BACKGROUND:
Detection of diaphragmatic muscle activity during invasive ventilation may provide valuable information about patient-ventilator interactions. Transesophageal electromyography of the diaphragm (
) is used in neurally adjusted ventilatory assist. This technique is invasive and can only be applied with one specific ventilator. Surface electromyography of the diaphragm (
) is noninvasive and can potentially be applied with all types of ventilators. The primary objective of our study was to compare the ability of diaphragm activity detection between
and
.
METHODS:
In this single-center pilot study,
and
recordings were obtained simultaneously for 15 min in adult subjects in the ICU who were invasively ventilated. The number of breathing efforts detected by
and
were determined. The percentage of detected breathing efforts by
compared with
was calculated. Temporal and signal strength relations on optimum recordings of 10 breaths per subject were also compared. The Spearman correlation coefficient was used to determine the correlation between
and
. Agreement was calculated by using Bland-Altman statistics.
RESULTS:
Fifteen subjects were included. The
detected 3,675 breathing efforts, of which 3,162 (86.0%) were also detected by
. A statistically significant temporal correlation (r = 0.95, P < .001) was found between
and
in stable recordings. The mean difference in the time intervals between both techniques was 10.1 ms, with limits of agreement from –410 to 430 ms.
CONCLUSIONS:
Analysis of our results showed that
was not reliable for breathing effort detection in subjects who were invasively ventilated compared with
. In stable recordings, however,
and
had excellent temporal correlation and good agreement. With optimization of signal stability,
may become a useful monitoring tool.
