Views:18 Author:Site Editor Publish Time: 2020-03-30 Origin:Site
Adults often experience complications such as hypoxemia, lung infections, and atelectasis after cardiac surgery. Oxygen therapy is often required after tracheal extubation to maintain adequate alveolar ventilation and oxygenation.
Recently, a 64-year-old bypass patient in cardiac surgery was immediately transferred to ICU for hypoxia due to cough, thick sputum, and respiratory distress. According to the previous routine, after suctioning sputum to patients, non-invasive ventilator-assisted ventilation is needed to improve hypoxemia, but this time the ICU used a highly effective nasal high-flow oxygen inhalation device. Breathing was smooth, hypoxia symptoms were significantly improved, and comfort was greatly improved.
What is such a "black technology" for such an effective transnasal high-flow oxygen inhalation device?
This has to start from its source: common nasal catheters, common masks, oxygen storage masks and other commonly used oxygen therapy equipment commonly used in clinical practice, due to the effect of oxygen flow brought into the air, the oxygen concentration increases with the inhaled gas flow It is significantly reduced and difficult to determine. For some patients, especially those who are difficult to go offline after invasive ventilation, cannot cooperate with non-invasive ventilator, and are unwilling to use invasive ventilation, the flow provided by these measures is far from enough. . Under clinical needs and professional research, a nasal high-flow oxygen inhalation device came into being.
So what exactly is nasal high-flow oxygen therapy?
1. The concept of high flow: There is no specific value, and the oxygen inhalation device higher than the peak inspiratory flow rate of the patient is clinically called a high flow oxygen therapy device. HFNC: (High-flow Nasal Cannula): Can not change with the change of breathing frequency and tidal volume, provided that the provided flow rate must be higher than the patient's inspiratory peak flow rate. High-flow nasal cannula oxygen therapy (HFNC) is an oxygen therapy method that directly delivers a certain oxygen concentration of air-oxygen mixed high-flow gas to a patient through a nasal obstruction catheter without sealing. This gas has a high Features of flow, precise oxygen concentration, and heating and humidification.
2. The transnasal high-flow oxygen inhalation device is composed of a high-flow output device, a professional heating and humidifying system, and a nasal plug system. It has the following three characteristics. (1) Constant oxygen concentration: 21% to 100%; (2) Continuous high flow: Up to 60 L / min; (3) Airway temperature humidification: 37 ℃ temperature, 100% relative humidity.
Why does transnasal high-flow oxygen therapy (HFNC) have a sense of high-level in the oxygen therapy session?
1. Patient comfort, especially when respiratory function is unstable, is particularly important for reducing breathing work and avoiding respiratory function. It provides the following functions: (1) Provides a stable high oxygen concentration to quickly and effectively improve blood oxygen. (2) Wash away the dead space of physiological anatomy and reduce the re-inhalation of carbon dioxide. (3) A certain positive airway pressure is formed to keep the airway open. (4) Sufficient humidification and warming make the airway mucus ciliary cleaning function at the best state. (5) Comfortable patient experience to improve oxygen therapy compliance.
2. High flow heating and humidifying oxygen. HFNC can provide warm and humidified high-concentration oxygen through a nasal catheter, and the air flow rate can reach 60L / min. Because the air flow rate can be set to exceed the peak inspiratory flow level of most patients with respiratory failure, thereby ensuring a constant oxygen concentration; HFNC's warming and humidifying functions can protect the airway mucosa and enhance the cleaning ability of mucous cilia. Reasonable airway humidification can dilute airway secretions, keep the airway open and moist, maintain normal airway function, and effectively prevent complications such as lung infections.
3. Increase functional residual capacity. Evaluation of the relationship between oxygen inhalation, body position, and end-expiratory volume of high-concentration nasal catheters by electrical impedance tomography indicates that no matter what posture is taken, inhalation of high-flow airflow through a nasal catheter can increase the overall regionality by increasing functional residual volume End-expiratory lung impedance.
4. Closely observe the patient's urine output. Potassium is mainly taken from food and is excreted by the kidneys with urine. Patients with chronic renal insufficiency have less urine than normal people, making it easier for potassium to accumulate in the body. Therefore, it is very important to closely observe the urine output of patients. Accurately record the urine output for 24 hours. For incontinence patients, it is not allowed to leave the urinary tube to accurately observe the urine output.
