Peripheral Immune Cell Profiles and Circulating Cytokine Signals in Vietnamese Children Hospitalized with Acute Asthma Exacerbations: A Cross-Sectional Study

Background/Objectives: We characterized peripheral inflammatory patterns during pediatric acute asthma exacerbations and explored clinical and cytokine differences by blood eosinophil status. Methods: This cross-sectional study included 59 children aged ≥5 years hospitalized in Can Tho, Vietnam, during April 2023–July 2024. Blood counts and six serum cytokines were classified using prespecified study thresholds. Associations were reassessed using Pearson or exact tests, crude odds ratios, and Holm adjustment across 46 unique exploratory hypotheses. Results: Study-defined leukocytosis, eosinophilia, neutrophilia, and basophilia occurred in 71.2%, 62.7%, 54.2%, and 22.0%, respectively. IL-6, IL-5, and TNF-α met their study thresholds in 69.5%, 23.7%, and 3.4%; IL-4, IL-12p70, and IFN-γ remained below those thresholds. The eosinophilia–severity comparison was not significant (exact p = 0.368). Personal and family allergy associations did not remain significant after multiplicity adjustment (adjusted p = 0.348 and 0.429). Cytokine-threshold frequencies did not differ significantly between eosinophil strata. Conclusions: Peripheral inflammatory patterns were heterogeneous, but no tested association survived multiplicity adjustment. These descriptive findings do not validate blood-based airway phenotypes or severity prediction. Larger longitudinal studies should standardize treatment and sampling-time records, infection assessment, and assay limits.