Blood oxygen saturation is one of the important indicators of physical health. The blood oxygen saturation of normal healthy people should be kept between 95% and 100%. If it is lower than 90%, it has entered the range of hypoxia. % is severe hypoxia, which will cause great damage to the body and endanger life.
Blood oxygen saturation is an important physiological parameter that reflects the respiratory and circulatory function. According to incomplete statistics, most of the reasons for emergency consultations with respiratory departments in relevant departments in hospitals are related to blood oxygen. We all know that low oxygen saturation is inseparable from respiratory diseases, but not all decreases in blood oxygen saturation are caused by respiratory diseases.
What are the causes of low blood oxygen saturation?
1. Whether the partial pressure of inhaled oxygen is too low. When the inhaled oxygen content is insufficient, oxygen saturation may decrease. Combined with the medical history, the patient should be asked whether he has ever been to plateaus above 3000m, high-altitude flight, ascent after diving, and poorly ventilated mines.
2. Whether there is airflow obstruction. It is necessary to consider whether there is obstructive hypoventilation caused by diseases such as asthma, COPD, tongue root drop, and foreign body obstruction of respiratory secretions.
3. Whether there is ventilation dysfunction. It is necessary to think about whether the patient has severe pneumonia, severe tuberculosis, diffuse pulmonary interstitial fibrosis, pulmonary edema, pulmonary embolism and other diseases that affect the ventilation function.
4. What is the quality and quantity of Hb that transports oxygen in the blood. The appearance of abnormal substances, such as CO poisoning, nitrite poisoning, and a large increase in abnormal hemoglobin, not only seriously affects the transport of oxygen in the blood, but also seriously affects the release of oxygen.
5. Whether the patient has appropriate colloid osmotic pressure and blood volume. Appropriate colloid osmotic pressure and sufficient blood volume are one of the key factors to maintain normal oxygen saturation.
6. What is the patient’s cardiac output? Maintaining normal oxygen delivery to organs should be supported by sufficient cardiac output.
7. Tissue and organ microcirculation. The ability to maintain proper oxygen is also related to the body’s metabolism. 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 passing through the shunted pulmonary circulation.
8. Oxygen utilization in surrounding tissues. Tissue cells can only use free oxygen, and the oxygen combined with Hb can only be used by tissues when it is released. Changes in pH, 2,3-DPG, etc. affect the dissociation of oxygen from Hb.
9. The strength of the pulse. Oxygen saturation is measured based on the change in absorbance produced by arterial pulsation, so the transducer must be placed on a site with pulsating blood. Any factors that weaken the pulsatile blood flow, such as cold stimulation, sympathetic nerve excitement, diabetes and arteriosclerosis patients, will reduce the measurement performance of the instrument. SpO2 cannot be detected even in patients with cardiopulmonary bypass and cardiac arrest.
Post time: Dec-22-2022