Respiratory failure is characterized by functional impairment of ventilation and/or air exchange, usually accompanied by hypoxia and/or carbon dioxide retention, also known as “breath-holding”. The diagnosis of overt respiratory failure is relatively straightforward, as it is usually accompanied by paroxysmal muscle twitching and chest elevation breathing, while for non-overt respiratory failure, arterial blood gas testing is the most common method of diagnosis. Usually a physician will use a blood gas needle to collect an arterial blood sample from the patient’s femoral or radial artery, and using a blood gas analyzer, an accurate value can be obtained in a short period of time. An arterial partial pressure of oxygen less than 60 mm Hg and a partial pressure of carbon dioxide greater than 50 mm Hg is called type II respiratory failure, and a determination of an arterial partial pressure of oxygen less than 60 mm Hg and a normal partial pressure of carbon dioxide is called type I respiratory failure. If the sample meets this criterion, then it can be confirmed that the oxygen carrying capacity of the blood in the human body has fallen below the standard value, and hypoxemia can be diagnosed as respiratory failure. It is important to keep the blood anticoagulated during the measurement and not to take venous blood. In general, the criteria for determining respiratory failure are relatively objective, but for more specific patients there may be differences in the criteria.