platelet activation, and other cardiovascular consequences such as cardiac arrhythmias especially atrial fibrillation (AF), coronary artery disease, asymptomatic early atherosclerosis, and silent brain infarction [9]. Moreover, the hypoxia, negative intrathoracic pressure, and arousal induced by upper-airway obstruction during sleep, as well as repeated activation of the sympathetic nervous system, have various effects on blood pressure and coagulation factors that may lead to an increased risk of cardiovascular morbidity [10]. CIMT is a useful marker for investigating the degree of early atherosclerosis. Several clinical studies have demonstrated that an increase in ultrasonographically measured CIMT is associated with elevated risks of cardiovascular diseases and stroke [11]. CIMT, as evaluated by ultrasound, correlates well with anatomic measurements and is recognized as a marker of pre-clinic atheroma. An increased CIMT is accepted as a potent predictor of myocardial infarction and stroke, even after adjustment for other risk factors. Accordingly, ultrasonogra-phy measurement intima-media thickness (IMT) has recently become established as a method of assessing the early stage of atherosclerosis. It also has been reported that the carotid-artery IMT is increased in patients with hypertension, hyperlip-idemia, or diabetes mellitus, as well as in the elderly [12]. Different studies have investigated the effect of OSA on atherosclerosis, and it has been demonstrated that the levels of soluble adhesion molecules, VEGF, and coagulation factors are increased in OSA patients, compared with control subjects, and are significantly decreased by the use of CPAP therapy.

These studies have suggested that OSA may be associated with the progression of atherosclerosis [13-15].

Aim of the work

The aim of this work was to assess the effect of OSAS in the carotid artery wall thickness as an indicator to cardiovascular complications, and to study the effect of CPAP usage on these changes.

Subjects and methods

Patients with symptoms and signs of sleep breathing disorders recruited from the chest department, Menoufiya University Hospitals were initially included. Those patients were subjected to: complete history taking, clinical examination both general and chest examinations. Patients were referred to the sleep disorders unit in Menoufiya University Hospital where a sleep questionnaire was completed including the patient's symptoms, anthropometric measures (height, weight and neck circumference), his sleep habits, and the Epworth sleepiness scale (ESS) [16]. Then, overnight polysomnography (PSG) was performed for patients using Embla S4000 Med-care, Iceland. The system has the following components: Somnologica studio 3.3.2 software; Pulse oximetery sensor, Airflow nasal pressure cannula; Airflow thermistor; Respiratory inductive plethysmography belts with thoracic and abdominal locks; Snoring microphone; Body position sensor; EEG electrodes with their cables; EOG electrodes; EMG electrodes for the chin and anterior tibialis muscle; and ECG electrodes with their cables. Patients were studied at night for at least 6 h. All studies were analyzed by sleep physicians using the criteria of Rechtschaffen and Kales [17] and in close concordance with scoring updates given by the American Academy of Sleep Medicine [18]. Apneas were scored when there was a complete cessation of airflow or P90% drop in the peak thermal sensor excursion for at least 10 s. Hypopne-as were scored when there was a drop in the nasal pressure by P30% of baseline lasting at least 10 s with a P4% desaturation from pre-event baseline, or when there was a drop in the nasal pressure signal excursion by P50% of baseline lasting at least 10 s with a P3% desaturation from pre-event baseline. The apnea-hypopnea index (AHI) which is number of apnea-hypopnea events per hour was determined after the exclusion of periods with movements, which were considered to be wake periods.

In the next morning, a fasting venous blood sample was taken for Fasting and 2 h post prandial blood glucose, lipid profile [included; high density lipoprotein (HDL), low density lipoprotein (LDL), triglycerides and Cholesterol].

The 29 patients diagnosed to have OSA and 10 subjects with normal polysomnographic findings but with BMI >30 (control group) were referred for measuring carotid IMT using ultraonography.

