Changes of inspiration: expiration ration from 1:2 to 1:1 could improve the arterial oxygenation and respiratory mechanics

Inverse ratio ventilation already known as effective to improve the oxygenation and respiratory mechanics in the ARDS patients. Recently, there were report of decrease in airway pressure and improve in respiratory compliance during inverse ration ventilation undergoing one lung ventilation. We hypothesized that changes of inspiration and expiration ratio from 1:2 to 1:1 could improve the arterial oxygenation and respiratory mechanics in the patients who undergoing laparoscopic low anterior resection. However, prolonged inspiratory time might compromise cerebral perfusion pressure due to an elevation in central venous pressure and concomitant reductions in mean arterial pressure.

Inclusion Criteria:

• colorectal cancer

Exclusion Criteria:

• obesity (BMI>35), uncontrolled hypertension, coronary artery disease, uncompensated cardiovascular disease, current respiratory disease, open procedure