Secretion management must be considered when reporting success or failure of noninvasive ventilation.

response in cardiac index as displayed in Figure 4, oxygen delivery did improve consistent with the patient’s clinical improvement. Of course, with systemic-to-pulmonary communications, the determination of pulmonary vs systemic blood flow depends upon several factors in addition to pulmonary vascular resistance vs systemic vascular resistance: obligatory shunting, effects of streaming, as well as right and left heart filling pressures and respiratory effects on intrathoracic pressures. We anticipate that ongoing clinical investigation, including patients with unrepaired or residual systemic-to-pulmonary communications, will further enlighten our understanding of the mechanisms of action of endothelin receptor antagonists.