1 Section on Pulmonary, Critical Care, Allergy and Immunologic Diseases, Wake Forest Baptist Medical Center, Winston-Salem, NC.
2 Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pa.
3 Louisiana State University Health Sciences Center, New Orleans, La.
4 Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pa. Electronic address: petrovaa@upmc.edu.