Affiliations: [a] Centre for Rehabilitation Engineering, University of Glasgow, UK | [b] Queen Elizabeth National Spinal Injuries Unit, Glasgow, UK
Correspondence:
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Address for correspondence: Dr. Henrik Gollee, Centre for Rehabilitation Engineering, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK. Tel.: +44 141 330 4406; Fax: +44 141 330 4343; E-mail: h.gollee@eng.gla.ac.uk.
Abstract: Paralysis of the respiratory muscles in people with tetraplegia affects their ability to breathe and contributes to respiratory complications. Surface functional electrical stimulation (FES) of abdominal wall muscles can be used to increase tidal volume (VT) and improve cough peak flow (CPF) in tetraplegic subjects who are able to breathe spontaneously. This study aims to evaluate the feasibility and effectiveness of a novel abdominal FES system which generates stimulation automatically, synchronised with the subjects' voluntary breathing activity. Four subjects with complete tetraplegia (C4-C6), breathing spontaneously, were recruited. The automatic stimulation system ensured that consistent stimulation was achieved. We compared spirometry during unassisted and FES-assisted quiet breathing and coughing, and measured the effect of stimulation on end-tidal CO2 (EtCO2) during quiet breathing. The system dependably recognised spontaneous respiratory effort, stimulating appropriately, and was well tolerated by patients. Significant increases in VT during quiet breathing (range 0.05–0.23 L) and in CPF (range 0.04–0.49 L/s) were observed. Respiratory rate during quiet breathing decreased in all subjects when stimulated, whereas minute ventilation increased by 1.05–2.07 L/min. The changes in EtCO2 were inconclusive. The automatic stimulation system augmented spontaneous breathing and coughing in tetraplegic patients and may provide a potential means of respiratory support for tetraplegic patients with reduced respiratory capacity.
Keywords: Tetraplegia, pulmonary function, electrical stimulation, automatic control system
