Procalcitonin Versus Serum Zinc for Diagnosis of Ventilator-Associated Pneumonia in ICU Patients

Ventilator-associated pneumonia (VAP) is a common and serious infection among mechanically ventilated ICU patients. Early diagnosis remains challenging because clinical and radiological findings may lack specificity. Procalcitonin (PCT) is a well-established biomarker of bacterial infection, while serum zinc has recently emerged as a potential marker of immune dysfunction and infection severity. This prospective observational cohort study will compare the diagnostic accuracy of serum procalcitonin and serum zinc for the diagnosis of ventilator-associated pneumonia in 84 adult ICU patients. Diagnostic performance will be assessed using ROC curve analysis, sensitivity, specificity, positive predictive value, and negative predictive value. Associations between biomarker levels, inflammatory markers, disease severity scores, and clinical outcomes will also be evaluated.

Inclusion Criteria: * \- Age 18 to 70 years. * Adult patients admitted to the Intensive Care Unit. * Receiving invasive mechanical ventilation for at least 48 hours. * Clinical suspicion of ventilator-associated pneumonia (VAP). * New or progressive pulmonary infiltrate on chest imaging. * At least two of the following: * Fever \>38°C or hypothermia \12,000/mm³) or leukopenia (\