Oxygenation index refers to a goal in respiratory therapy, and it is an important index to make organs and tissues get enough oxygen for oxygenation to obtain energy, also known as ventilation/perfusion index. The calculation formula is oxygenation index = arterial oxygen partial pressure (PaO2)/ oxygen absorption concentration (FiO2)X 100%, which is used to indicate the degree of acute lung injury, and the normal value is 400 ~ 500 mm Hg.
For patients with acute respiratory distress syndrome, the arterial oxygen partial pressure is obviously reduced due to severe intrapulmonary shunt, and the arterial oxygen partial pressure cannot be increased by increasing oxygen concentration, so the oxygenation index is often less than 300mmHg.
Precautions:
In order to judge the measured value of oxygenation index, there are some precautions:
1. The above formula for calculating the oxygenation index will be relatively accurate only when the nasal catheter is used for oxygen inhalation, the oxygen flow rate is below 6L/min, the breathing frequency is normal, and the sea level is under the condition.
2. When the mask is used to inhale oxygen (the dead space volume will increase), the breathing is too fast or too slow, and the altitude is too high, the calculation result will be inaccurate, and it needs to be recalculated according to the specific oxygen inhalation score.