Arterial partial pressure of oxygen is a test item of arterial blood gas analysis. Arterial blood gas analysis generally includes arterial blood PH, arterial blood carbon dioxide partial pressure, arterial blood oxygen partial pressure, alkali residual, arterial blood bicarbonate content, blood oxygen saturation, and sometimes the lactate content of blood, etc. In general, 2ml of blood is drawn from the radial artery puncture and sent to the laboratory for testing. An increased partial pressure of arterial blood oxygen is commonly seen in the state of oxygenation, while a decreased partial pressure of arterial blood oxygen is seen in pulmonary diseases such as chronic bronchitis, emphysema, pulmonary heart disease, pulmonary embolism and various causes of heart failure. A partial pressure of arterial oxygen below 60 mmHg is diagnostic of type I respiratory failure. If it is accompanied by carbon dioxide retention, with a partial pressure of carbon dioxide greater than 50 mmHg, it can be diagnosed as type II respiratory failure. Clinically, arterial blood gas analysis is recommended in all cases where hypoxemia is considered.