Hypothesis / aims of study
Background: Nocturia is defined as waking at night one or more times to pass urine, with each episode preceded
and followed by sleep (1). It is a common symptom contributing to poor sleep, significant morbidity and decreased quality of life. The prevalence of nocturia is known to increase with age. The aetiology of nocturia is complex and multi-factorial; co-existing morbidities may be associated with causal pathways extending beyond the urinary system (2). In older people with cardiovascular diseases such as chronic heart failure, nocturia may be increased due to lower limb oedema associated with third space fluid accumulation (3). The resolution of peripheral oedema with recumbence can lead to increased circulating fluid. The increased circulatory volume overnight may exacerbate nocturia related to nocturnal polyuria.
Current treatments to reduce nocturia are multi-modal, comprising lifestyle, behavioural and pharmacotherapy interventions. Initial management with first-line conservative interventions is commonly recommended (3). Resting with legs elevated to promote reabsorption of extracellular fluid is recommended, but consensus varies around specific patient instructions. The effect of lifestyle interventions on nocturia frequency has not been widely researched in older people with comorbid conditions.
Aims: The aim of this study was to investigate the effect of active leg elevation immediately prior to sleep on reducing nocturia frequency, with the rationale of decreasing the volume of third space fluid reabsorbed from the lower limbs overnight. This study also investigated the effect of this intervention on the duration of first undisturbed sleep time, the total volume of urine produced overnight and nocturia-specific quality of life.
Study design, materials and methods
Material and Methods:
A prospective single group pre-and post test study was conducted to evaluate calf exercises with 90 minutes of leg elevation for people with nocturia and pre-existing cardiac-related peripheral oedema. Additional inclusion criteria: aged 60 years and over, self-reported bilateral oedema of the lower legs which participants perceived to be worse at the end of the day. Exclusion criteria: any conditions associated with atypical nocturia, current urinary tract infection or bladder cancers. Participants unable to either rest comfortably supine or inability to measure their lower leg circumferences were also excluded. The recruitment period was between July and November 2017. Participants were recruited from an outpatient Continence Service of a tertiary hospital. The intervention was completed over a two-week period and monitored via home visits. Participants completed the intervention prior to going bed at night. The intervention consisted of 90 minutes rest in a supine position, ensuring legs and heart were raised to the same level. Active elevation required the participants to perform three sets of bilateral ankle dorsiflexion and plantar-flexion to activate calf pump muscles. Measurement tools: a three-day bladder diary for nocturia frequency and voided volumes, actigraphy for sleep patterns, patient-completed Nocturia-Quality of Life questionnaire and self-measured lower leg circumference (morning and night) to quantify ankle oedema. Data analysis was performed using SPSS V25. Paired Students t-test or Wilcoxon signed rank tests were used to compare pre-post-intervention differences.
Twenty-one participants, seven males (33%), with a Mean age (SD) 79 years (11) were included in the study. Following the intervention, there was a statistically significant improvement in lower leg oedema (p=0.008) and nocturia-specific quality of life (p=0.001). No statistically significant difference in nocturia frequency (p=0.50), or first undisturbed sleep time (p=0.37) were identified. Nocturnal urine volume decreased by 180mL, with the difference approaching significance (p=0.09). Over 60% of participants self-reported non-adherence to the intervention on three or more nights.
Interpretation of results
In this multi-morbidity population, active leg elevation before bed reduced oedema and improved nocturia-specific quality of life. The reduction in overnight urine volume was insufficient to change the duration of first undisturbed sleep time or impact nocturia frequency. A better understanding of barriers to adherence with leg elevation is needed.