Background: Sepsis after paediatric cardiac surgery remains a formidable challenge, particularly when cardiopulmonary bypass (CPB) times are prolonged. Distinguishing true infection from the expected post‑operative inflammatory surge is critical, as delayed recognition can be fatal while premature antibiotic escalation risks resistance.

Methods: We conducted a prospective study at PGIMER, Chandigarh, enrolling 176 children (<12 years) undergoing cardiac surgery with CPB >100 minutes. Clinical signs (fever, hypotension, tachycardia), serum lactate, chest X‑ray findings, and biomarkers (procalcitonin, C‑reactive protein, serum albumin) were tracked on post‑operative days (POD) 1, 3, 5, and 10. Sepsis was confirmed by positive cultures. ROC analysis determined diagnostic accuracy and cut‑off thresholds.

Results: Sepsis developed in 38 patients, predominantly neonates and infants with smaller body surface area and longer CPB times (mean 267.7 vs. 211.7 minutes, p=0.011). Clinical indicators were the earliest red flags: fever, hypotension, tachycardia, and lactate >2.5 mmol/L were significant from POD‑1. Radiological infiltrates became evident from POD‑3. Biomarkers showed delayed utility: procalcitonin was predictive from POD‑5 (cut‑off 2.07 ng/ml, AUC 0.702), while C‑reactive protein reached significance only at POD‑10 (cut‑off 33.3 mg/dl, AUC 0.770). Serum albumin <3.95 g/dl on POD‑5 also correlated with sepsis.

Conclusion: In paediatric patients with prolonged CPB, clinical vigilance outperforms laboratory markers for early sepsis detection. Bedside signs—fever, hypotension, tachycardia, and lactate elevation—remain the most reliable early indicators, while biomarkers such as procalcitonin and CRP are better suited for later confirmation and monitoring. Neonates and infants with extended CPB and clamp times represent the highest risk group. This study highlights the primacy of clinical assessment in guiding timely intervention, offering a practical framework for improving outcomes in paediatric cardiac surgery.

Nitish Kumar is an Assistant Professor in the Department of Cardiothoracic and Vascular Surgery at the All India Institute of Medical Sciences (AIIMS), Nagpur, India. He completed his M.Ch. in Cardiothoracic and Vascular Surgery and M.S. in General Surgery from the Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, one of India’s foremost academic medical institutions. He has a strong academic focus on pediatric cardiac surgery outcomes, perioperative inflammatory and septic responses associated with cardiopulmonary bypass, and translational clinical research aimed at improving postoperative care. He has authored multiple publications in internationally indexed, peer-reviewed journals, including original research articles, systematic reviews, and unique surgical case reports spanning pediatric and adult cardiac surgery. His published work addresses early biomarkers of sepsis in pediatric cardiac patients, advanced imaging in coronary artery disease, congenital coronary anomalies, and innovative surgical strategies in complex congenital heart disease. He is actively involved in prospective and retrospective clinical studies and contributes to institutional research initiatives focused on evidence-based cardiac surgical practice.He regularly presents at national and international scientific forums and is committed to academic collaboration and surgical education. At Heart and Cardiovascular Disease Conference 2026, he will present his research on early detection of sepsis in pediatric patients undergoing prolonged cardiopulmonary bypass, emphasizing clinically actionable markers to improve perioperative outcomes.