Muscling Up Pharyngeal Airflow,

FOR RELATED ARTICLE, SEE PAGE 1212For three decades, OSA therapy has primarily been nocturnal CPAP, which, although mostly effective, is limited by poor long-term compliance. An alternative, more recent approach hypoglossal nerve stimulation (HGNS), aimed at activating upper airway muscle activity to maintain pharyngeal patency during sleep. HGNS younger, less obese, carefully selected subjects, and not always effective. In this issue of CHEST, Kent et al1Kent D.T. Zealear D. Schwartz A.R. Ansa cervicalis stimulation: a new direction in neurostimulation for OSA.Chest. 2021; 159: 1212-1221Abstract Full Text PDF Scopus (4) Google Scholar describe both ansa nerves, separately together sedated patients with OSA. This small pilot study demonstrated an improvement characterized using peak inspiratory flow separate neural activation; however, simultaneous activation resulted greater improvements than alone. addition directions OSA, these findings contribute the understanding interactions between thoracic structures pathophysiology collapse. 1212 Interactions lower respiratory tracts were first documented pivotal Van de Graaff,2Van Graaff W.B. Thoracic traction on trachea: mechanisms magnitude.J Appl Physiol (1985). 1991; 70: 1328-1336Crossref PubMed (106) who proposed that increasing lung volume may improve collapsibility unfolding walls, lowering wall compliance, extraluminal tissue pressure (ETP) retraction hyoid bone. Lung have confirmed healthy human subjects3Jordan A.S. White D.P. Owens R.L. al.The effect increased genioglossus end-expiratory collapse.J 2010; 109: 469-475Crossref (42) whom increases reduce required CPAP levels, severity, passive collapsibility. Similar al,1Kent mechanical effects elevation (similar outcomes stimulation) genioglossal HGNS) caused alone.3Jordan These occur as result movement cervical including muscles trachea, resulting reductions ETP changes bone position (Fig 1). The mobile several attachments originating from surrounding locations. moves response active contraction or loads (eg, mandibular advancement, tracheal displacement). results transfer applied one other regions throughout 1A). displaces anterior/anterior-cranial through its hyoid-connected (genioglossus/geniohyoid).4ElShebiny T. Venkat Strohl K. Hans M.G. Alonso A. Palomo J.M. Hyoid arch displacement stimulation.Am J Respir Crit Care Med. 2017; 196: 790-792Crossref (3) (ACS) caudally, indirectly via hyoid-thyroid attachments, sternothyroid activation5Roberts J.L. Reed W.R. Thach B.T. Pharyngeal airway-stabilizing function sternohyoid rabbit.J Environ Exerc Physiol. 1984; 57: 1790-1795PubMed 1B). Movement consequence ACS (predicted Fig 1C) likely play fundamental role ability patency. Evidence support comes computational finite element modeling rabbit airway, which advancement caudal mechanics investigated.6Amatoury J. Cheng S. Kairaitis Wheatley J.R. Amis T.C. Bilston L.E. Development validation model airway: simulations displacement.J 2016; 120: 743-757Crossref (9) HGNS, anterior-cranial direction,7Amatoury Peripharyngeal deformation, stress distributions, advancement.J 2015; 118: 282-291Crossref (6) displacement, like ACS, direction.8Amatoury deformation distributions displacement: influence bone?.J 2014; 116: 746-756Crossref (13) model,6Amatoury individually undertaken free move completely restricted. With immobile hyoid, could load below otherwise occurred when was free. enlarge stiffen region reduced. Similarly, tissues connected above would similar ACS. combined contributes additive enlargement stiffening 1C). displacing bone,8Amatoury animal studies also indicated longitudinal tension walls.8Amatoury Scholar,9Kairaitis Byth Parikh R. Stavrinou Tracheal rabbits: pressure.Sleep. 2007; 30: 179-186Crossref (70) Active reduces airway.10Kairaitis Verma M. Fish V. modifies peri-pharyngeal rabbits.Respir Neurobiol. 2009; 166: 95-101Crossref (17) laryngeal apparatus will alter resting lengths attached muscles, such effectiveness under some conditions, volumes.11Kairaitis Amatoury A threshold optimal airflow dynamics: anesthetized model.J 2012; 112: 1197-1205Crossref (19) Body influences awake12Watson R.A. Pride N.B. Postural volumes resistance subjects obesity.J 2005; 98: 512-517Crossref (134) sleeping13Avraam Dawson Rochford P.D. sex body weight sleep.Sleep. 2019; 42: zsz141Crossref individuals. awake individuals postural are obese individuals.12Watson supine non-rapid eye sleep, can fall approximately 60% predicted individuals, even overweight individuals.13Avraam Sleeping supine, volumes, cranially. suggests occurs be important determining efficacy. this, rabbits ETP, resistance, differs functional residual capacity,11Kairaitis indicating possibility activation. plus described part due improved length apparatus/hyoid movement. There limitations study, number patients, imprecise techniques control jaw head/neck position, timing stimulation, measurement volumes. investigated rather sleeping state, it anticipated particularly arousing Despite limitations, initial promising current contributions patency, well tract. Further research strategies prove next major advance treating Cervicalis Stimulation: New Direction Neurostimulation OSACHESTVol. 159Issue 3PreviewACS independently VImax propofol sedation drove further HNS. branch innervating easily accessed. Confirmation viable target enable novel strategy Full-Text