Impact of laparoscopic surgery on thoracoabdominal mechanics and inspiratory muscular activity

Abstract

Objective: To evaluate the effect of laparoscopic surgery on pulmonary volume distributions and inspiratory muscles activity. Respiratory consequences associated with postoperative pain were also evaluated. Methods: This study enrolled 20 patients without lung disease performed spirometry and chest wall kinematic analyses (i.e., chest wall, upper and lower ribcage and abdominal volumes), and measured the activity of inspiratory muscular before and 2 days after laparoscopic surgery. Pain was also assessed. Results: After laparoscopy, the patients demonstrated decreased volumes in all three thoracoabdominal compartments: abdomen (ABD), upper and lower rib cage (URC and LRC, respectively) compared with the pre-operative measurements: ABD = 0.38 +/- 0.20 L vs. 0.55 +/- 0.25 L; URC = 0.45 +/- 0.18 L vs. 0.55 +/- 0.21 L; and LRC = 0.31 +/- 0.18 L vs. 0.41 +/- 0.23 L; p <0.05. A reduction in the inspiratory muscular activity after surgery was also observed (sternocleidomastoid: 10.6 +/- 5.1 x 10(-3) mV vs. 12.8 +/- 6.3 x 10(-3) my; intercostals: 16.8 +/- 12.4 x 10(-3) mV vs. 25.1 +/- 21.3 x 10(-3) my; p <0.05). In addition, lower volumes during deep breathing were observed in patients who reported significant pain than those who did not (0.51 +/- 0.17 L vs. 0.79 +/- 0.29 L; p <0.05, respectively). Conclusion: Laparoscopic surgery reduces chest wall ventilation and inspiratory muscular activity during deep breathing. The effects appear to depend on the patient's reported pain level.