Dyspnea and surface inspiratory electromyograms in mechanically ventilated patients

Abstract

Surface electromyograms of extradiaphragmatic inspiratory muscles provides a simple, reliable and non-invasive indicator of respiratory muscle loading/unloading in mechanically ventilated patients. Because this EMG activity is strongly correlated to the intensity of dyspnea, it could be used as a surrogate of respiratory sensations in mechanically ventilated patients, and might, therefore, provide a monitoring tool in patients in whom detection and quantification of dyspnea is complex if not impossible.

Neural respiratory drive and breathlessness in COPD

“…A close relationship between breathlessness and the EMG of the parasternal intercostals, scalene, and alae nasi muscles, has also been observed in mechanically-ventilated intensive care patients [22]. Similar to the results presented here, the strength of the relationship to breathlessness in the study by SCHMIDT et al [22] was not improved (and in some cases deteriorated) when ventilation achieved in response to increases in NRD was considered. Also, in healthy young males and females [23,24], and in the altered "normal" physiological states of advancing age, obesity, and pregnancy [25][26][27], breathlessness can be mostly explained by an increased awareness of NRD (measured as V′E and ΔPoes/PImax) with little contribution by impaired respiratory mechanics, particularly at submaximal exercise.…”

“…Diaphragm and parasternal intercostal muscle EMG have also been recently shown to closely correlate with breathlessness in cystic fibrosis, before and after the onset of neuromechanical dissociation when the ventilation-breathlessness relationship again became less strong [14]. A close relationship between breathlessness and the EMG of the parasternal intercostals, scalene, and alae nasi muscles, has also been observed in mechanically-ventilated intensive care patients [22]. Similar to the results presented here, the strength of the relationship to breathlessness in the study by SCHMIDT et al [22] was not improved (and in some cases deteriorated) when ventilation achieved in response to increases in NRD was considered.…”

“…Quantification of NRD using surface recordings of another obligate inspiratory muscle, parasternal intercostal muscle EMG activity (EMGpara), have the advantage over EMGdi recorded using oesophageal catheters of being noninvasive. Surface recordings of EMGpara have also been shown to be closely related to breathlessness in healthy subjects [14,21] and in respiratory disease [14,21,22,37]. However, work by our group [13,14,20] and others [16,24] has shown that EMGdi activity in patients with chronic airflow limitation and healthy individuals increases continuously throughout the duration of incremental exercise protocols, and that breathlessness is closely related to EMGdi activity in healthy subjects [14,24] and in cystic fibrosis [14].…”

Patient-ventilator asynchrony

“…As in previous studies, IIE was the most common asynchrony in all modes. Identifying asynchronies by using esophageal balloons [3], dedicated software [12 && , 13,14], or electromyography of respiratory muscles [15,16] might help obtain a more accurate picture of the prevalence of asynchronies.…”

Year in review in Intensive Care Medicine 2013: II. Sedation, invasive and noninvasive ventilation, airways, ARDS, ECMO, family satisfaction, end-of-life care, organ donation, informed consent, safety, hematological issues in critically ill patients

“…These parameters provide valuable information to assess weakness or paralysis. Schmidt et al [19] reported that surface electromyograms (sEMGs) of extradiaphragmatic inspiratory muscles vary with PSV settings and relate to the degree of discomfort and the intensity of dyspnea. A strong correlation was found between dyspnea and EMGmax.…”