Lung expansion techniques (LETs) are widely used to prevent postoperative pulmonary complications (PPCs). However, the effects of each of these techniques on thoracoabdominal mechanics and PPC incidence after abdominal surgery remain unclear. The objective of this study was to compare the effects of LET on pulmonary volumes, respiratory muscle activation, and PPC incidence after major, elective upper abdominal surgery.
This randomized controlled trial enrolled 137 patients who were randomly assigned into four groups: control (n = 35), flow incentive spirometry (n = 33), deep breathing (n = 35), and volume incentive spirometry (n = 34). Each intervention was performed tid during 5 consecutive days. Subsequently, PPCs (pneumonia, atelectasis, or severe hypoxemia) were analyzed by a blinded assessor until hospital discharge. Lung volumes (optoelectronic plethysmography) and inspiratory muscular activation (surface electromyography) were assessed before and 3 days after surgery. Intention-to-treat analysis was performed.
Before surgery, all groups were homogenous for age, sex, BMI, lung function, and thoracoabdominal mechanics. After surgery, no difference was observed in the lung volumes and inspiratory muscular activation during the lung expansion technique (P > .05). The PPC incidence was higher in the deep breathing group (P < .05). Higher American Society of Anesthesiologists scores and surgery duration were the only predictors of PPC (n = 14, 11.2%).
LETs do not modify the changes on thoracoabdominal mechanics or prevent PPCs after abdominal surgery. The indiscriminate use of LETs should not be routinely prescribed to prevent PPCs; however, more studies are required to confirm our results and to change the standard practice.
ClinicalTrials.gov; No.: NCT01993602; URL: www.clinicaltrials.gov