Introduction
Acute Respiratory Failure (ARF) is a clinical syndrome caused by various etiologies, resulting in significant impairments in patients’ ventilation and lung function. In this condition, patients are unable to perform effective spontaneous gas exchange, leading to a series of physiological and metabolic disorders [
1]. The current clinical treatment primarily relies on mechanical ventilation, which effectively restores patients’ ventilation, improves gas exchange, and maintains the required arterial oxygen levels [
2]. As patients’ respiratory function gradually recovers, a transition to weaning and subsequent treatment becomes necessary. In this process, High-Flow Nasal Cannula (HFNC) oxygen therapy has become a crucial sequential therapy following mechanical ventilation globally [
3].
HFNC offers several advantages in the treatment of critically ill patients with acute respiratory failure. Its heating system improves ciliary function, promoting sputum clearance; the low-level positive airway pressure generated by high oxygen flow reduces respiratory rate and inspiratory resistance, while providing constant oxygen concentration to improve oxygenation. Additionally, it preserves patients’ ability to cough, reduces the risk of aspiration, and decreases complications such as ventilator-associated pneumonia, barotrauma, or secondary infections. HFNC can deliver heated and humidified oxygen at rates of 30-60 L/min, offering good comfort and tolerability, effectively relieving respiratory distress and improving oxygenation [
4,
5,
6]. In recent years, this technology has been widely applied and promoted domestically.
However, despite the significant success of HFNC in respiratory support, its application in sequential therapy following mechanical ventilation weaning still faces many challenges. Mechanical ventilation weaning is a critical step in the treatment of respiratory failure, requiring precise care and close monitoring to ensure a smooth transition to spontaneous breathing [
7]. Currently, there is still insufficient understanding regarding the optimal application of HFNC during this stage and how to predict and manage potential complications after weaning. If treatment failure occurs, it significantly impacts patient prognosis, with high-flow oxygen therapy failure typically defined as requiring a switch to invasive ventilation or resulting in death during HFNC. Studies have shown that mortality rates among patients who fail high-flow oxygen therapy can reach 28% to 48% [
8]. Therefore, assessing and predicting the effectiveness of high-flow oxygen therapy in critically ill patients to avoid reintubation remains a major challenge for clinical staff.
To address this issue, this study aims to develop an early warning model using the Random Forest (RF) algorithm developed by Leo Breiman and Adele Cutler [
9] to assist clinicians in identifying patients at high risk of high-flow oxygen therapy failure. The Random Forest algorithm is a powerful machine learning tool that combines multiple decision trees to improve predictive accuracy and reliability. Compared to traditional logistic regression models, Random Forest demonstrates significant advantages in reducing the risk of overfitting, offering greater flexibility, and facilitating the identification of important features [
10]. By constructing a Random Forest-based risk prediction model, this study aims to accurately predict which patients receiving high-flow oxygen therapy after mechanical ventilation weaning are at higher risk of treatment failure. This will provide clinicians with more precise decision-making support, help improve treatment outcomes, reduce unnecessary medical interventions, and ultimately enhance patients’ quality of life and prognosis.
Discussion
This study used the Random Forest algorithm to construct an early risk warning model aimed at predicting the risk of failure in sequential High-Flow Nasal Cannula (HFNC) therapy after mechanical ventilation weaning. Through the analysis of data from 145 patients, the study found that the warning model demonstrated high predictive accuracy, with an AUC of 0.98 in the training set and 0.84 in the validation set. The calibration curve and decision curve showed that the model has good stability and clinical applicability. Based on the Random Forest algorithm, this study further developed a nomogram for the early warning model, providing a convenient and effective tool for clinical use, facilitating the early identification of high-risk patients and enabling more precise treatment decisions.
The Random Forest algorithm is widely recognized for its efficiency in handling large datasets and its ability to process complex data structures. The Random Forest (RF) algorithm is now extensively used for risk factor screening and prediction model construction. For example, Giri J et al. [
15] used RF to construct a model for predicting early mortality risk in critically ill patients, while Daiquan Gao et al. [
16] combined Lasso analysis with RF to develop a model predicting poor functional outcomes in patients with cerebral hemorrhage, both demonstrating good predictive performance.
