Nocturia Episodes Reduced by Breathing Aids, Less Salt

Neil Osterweil

March 29, 2017

LONDON — Patients with obstructive sleep apnea who make frequent night-time trips to the bathroom might find relief from both urinary and sleep problems with continuous positive airway pressure (CPAP).

Two-thirds of patients assigned a CPAP mask experienced a reduction in nocturia episodes, Sajjad Rahnama'i, MD, PhD, from the Zuyderland Medical Center in Heerlen, the Netherlands, said here at the European Association of Urology 2017 Congress.

"The hypothesis for why this may work is twofold. First of all, we think it could be that the patients sleep more deeply, so have their nocturnal urge sensation suppressed," he told Medscape Medical News.

"But we also see that actual urine production during the night decreases during CPAP treatment, which would mean that it's not only the sensation and the deeper sleep, but that there's actually something happening in the physiology of urine in the kidneys and the fluid balance of the body," he explained.

There's actually something happening in the physiology of urine in the kidneys and the fluid balance of the body.

For their study, Dr Rahnama'i and his colleagues looked at the incidence of nocturia in 358 patients with obstructive sleep apnea who were prescribed a CPAP mask by a pulmonologist at their center in 2015.

The 206 men and 50 women who participated in the study were interviewed about nocturia before and after starting on CPAP. Mean age was 60 years.

At baseline, 176 of these patients (69%) reported nocturia, defined as at least one void each night.

After starting CPAP, 106 of the 176 patients reported a reduction in the number of nocturia episodes.

Table: Reduction in Night-time Voiding Episodes With CPAP in 176 Patients

Number of Night-time Voids at Baseline No Episodes 1 Episode 2 Episodes 3 Episodes 4 Episodes
1 (n = 55) 17 0 0 0 0
2 (n = 77) 32 22 0 0 0
3 (n = 19) 16 2 0 0 0
4 (n = 17) 7 0 1 2 0
5 (n = 6) 0 2 2 0 1
7 (n = 2) 0 1 1 0 0


The study is limited by its retrospective design, which could lead to recall bias, Dr Rahnama'i pointed out.

CPAP appears to have been effective in reducing nocturia, said session comoderator Alan Wein, MD, from the University Pennsylvania School of Medicine in Philadelphia. However, he said he wonders whether patients will continue to use it.

"What's the persistence rate of using these masks? It's my understanding that most of the time, they wind up under the nightstand after about 2 or 3 months," he said.

But Dr Rahnama'i thinks otherwise. "As I understand it — this is anecdotal and hearsay — once patients get the CPAP, their quality of life is so improved that they don't even leave the house without it," he said.

"At least one subgroup of patients is so happy with the treatment that they even take it to the hospital when they are hospitalized for a surgery," he reported.

Easy on the Salt

A separate study, demonstrating that a 2.7 g decrease in the daily intake of salt reduces nocturia episodes and significantly improves quality of life, was presented by investigator Matsuo Tomohiro, MD, from Nagasaki University in Japan.

But that target could be a challenge for many patients, especially in Japan, he acknowledged, where traditional diets are heavy on the sodium.

Dr Matsuo and his colleagues studied 321 patients with nocturia who consumed a high-salt diet, defined as at least 8 g daily for men and at least 7 g for women. The patients were given written guidance on reducing salt consumption. Patients with organic or functional abnormalities, including neurogenic bladder, were excluded from the study.

Voided volume, urinary frequency, daytime and night-time frequency, and other urinary parameters were recorded at baseline and at 12 weeks. Changes in lower urinary tract symptoms at baseline and at 12 weeks were compared using the Core Lower Urinary Tract Symptom Score (CLSS).

The investigators measured sodium and creatinine concentrations in spot urine samples to estimate the daily salt intake of each patient.

For the 223 patients who reduced their mean daily salt intake over the 12-week study period — from 10.7 g to 8.0 g — the mean number of nocturia episodes dropped from 2.3 to 1.4 (P < .001). In contrast, for the 98 patients who increased their mean daily salt intake — from 9.6 g to 11.0 g — the mean number of nocturia episodes increased slightly but significantly, from 2.3 to 2.7 (P < .001).

Frequency of daytime voiding, fluid intake, voided volume, diurnal and nocturnal urine volume, nocturnal polyuria, and CLSS quality-of-life measures all improved significantly in the reduced-salt group. In contrast, all parameters except nocturnal polyuria worsened in the increased-salt group.

This study shows how patients can take at least some control over their urinary destiny, said Marcus Drake, MD, from the University of Bristol in the United Kingdom.

"Research generally focuses on reducing the amount of water a patient drinks; salt intake is generally not considered," he pointed out. "Here we have a useful study showing how we need to consider all influences to have the best chance to improve the symptom."

Both studies were institutionally funded. Dr Rahnama'i and Dr Tomohiro have disclosed no relevant financial relationships. Dr Wein reports consulting or advising for multiple companies. Dr Drake reports financial relationships with Allergan, Ferring, and Astellas.

European Association of Urology (EAU) 2017 Congress: Abstracts 566 and 399. Presented March 26, 2017.


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