Low flow anesthesia; It is an anesthesia practice in which, after absorbing at least 50% of the exhaled air and carbon dioxide (CO2) using a semi-closed rebreathing system, the unused anesthetic gases are mixed with a certain amount of fresh gas and then completely or partially returned to the patient in the next inspiration. Theoretically, when low flow anesthesia is compared to high or normal flow anesthesia; it is known to have advantages such as using less inhalation agent, preserving mucociliary activity, preventing microatelectasis, preserving the amount of moisture, and reducing temperature loss.

In studies conducted in different fresh gas flows, it has been observed that CO, which is thought to accumulate in the body by rebreathing in a closed circuit, increases as a result of the chemical interaction and dry CO2 absorbent. However, there is no evidence in these studies that low-flow anesthesia increases CO accumulation and alters hemodynamics.

In our clinic, low-flow and high-flow anesthesia technics are both being used. In this study, we aimed to evaluate the effects of high- and low-flow sevoflurane anesthesia applied with a closed system on perioperative carboxyhemoglobin (COHb) levels and hemodynamic system in pediatric cardiovascular surgery cases.

Inclusion Criteria:

• Patients between the ages of 2 months and 7 years undergoing elective cardiac surgery
• American Society of Anesthesiology (ASA) score II ve III patients

Exclusion Criteria:

• Patients undergoing emergency surgery
• Patients who need mechanical ventilation or any respiratory support before the operation
• Patients with left to right shunt
• cyanotic patients
• Patients younger than 2 months and older than 7 years

Patients will be selected among the patients who will undergo cardiac surgery at Basaksehir Cam and Sakura City Hospital Pediatric Cardiovascular Surgery Clinic.