1. School of Medicine, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
2. Adult Critical Care Services, Northwest Texas Hospital, Amarillo, TX 79106, USA
3. Infection Control, Northwest Texas Hospital, Amarillo, TX 79106, USA
4. Respiratory Care, Northwest Texas Hospital, Amarillo, TX 79106, USA
5. Department of surgery, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
6. Section of Critical Care Medicine, Department of Internal Medicine, Texas Tech University Health Sciences Center, 1400 S. Coulter Street, Amarillo, TX 79106, USA