Carotid IMT assessment: [19] Carotid artery IMT was assessed by B-mode ultrasound scanning with a 10-MHz linear phase array transducer (Hitachi AUB 7000). The patient's head was rotated away from the side being examined. The evaluation of common carotid arteries was done in a longitudinal plane then confirmed in axial plans. Bilateral IMT (the

distance between the leading edge of the luminal echo to that of the media/adventitia echo) measurements were obtained at the distal 10 mm of the common carotid artery. Three measures were taken for each side and the mean measure was calculated. The carotid scan operator was blinded to the clinical treatment status of the studied subjects and was not involved in the clinical assessment.

• Normal measures of carotid intima-media: 0.04-0.07 cm

with 0.001 cm more in female.

• Equivocal measures: 0.07-0.11 cm.

• Atherosclerotic measures >0.11 cm.

Patients with confirmed OSA were re-refered to the sleep disorders unit in the Menoufiya University Hospital for a titration study using the same system in addition to CPAP device (Fisher & Paykel Sleep Style 254) to document abolishing of respiratory events and to determine the appropriate pressure needed for each patient. Patients were encouraged to use CPAP every night for six consecutive months. A follow up CIMT study was done and the same measurements were taken and compared to the initial ones.

Statistical methodology [20]

The data collected were tabulated & analyzed by SPSS (statistical package for the social science software) statistical package version 11 on IBM compatible computer. Quantitative data were expressed as mean and standard deviation (X ± SD). ANOVA test for analysis of variance (f-test) was used for comparison of more than two groups of normally distributed variables; and krauskal wallis test was used for comparison of more than two groups of non-normally distributed variables. Students T test was used for comparison of two quantitative variables. Qualitative data were expressed as number and percentage (No and %) and analyzed by applying chi-square test (X2). Pearson correlation (r) was used to detect association be-

tween quantitative variables. All these tests were used as: • P value >0.05 was considered statistically non-significant. • P value 60.05 was considered statistically significant. • P value 60.01 was considered statistically highly significant.

Results

From the 45 patients who were initially included and did the polysomnographic study, 29 patients had OSA syndrome, and of the remaining 16 cases (14 normal, and 2 mixed sleep apnea), 10 subjects with normal polysomnographic findings with BMI >30 were included as a control obese group. The proved 29 cases with OSA were; 12 cases with severe OSA, 9 cases with moderate OSA, and 8 cases with mild OSA. All the 29 patients and the 10 control cases had initially measured carotid IMT using ultrasonography. In the present study there were no significant differences between patients and the control groups in general characteristics such as sex, age, BMI and risk factors for atherosclerosis (Table 1). Regarding ply-somnographic data, there were significant differences between OSA patients and the control group and also regarding the severity of OSA. (Table 2) Table 3 and Table 4 show that there was a marked increase in CIMT in patients with OSA compared to the control group and this increase was a highly significant difference between patients with severe or moderate OSA and the control group and also this increase was significantly different in regard to patients with mild OSA. Also, there was a highly significant increase in CIMT between mild and severe OSA patients with no difference between patients with moderate and severe OSA. From different factors that are already known to predispose to atherosclerosis (such as, DM, HTN, BMI, smoking, age and dyslipidemia) only factors related to the OSA syndrome were found to be significantly correlated with the degree of CIMT (O2 desaturation, Lowest O2 Saturation, SaO2 < 90% of TST, and AHI). (Table 5) Patients with moderate and severe OSA were recommended to use overnight CPAP. From the 21 cases with moderate or

Table 1 Comparisons between patients and control groups regarding different characteristics.

