title: Investigation of the link between fluid shift and airway collapsibility as a mechanism for obstructive sleep apnea in congestive heart failure.
abstract: The increased prevalence of obstructive sleep apnea (OSA) in congestive heart failure (CHF) may be associated with rostral fluid shift. We investigated the effect of overnight rostral fluid shift on pharyngeal collapsibility (Pcrit), pharyngeal caliber (APmean), and apnea-hypopnea index (AHI) in CHF patients. Twenty-three optimally treated systolic CHF patients were studied. Neck circumference was measured immediately prior to sleep in the evening and immediately after waking in the morning as a marker of rostral fluid shift. Pcrit was measured during sleep, early and late in the night. APmean was measured using acoustic reflection at the same times as neck circumference measurements. 15/23 CHF patients experienced an overnight increase in neck circumference; overall neck circumference significantly increased overnight (mean±SD, evening: 41.7 ± 3.2 cm; morning: 42.3 ± 3.1 cm; P = 0.03). Pcrit increased significantly overnight (early-night: -3.8 ± 3.3 cmH2O; late-night: -2.6 ± 3.0 cmH2O; P = 0.03) and APmean decreased (evening: 4.2 ± 1.3 cm2; morning: 3.7 ± 1.3 cm2; P = 0.006). The total AHI correlated with neck circumference (r = 0.4; P = 0.04) and Pcrit (r = 0.5; P = 0.01). APmean correlated with neck circumference (r = -0.47; P = 0.02). There was no significant change in AHI between the first and second half of the night (first-half: 12.9 ± 12.4/h; second-half: 13.7 ± 13.3/h; P = 0.6). Overnight rostral fluid shift was associated with increased pharyngeal collapsibility and decreased pharyngeal caliber during sleep in CHF patients. Rostral fluid shift may be an important mechanism of OSA in this patient group.
authors.affiliation: Academic Unit of Sleep and Breathing, National Heart and Lung Institute, Imperial College London, London, UK t.carlisle@nhs.net.|NIHR Respiratory Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.|NIHR Cardiovascular Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.
authors.forename: Tom
authors.initials: T
authors.lastname: Carlisle
authors.affiliation: Academic Unit of Sleep and Breathing, National Heart and Lung Institute, Imperial College London, London, UK.|NIHR Respiratory Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.|NIHR Cardiovascular Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.
authors.forename: Neil R
authors.initials: NR
authors.lastname: Ward
authors.affiliation: Academic Unit of Sleep and Breathing, National Heart and Lung Institute, Imperial College London, London, UK.|NIHR Respiratory Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.|NIHR Cardiovascular Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.
authors.forename: Angela
authors.initials: A
authors.lastname: Atalla
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.
authors.forename: Martin R
authors.initials: MR
authors.lastname: Cowie
authors.affiliation: Academic Unit of Sleep and Breathing, National Heart and Lung Institute, Imperial College London, London, UK.|NIHR Respiratory Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.
authors.forename: Anita K
authors.initials: AK
authors.lastname: Simonds
authors.affiliation: Academic Unit of Sleep and Breathing, National Heart and Lung Institute, Imperial College London, London, UK.|NIHR Respiratory Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, London, UK.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Morrell
mesh_terms: D000368:Aged; D000402:Airway Obstruction / Q000503:physiopathology*; D005260:Female; D018495:Fluid Shifts / Q000502:physiology*; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000033:anatomy & histology; D010614:Pharynx / Q000503:physiopathology; D017286:Polysomnography; D015995:Prevalence; D012890:Sleep / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*
keywords: Heart failure; obstructive sleep apnea; pcrit; pharyngeal collapsibility; rostral fluid shift