title: Investigating the Dynamics of Supine Fluid Redistribution Within Multiple Body Segments Between Men and Women.
abstract: While supine, fluid moves from the legs and accumulates in the chest and neck. However, patterns of rostral fluid shift are not clear. Furthermore, real-time measurement of neck fluid volume has not been investigated. The objective of this study was to investigate the dynamics of rostral fluid shift in men and women. We developed a bioelectrical impedance system to measure leg, abdominal, thoracic and neck fluid volumes (LFV, AFV, TFV, NFV) continuously. Forty healthy non-obese adults (20 men) lay supine for 90 min while fluid volumes were measured. After 90 min, a similar volume of fluid shifted out of the legs in both sexes (p = 0.079), but men accumulated more fluid in their thorax (63 ± 6 vs. 44 ± 11 ml, p = 0.016) and neck (17 ± 2 vs. 14 ± 1 ml, p = 0.029) than women. In both sexes, the increase in NFV caused a significant increase in neck circumference, which was greater in men (p = 0.009). Furthermore, 80% of rostral fluid shift would occur in the first 2 h of lying supine. These results suggest that greater fluid shift into the thorax and neck may contribute to the higher prevalence of sleep apnea in men than in women.
authors: University Health Network Toronto Rehabilitation Institute, Room 12-106, 550 University Ave., Toronto, ON, M5G 2A2, Canada, azadeh.yadollahi@uhn.ca.
authors: Azadeh
authors: A
authors: Yadollahi
authors: B
authors: B
authors: Singh
authors: T Douglas
authors: TD
authors: Bradley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001826:Body Fluids; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012727:Sex Characteristics; D016683:Supine Position / Q000502:physiology*