Related Experiment Video
Updated: Apr 18, 2026

Assessment and Communication for People with Disorders of Consciousness
Published on: August 1, 2017
Detection of response to command using voluntary control of breathing in disorders of consciousness
Vanessa Charland-Verville1, Damien Lesenfants1, Lee Sela2
1Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liège and CHU Sart Tilman Hospital Liège, Belgium.
Background:
Detecting signs of consciousness in patients in a vegetative state/unresponsive wakefulness syndrome (UWS/VS) or minimally conscious state (MCS) is known to be very challenging. Plotkin et al. (2010) recently showed the possibility of using a breathing-controlled communication device in patients with locked in syndrome. We here aim to test a breathing-based "sniff controller" that could be used as an alternative diagnostic tool to evaluate response to command in severely brain damaged patients with chronic disorders of consciousness (DOC).
Methods:
Twenty-five DOC patients were included. Patients' resting breathing-amplitude was measured during a 5 min resting condition. Next, they were instructed to end the presentation of a music sequence by sniffing vigorously. An automated detection of changes in breathing amplitude (i.e., >1.5 SD of resting) ended the music and hence provided positive feedback to the patient.
Results:
None of the 11 UWS/VS patients showed a sniff-based response to command. One out of 14 patients with MCS was able to willfully modulate his breathing pattern to answer the command on 16/19 trials (accuracy 84%). Interestingly, this patient failed to show any other motor response to command.
Discussion:
We here illustrate the possible interest of using breathing-dependent response to command in the detection of residual cognition in patients with DOC after severe brain injury.
Related Concept Videos
Physiological Control of Respiration
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Neural Control of Respiration
Respiratory Centers in the Brainstem
Two primary areas comprise the respiratory center: the medullary respiratory center in the medulla oblongata and the pontine respiratory group in the pons. The...
Other Factors Affecting Respiration Centers
However, the ability to hold one's breath voluntarily is not limitless. When the CO2 concentration in the blood reaches a critical...
Physiology of Respiration II: Neurogenic Control of Respiration
Central Control
The brainstem is the primary site of central control, hosting respiratory centers:
Mechanism of Breathing II: Expiration
Expiration, or exhaling, is a complex physiological process that begins as the inspiratory muscles begin to relax. This relaxation triggers a series of events that epitomize the efficiency of the respiratory system.
Mechanism of Expiration:
Assessment of Airway, Skin Color, and Use of Accessory Muscles
Introduction
The initial evaluation of a patient's respiratory system...

