Dyspnea and surface inspiratory electromyograms in mechanically ventilated patients
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Pressure support ventilation (PSV) must be tailored to the load capacity balance of the respiratory system. While "over assistance" generated hyperinflation and ineffective efforts, "under assistance" increased respiratory drive and causes dyspnea. Surface electromyograms (sEMGs) of extradiaphragmatic inspiratory muscles were responsive to respiratory loading/unloading.
To determine if sEMGs of extradiaphragmatic inspiratory muscles vary with PSV settings and relate to the degree of discomfort and the intensity of dyspnea in acutely ill patients.
Pathophysiological study, prospective inclusions of 12 intubated adult patients.
Two PSV levels (high and low) and two expiratory trigger (ET) levels (high and low).
Surface electromyograms of the scalene, parasternal, and Alae Nasi muscles (peak, EMGmax; area under the curve, EMGAUC); dyspnea visual analogue scale (VAS); prevalence of ineffective triggering efforts.
For the three recorded muscles, EMGmax and EMGAUC were significantly greater with low PS than high PS. The influence of ET was less important. A strong correlation was found between dyspnea and EMGmax. A significant inverse correlation was found between the prevalence of ineffective efforts and both dyspnea-VAS and EMGmin.
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.
KeywordsMechanical ventilation Patient–ventilator interaction Electromyogram Positive pressure support Inspiratory muscles
We thank Mr. Paul E. Robinson for reviewing the manuscript. Matthieu Schmidt was supported by ANTADIR (Association Nationale pour le Traitement à Domicile, l’Innovation et la Recherche) and the Fonds d’etude et de recherche du corps medicale des Hôpitaux de Paris, France. Alexandre Demoule was supported by CARDIF (Centre d’Assistance Respiratoire à Domicile d’Ile-de-France), the Société de Réanimation Langue Française and the Société de Pneumologie de Langue Française, Paris, France. François Hug was supported by CARDIF (Centre d’Assistance Respiratoire à Domicile d’Ile-de-France), Paris, France. The study was funded by Association pour le Développement et l’Organisation de la Recherche en Pneumologie et sur le Sommeil (ADOREPS), Paris, France, a by the grant “EEG-PVI “ (ANR-11-EMMA-030-01) of Agence Nationale de la Recherche, Paris, France
Conflicts of interest
In 2009 and 2010, the Association pour le Développement et l’Organisation de la Recherche en Pneumologie et sur le Sommeil (ADOREPS) received an unrestricted research grant from Maquet France SA, Orléans, France, to support pathophysiological research studies on the “neurally adjusted ventilatory assist” (NAVA) mode.
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