Variable Control obese OSA (total) Chi square p-Value

Age 52.80±8.403 53.34±11.53 *0.137 >0.05

Male 4 40% 18 62.1% 1.47 >0.05

Female 6 60% 11 37.9%

Present 4 40% 10 34.5% 0.098 >0.05

Absent 5 60% 19 65.5%

Present 5 50% 10 34.5%

Absent 5 50% 19 65.5% 0.756 >0.05

Dyslipidemia

Present 7 70% 6 37.9%

Absent 3 30% 18 62.1% 3.07 >0.05

BMI 40.34± 5.71 37.93± 8.65 *0.815 >0.05

Smoking

Yes 2 20% 7 41.4%

No 8 80% 17 58.6% 1.47 >0.05

*: t test. OSA: obstructive sleep apnea. BMI: body mass index. HTN: hypertension. DM: diabetes mellitus.

Table 2 Polysomnographie characteristics in the studied groups.

Variable Control obese OSA (total) Mild OSA Moderate OSA Severe OSA ANOVA P-Value

AHI 2.72 ± 1.99 24.54 ± 22.45 9.31 ± 2.63 24.4 ± 5.3 53.01 ± 15.10 67.59 <0.001*

TST 393.5 ± 47.35 313.21 ± 77.19 358.78 ± 39.68 284.30 ± 46.71 237.58 ± 43.09 26.56 <0.001*

Sleep eff 77.67 ± 7.15 68.75 ± 8.93 72.21 ± 6.16 64.42 ± 5.06 62.26 ± 6.97 12.43 <0.001*

SaO2 <90% 1.02 ± 1.82 15.41 ± 12.70 6.60 ± 4.41 23.62 ± 6.96 27.14±7.54 48.94 <0.001*

Lowest O2 90.75 ± 2.20 75.85 ± 14.32 84.25 ± 3.84 75.44 ± 7.76 58.16 ± 7.58 60.39 <0.001*

Average O2 96..12 ± 1.39 91.11 ± 5.61 93.9 ± 1.57 91.66 ± 2.56 84.66 ± 5.15 25.09 <0.001*

ESS 3.40 ± 1.64 9.92 ± 4.24 10.25±1.28 12.66 ± 1.00 13.08 ± 1.56 101.45 <0.001*

OD 4.92 ± 4.17 27.27 ± 27.21 9.11 ± 3.67 30.31 ± 15.97 55.73 ± 27.65 19.01 <0.001*

OSA: obstructive sleep apnea. AHI: apnea-hypopnea index. TST: total sleep time. ESS: the Epworth sleepiness scale. OD: oxygen desaturation. Eff: efficiency. *: highly significance difference.

Table 3 Intima-media wall thickness in the studied groups before use of the CPAP.

Variable Control obese OSA (total) Mild OSA Moderate OSA Severe OSA ANOVAtest p-Value

IMT 0.084 ± 0.23 0.131 ± 0.04 0.11 ± 0.02 0.15 ± 0.017 0.166 ± 0.032 24.63 <0.01*

OSA: obstructive sleep apnea. IMT: intima-media thickness. *: highly significance difference.

Table 4 Comparison between different groups regarding IMT before the use of the CPAP.

Groups IMT X ±SD t-test P-Value

Control 0.084 ± 0.23 6.808 < 0.001*

Severe OSA 0.166 ± 0.032

Control 0.084 ± 0.23 7.16 < 0.001*

Moderate OSA 0.15 ± 0.017

Control 0.084 ± 0.23 2.45 < 0.05 s

Mild OSA 0.11 ± 0.02

Mild OSA 0.11 ± 0.02 4.503 < 0.001*

Severe OSA 0.166 ± 0.032

Mild OSA 0.11 ± 0.02 4.701 < 0.001*

Moderate OSA 0.15 ± 0.017

Moderate OSA 0.15 ± 0.017 1.214 > 0.05

Severe OSA 0.166 ± 0.032

Control 0.084 ± 0.23 5.32 < 0.001*

Total OSA 0.131 ± 0.04

OSA: obstructive sleep apnea. IMT: intima-media thickness SD: standared deviation. *: highly significance difference. S: significance difference.

severe OSA, 17 cases use the overnight CPAP regularly for 6 months while the remaining 4 cases did not. After the 6 months of regular use of the overnight CPAP, the 17 patients did another measurement of CIMT where there was a marked significant reduction in the IMT patients with severe and moderate OSA (Table 6).

