Among patients complaining of respiratory sleep disturbances, intermittent reductions in blood oxygen levels during sleep, but not persistent hypoxia, is associated with nocturia, a new study published in Sleep Medicine has found.
P. Finamore of Campus Bio-Medico University in Rome, and collaborators recruited 275 outpatients from their teaching hospital to undergo sleep polysomnography. Twenty-four percent of patients experienced 2 or more nocturia episodes nightly. On median, their oxygen desaturation index (ODI) was 15, respiratory efforts 22, and oxygen saturation (below 90%) 4.7.
Patients with nocturia scored significantly higher on the oxygen desaturation index (ODI) and on respiratory efforts. Oxygen desaturation occurred at a median rate of 24/h vs 13/h in patients with vs without nocturia. Upon multivariable analysis, ODI was associated with 3% greater likelihood of nocturia, with higher ODI scores linked with higher probability of nocturia. Unlike in previous studies, hypoxia length and severity, indicated by an oxygen saturation below 90%, did not relate with nocturia.
Nocturia commonly occurs among patients with respiratory sleep disturbances. According to the investigators, treating obstructive sleep apnoea might improve nocturia. In addition, the fact that nocturia increases with ODI might suggest that respiratory efforts to improve airflow during upper airways collapses, with their resulting increase in abdominal pressure, contribute to nocturia. The investigators also discussed overproduction of natriuretic peptides, left ventricular hypertrophy, and inflammatory changes that injure the bladder as possible contributors.
REFERENCE: Finamore et al. Occurrence of nocturia is not mediated by nocturnal hypoxia length and severity in patients with sleep-disordered breathing. Sleep Med. https://www.sleep-journal.com/article/S1389-9457(18)30023-6/abstract