Predicting ventilator-associated pneumonia in elderly patients requiring mechanical ventilation through the detection in tracheal aspirates

ABSTRACT

Objective

In this study, we evaluated the clinical utility of tracheal aspirates α-amylase (AM), pepsin, and lipid-laden macrophage index (LLMI) in the early diagnosis of ventilator-associated pneumonia (VAP) in elderly patients on mechanical ventilation.

Methods

Within 96 hours of tracheal intubation, tracheal aspirate specimens were collected from elderly patients on mechanical ventilation; AM, pepsin, and LLMI were detected, and we analyzed the potential of each index individually and in combination in diagnosing VAP.

Results

Patients with VAP had significantly higher levels of AM, pepsin, and LLMI compared to those without VAP (P < 0.001), and there was a positive correlation between the number of pre-intubation risk factors of aspiration and the detection value of each index in patients with VAP (P < 0.001). The area under a receiver operating characteristic (ROC) curve (AUC) of AM, pepsin, and LLMI in diagnosis of VAP were 0.821 (95% CI:0.713–0.904), 0.802 (95% CI:0.693–0.892), and 0.621 (95% CI:0.583–0.824), the sensitivities were 0.8815, 0.7632, and 0.6973, the specificities were 0.8495, 0.8602, and 0.6291, and the cutoff values were 4,321.5 U/L, 126.61 ng/ml, and 173.5, respectively. The AUC for the combination of indexes in diagnosing VAP was 0.905 (95% CI:0.812–0.934), and the sensitivity and specificity were 0.9211 and 0.9332, respectively. In the tracheal aspirate specimens, the detection rate of AM ≥ cutoff was the highest, while it was the lowest for LLMI (P < 0.001). The detection rates of AM ≥ cutoff and pepsin ≥ cutoff were higher within 48 hours after intubation than within 48–96 hours after intubation (P < 0.001). In contrast, the detection rate of LLMI ≥ cutoff was higher within 48–96 hours after intubation than within 48 hours after intubation (P < 0.001). The risk factors for VAP identified using logistic multivariate analysis included pre-intubation aspiration risk factors (≥3), MDR bacteria growth in tracheal aspirates, and tracheal aspirate AM ≥ 4,321.5 U/L, pepsin ≥ 126.61 ng/ml, and LLMI ≥ 173.5.

Conclusion

The detection of AM, pepsin, and LLMI in tracheal aspirates has promising clinical utility as an early warning biomarker of VAP in elderly patients undergoing mechanical ventilation.

KEYWORDS:

• Amylase
• aspiration
• elderly
• lipid-laden macrophage
• pepsin
• ventilator associated pneumonia

Declaration of financial/other relationships

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Authors’ contributions

Conception and design of the research: Ge-Ping Qu, Xiang-Qun Fang. Acquisition of data: Dan Wang, Peng Zhao,Mei-Liang Gong,Ya-Ping Qian. Analysis and interpretation of the data: Yan-Xin Liu, Peng Wang. Statistical analysis: Yan-Xin Liu, Peng Wang,Mei-Liang Gong. Obtaining financing: Ge-Ping Qu, Xiang-Qun Fang. Writing of the manuscript: Dan Wang,Ge-Ping Qu,Ya-Ping Qian. Critical revision of the manuscript for intellectual content: Ge-Ping Qu, Xiang-Qun Fang. All authors read and approved the final draft.

Ethics statement

The study was conducted in accordance with the Declaration of Helsinki (as was revised in 2013). The study was approved by Ethics Committee of the The Chinese PLA General Hospital (approval number: S2023-061-01). Written informed consent was obtained from all participants.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This paper was funded by the Chinese People’s Liberation Army Health Care Research Project (Grant Number: 21BJZ24) and the major logistics research projects of Chinese People’s Liberation Army (Grant Number: 2022JZH378).