The most basic modes of mechanical ventilation are volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). VCV guarantees a target volume of ventilation using a constant flow, but may lead to high peak airway pressure (Ppeak) during the gas insufflation . In PCV mode, on the other hand,

The laryngeal mask airway (LMA) provides a useful alternative for airway management during general anaesthesia. Inflation of the LMA cuff produces a low-pressure seal around the larynx, enabling positive pressure ventilation (PPV). The use of LMA as an airway management technique is common in the pediatric anesthesia because of its less irritating effect on the airways due to its location in the upper larynx. Now, the use of laryngeal mask instead of tracheal intubation for airway management has been achieved in day surgery, therefore, how to perform a respiratory management with a laryngeal mask is particularly important. In addition, mechanical ventilation is also a commonly used method of airway management in clinical practice. the ventilator will deliver a constant pressure by decelerating the flow. However, the ventilation volume varies according to the patient's respiratory mechanics . Pressure-controlled ventilation-volume guaranteed (PCV-VG) combines the advantages of both VCV and PCV, which delivers a stable ventilation volume using a decelerating flow pattern.

Inclusion Criteria:

1. age between 1 and 5 years.
2. patient scheduled for laparoscopic inguinal hernia repair.
3. American Society of Anesthesiologists classification of physical status of I-II.

Exclusion Criteria:

1. cardiopulmonary disease.
2. severe hepatorenal dysfunction.
3. history of upper respiratory tract infection 2 weeks before the operation.
4. overweight [more than 20% of standard body weight].
5. neuromuscular disease.
6. anticipated difficult airway.
7. hiatus hernia or gastroesophageal reflux disease.