The following is a summary of “Advanced waveform analysis of diaphragm surface EMG allows for continuous non-invasive assessment of respiratory effort in critically ill patients at different PEEP levels,” published in the June 2024 issue of Critical Care by Warnaar, et al.

Accurately monitoring respiratory effort is crucial for patients in mechanically ventilated ICUs to avoid over- or under-assistance. Surface electromyography of the diaphragm (sEMGdi) offers a noninvasive way to assess this via neuromuscular coupling of the diaphragm (NMCdi). However, its utility is limited because crosstalk from other muscles can distort the signal of the sEMGdi-derived electrical activity of the diaphragm (sEAdi).

Researchers conducted a retrospective study to analyze sEAdi waveforms using newly developed criteria and evaluated the impact of clinically relevant PEEP levels on non-invasive NMCdi assessment.

They calculated NMCdi by dividing the end-expiratory occlusion pressure (Pocc) by sEAdi, using three consecutive Pocc maneuvers at four PEEP levels increased by 2 cmH2₂O increments in stable patients in ICU on pressure support ventilation. Quality assessment of Pocc and sEAdi employed a new automated signal analysis method with tolerant and strict cutoff criteria, excluding inadequate waveforms. The coefficient of variation (CoV) of NMCdi following basic manual and advanced automated quality assessment was measured alongside the impact of incremental PEEP trials on NMCdi.

The results showed that 593 maneuvers were conducted across 42 PEEP trials involving 17 patients in ICU. Waveform exclusion criteria included low sEAdi signal-to-noise ratio (N_tolerant = 155, 37%; N_strict = 241, 51%), irregular or abrupt cessation of Pocc (N_tolerant = 145, 35%; N_strict = 145, 31%), and high sEAdi area under the baseline (N_tolerant = 94, 23%; N _strict = 79, 17%). Strict automated assessment reduced the CoV of NMCdi from 37% to 15% compared to basic quality assessment. Increasing PEEP levels resulted in a significant 4.9 percentage point decrease in NMCdi per cmH₂O.

Investigators concluded a method for analyzing sEAdi waveforms and demonstrated its utility in detecting PEEP-dependent changes in NMCdi, supporting the need for PEEP consideration in sEAdi-based respiratory effort assessment.

Source: ccforum.biomedcentral.com/articles/10.1186/s13054-024-04978-0