Editor’s intro: The distinction between inspiratory flow limitation and obstructive sleep apnea calls for different approaches to treatment for the conditions as well as for adult or pediatric patients. Read all about these two airway-related issues.
Drs. Barry Raphael and Mark Cruz explain how “Airway” goes well beyond Obstructive Sleep Apnea
Whether you have a deep understanding of the relevance of the airway and breathing to dentistry and facial development, or whether you are still wondering what “this airway fad” is all about, one thing is for certain — with the American Dental Association’s 2017 Policy Statement on the Role of the Dentist in Sleep Disordered Breathing, the issue is now a bona fide part of the profession. Whether you treat airway, breathing, or sleep problems or not, now every dental, pediatric, and orthodontic practice must at least screen for these problems, even if you have to refer patients for treatment elsewhere.
In this article we will describe to you some of the significant aspects of the ADA policy and how it will (or can) impact your practice. We will also discuss how some are trying to limit the conversation to an overly narrow focus.
It is important to consider two factors in the airway issue. The first is that there is a distinction between obstructive sleep apnea (OSA) and inspiratory flow limitation (IFL). The two are different conditions along a continuum and require different approaches. The second is that there is a difference between adult and pediatric conditions.
OSA versus IFL
Obstructive sleep apnea (OSA) implies a stoppage of breathing accompanied by a lowering of blood oxygen and usually (thankfully), an arousal from deep sleep when the situation becomes too dire for survival. The combination of desaturation, an unrequited effort to breathe, and the constant rebooting of sleep levels takes a tremendous toll on the heart, the brain, and many other bodily systems. Hypoxia can result in specific symptoms that are often treated independently by medical specialists without realizing that sleep may be a central etiology. People who suffer from OSA have trouble keeping awake during the day.
Inspiratory flow limitation (IFL) on the other hand, happens when there is enough of a narrowing of the airway to make breathing more difficult but not enough to stop it. In IFL, there may be only minimal drops in blood oxygen. Typically, the body will react to flow limitation with an arousal as well, but it happens quickly enough that there is no or very little desaturation. A shot of adrenaline, a quick spike in heart rate, a shift in the body’s position, and an opening of the oral airway keep the air flowing. While this can help a person avoid some of the sequelae of desaturation, it also fragments sleep by lessening the amount of deep and REM sleep a person has. Fragmented sleep often results in more global symptoms such as chronic pain, central sensitization, metabolic dysregulation, autonomic imbalance, anxiety or depression, and neurocognitive deficits. People who suffer from IFL are more fatigued than sleepy during the day.
It is important to note that IFL is not just a problem of sleep, although sleep tends to aggravate the problem as flow can become more restricted as we lie flat in bed and muscles relax. Instead, IFL should be considered a breathing problem independent from sleep. In IFL, there can be restriction in the structure of the airway (physical narrowing, poor posture, fat deposits, active lymphatic tissues), the physiologic function of the airway (anything that creates swelling, inflammation, mucus, or trauma), and the behaviors we use to breathe often adopted as compensations for the first two limitations (like mouth breathing, chest breathing, and chronic hyperventilation). One can almost assume that if you are having trouble breathing during the day that there is little chance you’ll be able to breathe well at night.
It is also critical to note that while the incidence of OSA is a shocking 20% among our adult population and may include millions of American adults, the incidence of flow limitation is far greater, including perhaps 50% of the population. The reasons for this are many, but for one, anthropologists affirm that the modern human face is not developing as fully as it did only a few hundred years ago, evidenced not only by increasing incidence of small jaws, malocclusion, and impacted third molars, but most significantly, smaller nasal and pharyngeal airways. This is not so much a genetic deficit as it is an epigenetic reaction to our modern environment — one that challenges our physiology to cope with the rapid changes of environment and culture that is so different than the one our bodies were developed in. As a result, we are now more susceptible to flow limitation from birth onward. We must understand OSA as merely the end stage of a long process that starts in childhood.
Pediatric versus adult airway
In children, frank OSA is rather limited since children can adopt a number of compensations to prevent apnea. However, with allergies, neurocognitive deficits, and deficient jaw growth on the rise, there are many reasons why a child can have trouble breathing and yet not have apnea.
It is the case that swollen lymph tissue can clog up the airway and cause apnea in children. The American Academy of Pediatrics recognizes that if a child has OSA and the tonsils and adenoids are the proximate cause, then removal is indicated. However, if the tonsils and adenoids are swollen, but the child does not have more than one apnea per hour, then the tissues are left in place no matter how difficult they make continuous breathing. Medical guidelines allow a child to suffer through 5 to 7 episodes of upper respiratory infections each year before a physician can choose to do something definitive.