Discussion

Obstructive sleep apnea syndrome is characterized by repetitive episodes of upper airway obstruction causing daytime sleepiness, impaired cognitive function and poor health status [21]. In patients with obstructive sleep apnea syndrome, the risk of fatal and non-fatal cardiovascular diseases and coronary artery disease is increased [8]. CIMT has recently become established as a method of assessing the early stage of atherosclerosis [12]. So, the aim of the present study was to evaluate the cardiovas-

Table 5 Pearson correlation coefficient between IMT and diff risk factors in OSA patients.

IMT R factor p-Value

Age 0.004 >0.05

HTN 0.068 >0.05

DM 0.036 >0.05

Dyslipidemia 0.0423 >0.05

BMI 0.033 >0.05

Smoking 0.045 >0.05

AHI 0.840 <0.001

Lowest O2 Saturation 0.795 <0.001

SaO2 < 90% of TST 0.736 <0.001

OD 0.684 <0.001

OSA: obstructive sleep apnea. BMI: body mass index. HTN: hypertension. DM: diabetes mellitus.

BMI: body mass index. AHI: apnea-hypopnea index. OD: oxygen desaturation.

cular complication in patients with obstructive sleep apneas by measuring CIMT and study the effect of using the overnight CPAP on CIMT. In this work, 10 control obese patients not complaining from OSAS were included and there was no significant difference (p value <0.01) between them and the OSA patients group regarding the general characteristics (age, sex, BMI, DM, dyslipidemia, and smoking habits) and this matched characteristics helped us in studying the effect of OSA as a predisposing factor for atherosclerosis. The previous findings were in accordance with that of Silvestrini [22] who did not exclude risk factors from the studied group but used matched groups, while Minoguchi [23] excluded patients with hypertension, diabetes, or hyperlipidemia because these conditions can increase carotid IMT while age and body mass index, which also affect carotid IMT, were matched between patients with OSA and obese control subjects. In the present study there was a marked increase in CIMT in patients with OSA compared to the control group and this increase was a highly significant difference (p value <0.01) between patients with severe or moderate OSA and the control group and also this increase was significantly different (p value <0.05) regarding patients with mild OSA. Also, there was a highly significant increase in CIMT from mild to severe (p value <0.01). The previous findings are in agreement with that of Schulz [24] who found that Carotid IMT was significantly elevated in patients with OSA compared with obese control subjects (1.07 ± 0.05 vs. 0.71 ± 0.03 mm, p < 0.001). In addition, carotid IMT in patients with moderate to severe OSA (1.16 ± 0.05 mm) was significantly elevated compared with patients with mild OSA (0.92 ± 0.07 mm, p < 0.003) or compared with obese control subjects (0.71 ± 0.03 mm, p < 0.0001). Also, the present work's results confirmed with that of Schulz [24] where ultrasonography of the large extracranial vessels was performed in a group of consecutively admitted OSA patients (n = 535) and a control group of non-OSA patients (n = 535) and CIMT was measured at the far wall of both proximal carotid arteries. They [24] found that mean CCA-IMT was markedly increased in the OSA patients when compared with the control group (p < 0.01). Suzuki [25] agreed with the previous results and concluded that OSA is independently related to atherosclerosis, and that the severity of OSA-related hypoxemia is more important than is the frequency of obstructive events. Jean-Philippe Baguet [26] stated the same conclusion. In this study by using Pearson correlation for different factors that are already known to predispose to atherosclerosis (such as, DM, HTN, BMI, smoking, age and dyslipidemia), only factors related to the OSA syndrome were found to be significantly correlated with the degree of CIMT (O2 desaturation, Lowest O2 Saturation, SaO2 < 90% of TST, and AHI). The previous findings are in agreement with many studies [24-26] in that the severity of oxygen desaturation and the longer period of SaO2 < 90% of TST, the more severe degree of CIMT and so the more incidence of atherosclerosis.

