Alveolar recruitment maneuver had been reported of improving arterial oxygenation and pulmonary mechanics and reduce the pulmonary complications. Investigator designed this study for comparision of incidence of pulmonary complications after applying alveolar recruitment maneuver during peumoperitoenum for laparoscopic surgery.

Peumopritoneum might increase the pulmonary dead space and deteriorate the pulmonary mechanics. Especially in the eldery, decreased pulmonary function might aggravate negative response to pneumoperitoneum. Alveolar recruitment maneuver had been reported of improving arterial oxygenation and pulmonary mechanics. Investigator designed this study for comparision of the incidences of pulmonary complications after applying alveolar recruitment maneuver or not during peumoperitoenum for laparoscopic surgery in the elderly patients.

Inclusion Criteria:

• over 65 years, patients who undergoing elective laparoscopoic colorectal surgery for cancer under general anesthesia. ASA pysical status I or II

Exclusion Criteria:uncontrolled cardiovascular disease, obstructive pulmonary disorder, acute or chronic inflammatory lesion in lung.

not yet decided