Electrical stimulation of abdominal muscles increases tidal volume and cough peak flow rates in tetraplegia

Gollee, H., Coupaud, S., Hunt, K.J. and McLean, A.N. (2003) Electrical stimulation of abdominal muscles increases tidal volume and cough peak flow rates in tetraplegia. In: Annual Meeting of the Scottish Thoracic Society, Stirling, 14 November 2003,

Abstract

Introduction <br />People with tetraplegia have poor respiratory function due to: 1) intercostal paralysis causing reduced tidal volume (VT) and 2) abdominal paralysis reducing cough peak flow (CPF). These problems may cause respiratory failure during both the initial admission and subsequent intercurrent illness. We hypothesised that electrical stimulation of abdominal muscles during expiration may improve respiratory function by increasing VT and CPF. <br /><br />Methods <br />Sixteen-year-old male injured at C4 level. One year post-injury. The subject breathed spontaneously but with reduced lung volumes and cough peak flow. We stimulated rectus and transversus abdominis bilaterally using surface electrodes and four channel stimulator. The muscles were stimulated at the onset of expiration. The trigger signal for stimulation was provided by a plethysmographic belt which measured changes in abdominal girth in the respiratory cycle. To increase VT the stimulation was controlled in a closed loop system to trigger stimulation in time with the onset of natural expiration. To increase CPF the stimulation was manually triggered at the onset of expiration by the investigator. We designed control software to allow the subject to speak without inappropriate triggering of the system. <br />We measured <br /> breath by breath lung volumes during quiet breathing <br /> forced expiratory volume (FEV)<br /> cough peak flow <br /> before and during stimulation.<br /><br />Results<br />The subject tolerated five minutes of stimulation without discomfort or other adverse effects. The subject could speak normally without inappropriate triggering of the stimulation.<br /> quiet breathing: VT increased from 0.35l to 0.55l<br /> forced expiration: FEV increased from 1.3l to 1.5l<br /> coughing: peak flow increased from 0.73l/sec to 1.31l/sec.<br /><br />Discussion<br />This proof of concept technique may have potential use in both acute and established tetraplegia to increase minute ventilation and to improve cough clearance of secretions. Once applied, the closed loop system allows operators to leave the system running automatically. There may be application for the technique in other causes of respiratory neuromuscular weakness.

• Item Type: Conference Proceedings
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Coupaud, Dr Sylvie and Hunt, Prof Kenneth and Gollee, Dr Henrik
• Authors: Gollee, H., Coupaud, S., Hunt, K.J., and McLean, A.N.
• Subjects: T Technology > TJ Mechanical engineering and machinery; Q Science > QP Physiology
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering; College of Science and Engineering > School of Engineering > Systems Power and Energy