Determination of Best PEEP (Positive End-expiratory Pressure) in Anesthetized Infants in Terms of Prevention of Atelectasis

"The baseline atelectasis score is measured using sonography with no PEEP. And then, the baseline cardiac index is measured using transesophageal doppler for 5 minutes each with 3 cmH2O of PEEP.~Apply PEEP (3 cmH2O) according to the patient's randomized group, and maintain the PEEP until the end of the operation."

"The baseline atelectasis score is measured using sonography with no PEEP. And then, the baseline cardiac index is measured using transesophageal doppler for 5 minutes each with 3 cmH2O of PEEP.~Apply PEEP (6 cmH2O) according to the patient's randomized group, and maintain the PEEP until the end of the operation."

"The baseline atelectasis score is measured using sonography with no PEEP. And then, the baseline cardiac index is measured using transesophageal doppler for 5 minutes each with 3 cmH2O of PEEP.~Apply PEEP (9 cmH2O) according to the patient's randomized group, and maintain the PEEP until the end of the operation."