Hillen, Brian K

Jung, Ranu

BMC Neuroscience

English

PubMed

Brian K Hillen

Ranu Jung

Springer - Publisher Connector

POSTER PRESENTATION Open Access
Computational model of human ventilation for
electrical stimulation following cervical spinal
cord injury
Brian K Hillen*, Ranu Jung
From The Twenty Third Annual Computational Neuroscience Meeting: CNS*2014
Québec City, Canada. 26-31 July 2014
Towards the development of an implantable stimulator
for respiratory pacing, we have developed a computa-
tional model of the human ventilatory system to simulate
breathing maneuvers. Following cervical spinal cord
injury, control of breathing is lost or diminished. If the
loss is severe, patients are dependent on mechanical ven-
tilators or electrical stimulators to regain functional
breathing. Existing electrical stimulation based respira-
tory pacing systems typically activate only the diaphragm
and cannot adapt to muscle fatigue, changes in respira-
tory demands, or changes in electrode quality over time.
This model will be used to test stimulation controllers
that can adapt to such conditions. The model was devel-
oped in Simulink/SimMechanics implementing the phy-
siologically realistic muscle model from MSMS [1,2]
using published parameters for muscle geometry [3,4].
Diaphragm geometry was modeled as a pulley system in
one dimension. Ventilatory compliance was modeled as a
damped spring with non-linear stiffness. Integrated phre-
nic drive was modeled as either a spaced sawtooth (tidal
breathing) or a step function (maximal inspiration). The
model was able to reproduce tidal breathing and maximal
inspiration for uninjured subjects (see Figure 1). When
simulating electrical stimulation without fatigue, maximal
inspiration was similar but tidal breathing was higher due
to the recruitment of larger motor units first. When
simulating electrical stimulation as well as fatigue (50%
reduction in maximal force and a decrease in the power
of the fast motor units), tidal breathing was similar to the
uninjured case (see Figure 1). Thus, even with fatigue,
electrically stimulated muscles are strong enough to pro-
duce the submaximal contractions needed for tidal
breathing. In the future, this model will be enhanced to
incorporate additional muscles of respiration as well as
atrophy associated with spinal cord injury and will be
used to iteratively develop adaptive controllers to achieve
functional ventilation and to promote weaning from a
mechanical ventilator.
Acknowledgements
This work was supported by NIH R01-NS086088.
Published: 21 July 2014
References
1. Cheng EJ, Brown IE, Loeb GE: Virtual muscle: a computational approach
to understanding the effects of muscle properties on motor control. J
Neurosci Methods 2000, 101:117-130.
* Correspondence: Brian.Hillen@fiu.edu
Department of Biomedical Engineering, Florida International University,
Miami, Florida, 33174, USA
Figure 1 Diaphragm displacement during tidal breathing (grey
lines) and maximal inspiration (black lines). Uninjured curves (solid
lines) reproduce published experimental data. When simulating
electrical stimulation (reverse recruitment) and fatigue (a 50%
reduction in maximal muscle force), tidal breathing results are
similar to uninjured simulations due to increased force generated by
the larger motor units being recruited first (dashed lines).
Hillen and Jung BMC Neuroscience 2014, 15(Suppl 1):P133
http://www.biomedcentral.com/1471-2202/15/S1/P133
© 2014 Hillen and Jung; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
2. Song D, Raphael G, Lan N, Loeb GE: Computationally efficient models of
neuromuscular recruitment and mechanics. J Neural Eng 2008, 5:175-184.
3. Gorman RB, McKenzie DK, Pride NB, Tolman JF, Gandevia SC: Diaphragm
length during tidal breathing in patients with chronic obstructive
pulmonary disease. Am J Respir Crit Care Med 2002, 166:1461-1469.
4. Stubbings AK, Moore AJ, Dusmet M, Goldstraw P, West TG, Polkey MI,
Ferenczi MA: Physiological properties of human diaphragm muscle fibres
and the effect of chronic obstructive pulmonary disease. J Physiol 2008,
586:2637-2650.
doi:10.1186/1471-2202-15-S1-P133
Cite this article as: Hillen and Jung: Computational model of human
ventilation for electrical stimulation following cervical spinal cord injury.
BMC Neuroscience 2014 15(Suppl 1):P133.
Submit your next manuscript to BioMed Central
and take full advantage of: 
• Convenient online submission
• Thorough peer review
• No space constraints or color figure charges
• Immediate publication on acceptance
• Inclusion in PubMed, CAS, Scopus and Google Scholar
• Research which is freely available for redistribution
Submit your manuscript at 
www.biomedcentral.com/submit
Hillen and Jung BMC Neuroscience 2014, 15(Suppl 1):P133
http://www.biomedcentral.com/1471-2202/15/S1/P133
Page 2 of 2


Computational model of human ventilation for electrical stimulation following cervical spinal cord injury

