Blood oxygen saturation is an important physiological parameter that reflects the function of breathing and circulation, which is very common in clinical applications such as internal medicine, surgery, and intensive care units. It is a reliance on clinical rescue and nursing.
But can you quickly determine whether the patient needs rescue based on the blood oxygen saturation? How to understand SpO2 correctly is a big problem. Here we are going to discuss it.
What is the working principle of pulse oximetry?
Pulse oximetry (SpO2) monitoring is to fix the Finger spo2 sensor on the nail bed of the fingertips. During the measurement, the finger acts as a transparent container for hemoglobin, and red light with a wavelength of 660nm and near-infrared light with a wavelength of 940nm is the incident light source for measurement.
SpO2 is a percentage. What does it mean?
The blood oxygen saturation is to measure the ability of blood to carry and transport oxygen. Pulse blood oxygen saturation is SpO2, which is the degree to which hemoglobin (Hb) binds to oxygen, that is, the percentage of oxygen and Hb to total Hb, or the ratio of Hb bound oxygen to Hb oxygen capacity.
Calculation formula: SpO2=HbO2/(HbO2+Hb)×100%.
The value of oxygen saturation is 95%-99%. Oxygen saturation is directly related to oxygen partial pressure. The SpO2 should not be less than 94%, and that below 94% is insufficient oxygen supply. Some scholars set SpO2<90% as the standard for hypoxemia. When SpO2 is higher than 70%, the accuracy of monitoring can reach ±2%, and when SpO2 is lower than 70%, the error will increase.
What changes should be paid attention to in SpO2 monitoring during sputum suction?
Nurses can fully grasp the timing and duration of sputum suction through SpO2 monitoring. These points in the sputum suction operation should be paid attention to and adjusted through SpO2 monitoring.
If SpO2 gradually drops by 2% to 3%, and there is sputum sound in the lungs on auscultation, oxygen inhaling continued.
Do not attract too much after SpO2 returns to normal within 15 minutes after sputum suction.
When the spo2 drops to 85%, we have to suspend sputum suction and inhale high-concentration oxygen or connect it to a ventilator for patients. Then, we continue suction after SpO2 rises to avoid excessive sputum suction and excessive sputum suction aggravating the respiratory tract Stimulus affects lung ventilation, leading to hypoxemia.
What are the advantages of SpO2 monitoring for mechanical ventilation?
1. For patients undergoing mechanical ventilation, choose the working conditions of the ventilator, adjust the parameters, and provide a reference for evacuation of the ventilator, avoid multiple collections of patients' arterial blood for blood gas analysis, and reduce the pain of the patient and the workload of the nurse. The literature proves that non-invasive measurements of SpO2 through the skin are close to the SpO2 by arterial blood samples.
2. SpO2 monitoring can be a reference for the patient's oxygen concentration and oxygen flow adjustment, which can avoid oxygen poisoning caused by excessive oxygen concentration or hypoxemia caused by low oxygen concentration and truly achieve reasonable oxygen use. It is also an indicator for patients to stop oxygen inhaling.
Why use SpO2 monitoring during the recovery period from general anesthesia?
SpO2 monitoring is conducive to the timely observation of the recovery of spontaneous breathing in patients awakened after general anesthesia.
For example, after the tracheal intubation is removed clinically after general anesthesia, especially in patients with obesity, severe intubation injury, and respiratory diseases, the patient's spontaneous breathing is weak after awakening, and hypoxemia may occur at any time.
What is the purpose of SpO2 monitoring after surgery?
1. It helps to judge the end circulation and the oxygenation of the limb tissue after orthopedic limb surgery.
2. Helps to detection of complications early after surgery and prevention of complications.
3. Assist in observing the body's circulatory state. It can display not only SpO2 but pulse rate and pulse waveform. When the patient's blood pressure drops and the pulse is weak. The pulse waveform will become flat or no waveform.
What other situations can we use the SpO2 monitoring?
1. We use the spo2 monitoring for screening of neonatal congenital heart disease. If the blood oxygen saturation of hands and feet is less than 98% at the same time or the difference of blood oxygen saturation between hands and feet is ±3%, we usually initially diagnose it as a congenital heart.
2. The spO2 monitoring to patients in the 6-minute walk test. The prognosis of COPD patients with decreased blood oxygen saturation during the 6-minute walk test is worse than that of patients without blood oxygen saturation decreasing.
3. After the stroke patient eats, the bedside pulse oximetry measurement can reflect the swallowing function of the stroke patient. Aspiration can cause reflex bronchoconstriction and decrease blood oxygen saturation.
The spo2 monitoring is not only a monitoring method. But also a simple, non-invasive, and effective diagnostic method.
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