Prospective, Randomized, Double-blind Trial of Desmopressin on Nocturia in Obstructive Sleep Apnoea Patients

Nocturia is one of the commonest urinary symptoms in elderly and in patients with obstructive sleep apnoea (OSA). According to the International Continence Society (ICS) definition, nocturia is defined as "the complaint that the individual has to wake at night one or more times to void" . It implies a continuum beginning from what might be considered normal, to a bothersome state. Bothersome nocturia is a common and age-dependent condition. A prevalence ranging from 48.6% to 77% were reported in the literature. Pathogenesis of nocturia is multi-factorial, and has closely related to OSA. OSA patients generate negative intrathoracic pressure during sleep, this leads to increased venous return and distension of the right atrium. This leads to an increase of hormone secretion, namely Atrial Natriuretic Peptide (ANP). ANP causes increased sodium and water excretion, and inhibits the secretion of antidiuretic hormone. All of the above factors results in an increased nocturnal urine production and nocturia.

Middle-aged men with OSA always present to urology clinic with lower urinary tract symptoms with predominant nocturia. Many a time they were treated as benign prostatic hyperplasia with multiple medications with suboptimal response. The underlying genuine pathology of OSA-related nocturia is overlooked.

Desmopressin is an analogue of antidiuretic hormone, it is the pharmacological therapy of choice for patients with nocturia where night-time polyuria is present.

In this study, the investigators would like to evaluate the efficacy of desmopressin on symptoms of nocturia in patients with Obstructive Sleep Apnoea (OSA). The improvement of sleep quality and the quality of life will be measured.