End‐tidal carbon dioxide monitoring revealed severe complications during cardiothoracic surgery

INTRODUCTION: With the continuous progress being made in medicine and surgery, increasingly more advanced technology and monitoring equipment are being used in anesthesia, end‐tidal carbon dioxide (PETCO (2)) monitoring revealed serious complications of cardiothoracic surgery. CASE PRESENTATION: A 3‐year‐old boy with a body weight of 15 kg presented with a >1‐month history of a heart murmur. At the moment of arterial catheter ligation, the PETCO (2) decreased from 37 to 15 mmHg, while the blood pressure, heart rate, and airway resistance did not change significantly. After re‐separation of the ligation catheter, the surgeons carefully exposed the ductus and left pulmonary artery again and ligated the ductus arteriosus. CONCLUSION: This case suggests that PETCO(2) monitoring reflects the circulatory status and pulmonary blood flow.