1. allergic to vitamin c; 2. dyspnea due to cardiogenic pulmonary edema; 3. pregnant or breastfeeding; 4. expected life is less than 24 hours; 5. there is a state of tracheotomy or home oxygen therapy in the past; 6. previously complicated with end-stage lung disease, end-stage malignancy, glucose-6-phosphate dehydrogenase deficiency, diabetic ketoacidosis, and active kidney stone disease; 7. the patient participates in another clinical trial at the same time.

1. allergic to vitamin c; 2. dyspnea due to cardiogenic pulmonary edema; 3. pregnant or breastfeeding; 4. expected life is less than 24 hours; 5. there is a state of tracheotomy or home oxygen therapy in the past; 6. previously complicated with end-stage lung disease, end-stage malignancy, glucose-6-phosphate dehydrogenase deficiency, diabetic ketoacidosis, and active kidney stone disease; 7. the patient participates in another clinical trial at the same time.

allergic to vitamin c; dyspnea due to cardiogenic pulmonary edema; pregnant or breastfeeding; expected life is less than 24 hours; there is a state of tracheotomy or home oxygen therapy in the past; previously complicated with end-stage lung disease, end-stage malignancy, glucose-6-phosphate dehydrogenase deficiency, diabetic ketoacidosis, and active kidney stone disease; the patient participates in another clinical trial at the same time.

allergic to vitamin c; dyspnea due to cardiogenic pulmonary edema; pregnant or breastfeeding; expected life is less than 24 hours; there is a state of tracheotomy or home oxygen therapy in the past; previously complicated with end-stage lung disease, end-stage malignancy, glucose-6-phosphate dehydrogenase deficiency, diabetic ketoacidosis, and active kidney stone disease; the patient participates in another clinical trial at the same time.

1. allergic to vitamin c; 2. dyspnea due to cardiogenic pulmonary edema; 3. pregnant or breastfeeding; 4. expected life is less than 24 hours; 5. there is a state of tracheotomy or home oxygen therapy in the past; 6. previously complicated with end-stage lung disease, end-stage malignancy, glucose-6-phosphate dehydrogenase deficiency, diabetic ketoacidosis, and active kidney stone disease; 7. the patient participates in another clinical trial at the same time.

1. allergic to vitamin c; 2. dyspnea due to cardiogenic pulmonary edema; 3. pregnant or breastfeeding; 4. expected life is less than 24 hours; 5. there is a state of tracheotomy or home oxygen therapy in the past; 6. previously complicated with end-stage lung disease, end-stage malignancy, glucose-6-phosphate dehydrogenase deficiency, diabetic ketoacidosis, and active kidney stone disease; 7. the patient participates in another clinical trial at the same time.