The normal value of partial pressure of carbon dioxide in venous blood should be between 45-55 mmHg, but it is also necessary to know the normal range of partial pressure of carbon dioxide in arterial blood because it is necessary to analyze the acid-base balance of the body with reference to the partial pressure of carbon dioxide in arterial blood. The normal range of arterial partial pressure of carbon dioxide is 35-45 mmHg, while the oxygen content of blood in venous blood analysis should not be lower than 60 mmHg and carbon dioxide should not be lower than 50 mmHg. Low carbon dioxide indicates that the patient may have respiratory alkalosis and other symptoms, while high carbon dioxide indicates that the patient may have respiratory acidosis and other symptoms.