Reference values for arterial stiffness indices in an Omani Arab population.

OBJECTIVES: To determine the reference values of arterial stiffness indices, particularly augmentation index (AIx) and pulse wave velocity (PWV) using applanation tonometry in a healthy Omani Arab population. METHODS: This prospective study was carried out in the Department of Clinical Physiology, Sultan Qaboos University Hospital, Muscat, Oman over a 2-year period from June 2011 to June 2013. The central AIx, aortic PWV (AoPWV), and central pulse pressure (CPP) were recorded from 120 healthy subjects recruited randomly from a normal population using a SphygmoCor device. The 2.5th and 97.5th percentiles were used to determine the reference ranges for men and women separately. Analyses were performed using univariate statistics. RESULTS: The mean age of the cohort was 38 years for men, and 35 years for women, with the ages ranging from 20-53 years. The overall mean central AIx was 13±11%, and for AoPWV was 6.7±1.6 m/s. The central AIx was higher in women (17 versus 10%; p<0.001), whereas the AoPWV was higher in men (7.1 versus 6.3 m/s; p=0.003). Subjects were categorized according to the gender and age decade, and reference values for CPP, central AIx, and AoPWV were obtained. CONCLUSION: This study reports the reference values for arterial stiffness indices from an Omani Arab population; the results of which should be interpreted in the context of its limitations.

An audit of the sleep medicine service in Oman.

OBJECTIVE: To audit the sleep service at Sultan Qaboos University Hospital (SQUH), Muscat, Oman, and to explore deficiencies to introduce new measures of improvement. METHODS: Polysomnography (PSG) reports and SQUH medical records of all patients who underwent sleep studies from January 1995 to December 2006 in the sleep laboratory at SQUH were reviewed and analyzed. RESULTS: Out of a total of 1042 sleep studies conducted in the specified period, 768 PSG recordings were valid for analysis. The audit showed that the Otolaryngology Department was the main referring specialty for PSG (43%). Snoring was the main symptom for 33% of the subjects referred, but suspicion of obstructive sleep apnea was the main reason for referral (38%). Three quarters of the patients were males who were also younger, and with lower body mass index compared to females (p=0.0001 for all). Despite large number of patients with an apnea-hypopnea index of >15 (n=261), only 94 (36%) patients received continuous positive airway pressure titrations and treatment. CONCLUSION: The sleep medicine service in SQUH provided the basic service, and raised the awareness of the importance of this specialty. However, substantial effort is required to bring it to international standards.

Obstructive sleep apnoea/hypopnoea syndrome and hypertension.

The obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a common disorder, affecting around 2-4% of the middle-aged population. There is a strong association between OSAHS and hypertension, based on animal, large epidemiological and interventional studies. The epidemiological studies have shown a dose-response relationship between apnoea/hypopnoea index (AHI) and the risk of developing hypertension. Different mechanisms may have a role in the process of elevated blood pressure in OSAHS. Sympathetic activity is increased in OSAHS patients during sleep and wakefulness. This increase in sympathetic activity is probably due to activation of baroreflexes and chemoreflexes by frequent arousals and hypoxaemia a result of apnoea or hypopnoea events. Continuous positive airway pressure (CPAP) has been shown to reduce sympathetic stimulation and blood pressure in OSAHS patients. Altered endothelial function may also have a role in the pathogenesis of hypertension in OSAHS subjects. Reduction of nitric oxide (NO) production and increase in the formation of free radicals may be responsible for the impairment of the vasodilatation of micro-vasculature in these subjects as a result of hypoxaemia. It has been shown that effective CPAP therapy has a reversible effect on endothelial dysfunction.