DigitalCommons@Florida International University

Florida International UniversityFIU Digital CommonsAll Faculty7-26-2014Computational model of human ventilation forelectrical stimulation following cervical spinal cordinjuryBrian K HillenDepartment of Biomedical Engineering, Florida International University, bhillen@fiu.eduRanu JungDepartment of Biomedical Engineering, Florida International University, rjung@fiu.eduFollow this and additional works at: https://digitalcommons.fiu.edu/all_facultyThis work is brought to you for free and open access by FIU Digital Commons. It has been accepted for inclusion in All Faculty by an authorizedadministrator of FIU Digital Commons. For more information, please contact dcc@fiu.edu.Recommended CitationHillen, Brian K and Jung, Ranu, "Computational model of human ventilation for electrical stimulation following cervical spinal cordinjury" (2014). All Faculty. 59.https://digitalcommons.fiu.edu/all_faculty/59POSTER PRESENTATION Open AccessComputational model of human ventilation forelectrical stimulation following cervical spinalcord injuryBrian K Hillen*, Ranu JungFrom The Twenty Third Annual Computational Neuroscience Meeting: CNS*2014Québec City, Canada. 26-31 July 2014Towards the development of an implantable stimulatorfor respiratory pacing, we have developed a computa-tional model of the human ventilatory system to simulatebreathing maneuvers. Following cervical spinal cordinjury, control of breathing is lost or diminished. If theloss is severe, patients are dependent on mechanical ven-tilators or electrical stimulators to regain functionalbreathing. Existing electrical stimulation based respira-tory pacing systems typically activate only the diaphragmand cannot adapt to muscle fatigue, changes in respira-tory demands, or changes in electrode quality over time.This model will be used to test stimulation controllersthat can adapt to such conditions. The model was devel-oped in Simulink/SimMechanics implementing the phy-siologically realistic muscle model from MSMS [1,2]using published parameters for muscle geometry [3,4].Diaphragm geometry was modeled as a pulley system inone dimension. Ventilatory compliance was modeled as adamped spring with non-linear stiffness. Integrated phre-nic drive was modeled as either a spaced sawtooth (tidalbreathing) or a step function (maximal inspiration). Themodel was able to reproduce tidal breathing and maximalinspiration for uninjured subjects (see Figure 1). Whensimulating electrical stimulation without fatigue, maximalinspiration was similar but tidal breathing was higher dueto the recruitment of larger motor units first. Whensimulating electrical stimulation as well as fatigue (50%reduction in maximal force and a decrease in the powerof the fast motor units), tidal breathing was similar to theuninjured case (see Figure 1). Thus, even with fatigue,electrically stimulated muscles are strong enough to pro-duce the submaximal contractions needed for tidalbreathing. In the future, this model will be enhanced toincorporate additional muscles of respiration as well asatrophy associated with spinal cord injury and will beused to iteratively develop adaptive controllers to achievefunctional ventilation and to promote weaning from amechanical ventilator.AcknowledgementsThis work was supported by NIH R01-NS086088.Published: 21 July 2014References1. Cheng EJ, Brown IE, Loeb GE: Virtual muscle: a computational approachto understanding the effects of muscle properties on motor control. JNeurosci Methods 2000, 101:117-130.* Correspondence: Brian.Hillen@fiu.eduDepartment of Biomedical Engineering, Florida International University,Miami, Florida, 33174, USAFigure 1 Diaphragm displacement during tidal breathing (greylines) and maximal inspiration (black lines). Uninjured curves (solidlines) reproduce published experimental data. When simulatingelectrical stimulation (reverse recruitment) and fatigue (a 50%reduction in maximal muscle force), tidal breathing results aresimilar to uninjured simulations due to increased force generated bythe larger motor units being recruited first (dashed lines).Hillen and Jung BMC Neuroscience 2014, 15(Suppl 1):P133http://www.biomedcentral.com/1471-2202/15/S1/P133© 2014 Hillen and Jung; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the CreativeCommons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.2. Song D, Raphael G, Lan N, Loeb GE: Computationally efficient models ofneuromuscular recruitment and mechanics. J Neural Eng 2008, 5:175-184.3. Gorman RB, McKenzie DK, Pride NB, Tolman JF, Gandevia SC: Diaphragmlength during tidal breathing in patients with chronic obstructivepulmonary disease. Am J Respir Crit Care Med 2002, 166:1461-1469.4. Stubbings AK, Moore AJ, Dusmet M, Goldstraw P, West TG, Polkey MI,Ferenczi MA: Physiological properties of human diaphragm muscle fibresand the effect of chronic obstructive pulmonary disease. J Physiol 2008,586:2637-2650.doi:10.1186/1471-2202-15-S1-P133Cite this article as: Hillen and Jung: Computational model of humanventilation for electrical stimulation following cervical spinal cord injury.BMC Neuroscience 2014 15(Suppl 1):P133.Submit your next manuscript to BioMed Centraland take full advantage of: • Convenient online submission• Thorough peer review• No space constraints or color figure charges• Immediate publication on acceptance• Inclusion in PubMed, CAS, Scopus and Google Scholar• Research which is freely available for redistributionSubmit your manuscript at www.biomedcentral.com/submitHillen and Jung BMC Neuroscience 2014, 15(Suppl 1):P133http://www.biomedcentral.com/1471-2202/15/S1/P133Page 2 of 2

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Computational model of human ventilation for electrical stimulation following cervical spinal cord injury

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