The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts


Kevin J. Bullock1, Sarah Teele2; 1Respiratory Care, Boston Children’s Hospital, Boston, MA; 2Cardiology, Boston Children’s Hospital, Boston, MA

Introduction: High-frequency oscillation (HFO) has been used in a variety of forms for secretion mobilization. We report a case of continuous HFO (CHFO) using the Metaneb® System (Advanced Respiratory Inc., St. Paul, MN) in a patient with severe ARDS complicated by continuous pulmonary air leak and pulmonary hemorrhage. Case: A 31yo, 68kg man suffered pulmonary hemorrhage and fulminate pulmonary edema following an elective aortic homograft replacement. He was unable to wean from cardiopulmonary bypass and was transferred to our facility for transition to V-A ECMO. Despite ongoing bleeding, further complicated by heparin induced thrombocytopenia and renal failure, cardiac function improved and the patient transitioned to V-V ECMO at hour 301. Pulmonary function made little recovery in the first two weeks despite maintenance on HFOV with mean airway pressures of 40-45 cm H2O on days 9-14. Upon transition to back CMV, the chest x-ray revealed bilateral white-out and dynamic compliance (Cdyn ) was 5.66 mL/cm H2O on PC-SIMV PIP/PEEP 26/14 cm H2O. At ECMO hour 635, a bedside tracheotomy was performed. Over the next 72hrs, daily bronchoscopies failed to mobilize several large, fibrinous clots obstructing the major bronchi and branching airways. CHFO with nebulized n-acytelcysteine, was used in-line with mechanical ventilation in an attempt to mobilize the clot burden. Following the first treatment, several large clots were suctioned from the airway. As a result, on PC-SIMV PIP/PEEP 30/10 cm H2O, the patient’s tidal volume increased from 3 mL/kg to 6 mL/kg. Five additional treatments were conducted over the next 24 hours with continued removal of large clots. The continuous air leak in the right lung remained stable throughout CHFO treatment, despite improved Cdyn from 10 to 20 mL/cm H2O. At ECMO hour 703, a flexible bronchoscopy revealed widely patent and clear proximal airways. The patient’s gas exchange continued to improve and he was decannulated at ECMO hour 756. Discussion: Two relative contraindications to the Metaneb® System, pulmonary air leak and pulmonary hemorrhage, were present in this patient and were carefully considered. The transthoracic pressures transmitted during CHFO are not completely understood, however, our case suggests they may not contribute substantially to shear stress which may aggravate an existing pulmonary air leak. Further research is needed to assess pressure attenuation across various ETTs during treatment with CHFO. Sponsored Research - None