In this study, Random Forest analysis showed that APACHE II, BNP, NLR, mROX, and SOFA had significant impacts on predicting HFNC treatment failure. Particularly, the APACHE II score, the most important feature, was significantly associated with treatment failure risk. APACHE II is a widely used scoring system in critical care that considers both physiological abnormalities and chronic health conditions to assess the severity of a patient’s illness and predict in-hospital mortality. Wei Lu et al. [
17] found that the APACHE II score was significantly positively correlated with mechanical ventilation pressure parameters in patients with Acute Respiratory Distress Syndrome (ARDS) and had high diagnostic value for the prognosis of ARDS patients. Similarly, a meta-analysis by Wenrui Li et al. [
18] involving 22,304 patients assessed the risk factors for reintubation in mechanically ventilated patients and found that a high APACHE II score was a significant risk factor for reintubation. In this study, the APACHE II score was the most critical feature, and higher scores were associated with an increased risk of HFNC treatment failure. This may be because patients with higher APACHE II scores are physiologically more vulnerable and less tolerant and responsive to treatment, increasing the likelihood of HFNC failure.
BNP is a biomarker released during cardiac stress, commonly used to diagnose and assess heart failure. Elevated BNP levels reflect the extent of cardiac dysfunction [
19]. In this study, BNP was one of the feature variables, and its elevation was associated with an increased risk of HFNC treatment failure. This suggests that cardiac insufficiency is an important factor contributing to HFNC failure, possibly because patients with poor cardiac function may be less able to tolerate the potential cardiac load increase induced by high-flow oxygen therapy, thus increasing the risk of treatment failure [
20].
NLR is a simple biomarker of inflammation and immune status. An inflammatory response can trigger an increase in circulating neutrophils and a decrease in lymphocytes, leading to elevated NLR levels. The NLR index has significant prognostic value for various conditions, including inflammation, cancer, and autoimmune diseases [
21,
22,
23]. Elevated NLR is typically associated with enhanced inflammatory response, increased risk of infection, and suppressed immune function. In this study, NLR was identified as a feature variable predicting HFNC failure, reflecting patients’ inflammatory status and infection risk, both of which can affect the outcome of HFNC treatment.
The ROX index, derived from SpO2, FiO2, and RR, has previously been reported to have predictive value for HFNC outcomes in patients with pneumonia-induced respiratory failure [
24]. However, a meta-analysis by Xiaoyang Zhou et al. [
25] pointed out that the ROX index has limitations in early prediction of HFNC failure, including low sensitivity and specificity and a delayed time window. Compared to ROX, the modified ROX (mROX) index, which uses PaO2 instead of SpO2, was included in this study. A lower mROX value indicates poorer oxygenation and higher respiratory load. Roca O et al. [
26] evaluated the predictive value of ROX-related indices in HFNC outcomes, showing that the mROX index had a stronger association with HFNC failure in elderly patients with respiratory failure. In this study, the inclusion of the mROX index in the comprehensive analysis showed that its decrease was associated with HFNC failure risk, consistent with previous research.
The SOFA score is a scoring system used to assess organ dysfunction in critically ill patients. Higher SOFA scores indicate more severe organ dysfunction [
27]. In this study, SOFA was one of the feature variables, and higher SOFA scores were associated with HFNC failure risk. Patients with severe organ dysfunction are less tolerant and responsive to most treatments, and organ failure may lead to HFNC treatment failure.
The findings of this study are consistent with existing literature, indicating that patients who fail high-flow oxygen therapy tend to have higher levels of inflammation and poorer physiological function. The results align with the majority of previous research, but this study differs by applying machine learning techniques, offering a more precise and personalized risk assessment tool, which aids clinicians in making more targeted decisions during the weaning process. This innovation is rarely seen in prior studies. The methods and findings of this study provide new directions and ideas for future related research.
However, this study has some limitations. First, the sample size is relatively small, which may affect the generalizability and predictive accuracy of the model. Second, the study was conducted at a single center, which may introduce center-specific bias. Future studies need to validate the model in multicenter and diverse populations. Additionally, the model construction relies on clinical and laboratory indicators, and future research should consider incorporating more physiological signals and biomarkers to further improve the predictive performance of the model.