Sleep Apnea Caused by Rostral Fluid Shift: Identifying Risk Factors and Developing a Treatment Using Calf Muscle Electrical Stimulation
Year: 2018
Type: dissertation
Abstract: Rationale: Fluid accumulation in the legs due to a sedentary lifestyle can increase overnight fluid shifting from the legs and into the neck (i.e. rostrally) when lying down to sleep. Rostral fluid shift can increase pressure on the pharyngeal airway and severity of obstructive sleep apnea (OSA). This thesis contains three studies that together investigate risk factors for neck fluid accumulation when lying down, and explores a therapy of calf muscle electrical stimulation (ES) for reducing daytime leg fluid accumulation to treat OSA caused by fluid shift. Methods:The first study used data previously collected on the time-course of fluid shift from the legs and into the neck while lying supine for 90-minutes. Using demographic, anthropometric and fluid-based data captured before lying down, risk factors for increased neck fluid accumulation while supine were identified. Study two was a sham-controlled trial into the effects of using calf muscle ES while seated for two-and-a-half hours on leg fluid accumulation, consequent rostral fluid shift when supine, as well as OSA and snoring. Study three explored the time-course of seated leg fluid accumulation between sham and active calf muscle ES conditions to identify the optimal time-period for using the device to reduce leg fluid accumulation. Results: Study one found that male sex and greater leg and neck fluid volumes prior to lying down increased risk for neck fluid accumulation when lying down. Study two demonstrated that compared to sham ES, active calf muscle ES reduced seated leg fluid accumulation by 46%. Consequently, rostral fluid shift out of the legs and into the neck reduced by 17% and 31%, respectively. Lastly, while OSA severity did not change after ES, calf muscle ES reduced snoring index. Study three did not identify an optimal time-period for using calf muscle ES, but found the effectiveness in reducing leg fluid accumulation increases with time. Conclusion: The thesis shows that calf muscle ES is an effective therapy for reducing leg fluid accumulation and consequent pharyngeal narrowing likely through reduction of overnight neck fluid accumulation. Future work should explore the effects of long-term use of calf muscle ES on OSA severity.
Source: TSpace (University of Toronto)
Author: Daniel Vena
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2931745734