The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts


Julie Griffin1, Raisha G. Mahon1, Brian K. Walsh1, 2, John Kheir2

Introduction: We present a case in which heliox therapy was combined with non-invasive positive pressure ventilation (NPPV) to treat a child with upper airways obstruction due to an anterior mediastinal mass.

Case: A previously healthy 15-year old male presented with severe dyspnea and orthopnea. The patient was aphonic with significant retractions and anxious stance, tripodding. Workup revealed a large anterior mediastinal mass with compression of the trachea and great vessels (see Figure 1). Heliox 80/20 via simple mask was initiated, with only transient and mild alleviation of symptomatology. Continuous positive airway pressure via face mask was initiated, and was well tolerated with some improvement in dyspnea. Several hours later, however, the patient exhibited fatigue. Given the high risk of circulatory collapse upon induction of anesthesia, the patient was treated with NPPV combined with heliox therapy. Using the Avea ventilator (Cardinal Healthcare), the patient received pressure-supported ventilation with an 80/20 admixture of heliox. This provided a dramatic decrease in dyspnea and improvement in markers of gas exchange. The patient underwent five days of heliox via NPPV, following which he successfully transitioned to oxygen via nasal cannula. With aggressive chemotherapy, he was transferred to the ward on hospital day nine, and discharged to home on day fifteen.

Discussion: The care of children with symptomatic mediastinal masses must be managed with extreme caution, when possible in a facility with extracorporeal support capability. Maintenance of spontaneous ventilation in these patients is paramount due to the expansive effects it provides to the intrathoracic airways. The use of NPPV in this patient allowed the maintenance of spontaneous ventilation. The therapeutic effect of heliox is to lower the density of inhaled gas. This, in turn, lowers the Reynold's number to a point in which it is less likely to reach the critical value above which laminar flow becomes turbulent. Laminar flow is more efficient allowing heliox therapy to improve the volume of gas entering and exiting the obstructed lung for given pressure changes. The Avea ventilator was utilized in this instance because the internal blending system that compensates for the gas mixture providing accurate delivered and monitored parameters.