RT Journal Article
SR Electronic
T1 Dynamic Relative Regional Lung Strain Estimated by Electrical Impedance Tomography in an Experimental Model of ARDS
JF Respiratory Care
FD American Association for Respiratory Care
SP respcare.09682
DO 10.4187/respcare.09682
A1 Emiliano Gogniat
A1 Matías Madorno
A1 Pablo O Rodriguez
A1 José Dianti
A1 Pablo E Otero
A1 Lisa Krukewitt
A1 Stephan H Böhm
A1 Eduardo San Roman
A1 Gerardo Tusman
YR 2022
UL http://rc.rcjournal.com/content/early/2022/05/24/respcare.09682.abstract
AB BACKGROUND: To analyze the role of PEEP on dynamic relative regional strain (DRRS) in a model of ARDS, respective maps were generated by electrical impedance tomography (EIT).METHODS: Eight ARDS pigs submitted to PEEP steps of 0, 5, 10, and 15 cm H2O at fixed ventilation were evaluated by EIT images. DRRS was calculated as (VT-EIT/EELI)/(VT-EIT[15PEEP]/EELI[15PEEP]), where the tidal volume (VT)-EIT and end-expiratory lung impedance (EELI) are the tidal and end-expiratory change in lung impedance, respectively. The measurement at 15 PEEP was taken as reference (end-expiratory transpulmonary pressure > 0 cm H2O). The relationship between EIT variables (center of ventilation, EELI, and DRRS) and airway pressures was assessed with mixed-effects models using EIT measurements as dependent variables and PEEP as fixed-effect variable.RESULTS: At constant ventilation, respiratory compliance increased progressively with PEEP (lowest value at zero PEEP 10 ± 3 mL/cm H2O and highest value at 15 PEEP 16 ± 6 mL/cm H2O; P < .001), whereas driving pressure decreased with PEEP (highest value at zero PEEP 34 ± 6 cm H2O and lowest value at 15 PEEP 21 ± 4 cm H2O; P < .001). The mixed-effect regression models showed that the center of ventilation moved to dorsal lung areas with a slope of 1.81(1.44–2.18) % points by each cm H2O of PEEP; P < .001. EELI increased with a slope of 0.05 (0.02–0.07) (arbitrary units) for each cm H2O of PEEP; P < .001. DRRS maps showed that local strain in ventral lung areas decreased with a slope of −0.02(−0.24 to 0.15) with each cm H2O increase of PEEP; P < .001.CONCLUSIONS: EIT-derived DRRS maps showed high strain in ventral lung zones at low levels of PEEP. The findings suggest overdistention of the baby lung.