1999 OPEN FORUM Abstracts

WEANING TO EXTUBATION DIRECTLY FROM HIGH FREQUENCY OSCILLATORY VENTILATION (HFOV) IN AN INFANT WITH CYSTIC LUNG DISEASE AND PERSISTENT AIR LEAK: A STRATEGY FOR LUNG PROTECTION

Lori Seller RRT, Krishna Mullahoo RRT, Stephen Liben MD, Larry C. Lands MD, PhD. Montreal Children's Hospital, Montreal, Quebec, Canada.

Introduction: HFOV is generally used in the acute stage of respiratory failure, providing a lung protective strategy while maximizing gas exchange. Typically, patients are weaned from HFOV to conventional ventilation (CV) and progress to extubation. We report the successful weaning and extubation from a SensorMedics 3100A high frequency oscillator without returning to CV in a infant with respiratory syncytial virus (RSV) bronchiolitis, complicated by cystic pulmonary lesions and recurrent pneumothoraces.

Case study: A 7 week old term infant with severe RSV bronchiolitis, was ventilated on pressure regulated volume control mode (Siemens 300; f = 38 breaths/minute, V_T = 10 mL/kg, Pressure = 33/7 cmH₂O, FiO₂ = 0.50) for 5 days. Due to persistent collapse and decreasing lung volumes on the chest x-ray (CXR), as well as increasing oxygen needs, HFOV with inhaled nitric oxide was started on day 6. On day 8, cystic structures became apparent on CXR. As the RSV infection abated, attempts to switch the patient back to CV for weaning failed due to recurrent pneumothoraces. A computed tomography (CT) of the chest revealed multiple, well defined cysts of varying sizes involving both lungs. These results ruled out any surgical or unilateral ventilation options due to the bilateral and multifocal nature of the cysts. Weaning to extubation from HFOV was proposed as a possible way of preventing further air leak. The patient was then stabilized on HFOV for 12 days with the use of a minimal mean airway pressure (MAP) of 9 cmH₂O, during which time the air leak resolved. Sedation was weaned to allow spontaneous breathing. A weaning schedule was started whereby the patient was ?sprinted? by decreasing the amplitude (DP) from 30 to 10 cmH₂O and the MAP from 9 to 7 cmH₂O for twenty minutes three times a day. The frequency and duration of the ?sprints? were gradually increased, eventually stopping oscillation (DP) while maintaining a continuous positive airway pressure (CPAP) or MAP of 7 cmH₂O for the ?sprinting? period. On day 39, the patient was successfully extubated directly from HFOV with no complications. A follow up CT of the chest showed marked improvement in the size of the cystic lesions. The patient was discharged home 10 days later with no need for home oxygen therapy, and an almost normal CXR.

Discussion: Most reports of extubation directly from HFOV involve the premature, neonatal population. Effective tidal breathing adequate to maintain normocapnia can be achieved by the pediatric patient on HFOV by decreasing the MAP, and the DP to the point of minimal or no oscillation. Weaning directly to CPAP from HFOV may be a feasible option for patients requiring a protective lung strategy throughout the weaning stage.

OF-99-019