Genotypes and Phenotypes in Pediatric SIRS and Sepsis

The investigators will undertake a proof-of-concept, pilot, prospective, observational trial that aims to recruit \~90 children from the Seattle Children's Hospital Pediatric Intensive Care Unit (PICU) and Cardiac Intensive Care Unit (CICU). The study will plan to recruit 30 children who are scheduled for surgery to repair congenital cardiac malformations, 15 - 25 immunocompetent children with culture positive sepsis, and 15 - 25 immunocompromised children with culture positive sepsis, and 30-40 children who are polymerase chain reaction (PCR) positive for viral respiratory pathogens (RSV, influenza, parainfluenza, rhinovirus, etc), and who meet the eligibility criteria. In total, accounting for culture negative bacterial sepsis (estimated 40%), the investigators plan to enroll 50 children with sepsis, 30-40 with viral sepsis, and 20 children undergoing surgery for congenital heart disease. Demographic data will be collected at the time of ICU admission. Illness severity will be quantified by PRISM III and day 1 PELOD scores. Additional measures of sepsis severity will include oxygenation index, saturation index and duration of mechanical ventilation, vasoactive inotropic score and duration of vasoactive-inotropic support and highest serum creatinine on day 1. Resource utilization will be measured as PICU and hospital duration of stay. For all children enrolled in the study, blood samples will be obtained on study days 1, 2 and 3. For children with sepsis, if cultures remain sterile or PCR negative, no additional research blood samples will be obtained. For children with sepsis and a positive culture or positive PCR by study day 3, additional blood samples will be obtained on the day of PICU discharge.