1. Collapsing Trachea Mark Bohling, DVM Diplomate, American College of Veterinary Surgeons Assistant Professor of SurgeryUniversity of TennesseeCollege of Veterinary Medicine

2. What is Tracheal Collapse? • Normal airflow dynamics in respiration • Inspiration • Expansion of chest by muscles of respiration • Pressure gradient - chest negative • Effect on the air conduit: • Thorax - expansion • Neck - compression • Expiration • Reverse effects

3. History of Collapsing Trachea in Veterinary Medicine • Described as early as 1960 • Review of early treatments • Single plastic tube • Ventral chondrotomy • Modified ventral chondrotomy • Dorsal membrane plication

4. Tracheal Collapse in Other Species • Tracheal collapse in human beings • History • Dates to 1930’s • Similarities • Softening of tracheal cartilage • Lateral collapse (same as dorsoventral in dogs) • Differences • Classification • Primary vs secondary collapse • Pediatric vs adult collapse

5. Tracheal Collapse in Other Species • Tracheal collapse in large animals • Horses • Congenital • Secondary to laryngeal paralysis • Cattle • Acquired neonatal • Tracheal collapse in birds • Bordetella avium in turkeys

6. Tracheal Collapse in the Dog • Miniature breeds • Middle aged to older • Other risk factors • More pronounced in obese individuals

7. Levels of Collapse Normal G1 G2 G3 G4

8. Levels of Collapse

9. Clinical Signs • Chronic, dry nonproductive cough (honking) • Intermittent dyspnea (worsens with excitement) • Cyanosis & syncope in severe cases • Inspiratory/ expiratory dyspnea • Prone to heat stroke

10. Clinical Signs

11. Pathophysiology • Disease causes the trachea rings to weaken • Dorsal ligament and trachealis muscle weaken and stretch • Trachea changes from oval tube to a flattened conduit

12. Etiology • Congenital • Nutritional tracheomalacia • Obesity • Bacterial infection • Neurologic • Chronic airway disease • Idiopathic – “who knows why”

13. Diagnosis • Tracheal palpation • Radiographs (inspiratory / expiratory ) • Fluoroscopy • Tracheoscopy

14. Radiographs

15. Tracheoscopy

16. Medical Management • Cough suppression(Hydrocodone, butorphanol) • Bronchial dilators(Aminophylline, terbutaline) • Sedation(Acepromazine) • Weight loss

17. Medical Management • Help control symptoms • Can not be cured • Disease usually progressive

18. Surgical Correction • External stenting with plastic rings

24. Before After

25. Surgical Correction • External spiral stent

26. External Stent Complications • Collapse between rings

27. External Stent Complications • Damage to recurrent laryngeal nerve

28. External Stent Complications • Interruption of tracheal bloodsupply

29. Internal Stenting • What is a stent? • History of stenting • History of tracheal stenting • Modern stents and stent materials • Stents in veterinary medicine

30. Ultraflex® Stent • Radiopaque, self-deployed • 4 - 8 cm length, 10 - 20mm diameter • Made of nitinol (nickel-titanium alloy) • Proximal or distal deployment • Single strand, open loop knitted design (flexible, contourable) Boston Scientific/ Microvasive.

31. Ultraflex® Stent

34. Ultraflex® Stents

35. SmartStent® • Nitinol tube • Laser cut • No overlapping wires • Less breakage in human vascular applications • Cordis Endovascular®

36. Infiniti Stent • Also nitinol • Single woven wire • Only stent produced exclusively for vet use • Claims as yet unproven

37. Stent Placement • Stent deployed under fluoroscopic guidance • Target – 5mm cranial to bifurcation • Placement checked with tracheoscopy

38. Stent in Place

39. Radiographs

40. Postoperative Care • Perioperative antibiotics • Corticosteroids for 7 days • Sedation • Cough suppression • 24 hours oxygen if needed • Humidification

41. 6 Month Post Implant

42. Stent Results • The little girl with the curl syndrome… • Good outcomes… • Immediate improvement • Breathing near normal • Mild chronic cough • And the not-so-good outcomes…

43. Stent Complications • Stent fracture • Granulation in stent • Tracheal exudate • Additional collapse at ends of stent

44. Fractured Stent

45. Fractured Stent

46. Stent Fracture • Originally thought to be due to bending stresses • All brands/types of nitinol stents can fracture - there is NO unbreakable stent • At this time, removal is best option - BUT - not for the fainthearted!

47. Granulation Tissue

49. Tracheal Mucus

50. Collapsed at Ends