Pulse wave amplitude drops as a sensitive marker of cardiovascular system activation during sleep

Author: Felix Decup

Decup, Felix, 2020 Pulse wave amplitude drops as a sensitive marker of cardiovascular system activation during sleep, Flinders University, College of Science and Engineering

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Background: Chronically disturbed or reduced sleep is associated with adverse health outcomes. Pulse wave amplitude (PWA)-drops during sleep indicate vasoconstriction responses detectable using pulse oximetry could be associated with cardiovascular disease and be useful clinical markers of sleep disruption.

Objectives: To develop an automated PWA-drop detection algorithm for exploration of 1) the relationship between PWA-drops and clinical cardiovascular outcomes in general population samples and 2) the disruption of sleep due to environmental noise.

Methods: An automated algorithm to detect PWA-drops from pulse-oximeter photoplethysmogram responses was developed, incorporating inter-pulse baseline de-trending and moving average-based criteria for detecting the onset, offset, duration and area under curve (AUC) of each PWA-drop, and the number of drops per hour of sleep. Effects of noise on traditionally scored electroencephalogram (EEG) sleep arousals >3-sec and PWA-drops were studied during two nights of sleep experiments in 25 participants (11 males, aged 26.5±16.4 years, range: 18-75 years and 14 females, aged 24.1±9 years, range: 19-55 years) exposed to 20-sec environmental noise stimuli (windfarm and traffic noises) at levels ranging from 33 to 48 dBA¬. Associations between sound pressure level and PWA-drops, controlled for noise type and conventionally scored sleep stage, were investigated using survival analysis. To explore the relationship between PWA-drops and cardiovascular pathophysiology, two large-population based cohorts were also studied: the HypnoLaus cohort of 2162 individuals who underwent home-based sleep studies from a general population in Lausanne, Switzerland; and the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) cohort which included home-based polysomnography from 752 men in Adelaide, Australia. An association between PWA-drop features (number of PWA-drops per hour, mean duration and mean AUC), and prevalent hypertension and/or cardiovascular disease in these cohorts were analysed using multivariate-adjusted logistic regression analysis.

Results: PWA-drops were more sensitive predictors of the presence versus absence of noise stimuli than traditionally scored EEG arousals at lower sound pressure level during stage 2, 3 and REM sleep (Control vs 48 dBA: HRPWA = 2.9 [2.2 – 3.8] and HREEG = 2.5 [1.5 – 4.2], Control vs 39 dBA: HRPWA = 1.5 [1.1 – 2.0] and HREEG = 1.1 [0.6 – 2.1], Control vs 33 dBA: HRPWA = 1.1 [0.8 – 1.5] and HREEG = 0.6 [0.3 – 1.3], respectively). The mean AUC of PWA-drops was the only feature consistently associated with the hypertension prevalence in both the HypnoLaus and MAILES cohorts (OR [95%CI] = 1.42 [1.03-1.96] and OR = 1.84 [1.10-3.08], respectively, pooled cohorts OR = 1.58 [1.21-2.07]). However, no consistent association was observed from pooled datasets between the prevalence of cardiovascular disease and PWA-drop features (number of PWA-drops per hour: OR = 0.73 [0.46-1.17], mean duration: OR = 0.82 [0.53-1.28], and mean AUC: OR = 0.90 [0.55-1.47]).

Conclusions: Automatically scored PWA-drops during sleep are a sensitive marker of cardiovascular system activation responses to noise and in two large population cohorts are associated with hypertension. Further studies are clearly warranted to better understand the nature of potential causal relationships between prolonged environmental noise exposure, cardiovascular disturbances in sleep more generally, and potential long-term adverse health effects such as hypertension.

Keywords: sleep, pulse wave amplitude, environmental noise, hypertension, cardiovascular biomarker

Subject: Engineering thesis

Thesis type: Masters
Completed: 2020
School: College of Science and Engineering
Supervisor: Kristy Hansen