Biomimicry may cure obstructive sleep apnea

Biomimicry is the use of nature to inspire human innovation and cutting-edge designs.¹ Examples include: Velcro fasteners (modeled after burrs), the shape of airplanes (modeled after birds), and fluid-drag reduction swimsuits (modeled after shark skin).² Biomimicry has provided inspiration and design clues for fields as distinct as architecture, telecommunications, and medicine (http://biomimicry.org/biomimicry-examples/).

Currently, there is no universal cure for obstructive sleep apnea (OSA). As such, many treatment options exist. Medical management spans from non-invasive (e.g. myofunctional therapy, including tongue exercises)³ to more invasive (e.g. surgeries such as supraglottoplasty⁴ or maxillomandibular advancement⁵). Soft tissue surgeries attempt to improve OSA by excising redundant soft tissue. There are challenges in performing upper airway surgery, especially with visualization of the tongue base and epiglottis; however, with advancing technologies, surgeons are now able to incorporate additional tools, such as transoral robotic surgery. Despite these advances in technology, no method is 100% effective. It may be time to turn to nature for answers.

Given that in nature, animals generally do not have OSA,^6,7 studies evaluating the airway in sleeping animals may hold the answer for curing OSA in humans. Prior work has analyzed English bulldogs, due to their enlarged soft palate and narrow oropharynx.^6,7 However, the solution to curing OSA may best be achieved by considering animals without airway collapse. Examination of evolutionary changes suggests that posterior migration of the facial skeleton under the neurocranium and the descent of the larynx contribute to the predisposition to OSA in humans.⁶ The human upper respiratory tract enhances speech, but an adverse consequence is the risk for upper airway collapse.

Human studies have demonstrated that the areas of upper airway obstruction during sleep can be categorized into major regions to include the soft palate/uvula, oropharynx, hypopharynx, retrolingual, and supraglottis. Humans who do not have OSA are able to keep patent upper airways by maintaining tone in the various dilator muscles to include the genioglossus muscle, pharyngeal muscles, and tensor veli palatini.⁸ One of the newer technologies applied to OSA that aims to maintain a patent upper airway is by stimulating the hypoglossal nerve,⁹ which protrudes the tongue anteriorly; because the palatoglossus muscle is attached to the palate, the palate is generally anteriorly displaced as well. The future of biomimetics may be the key as nanotechnology has accelerated the development and understanding of proteins and materials in the natural world. New materials or synthetic tissues inspired by nature may transform and increase the resilience of the collapse-prone upper airway of humans.²

Despite these newer technologies and innovative treatments, there is still no universal cure. Given that nature has provided other animals with the ability to breathe in an unobstructed fashion during sleep, there must be something missing. Biomimicry has provided humans with the inspiration to create innovative and cutting-edge designs. Biomimicry may someday provide the cure for OSA. The views expressed in this letter are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the US Government.

Macario Camacho
Tripler Army Medical Center, Honolulu, HI, USASungjin A. Song
Tripler Army Medical Center, Honolulu, HI, USA
[email protected] M. Tolisano
Tripler Army Medical Center, Honolulu, HI, USA