OBJECTIVES: To calculate an index (termed Pmusc/Eadi index) relating the pressure generated by the respiratory muscles (Pmusc) to the electrical activity of the diaphragm (Eadi), during assisted mechanical ventilation and to assess if the Pmusc/Eadi index is affected by the type and level of ventilator assistance. The Pmusc/Eadi index was also used to measure the patient's inspiratory effort from Eadi without esophageal pressure. DESIGN: Crossover study. SETTING: One general ICU. PATIENTS: Ten patients undergoing assisted ventilation. INTERVENTION: Pressure support and neurally adjusted ventilator assist delivered, each, at three levels of ventilatory assistance. MEASUREMENT AND MAIN RESULTS: Airways flow and pressure, esophageal pressure, and Eadi were continuously recorded. Sixty tidal volumes for each ventilator settings were analyzed off-line, at three time points during inspiration. For each time point, Pmusc/Eadi index was calculated. Pmusc/Eadi index was also calculated from airway pressure drop during end-expiratory occlusions. Pmusc/Eadi index was very variable among patients, but within one patient it was not affected by type and level of ventilator assistance. Pmusc/Eadi index decreased during the inspiration. Pmusc/Eadi index obtained during an occlusion from airway pressure swing was tightly correlated with that derived from esophageal pressure during tidal ventilation and allowed to estimate pressure time product. CONCLUSIONS: Pmusc is tightly related to Eadi, by a proportionality coefficient that we termed Pmusc/Eadi index, stable within each patient under different conditions of ventilator assistance. The derivation of the Pmusc/Eadi index from Eadi and airway pressure during an expiratory occlusion enables a continuous estimate of patient's inspiratory effort.
Estimation of patient's inspiratory effort from the electrical activity of the diaphragm / G. Bellani, T. Mauri, A. Coppadoro, G. Grasselli, N. Patroniti, S. Spadaro, V. Sala, G. Foti, A. Pesenti. - In: CRITICAL CARE MEDICINE. - ISSN 0090-3493. - 41:6(2013 Jun), pp. 1483-1491.
Titolo: | Estimation of patient's inspiratory effort from the electrical activity of the diaphragm |
Autori: | |
Parole Chiave: | diaphragmatic electromyogram; mechanical ventilation; monitoring; neurally adjusted ventilatory assist; pressure support ventilation; work of breathing; adult; aged; aged, 80 and over; cross-over studies; diaphragm; electromyography; female; humans; inhalation; male; middle aged; respiration artificial |
Settore Scientifico Disciplinare: | Settore MED/41 - Anestesiologia |
Data di pubblicazione: | giu-2013 |
Rivista: | |
Tipologia: | Article (author) |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1097/CCM.0b013e31827caba0 |
Appare nelle tipologie: | 01 - Articolo su periodico |
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