1. Intensive Care Unit, Long Beach Memorial Hospital, Long Beach, CA, USA
2. David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
3. Pulmonary Division, Long Beach Memorial Hospital, Long Beach, CA, USA
4. Department of Public Health and Community Medicine, Tufts School of Medicine, Boston, MA, USA
5. MemorialCare Health System, Fountain Valley, CA, USA