In clinical practice, both in intensive care units and in respiratory medicine, the respiratory index is one of the commonly used indicators to specify the ratio between the alveolar arterial partial pressure difference and the arterial partial pressure difference, mainly as a relatively simple response to the ventilation of lung tissue and the function of oxygen exchange. It has a normal reference range of less than or equal to 1.0 and is used to evaluate the respiratory distress syndrome caused by adults and the application of evacuation ventilators after mechanical ventilation with ventilators for various reasons. It is also used in some acute abdominal conditions, including acute pancreatitis and peritonitis, where the stability of vital signs is monitored. If the respiratory index is low, it clinically indicates that there is a state of hypoxia in the body, and the oxygenation function is significantly reduced, requiring the use of a ventilator to maintain normal respiratory function.