The effects of advanced waveform analysis and peep on non-invasive respiratory effort assessment from diaphragm surface emg in critically ill icu patients
R.S.P. Warnaar MSc (TNW-CRPH), A.D. Cornet, MD PhD (MST-ICC), A. Beishuizen, MD PhD (MST-ICC), C.M. Moore MD (eScience Centre), prof. D.W. Donker MD PhD (TNW-CRPH, UMCU-ICC), E. Oppersma PhD (TNW-CRPH)
Abstract
Background
Respiratory effort should be closely monitored in mechanically ventilated intensive care patients to avoid both overassistance and underassistance. Surface electromyography of the diaphragm (sEMGdi) offers a continuous and non-invasive modality to assess respiratory effort based on neuromuscular coupling (NMCdi). The sEMGdi derived electrical activity of the diaphragm (sEAdi) is prone to distortion by crosstalk from other muscles, hindering its widespread use in clinical practice. We developed an advanced analysis as well as quality criteria for sEAdi waveforms.
Methods
NMCdi was derived by dividing end-expiratory occlusion pressure (Pocc) by sEAdi, based on three consecutive Pocc manoeuvres at four incremental (+2 cmH2O/step) levels of positive end-expiratory pressure. Pocc and sEAdi quality was assessed by applying a novel, automated advanced signal analysis, based on tolerant and strict cut-off criteria, and excluding inadequate waveforms. The coefficient of variations (CoV) of NMCdi after basic manual and automated advanced quality assessment were evaluated.
Results
Results: 593 manoeuvres were obtained from 42 PEEP trials in 17 ICU patients. Waveform exclusion was primarily based on low sEAdi signal-to-noise ratio (Ntolerant=155, Nstrict=241 waveforms excluded), irregular or abrupt cessation of Pocc (Ntolerant=145, Nstrict=145), and high sEAdi area under the baseline (Ntolerant=94, Nstrict=79). Strict automated assessment allowed to reduce CoV of NMCdi to 15% from 37% for basic quality assessment.
Conclusion
Advanced signal analysis of both Pocc and sEAdi greatly facilitates automated and well-defined identification of high-quality waveforms. This novel, non-invasive methodology forms an important methodological foundation for more robust, continuous, and comprehensive assessment of respiratory effort at the bedside.