OBJECTIVE: The diaphragmatic pressure-time product (PTPdi) has been used to quantify the loading and unloading of the diaphragm. The validity of the relationship between PTPdi and diaphragm electrical activity (EMGdi) during pressure-support ventilation (PSV) is unclear. We examined this relationship. DESIGN AND SETTING: Physiological study in a physiology laboratory. SUBJECTS: Six healthy adults. INTERVENTIONS: Spontaneous breathing (SB) and two levels of PSV (6 and 12 cmH(2)O), breathing room air and incremental concentrations of carbon dioxide, sufficient to achieve an EMGdi signal of approximately 200% of baseline value. MEASUREMENTS AND RESULTS: We measured the electrical (EMGdi) and mechanical (PTPdi) activity of the diaphragm using oesophageal electrode and oesophageal and gastric balloon catheters. The relationship between EMGdi and PTPdi during SB was linear in five subjects and curvilinear in one. However, with PSV 12 cmH(2)O we observed that the relationship between EMGdi and PTPdi was 'left shifted'; specifically, for any given level of EMGdi the PTPdi was smaller with PSV 12 cmH(2)O than during SB. However, when PTPdi was converted to power (the product of pressure and flow) the tendency to left shift was largely reversed. CONCLUSIONS: We conclude that when assessing of diaphragm unloading during PSV flow measurements are required. Where flow is constant, PTPdi is a valid measure of diaphragm unloading, but if not these data may be used to make an appropriate correction.
OBJECTIVE: The diaphragmatic pressure-time product (PTPdi) has been used to quantify the loading and unloading of the diaphragm. The validity of the relationship between PTPdi and diaphragm electrical activity (EMGdi) during pressure-support ventilation (PSV) is unclear. We examined this relationship. DESIGN AND SETTING: Physiological study in a physiology laboratory. SUBJECTS: Six healthy adults. INTERVENTIONS: Spontaneous breathing (SB) and two levels of PSV (6 and 12 cmH(2)O), breathing room air and incremental concentrations of carbon dioxide, sufficient to achieve an EMGdi signal of approximately 200% of baseline value. MEASUREMENTS AND RESULTS: We measured the electrical (EMGdi) and mechanical (PTPdi) activity of the diaphragm using oesophageal electrode and oesophageal and gastric balloon catheters. The relationship between EMGdi and PTPdi during SB was linear in five subjects and curvilinear in one. However, with PSV 12 cmH(2)O we observed that the relationship between EMGdi and PTPdi was 'left shifted'; specifically, for any given level of EMGdi the PTPdi was smaller with PSV 12 cmH(2)O than during SB. However, when PTPdi was converted to power (the product of pressure and flow) the tendency to left shift was largely reversed. CONCLUSIONS: We conclude that when assessing of diaphragm unloading during PSV flow measurements are required. Where flow is constant, PTPdi is a valid measure of diaphragm unloading, but if not these data may be used to make an appropriate correction.
Authors: Edward Abraham; Peter Andrews; Massimo Antonelli; Laurent Brochard; Christian Brun-Buisson; Geoffrey Dobb; Jean-Yves Fagon; Johan Groeneveld; Jordi Mancebo; Philipp Metnitz; Stefano Nava; Michael Pinsky; Peter Radermacher; Marco Ranieri; Christian Richard; Robert Tasker; Benoît Vallet Journal: Intensive Care Med Date: 2004-05-15 Impact factor: 17.440
Authors: Mathieu Delorme; Karl Leroux; Ghilas Boussaid; Marius Lebret; Helene Prigent; Antoine Leotard; Bruno Louis; Frédéric Lofaso Journal: Arch Bronconeumol Date: 2021-02-02 Impact factor: 4.872
Authors: Miguel Angel Martinez-García; Carmen Villa; Yadira Dobarganes; Rosa Girón; Luis Maíz; Marta García-Clemente; Oriol Sibila; Rafael Golpe; Juan Rodríguez; Esther Barreiro; Juan Luis Rodriguez; Rosario Menéndez; Concepción Prados; David de la Rosa; Casilda Olveira Journal: Arch Bronconeumol (Engl Ed) Date: 2020-02-17 Impact factor: 4.872