This study was designed as a prospective observational study.

In this study, it was planned to evaluate the effect of positive end-expiratory pressure on gastric residual volume in patients who will undergo outpatient pediatric surgery with laryngeal mask application on the specified dates. Patients aged 1-11 years, ASA I-II and undergoing outpatient lower abdominal and genitourinary surgery were included in the study. Since the use of positive end-expiratory pressure varies in our clinic depending on the anesthesiologist preference, the effect of this application on gastric volume will also be evaluated primarily by recording images with gastric ultrasonography at certain perioperative time periods. Secondarily, the effect of this positive end-expiratory pressure on mechanical ventilator parameters and airway pressures will be evaluated.

Inclusion Criteria:

• Pediatric patients who will undergo elective outpatient minor surgery (lower abdominal and urogenital)
• 1-11 years old
• American Society of Anesthesiology (ASA) classification 1-2 patient groups
• Patients who are fully hungry and whose fasting period is appropriate for their age and diet.

Exclusion Criteria:

• Patients whose fasting period is not appropriate
• Acute abdominal and emergency surgeries
• ASA 3-4 patient group
• Patients with diseases or medication use that will affect gastric emptying time
• Previous nasogastric tube placement and re-operation • Patients with known difficult airway or failure to fit the laryngeal mask

A total of 90 patients were planned for this study.