Surface electromyography for respiratory assessment of liver transplant candidates, healthy subjects and after chevron post-operative incision

Abstract

Background: Surface electromyography is a noninvasive technique for detecting the activity of skeletal muscles and especially the muscles for respiratory compliance; namely, the diaphragm and rectus abdominis. This study compares these muscles in healthy individuals, liver disease patients, and after abdominal surgery.

Objective: To study muscle activity by surface electromyography of the right diaphragm muscles and right rectus abdominis (root means square, RMS), and the manovacuometry muscle strength (maximal inspiratory pressure, MIP; and maximal expiratory pressure, MEP).

Results: We evaluated 246 subjects who were divided into 3 groups: healthy (65), liver disease (171), and post-surgery (10). In liver disease group the BMI was higher significantly for ascites (P = .001), and was increase in RMS rectum (P = .0001), RMS diaphragm (P = .030), and a decreased inspiratory and expiratory indices (P = .0001) pressure in the post-surgery group. A multivariate analysis showed tendency to an increased BMI in liver disease and in the post-surgery groups correlated with an increased RMS rectum and the lower MIP/MEP (P = .11). The receiver operating characteristic curve showed that RMS rectus was capable of discriminating liver disease and post-surgery patients from healthy subjects (area = 0.63; 95% CI 0.549-0.725).

Conclusion: The muscle activity of normal individuals is lower than in subjects with deficit muscles because less effort is necessary to overcome the same resistance, observed by surface electromyography and muscle strength.