[1] S Texas Vet Hlth Care Syst, Audie L Murphy Mem Vet Hosp Div, Pulm Sect 111E, San Antonio, TX 78284 USA
[2] Univ Texas, Hlth Sci Ctr, Dept Med, Div Pulm Dis Crit Care Med, San Antonio, TX 78284 USA
[3] Univ Texas, Hlth Sci Ctr, Dept Surg, Div Cardiothorac Surg & Transplant, San Antonio, TX 78284 USA