Salivary Alpha Amylase Bronchial Measure for Early Aspiration Pneumonia Diagnosis in Patients Treated With Therapeutic Hypothermia After Out-of-hospital Cardiac Arrest

Value of bronchial amylase level for predicting ventilator associated pneumonia in intubated adults: a systematic review and meta-analysis

BACKGROUND

The ability of bronchial amylase level for predicting ventilator associated pneumonia (VAP) has been extensively studied with conflicting results. This meta-analysis aimed to explore the value of bronchial amylase for predicting VAP in intubated adults.

METHODS

PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched up to November 2023. The diagnostic odds ratio (DOR), sensitivity, and specificity were calculated. The summary receiver operating characteristic curve was estimated, and the area under the curve (AUROC) was calculated.

RESULTS

Overall, six studies including 769 patients were included in this review, of whom 273 (36%) were developed VAP. The cutoff values of bronchial amylase level were ranged from 8.1 U/L to 4681.5U/L. Heterogeneity between studies was assessed with an overall Q = 1.99, I2 = 0, and P = 0.185, The pooled sensitivity and specificity for the overall population were 0.78 [95% confidence interval (CI) 0.67-0.86] and 0.75(95% CI 0.56-0.88) respectively. The DOR was 11(95% CI 3.0-40.0). The pooled AUROC was 0.83 (95%CI 0.80-0.86).

CONCLUSIONS

The bronchial amylase is a helpful marker for predicting VAP in intubated adults. However, it cannot be recommended as the single definitive test for VAP, but rather it must be interpreted in context with information from careful medical history, physical examination, and when feasible, microbiological assessment.

Transitions in lung microbiota landscape associate with distinct patterns of pneumonia progression

The precise microbial determinants driving clinical outcomes in severe pneumonia are unknown. Competing ecological forces produce dynamic microbiota states in health; infection and treatment effects on microbiota state must be defined to improve pneumonia therapy. Here, we leverage our unique clinical setting, which includes systematic and serial bronchoscopic sampling in patients with suspected pneumonia, to determine lung microbial ecosystem dynamics throughout pneumonia therapy. We combine 16S rRNA gene amplicon, metagenomic, and transcriptomic sequencing with bacterial load quantification to reveal clinically-relevant pneumonia progression drivers. Microbiota states are predictive of pneumonia category and exhibit differential stability and pneumonia therapy response. Disruptive forces, like aspiration, associate with cohesive changes in gene expression and microbial community structure. In summary, we show that host and microbiota landscapes change in unison with clinical phenotypes and that microbiota state dynamics reflect pneumonia progression. We suggest that distinct pathways of lung microbial community succession mediate pneumonia progression.

Aspiration Pneumonia

Aspiration pneumonia is a lower respiratory tract infection that results from inhalation of foreign material, often gastric and oropharyngeal contents. It is important to distinguish this from a similar entity, aspiration with chemical pneumonitis, as treatment approaches may differ. An evolving understanding of the human microbiome has shed light on the pathogenesis of aspiration pneumonia, suggesting that dysbiosis, repetitive injury, and inflammatory responses play a role in its development. Risk factors for aspiration events involve a complex interplay of anatomical and physiological dysfunctions in the nervous, gastrointestinal, and pulmonary systems. Current treatment strategies have shifted away from anaerobic organisms as leading pathogens. Prevention of aspiration pneumonia primarily involves addressing oropharyngeal dysphagia, a significant risk factor for aspiration pneumonia, particularly among elderly individuals and those with cognitive and neurodegenerative disorders.