Reasons for Low Blood Oxygen Saturation:
1. Whether the partial pressure of inhaled oxygen is too low. When the oxygen content of the inhaled gas is insufficient, it may cause a decrease in oxygen saturation. In combination with the medical history, the patient should be asked whether he has ever gone to the plateau above 3000 m above sea level, flying at high altitude, rising after diving, and poorly ventilated mines.
2. Is there any airflow obstruction? It is necessary to consider whether there is obstructive ventilation deficiency caused by diseases such as asthma and COPD, tongue root fall, and respiratory secretions.
3. Is there any dysfunction in ventilation? Think about whether the patient has severe pneumonia, severe tuberculosis, diffuse pulmonary interstitial fibrosis, pulmonary edema, pulmonary embolism and other diseases that affect ventilation.
4. What is the quality and quantity of Hb that transports oxygen in the blood. The emergence of abnormal substances, such as CO poisoning, nitrite poisoning, and abnormal hemoglobin increase, not only seriously affect the transport of oxygen in the blood, but also seriously affect the release of oxygen.
5. Whether the patient has proper colloid osmotic pressure and blood volume. Proper colloid osmotic pressure and adequate blood volume are among the key factors in maintaining normal oxygen saturation.
6. How is the patient’s cardiac output? The amount of oxygen delivered to maintain normal organs should be supported by sufficient cardiac output.
7, tissue organ microcirculation. Whether to maintain proper oxygen and also related to the metabolism of the body, when the body’s metabolism is too large, the venous blood oxygen content will be significantly reduced, and the venous blood will lead to more severe hypoxia after the shunted pulmonary circulation.
8. Utilization of oxygen in surrounding tissues. Tissue cells can only use free oxygen, and the oxygen combined with Hb can only be released for tissue utilization. Changes in PH, 2,3-DPG, etc. affect the dissociation of oxygen from Hb.
9. After eliminating all the above factors, don’t forget that it may be due to the oxygen saturation caused by the instrument failure.