What are the clinical applications of transnasal high-flow oxygen therapy (HFNC) in ICU?
1. In ICU, suitable for acute hypoxic respiratory failure with spontaneous breathing and no hypercapnia-type I respiratory failure, acute respiratory failure, acute respiratory distress syndrome, cardiac surgery, tracheal intubation or tracheotomy Before, after, heart failure and other patients.
2. Patients use a dedicated nasal catheter system to generate continuous positive airway pressure (ie, non-invasive continuous positive airway pressure) under continuous high-flow conditions output by the device to prevent alveolar collapse and increase functional residual volume. Reduces work of breathing, which improves oxygenation.
3. In patients with open airways, an effective airway protection strategy is provided; in patients with noninvasive ventilation, the problem of the intolerance of the respiratory tract to high-flow gas is effectively solved.
4. The scope of contraindications to HFNC application has not yet been clarified, but as a partial alternative to non-invasive ventilation, HFNC has similar contraindications. If there is no spontaneous breathing and severe internal environment disorders, but different from noninvasive ventilation, for patients with acute respiratory failure associated with hypercapnia (type II respiratory failure), HFNC needs to be carefully selected.
5. From our clinical application, HFNC has no reliable effect in severe type 2 respiratory failure, but it can be partially used in patients with compensated type 2 respiratory failure or milder hypercapnia. HFNC treatment can partially reduce CO2 and strengthen humidification, which is helpful for sputum drainage. However, for COPD patients, pay attention to the setting of inhaled oxygen concentration and avoid giving high concentration oxygen therapy.
How is HFNC clinically implemented and evaluated for efficacy?
1. in principle. Based on existing research and our clinical experience, early implementation, setting appropriate parameters, and timely assessment of curative effects are the main principles for effective clinical implementation of HFNC. For patients who may be applicable, especially those with severe hypoxemia, if HFNC treatment is selected, it should be implemented as early as possible, otherwise it will reduce the success rate of treatment, increase the risk of hospital-acquired pneumonia (HAP), and extend the length of hospital stay.
2. Parameter adjustment. In the treatment of hypoxemia, the initial setting of HFNC can be given a larger flow setting according to the tolerance of the patient: (40 ～ 50 L / min), FiO2 can also be set at a higher level (70% ～ 100%), and then further adjust the flow and the set value of FiO2 according to the target SpO2. We found during work that many patients often cannot tolerate excessive gas inhalation at the beginning of treatment, and clinicians need to set relevant parameters at the bedside according to the needs and tolerance of the patient, but try to set the flow rate as much as possible At a high level that can meet the patient's airflow inhalation requirements, to reduce the dilution of the indoor air, ensure that the concentration of inhaled oxygen can reach the preset value, and help the patient to promote alveolar expansion. When the patient's condition improves, the FiO2 can be reduced first and adjusted according to the target SpO2, but the flow rate does not need to be too high, generally 20-30 L / min. However, for patients with OSAHS, considering the need for a certain positive airway pressure support, the flow rate can be increased according to the patient's tolerance.
3. Observe the main points. All patients treated with HFNC, especially the critically ill, need to closely monitor the changes in the respiratory system and the circulatory system, and evaluate the effect of implementation as soon as possible, especially within 2 hours before the start of implementation, and should be combined with the patient's complaints, symptoms and physical signs And changes in ECG monitoring, blood gas analysis, and other factors, evaluate the patient's implementation effect, decide whether to continue or replace the treatment plan, avoid delay intubation due to insufficient monitoring and evaluation, and increase patient mortality.
In short, HFNC is a newer means of respiratory support. Compared with traditional oxygen therapy, active warm-humidity transnasal high-flow oxygen therapy improves oxygenation better, and its safety and efficacy have gradually been recognized. Compared with non-invasive ventilation, patients with active warm-humidified transnasal high-flow oxygen therapy are more comfortable. Proper application of nasal high-flow oxygen therapy has the potential to reduce the benefits of tracheal intubation.