Meanwhile, flow limitation constantly demands breathing compensations like open mouth posture, forward head posture, restless sleep, and soft tissue dysfunctions that negatively influence the way the facial bones grow and the teeth erupt. Unfortuntately, children whose facial development is deformed from an early age are often being put on long-term steroids and being told to wait for braces to straighten their teeth. The negative growth trajectory of the face that increases the risk factors for airflow limitations is left to progress unabated and often left untreated. Standard orthodontic practices call for adapting the teeth to the poorly grown face since it is often too late to change the facial structures at “braces age.”
Worse yet, the literature is clear that the fragmented sleep caused by flow limitation, even when no apnea is present, is damaging to a child’s brain development.
It is critical to understand that facial and airway growth is a process that can be allowed to deteriorate or can be enhanced by reducing the obstacles to good growth.
So when the ADA’s policy statement says that it is our job is to help children develop “an optimal physiologic airway and breathing pattern,” it means that we must do more than watch a child suffer. We must remove obstacles to growth and foster conditions that will enhance facial and airway growth as soon a poor growth is discovered or as soon as the habits that will lead to poor growth are seen. Our children need more than just relief of symptoms, like apneas. We need a fundamental rethinking of how we manage health in children. It calls for a whole-body focus on proper growth and development that eliminates the need compensatory behaviors that would otherwise lead to trouble down the line.
The dangers of an OSA-based policy
In reaction to the attention that airway and sleep has gotten from both the dental profession and mothers that are demanding more responsiveness, the American Association of Orthodontists held a “consensus conference” with a follow-up White Paper: Obstructive Sleep Apnea and Orthodontics in 2019. The title alone belies the contents and recommendations. Essentially, the policy concludes that every orthodontist “should” screen for OSA in children and refer to a sleep physician if OSA is suspected. But while the AAO recognizes that the orthodontist is well placed to address craniofacial growth and development, the policy defers diagnosis and treatment to the sleep physician and relegates the orthodontist to a supportive role when the physician recommends orthodontic treatment.
There are two significant dangers in this policy.
First, this policy assumes that the sleep physician knows about the relevance of flow limitation to facial growth and sleep fragmentation in the absence of apnea. And while many physicians are learning more about UARS, the sleep labs and their technicians have to be specifically instructed to score the PSG for more than just apnea lest the condition is missed. Currently it is not a routine protocol.
Second, a child who has flow limitation but does not register apneas in a polysomnogram will be returned to the orthodontist being told that the test was negative for OSA. Parents will be misled to think that “no OSA” means “no problem,” and treatments that could have helped alleviate the flow limitation will be overlooked.
When the AAO came out with its white paper, it recognized “upper airway resistance” as part of the sleep and breathing disorders but chose to limit its focus to OSA alone. And while the guidance that only a physician can diagnose and proscribe treatment to OSA is sound, no mention was made of how to handle children or adults who do not qualify under current guidelines that define OSA.
This is a crucial point to understand. OSA is an illness. IFL is suboptimal wellness. Flow limitation is a precursor to OSA. If all we do is pay attention to apnea we are just managing a medical symptom. But if we want to live the best lives we can, we work toward optimal health and wellness. When we see children who are not well, and we want to help them to be the best they can be, we must use best practices to help them achieve optimal structure, function, and behavior to do so.
The current “gold standard” treatment strategy for OSA is to somehow pry open the naso- and oral-pharyngeal airway enough to keep it from collapsing. Treatments use forced air (CPAP), pull the jaws forward (mandibular advancement device or jaw advancement surgery), pull the tongue forward (hypoglossal stimulator, advancement genioplasty),or remove tissue from the nose and throat (plasty, T&A, nasal surgery). While these techniques have their place for the very ill, they only address the symptoms and not the cause of the limited airflow. As such, they are themselves compensations designed solely to help a person get through the night.
On the other hand, the treatments for flow limitation directly address the daytime etiologies in order to make the breathing space easier to breathe through and with less effort. To create an optimal airway one must:
- Improve the anatomy to minimize turbulence by helping bones grow and remodel to reduce constrictions in the nose and pharynx, and provide maximal tongue space in the front of the mouth
- Address physiology by reducing swelling, inflammation, mucus, and trauma while also toning muscles to keep the airway flexed open
- Teach efficient breathing behaviors that don’t create so much turbulence in the airway.
Making the transition
While all this may be easy to say, adding wellness services into an orthodontic practice can be challenging. It requires moving from a “mechanical” mindset to a “whole-body” mindset. Fortunately, there are protocols that can be installed in an orthodontic practice without interrupting the flow of the day.
