A.V. Sakellaropoulou, M.N. Hatzistilianou, M.N. Emporiadou, V.T. Aivazis, J. Goudakos, K. Markou, F. Athanasiadou-Piperopoulou predictive of OSA in children [6, 7]. Moreover, nocturnal polyuria is considered a cardiovascular response to negative pressure breathing (inspiration against a closed glottis), which is characteristic of OSA [8]. The association between these two conditions in paediatric subjects is supported by the decrease or complete resolution of bedwetting after successful treatment of SDB with adenotonsillectomy or the use of intranasal corticosteroids [4, 6, 9]. Moreover, patients with untreated obstructive sleep apnoea syndrome (OSAS) excrete large amounts of sodium and urine overnight, probably because of increased secretion of atrial natriuretic peptide which is caused by the stimulation of right atrial receptors exposed to the exaggerated intra-thoracic pressure swings which accompany narrowing and obstruc- tion of the upper airway. The natriuresis and polyuria are completely suppressed by effective treatment of OSAS [8, 10]. A few series have been published of hospitalised children with SDB and concomitant enuresis [1, 2, 7, 11], and also a number of popula- tion-based studies have reported a significant corre- lation between habitual snoring and nocturnal enu- resis [12-14]. The purpose of this research was to assess whether habitual snoring, mouth breathing and daytime sleepi- ness are associated with increased incidence of enu- resis in children with obstructive apnea hypopnea syndrome during sleep (OSAHS), and whether the prevalence of enuresis was modified by the severity of OSAHS. Material and methods Study sample and location The study group included 42 children who visited the Paediatric Sleep Laboratory of the 2nd University Paediatric Department of AHEPA Hospital in Thes- saloniki, Greece. There were 28 males (66.7%) and 14 females (33.3%). Their age ranged from 3.5 to 14.5 years old (range ± SD: 7.63 ±2.90 years). Children entered the Sleep Laboratory with their parents between 9 and 9.30 p.m. After cleaning the study area of electrodes’ placement, the recording started at about 11 p.m. Study protocol Information was gathered concerning the child’s gender, age, difficulty in breathing during sleep, mouth breathing, witnessed apnoea, daytime sleepiness, restless sleep, difficulty in arousal, fatigue, mouth breathing and enuresis. Snoring and its severity were also recorded. The frequency of snoring was graded as “never,” “rarely” (once per week), “occasionally” (twice per week), “frequently” (3-4 times per week), and “almost always” (> 4 times per week). Otolaryngological evaluation was performed in each child, and tonsils size was classified according to Mallampati criteria [15]. Subjects were excluded if they had any known genetic or craniofacial syn- dromes. Polysomnographic study (PSG) was performed in 42 patients with a commercially available system, Sleep Screen, Viasys Healthcare Corporation. The recording of polysomnographic information was clas- sified based on the existing criteria, since polysomnographic sleep study is recommended by the American Paediatric Academy as the gold stan- dard for confirmation and classification of the severity of OSAHS in children [13, 16]. A single night of attended polysomnography was performed in each subject at the sleep laboratory, and no drugs were used to induce sleep. The poly- somnographic sleep study included measurements of right and left electrooculograms, heart rate by electrocardiogram (ECG), a bipolar submental elec- tromyogram, electro-encephalogram (EEG), anterior tibial electromyograms (EMG), thoracic and abdom- inal excursions as detected by inductance plethys- mography bands, air flow monitored with a nasal pressure cannula, a thermistor, and an end-tidal cap- nograph that also provided breath-by-breath assess- ment of end-tidal carbon dioxide levels with simul- taneous recording of the pulse waveform, and was recorded with a 3-seconds averaging routine (Capno- graph Sleep, Smith Medical family of companies), oxygen saturation via a palm oximeter, snoring through a microphone placed at the trachea area, and also evaluation of the body placement. Acceptable studies were those with at least 6 h of recorded data of sufficient quality to allow respiratory event detec- tion and distinction of wakefulness from sleep. Definitions The proportion of time spent in each sleep stage was expressed as a percentage of total sleep time (TST). Obstructive apnoea was defined as the ab- sence of airflow with continued chest wall and abdo- minal movement that lasts 2 respiratory cycles [16-18], and hypopnoea as a decrease in oro-nasal flow grea- ter than 50% despite continuous respiratory efforts followed by a reduction of saturation of oxyhaemo- globin at least for 3%, and/or arousal [16, 18, 19]. The obstructive apnoea-hypopnoea index (AHI) was defined as the number of apnoeas and hypop- noeas per hour of TST. The abnormal diagnostic for children would be AHI > 1/h of sleep [17, 18]. Since there are no definite diagnostic criteria for the clas- sification of OSAHS severity in children, the classifi- cation of mild, moderate and severe degree of OSAHS in children with OSAHS was performed based on their clinical appearance, the number of obstructive events per hour of sleep, the end-tidal expiratory pressure of carbon dioxide (PetCO2), the incidence and the severity of oxygen desaturation and the 522 Arch Med Sci 3, June / 2012