Critical Illness in Children

Metabolic acidosis is one of the most common acid-base disturbances encountered in critically ill children and often reflects underlying disease severity. Despite its clinical importance, prospective epidemiological data regarding its frequency, underlying etiologies, and associated clinical outcomes among pediatric intensive care unit (PICU) admissions in Upper Egypt remain limited. The primary objective of this prospective observational cohort study is to determine the frequency of metabolic acidosis among pediatric patients admitted to the Pediatric Intensive Care Unit at Assiut University Children Hospital. Secondary objectives include identifying the common etiologies and types of metabolic acidosis, as well as evaluating its relationship with clinical outcomes such as mortality, duration of PICU stay, need for mechanical ventilation, and requirement for vasoactive support. A total of 140 eligible pediatric patients aged 1 month to 18 years admitted to the PICU will be enrolled. Eligible patients will undergo arterial blood gas (ABG) analysis and standard clinical and laboratory evaluations upon admission. Metabolic acidosis will be defined based on admission ABG criteria (serum/arterial bicarbonate \< 22 mmol/L and/or base deficit ≥ 5 mmol/L). Patients will be monitored throughout their hospital stay to assess clinical outcomes without interfering with routine medical management.

Acute respiratory infections (ARIs) are among the leading causes of hospitalization, morbidity, and mortality in children worldwide, particularly among critically ill patients admitted to pediatric intensive care units (PICUs). Vitamin D has an important role not only in bone metabolism but also in regulation of innate and adaptive immune responses, especially within the respiratory tract. Recent evidence suggests that vitamin D deficiency may be associated with increased susceptibility to respiratory infections, greater disease severity, prolonged hospitalization, and higher mortality rates in critically ill children. This observational cross-sectional study aims to assess serum vitamin D status among critically ill children admitted to the PICU with acute respiratory infections and to evaluate the relationship between vitamin D levels, severity of respiratory illness, and risk of mortality. The study will include pediatric patients aged 1 month to 16 years admitted to the Pediatric Intensive Care Unit of Assiut University Children's Hospital. Clinical evaluation and laboratory investigations, including serum 25-hydroxyvitamin D levels, serum calcium, and alkaline phosphatase, will be performed within the first 24 hours of admission. Severity of respiratory distress will be assessed using the Pediatric Respiratory Severity Score (PRESS), while mortality risk will be evaluated using the Pediatric Risk of Mortality Score (PRISM III). The findings of this study may contribute to better understanding of the role of vitamin D in critically ill children with respiratory infections and may support future strategies for early risk assessment and improved clinical management in pediatric intensive care settings.