Two-handed mask ventilation has been shown to provide higher tidal volume than one-handed mask ventilation. The effects of the two techniques on respiratory mechanics during induction of general anesthesia, however, still need to be determined.

Mask positive pressure ventilation always causes the changes of respiratory mechanics such as ventral redistribution of regional ventilation, which impairs gas exchange. Two-handed mask ventilation has been shown to improve gas exchange by providing higher tidal volume than one-handed mask ventilation. We hypothesis that those higher tidal volume caused by two-handed mask ventilation would also improve the respiratory mechanics during induction of general anesthesia.

Inclusion Criteria:

• Scheduled for elective surgery with general anesthesia
• American Society of Anesthesiologist (ASA) physical class of I-II.

Exclusion Criteria:

• acute and chronic respiratory disorders, including chronic obstructive
• pulmonary disease (COPD) and asthma;
• a history of lung surgery;
• exist risk of reflux and aspiration;
• patients requiring an awake intubation;
• facial and thoracic deformities;
• implants exist in the body, such as cardiac pacemakers;
• pregnant women.

Data or documents can be obtained by contact the corresponding authors. Files can be emailed to anyone that concerned.

During the submission and after the acceptance.

Anyone who is interested in or has questions in this study.