Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan. fangwf@hotmail.com. Department of Respiratory Therapy, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan. fangwf@hotmail.com. Department of Respiratory Care, Chang Gung University of Science and Technology, Chiayi, Taiwan. fangwf@hotmail.com. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan. Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, Taiwan. Department of Nutritional Therapy, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan. Department of Respiratory Care, Chang Gung University of Science and Technology, Chiayi, Taiwan. Department of Respiratory Therapy, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.