Airway Anatomy and Pathology

3/8/2018

AIRWAY ASSESSMENT

UPPER AIRWAY ANATOMY AND PATHOLOGY

SMALL AIRWAY What Happened?

David C. Hatcher, DDS, MSc, MRCD ( C ) Oral and Maxillofacial Radiologist Airway Anatomy & Pathology

Sleep Disordered Breathing (SDB) Increasing Upper Airway Collapsibility Polysomnography (PSG) . Abnormal Respiratory Pattern During Sleep . Apnea Hypopnea Index (AHI) . Snoring  Apnea = Cessation of Airflow > 10 seconds

. Upper Airway Resistance Syndrome  Hypopnea = Decrease in Airflow by > 30% for > 10 . Obstructive Sleep Apnea Syndrome Seconds . Obesity‐Hypoventilation Syndrome  Associated with Drop SaO2 by > 3 %

 AHI = A+ H / Hour Sleep  > 5 Abnormal

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Obstructive Sleep Apnea Pathophysiology of OSA Role of Anatomy Awake: Small Airway + Neuromuscular Compensation

Sleep Onset . . Recurrent Collapse of Airway During Sleep Loss of Hyperventilate: Abnormal Upper Airway Anatomy Neuromuscualar Correct Hypoxia & Compensation Hypercapnia

. Abnormal AHI with Symptoms Pharyngeal Muscle . Increase Resistance Activity  Mild OSA‐ 5‐15 AHI Events/ Hour Airway Opens  Mod. OSA‐ 16‐30 AHI Events/ Hour Airway Collapse Pharyngeal Muscle . Turbulent Air Flow Activity Restored  Sev. OSA‐ > 30 AHI Events/ Hour Apnea

Hypoxia & Arousal From Sleep Hypercapnia . Increases Collapsibility

Ventilatory Effort

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1 3/8/2018

OSA Airway Metric Analysis

. Related to Abnormal Timing of Upper Airway . Volume Dilator Muscle Contraction . Cross Sectional Area . Normally Dilator Muscles Contract BEFORE . Linear Distances Diaphragm & Accessory Inspiratory Muscles Move OR it will Create a Negative Pressure Leading to Airway Collapse

. Requires Good Neurological System

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Measurement Error Source Effect of Tongue Position on Airway Map Region of Interest (ROI)

. Soft Ware Accuracy . Head Position . Tongue Position . Tongue Motion

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Cross Sectional Area

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2 3/8/2018

CSA v. Age Airway: Role of Imaging Upright Imaging

180 . Airway Imaging Can Not Confirm Or Exclude 160 (mm2) OSA 140 Area

120

. Imaging Can Help Understand Airway 100 Sectional Anatomy (Phenotype) 80 Medium OSA Risk

 Identify Potential Obstruction Sites Cross 50  Evaluate Airway Support Structures High OSA Risk

8 1012 14 16 20 40 >50 Age UOP Ortho Alumni Hatcher UOP Ortho Alumni Hatcher UOP Ortho Alumni Hatcher

Airway Resistance and Flow Airway Dimensions and OSA 3d CBCT Trends . Poiseuille’s Law . Ohm’s Law 4 OSA Control  (R = 8nl / π r )  (V = Pmouth –Palveoli / R) . Retroglossal and Retropalatal Space  R = Reistance  V = Flow Predictive of RDI BMI 29.5 23.1  N = Viscosity  P = Pressure 3 3  Π = phi  R = Resistance Cross Sectional Area OSA Probability Volume 4868 mm 6051 mm  R = Radius 2 < 52 mm High Smallest Area 46 mm2 147 mm2 52 ‐ 110 mm2 Medium > 110 mm2 Low AP 4.6 mm 7.8 mm Radius = Resistance = Pressure Gradient Lateral 11.6 mm 16.2 mm •Li HY, Chen NH, Wang CR, Shu YH, Wang PC. “ Use of 3-dimensional computed tomography scan to evaluate upper airway patency for patients undergoing sleep-disordered breathing surgery.” Otolaryngol Respiratory Effort Head Neck Surg 2003;1294):336-42 Ogawa, T, Reyes Enciso, W Shintaku Glenn Clark, OOOOE Jan 2007

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Nasal Valves

. External Nasal Valve

. Internal Nasal Valve

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3 3/8/2018

External Nasal Valve Internal Nasal valve

. Major Alar Cartilage:  Lateral Crus  Medial Crus

. Septal nasal cartilage . (Quadriangular cartilage)

Netter’s Head and Neck Anatomy for Dentistry

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Pyriform aperture

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Nasal Septum Nasal Cavity boundaries

. Cribriform plate of the Ethmoid . Ethmoid air cells . Maxillary sinuses . Nasal septum

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4 3/8/2018

Concha Bullosa Polyposis . Pneumatized Middle Turbinate . Etiology  Allergy + Inflammation ‐> Unstable Mucosa ‐> Epithelial Proliferation ‐> Morphological Changes

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Chronic RhinoSinusitis (CRS) . Group of Disorders Characterized by Inflammation of Nose & Sinuses >/= 12 Consecutive Weeks Duration

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5 3/8/2018

Rhinolith Foreign Body

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Sinonasal Tumor

Courtesy of Dr. Shikha Rathi

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6 3/8/2018

Oral & Nasopharynx Nasal Resistance

Boundaries . Mouth Breathing  Inferior Tongue posture . Narrowing of Dental Arches

. Clockwise Facial Growth Pattern . Increase Anterior Face Height

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7 3/8/2018

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SCC of Palatine tonsils

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8 3/8/2018

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2 UOP Ortho Alumni Hatcher UOP Ortho Alumni Hatcher 11.88 mm UOP Ortho Alumni Hatcher

9 3/8/2018

Support Structures for Airway

. Cervical Spine . Jaws

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•Local Insult Facial Growth Patterns •Regional Adaptation

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10 3/8/2018

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11 3/8/2018

Conclusions

. Imaging provides a Support Role in SDB . Granular Dx. Leads to a Tailored Treatment . Accurate Dx. Leads to the Best Treatment Outcomes

. Consider Airway from External Nasal Valves to Trachea . Consider Support Structures for Airway  Jaws  Spine  Tongue  Soft Palate

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