Suzukki [25] found That IMT was significantly correlated with the AHI (r = 0.327; P < .001),T90(r = 0.354; P < .001), and the mean nadir oxygen saturation (r = —0.331; P < .001) by Pearson's correlation analysis. But unlike the present study, by the same analysis they also found that IMT was also significantly correlated with age (r = 0.469; P < .001), BMI (r = 0.188; P < .05), total cholesterol (r = 0.187; P < .05), HbA1c (r = 0.264; P < .001), and systolic blood pressure (r = 0.174; P < .05). This difference may be a result of a small number of patients (29 cases of OSA) compared to 167 patients in Suzuki's study [25], also in Suzuki's study [25] there was no control group like the present study. Also Minoguchi [23] concluded that the primary factor influencing carotid IMT was the duration of hypoxia during total sleep time (p < 0.036) and these results suggested that OSA related hypoxia and systemic inflammation might be associated with the progression of atherosclerosis and thus might increase the risks of cardiovascular and cerebrovascular morbidity in patients with OSA. Minogu-chi [23] found that carotid IMT was positively correlated with age (r = 0.41,p < 0.004), AHI (r = 0.50,p < 0.002), andper-centage of time with SaO2 was less than 90% (r = 0.60, p < 0.0001), this difference between this study and Minogu-chi's study [23] in the positive correlation of age [23] may be due to the difference in the range of ages they studied 23y to 65 y while the range in the present study was 38-72 and also in the number of the studied group in this work was 29 patients and 10 controls while in this work while 36 patients and 16 control in their work. In this work the effect of CPAP on CIMT was studied. Patients with moderate and severe OSA were recommended to use overnight CPAP. From the 21 cases with moderate or severe OSA, 17 cases use the overnight CPAP regularly for 6 months while the remaining 4 cases did not. After the 6 months of regular use of the overnight CPAP, the 17 patients did another measuring of CIMT where there was a marked significant reduction (p < 0.001) in the IMT patients with either severe or moderate OSA. The importance of CPAP usage in patients with OSA in the reduction of CIMT was confirmed by Hui [27] who found that in a group of 50 symptomatic patients newly diagnosed with severe OSAS, showed that CPAP treatment (n = 28) resulted in a significant reduction in the carotid artery IMT compared to those who had opted for conservative treatment (CT, n = 22) over a study period of 12 months. Most of the reductions in the carotid artery IMT when comparing CPAP against the CT group appeared to have occurred within the first 6 months of treatment whereas there was no significant change from 6 to 12 months while the patients had maintained reasonable CPAP usage objectively throughout the study. The previous findings were also confirmed by the Baguet study [26] who confirmed the CPAP enables the reduction of cholesterol levels, systemic inflammation and improves nitric oxide production.

Table 6 IMT before and after the use of CPAP.

Variable IMT before IMT after Paired t test p-Value

Moderate 0.15 ± 0.017 0.097 ± 0.018 10.33 <0.001*

Severe 0.166 ± 0.032 0.10 ± 0.023 10.25 <0.001*

Total 0.131 ± 0.04 0.99 ± 0.021 14.16 <0.001*

OSA: obstructive sleep apnea. IMT: intima-media thickness. *: highly significance difference.

Conclusions

Obstructive sleep apnea syndrome is associated with cardiovascular complications which can be assessed by measuring the carotid intima-media thickness. CIMT is significantly increased in patients with OSAS and the use of CPAP in those patients is very important not only for improving sleep efficiency but also for reducing cardiovascular complications associated with OSAS. But more studies should be done for assessment of the effect of OSA patients free of any risk factors on CIMT, also, studies on the effect of CPAP serially within longer and shorter periods to select the optimum period for its use and the effect of CPAP usage on different associated risk factors and inflammatory markers associated with the OSAS.

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