ABSTRACT
Obstructive sleep apnea-hypopnea syndrome [OSAHS] is a major public health problem due to its high prevalence rate. Polysomnography is the current golden standard test for diagnosis of OSAHS. The studies with pulse oximetry reveal a high sensitivity and suggest that as a screening tool, these may exclude some patients with negative studies from further work-up for OSAHS. Acoustic analysis of snoring sounds would offer the advantage of a non-invasive technique that would be used to monitor normal sleep. The posterior vocal tract resonances [i.e. F1 and F2] of OSA patients would yield lower frequency values compared to non-OSA individuals. To determine the sensitivity and specificity of overnight oximetry and phoniatrics parameters in evaluation of OSAHS and to compare the results with those obtained from polysomnography [PSG] as the gold standard test. Twenty patients, were presented with presumptive clinical diagnosis of OSAHS, each patient was subjected to: Full history taking: including age, sex, complain and Epworth Sleepiness Scale [ESS]. Systemic examination: Including general examination and body mass index [BMI]. Standard ENT examination and fibroptic pharyngoscopy with Muller maneuver. Polysomnography was done using RESMED Apnea Link screening device. Other tests: Acoustic analysis of voice and acoustic analysis of snoring sounds using computerized speech lab [CSL]. Pulse oximetry: The overnight oximetry was analyzed using the Wrist Pulse Oximeter MD300W. Eighteen patients [90%] were found to have OSAHS and two patients [10%] were simple snorers. The sensitivity of overnight pulse oximetry for an apnea hypopnea index of >5, >15, and >30/h was 66.7%, 80%, and 100% respectively and the specificity was 50%. The formant frequencies of different vowels [i, u and a] in OSA patients and non-OSA snorers revealed that the mean F1 value for the vowel /i/ was significantly lowered in OSA patients. In addition, the mean F2 value of the vowel /i/ and /u/ was markedly lowered in OSA patients. There was significant increase in values of bandwidths [BW1 and BW2] for /i/ and /u/ vowels in OSA patients in comparison to non-OSA snorers. Acoustic analysis of snoring sounds revealed that; in the palatal snorers group, the average pitch was 105 +/- 8 Hz and in the tongue base snorers group the average pitch was 263 +/- 17 Hz; meanwhile the average pitch in the combined group was 160 +/- 14 Hz. The difference was highly significant between the 3 groups. However harmonic to noise ratio was increased in patients with tongue base obstruction. Polysomnography is the current golden standard test for diagnosis and evaluation of degree of OSA. Overnight pulse oximetry offers an inexpensive method of screening for and diagnosing OSAHS. Oximetry alone allowed confident recognition of moderate and severe cases of OSAHS. Acoustic analysis of snoring sounds and voice in patients with snoring and/or OSAHS is useful as a screening or supportive method with other investigations to diagnose the site of upper airway obstruction during sleep