The first thing to do is create a staff position called “Health Coach.” The Health Coach should be someone who is good with kids, likes to teach, and will take on a project and run with it. He/she will run the wellness program by teaching patients good health habits just like the dental hygienist teaches oral hygiene. Lessons will include the basic tenets of good growth and development including the following:
- Nasal breathing
- Lip competence
- Tongue-resting posture on the palate
- Swallowing with the tongue on the palate without having to recruit the facial musculature to help
- Good body posture to keep the head upright over the shoulders
- Good nutrition with food that nourishes and doesn’t inflame the body
- Good sleep habits to allow for peaceful, unfragmented sleep
- Good breathing behaviors during rest and stress that efficiently deliver oxygen to the brain, organs and muscles
The second thing is for the orthodontist to learn about why these habits are so important and how the orthodontist can help develop an anatomical structure for the child that will aid in learning these good habits. It is important to note that while “palatal expansion” is a helpful adjunct, the maxilla may need development in three dimensions of space. Learning to augment sagittal development is probably more important than lateral development since the tongue needs room to come forward to be out of the breathing space. There are several techniques — many of which have been practiced for decades — that can help sagittal development.
And of course, techniques that may hamper sagittal development are rarely, if ever, indicated. If a child has such crowding or overbite that extraction and retraction are even contemplated, the odds are great that flow limitation is already at play. Retraction mechanics may not “cause” flow limitation, but it certainly ignores it and may lock the risk factors in perpetually, and therefore should be avoided at all costs.
Finally, once you realize the health costs of flow limitation, you will never want to let it fester until a child is ready for braces — or until it becomes apnea. Addressing these issues as soon as they are discovered must become the standard of care.
Dr. Raphael’s interest in inspiratory flow limitation and obstructive sleep apnea is based on a long history of orthodontic training and inspiration. Read more about him in a practice profile titled, “Barry Raphael, DMD: Achieving a new equilibrium.”
- American Association of Orthodontists. (2019). Obstructive sleep apnea and orthodontics [White Paper]. https://www1.aaoinfo.org/wp-content/uploads/2019/03/sleep-apnea-white-paper-amended-March-2019.pdf. Accessed June 21, 2019.
- Catalano PJ, Walker J. Understanding Nasal Breathing: The key to evaluating and treating sleep disordered breathing in adults and children. Curr Trends Otolaryngol Rhinol. 2018; CTOR-121. https://www.gavinpublishers.com/articles/Review-Article/Current-Trends-in-Otolaryngology-and-Rhinology/Understanding-Nasal-Breathing-The-Key-to-Evaluating-and-Treating-Sleep-Disordered-Breathing-in-Adults-and-Children#solid-justified-tab6. Accessed June 21, 2019.
- Fitzpatrick MF, McLean H, Urton AM, Tan A, O’Donnell D, Driver HS. Effect of nasal or oral breathing route on upper airway resistance during sleep. Eur Respir J. 2003; 22(5):827-832.
- Georgalas C. The role of the nose in snoring and obstructive sleep apnoea. Eur Arch Otorhinolaryngol. 2011;268(9):1365-1373.
- Gold A. Functional somatic syndromes, anxiety disorders and the upper airway: a matter of paradigms. Sleep Med Rev. 2011;15(6):389-401.
- Gold A, Dipalo F, Gold MS, O’Hearn D. The symptoms and signs of upper airway resistance syndrome: a link to the functional somatic syndromes. Chest. 2003;123(1):87-93.
- Gozal D, Kheirandish-Gozal, L. Neurocognitive and behavioral morbidity in children with sleep disorders. Curr Opin Pulm Med. 2007;13:505–509.
- Guilleminault C, Sullivan S. Towards restoration of continuous nasal breathing as the ultimate treatment goal in pediatric obstructive sleep apnea. Enliven: Pediatrics and Neonatal Biology. 2014;1(1).
- Kim P, Sarauw MT, Sonnesen L. Cervical vertebral column morphology and head posture in preorthodontic patients with anterior open bite. Am J Orthod Dentofacial Orthop. 2014;145(3):359-366.
- Litchfield PM. CapnoLearning: Respiratory Fitness and Acid-Base Regulation. Psychophysiology Today. 2010;7(1):6-12.
- Luc GTM, Burschtin O, Setlur J, et al. REM-Associated Nasal Obstruction: A study with Acoustic Rhinometry during Sleep. Otolaryngol Head Neck Surg. 2018;139(5):619-623.
- Luginbuehl M, Bradley-Klug K, Ferron J, Anderson WM, Benbadis SR. Sleep Disorders: Validation of the Sleep Disorders Inventory for Students. School Psychology Review. 2008;37(3):409-431.
- Morais-Almeida M, Wandalsen GF, Solé D. Growth and mouth breathers. J Pediatr (Rio J). 2019;95(suppl 1):66-71.
- O’Brien LM, Mervis CB, Holbrook CR, et.al. Neurobehavioral correlates of sleep-disordered breathing in children. J Sleep Res. 2004;13(2):165-172.
- Pavone M, Cutrera R, Verrillo E, Salerno T, Soldini S, Brouillette RT. Night-to-night consistency of at-home nocturnal pulse oximetry testing for obstructive sleep apnea in children. Pediatr Pulmonol. 2013;48(8):754-760.
- Simmons MS, Clark GT. The potentially harmful medical consequences of untreated sleep-disordered breathing. J Am Dent Assoc. 2009;140(5):536-542.