HFNC is comparable to NIV as a mode of respiratory support for patients with respiratory failure, and it significantly improves pulmonary oxygenation and corrects hypoxemia.In this study, the 28-day mortality and reintubation rate of patients with hypoxemia after receiving high flow oxygen were significantly higher in the HFNC group than inthe NIV group (p = 0.044, p = 0.004). Our result was similar to a meta-analysis published in 2017, but Hernández suggested that HFNC has obvious advantages over NIV. In our study, reintubation rates of the patients with hypoxemia in the HFNC and NIV groups were 10.49% and 3.85%, respectively, which were lower than those reported in other studies,[4, 12] while 28-day mortality was also significantly lower than that reported in other studies.
The incidence of reintubation of patients with hypoxemia is affected by many factors. A studyhas shown that the reintubation rate of elderly patients is significantly higher than that of young patients. Suraseranivong recruited 127 intubated elderly patients and found a correlation between physiologically relevant parameters and reintubation in elderly patients. Additionally, several studies have shown that age is an important risk factor for reintubation.[15, 16] In our study, we observed that age was an important factor in intubation in patients with hypoxemia. This may be related to the physiological state of the elderly patient. With an increase in age, the elderly have stiffer thorax, increased residual volume during respiration, weakened respiration, impaired gas exchange, and cannot adapt to changes in respiration after extubation, all of which increasethe risk for reintubation.[14, 17]
In addition, this study found that several metabolic parameters (blood urea nitrogen, sodium, and calcium levels and anion gap) were significantly associated with the rate of reintubation. However, our study found that the serum sodium did not affect the reintubation rate in patients with hypoxemia, whereas the serum potassium was significantly correlated with reintubation rates. Previous studies have shown that hemoglobin and albumin are influencing factors for reintubation, and that patients with low hemoglobin levels are at an increased risk of reintubation. However, this phenomenon was not observed in our study. This may be related to the inclusion of elderly patients in Konishi's study which found that NT-proBNP was the only independent factor that could predict weaning failure in premature infants, but was unaffected by the serum potassium level. However, we also observed this result using the lasso model. Electrolyte levels are closely related to mechanical ventilation. Zhu20 analyzed the relationship between different levels of electrolytes and the success rate of short-term weaning and found that compared with the group with normal potassium levels, the hyperkalemic group had a significantly lower success rate, However, there were no significant differences between the normal potassium group and hyperkalemia group. Hypokalemia mainly affects electrically excited tissues, namely the heart and muscle. It can cause arrhythmia, aggravate heart failure, and even lead to cardiac arrest. It can cause the contraction ability of skeletal and smooth muscle to decrease, which manifests as myasthenia, muscle pain, and spasm, among others. Gastrointestinal tract and urinary tract smooth muscle dysfunction include abdominal distension, paralytic intestinal obstruction, constipation, and urinary retention. This study showed that potassium is an important influencing factor for reintubation in hypoxic patients, which may be related to a dysfunction in electrical excitation caused by hypokalemia.
According to an earlier study,LOS in the ICU was significantly shorter in the weaning success group than in the reintubation group. In our study, LOS in the ICU was an independent factor influencing reintubation in patients with hypoxemia. The longer the stay in the ICU, greater risk of infection, which increased the risk of reintubation. In addition, we used lasso analysis and found that sex, age, serum potassium level, LOS in the hospital, LOS in the ICU, respiratory support, and SPO2 can affect therisk of reintubation in patients with hypoxemia. However, after adjusting for the factors of LOS in the ICU and hospital for this model, we found that age, serum potassium level, respiratory support, and SPO2are the factors influencing reintubation in hypoxemia patients.
LIUconsiders HR/SpO2 as an easily accessible and a significant indicator for predicting treatment failure with HFNC. In our study, we found that SPO2was a major factor influencing reintubation in patients with hypoxemia. SpO2 is the most commonly used clinical parameter that can be obtained by noninvasive methods and be continuously monitored as an effective index for judging oxygenation. It hasbeen widely used as an independent index for judging the prognosis of ARDS. SPO2 directly reflects the respiratory status of the body. The normal range of SpO2 is 95%-100%. After extubation, the gas exchange in patients with hypoxemiais impaired, and the level of SPO2 is low, which can predict the success of weaning to a certain extent. In previous studies, SPO2 was an important offline predictor.
This study discusses HFNC treatments after extubation and hypoxemia NIV therapy in patients at risk of intubation, and found that age, serum potassium level, respiratory support, and SPO2are factors influencing reintubation in hypoxemia patients, which can be applied to predict successful extubation in real life.
There is a significant difference in quality between type 1 and type 2 respiratory failure, but only patients with hypoxemia were included in this study, and no distinction was made between the two types. In addition, previous studies have shown that patients with hypoxemia have a high probability of reintubation 24–48 hours after extubation, but this study only included the reintubation rate 28 days after extubation. Thus,further studies emphasizing these aspects are required.