3/10/15. Summary. Anatomy Larynx. Anatomy Trachea

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1 Summary Anatomy Brachycephalic Airway Syndrome (BCAS) Crisis Anatomy Larynx Anatomy Trachea Tracheal rings are incomplete, C-shaped cartilage with the dorsal membrane being completed by tracheal muscle (trachealis dorsalis muscle) Primary function: serve as conduit to gas flow Additionally: mucociliary apparatus 1

2 Anatomy Lower Airways The principal bronchi are formed by complete cartilage rings Secondary/lobar bronchi Tertiary/segmental bronchi Dichotomously branch into small bronchi/bronchioles Pathology Localization: Tracheal auscultation: Stridor, no sound, whistling, normal Dynamic Obstruction: Paradoxical movement of tissues into lumen during inspiration - Laryngeal paralysis, laryngeal collapse, tracheal collapse Static Obstruction: Neoplasia, cellulitis, foreign bodies, polyps 2

3 Laryngeal collapse Stage 1: Eversion of the laryngeal saccules into glottis Stage 2: Medial displacement of the cuneiform processes into laryngeal lumen - Aryepiglottic folds collapse ventromedial Stage 3: Corniculate process of each arytenoid collapse towards midline - Complete laryngeal collapse Laryngeal collapse Laryngeal paralysis 3

4 Tracheal collapse Tracheal collapse Causes of Tracheal Collapse: Softening of cartilage rings Bronchomalacia (45-83% incidence) Changes to matrix (inability to retain water leading to loss of rigidity) Extrinsic compression Redundant tracheal membranes or inflammation Tracheal collapse Sequelae of Tracheal Collapse: Additional inflammation Edema Alterations or failure of mucociliary apparatus Increased mucus secretion Lower airway collapse 4

5 Brachycephalic Airway Syndrome (BCAS aka BAOS) Stenotic nares Elongated soft palate Swollen or everted laryngeal saccules - Secondary concerns: everted tonsils, laryngeal collapse, pharyngeal swelling BCAS BCAS Elongated Soft Palate 5

6 BCAS Sequelae Compensatory increased negative pressure on inspiration - 50% reduction in tube radius leads to 16-fold resistance to flow Inflammation and stretching of pharyngeal tissue Obstruction of airways Marked increase in gastroesophageal reflux and regurgitation Marked increase in systemic inflammatory mediators Summary Anatomy Brachycephalic Airway Syndrome (BCAS) Crisis Crisis Dyspnea 3 Categories: Air hunger Increased work/effect Chest tightness The subjective experience of breathing discomfort that originates from interactions among physiological, psychological, social and environmental factors - American Thoracic Society 6

7 Crisis Respiratory Patterns and Effort Costoabdominal Restrictive - fast and shallow - Common in pleural space disease Paradoxical - inward movement of abdomen with inhale - Common in pleural space and thoracic wall disease Inspiratory > Expiratory time/effort - More likely upper airway disease Crisis Lower Respiratory Sequelae Non cardiogenic pulmonary edema Acute Lung Injury (ALI) Acute Respiratory Distress Syndrome (ARDS) Aspiration pneumonia Summary Anatomy Brachycephalic Airway Syndrome (BCAS) Crisis 7

8 Minimize Stress!! Sometimes less is more! Oxygen Therapy Sedation Sedation (IV/IM dosing) Acepromazine: mg/kg every 4-6 hours Butorphanol: mg/kg every 4-6 hours 8

9 Elevated Temperatures Active cooling indicated until <103.5F Room temperature water Aggressive IV fluid support: 10-20mL/kg crystalloid bolus mL/kg/day thereafter NO ICE BATHS NO ICING LINE NO COLD WATER ENEMAS NO ANTIPYRETICS Consider a fan Indications to Intubate Persistent hypoxia (PaO2 < 60mmHg) Persistent hypercapnia (PaCO2 > 60mmHg) Impending respiratory failure Bronchodilators Aminophylline/Theophylline: 7-10mg/kg every 8 hours IV/SQ/PO Terbutaline: 0.01mg/kg q4hr IM 0.03mg/kg q8hr PO Albuterol: 0.05mg/kg q8-12hr or mcg (1-2 puffs) total dose Why? Increase in diameter of small airways (<300um) may improve expiratory flow 9

10 Glucocorticoids Only if concurrent infectious condition is NOT suspected Anti-inflammatory dose: Prednisone: mg/kg Dexamethasone: same prednisone equivalent - divide your prednisone dose by 10 Tracheostomy Tracheostomy 10

11 Tracheostomy Pros: open airway! Cons: Epithelial erosion Submucosal inflammation Inhibition of mucociliary apparatus Airway obstruction (mucus/ dislodgement) Pneumothorax/mediastinum Felines: higher morbidity (Stepnik et al) Less Emergent Consider GI support Monitor acid/base status Thoracic radiographs Advanced imaging Planned surgical correction 11

12 Antibiotics? The role of bacterial infection of the upper airways remains unknown One study revealed 99% positive cultures (84/85) in dogs getting surgical correction of tracheal collapse Most commonly gram-negative bacteria and mixed populations of staph, Pseudomonas, Corynebacterium, Pasteurella, and E. coli species Because the trachea is not sterile, positive results are hard to interpret Novel Therapies Heliox: (Helium-Oxygen gas-carrier mixture) - May decrease work/effort of breathing - May lower A-a gradients Nebulized furosemide Nebulized opioids Summary Limit stress Be aggressive early to avoid increased morbidity later Oxygen therapy should always be considered Dyspnea and pain may be related Upper airway crisis can lead to lower airway disease Do not be afraid to intubate 12