Using a Sniff Controller to Self-Trigger Abdominal Functional Electrical Stimulation for Assisted Coughing Following Cervical Spinal Cord Lesions

Abstract

Individuals with cervical spinal cord lesions (SCLs) typically depend on caregivers to manually assist in coughing by pressing against their abdominal wall. Coughing can also be assisted by functional electric stimulation (FES) applied to abdominal muscles via surface electrodes. Efficacy of FES, however, depends on precise temporal synchronization. The sniff controller is a trigger that enables paralyzed individuals to precisely control external devices through alterations in nasal airflow. We hypothesized that FES self-triggering by sniff controller may allow for effective cough timing. After optimizing parameters in 16 able-bodied subjects, we measured peak expiratory flow (PEF) in 14 subjects with SCL who coughed with or without assistance. Assistance was either manual assistance of a caregiver, caregiver activated FES, button self-activated FES (for SCL participants who could press a button), or sniff-controlled self-activated FES. We found that all assisted methods provided equally effective improvements, increasing PEF on average by 25 ± 27% (F[4,52] = 7.99, p = 0.00004 ). There was no difference in efficacy between methods of assistance ( F[3,39] = 0.41, p = 0.75 ). Notably, sniff-controlled FES was the only method of those tested that can be activated by all paralyzed patients alone. This provides for added independence that is a critical factor in quality of life following SCL.

Olfactory sniffing signals consciousness in unresponsive patients with brain injuries

“…We used methods we have applied extensively in the past 11,13,17,44,45 . In brief, during the olfactory testing sessions, patients' nasal airflow was measured using a nasal cannula (1103, Teleflex medical) which carried a differential pressure wave to a spirometer (ML141, ADInstruments) that converted the pressure changes into a voltage sent to an instrumentation amplifier (PowerLab 16SP Monitoring System, ADInstruments), sampling at 1000 Hz using LabChart software (ADInstruments).…”

“…Relatedly, non-olfactory volitional nasal inhalations have been used in order to tap into the conscious brain of paralyzed individuals in the context of providing a means of communication 44 , or a method for device control 45 . Moreover, non-olfactory volitional nasal inhalation was also tested as a potential method for detection of consciousness in DoC, yet most DoC patients failed to inhale on command 46 .…”

Discernment on assistive technology for the care and support requirements of older adults and differently-abled individuals

“…Patients with cervical spinal cord lesions followed by coughing require assistance and in their study, Lior et al ( 27 ) propose a sniff controller to self-help stomach functional electrical stimulus. Through changes in nasal airflow, the sniff controller can trigger peripheral devices.…”

Soft human–machine interfaces: design, sensing and stimulation

“…Additionally, stimulations from electronic devices to humans is another kind of important interaction modes that make humans sense external environment or establish closed-loop control between humans and machines/robots via the soft HMIs integrated with stimulators and actuators [48,49]. Electrical stimulation evokes tactile sensations within the skin at the location of a small, cutaneous electrode by passing a local electric current through the skin to stimulate cutaneous afferent fibers [50,51]. Feedback to humans via different stimulators can be divided into electrotactile stimulation, sound and light stimulation, braille display, and EEG-EMG stimulation.…”