Author + information
- Received August 17, 2012
- Revision received October 23, 2012
- Accepted October 28, 2012
- Published online March 19, 2013.
- Takatoshi Kasai, MD, PhD⁎,†,
- Shveta S. Motwani, MD⁎,†,
- Dai Yumino, MD, PhD⁎,†,
- Joseph M. Gabriel, MSc⁎,†,
- Luigi Taranto Montemurro, MD⁎,†,
- Vinoban Amirthalingam, MB, ChB⁎,†,
- John S. Floras, MD, DPhil‡ and
- T. Douglas Bradley, MD⁎,†,‡,⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. T. Douglas Bradley, University Health Network Toronto General Hospital, 9N-943, 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada
Objectives This study sought to test the effects of rostral fluid displacement from the legs on transpharyngeal resistance (Rph), minute volume of ventilation (Vmin), and partial pressure of carbon dioxide (PCO2) in men with heart failure (HF) and either obstructive (OSA) or central sleep apnea (CSA).
Background Overnight rostral fluid shift relates to severity of OSA and CSA in men with HF. Rostral fluid displacement may facilitate OSA if it shifts into the neck and increases Rph, because pharyngeal obstruction causes OSA. Rostral fluid displacement may also facilitate CSA if it shifts into the lungs and induces reflex augmentation of ventilation and reduces PCO2, because a decrease in PCO2 below the apnea threshold causes CSA.
Methods Men with HF were divided into those with mainly OSA (obstructive-dominant, n = 18) and those with mainly CSA (central-dominant, n = 10). While patients were supine, antishock trousers were deflated (control) or inflated for 15 min (lower body positive pressure [LBPP]) in random order.
Results LBPP reduced leg fluid volume and increased neck circumference in both obstructive- and central-dominant groups. However, in contrast to the obstructive-dominant group in whom LBPP induced an increase in Rph, a decrease in Vmin, and an increase in PCO2, in the central-dominant group, LBPP induced a reduction in Rph, an increase in Vmin, and a reduction in PCO2.
Conclusions These findings suggest mechanisms by which rostral fluid shift contributes to the pathogenesis of OSA and CSA in men with HF. Rostral fluid shift could facilitate OSA if it induces pharyngeal obstruction, but could also facilitate CSA if it augments ventilation and lowers PCO2.
This study was supported by operating grant MOP-82731 from the Canadian Institutes of Health Research. Dr. Kasai is supported by an unrestricted research fellowship from Fuji-Respironics Inc. Dr. Motwani is supported by the Toronto Rehabilitation Institute, which receives funding under the Provincial Rehabilitation Research Program from the Ministry of Health and Long-Term Care, Ontario. Dr. Yumino is supported by an unrestricted research fellowship from Fuji-Respironics Inc. and Toronto Rehabilitation Institute. Mr. Gabriel is supported by Ontario Student Opportunity Trust Fund Awards from the Toronto Rehabilitation Institute and the Cardiovascular Sciences Collaborative Program of the University of Toronto. Dr. Taranto Montemurro is supported by fellowships from the Chair of Respiratory Medicine, University of Brescia, Brescia, Italy and from Toronto Rehabilitation Institute. Dr. Floras is supported by a Career Investigator Award from the Heart and Stroke Foundation of Canada and a Canada Research Chair in Integrative Cardiovascular Biology. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received August 17, 2012.
- Revision received October 23, 2012.
- Accepted October 28, 2012.
- American College of Cardiology Foundation