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Table 4 Neural and mechanical indices of respiratory effort at different levels of PEEPe during PSP and PSN

From: Neural versus pneumatic control of pressure support in patients with chronic obstructive pulmonary diseases at different levels of positive end expiratory pressure: a physiological study

Parameter Mode PEEPe0% PEEPe40% PEEPe80% PEEPe120% P*
Δ P̅esTRIG (cm H2O) PSP −0.9 (−2.2, −0.6)z −0.9 (−2.0, −0.5)z −0.6 (−1.2, −0.4)abz −0.4 (−0.9, −0.2)abcz <0.001
  PSN −0.2 (−0.3, −0.0)x −0.1 (−0.3, −0.0) −0.1 (−0.3, −0.0) −0.1 (−0.3, −0.0)  
Δ P̅esTOT (cm H2O) PSP −2.2 (−3.2, −0.8)z −1.7 (−3.3, −0.7)z −1.0 (−1.9, −0.1)abz −0.4 (−2.2, 0.2)acz <0.001
  PSN −0.7 (−1.6, −0.3) −0.6 (−1.0, −0.2)a −0.4 (−0.8, 0.4)ab −0.3 (−0.8, 0.4)abc  
PTPesTRIG (cm H2O*s/min) PSP −5.0 (−23.8, −2.7)z −3.3 (−19.4, −1.5)z −2.4 (−10.5,−1.1)abz −1.3 (−4.2, −0.3)abcz <0.001
  PSN −0.2 (−0.6, −0.1)x −0.2 (−0.4, −0.0) −0.0 (−0.3, 0.1) −0.1 (−0.4, 0.0)  
PTPesTOT (cm H2O*s/min) PSP −44.5 (−81.3, −13.9)z −29.7 (−58.3, −11.5)z −17 (−34.2, −2.6)abz −7.3 (−49.8, 3.0)abcz <0.001
  PSN −15.8 (−27.7,−5.9) −11.5 (−16.7, −4.9)a −7.5 (−15.4, 5.5)ab −5.1 (−14.1, 4.2)abc  
ÊAdiTRIG (μV) PSP 3.1 (1.9, 4.8)z 2.6 (2.0, 4.1)z 2.1 (1.8, 4.1)abz 1.8 (1.7, 3.4)abcz <0.001
  PSN 1.3 (1.1, 1.7)x 1.1 (1.0, 1.3)a 1.1 (1.0, 1.3)ab 1.0 (0.9, 1.2)ab  
ÊAdiTOT (μV) PSP 7.9 (5.7, 11.6) 7.0 (6.2, 11.8) 6.3 (5.0, 9.5) 6.7 (4.7, 9.9) <0.001
  PSN 7.1 (4.8, 11.8) 6.4 (5.5, 11.8) 6.3 (4.6, 9.5) 6.2 (4.4, 9.1)  
Δ P̅es/Δ P̅L (%) PSP 24.5 (35.4, 11.0)z 18.2 (29.8, 8.3)z 12.5 (22.7, 1.3)abz 6.6 (21.1, −2.70)abcz <0.001
  PSN 7.0(12.1, 2.9)x 5.4 (6.9, 2.2) 2.8 (7.6, −4.5)ab 2.2 (7.6, −5.1)abc  
NME (cm H2O/μV) PSP −0.27 (−0.34, −0.16)z −0.22 (−0.32, −0.11)az −0.13 (−0.28, −0.03)abz −0.09 (−0.15, 0.02)abcz <0.001
  PSN −0.11 (−0.22, −0.04) −0.07 (−0.15, −0.03)a −0.06 (−0.10, 0.04)ab −0.05 (0.08, 0.06)abc  
  1. Values are presented as median (25–75 % interquartile range). *P values for one-way repeated measures analysis of variance on ranks for the eight conditions: •within the same mode: a P <0.05 compared to PEEPe0%; b P <0.05 compared to PEEPe40%; c P < 0.05 compared to PEEPe80%. Between modes: z P <0.05 compared to PSN at same PEEPe comparison of PSN zero PEEP to PSP optimal PEEP: x P <0.05 PEEPe0% at PSN vs. PEEPe80% at PSP. PSP pneumatically triggered and cycled-off pressure support, PSN neurally triggered and cycled-off pressure support ventilation, ΔP̅esTRIG pre-trigger mean deflection of esophageal pressure, ΔP̅esTOT total inspiratory mean deflection for esophageal pressure, PTPesTOT total inspiratory pressure time product per minute for esophageal pressure, PTPesTRIG pre-trigger pressure time product per minute for esophageal pressure, ÊAdiTOT peak inspiratory diaphragm electrical activity (EAdi) for total inspiration, ÊAdiTRIG peak pre-trigger EAdi, ΔP̅es/ΔP̅L esophageal pressure contribution to transpulmonary pressure during inspiration, NME neuromechanical efficiency calculated for esophageal pressure