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Table 2 Ventilation parameters, arterial blood gases, and mean arterial pressure at different PEEPe for PSN and PSP

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*
P̅aw (cm H2O) PSP 10.9 (10.3, 11.3) 12.9 (12.3, 13.3)a 15.0 (14.8, 16.3)ab 17.4 (16.8, 18.3)abc <0.001
  PSN 11.4 (10.8, 11.6)x 13.1 (12.1, 13.3)a 15.2 (14.4, 16.4)ab 17.5 (16.9, 18.6)abc  
PEEPe (cm H2O) PSP 0.6 (0.4, 1.0)z 2.3 (2.2, 2.5)az 4.7 (4.2, 5.4)ab 7.1 (6.5, 7.5)abc <0.001
  PSN 1.0 (0.5, 1.2)x 2.5 (2.3, 3.0)a 4.7 (4.4, 5.4)ab 7.0 (6.6, 7.5)abc  
VT (ml/kg) PSP 5.4 (4.2, 6.7)z 5.8 (4.9, 6.8)z 5.9 (5.0, 6.6)abz 5.5 (5.2, 7.0)ab <0.001
  PSN 4.6 (4.3, 5.8)x 5.0 (4.4, 5.9)a 4.9 (4.6, 6.7)ab 5.0 (4.6, 7.1)abc  
BfN (breaths/min) PSP 20.2 (17.7, 29.3)z 20.5 (17.6, 28.9)z 21.5 (17.2, 26.9)z 20.9 (17.9, 30.3) 0.003
  PSN 26.4 (17.3, 30.7)x 24.4 (17.2, 33.2) 22.1 (18.1, 31.5)ab 20.5 (16.0, 29.6)ab  
VE (l/min) PSP 6.05 (5.25, 8.13)z 6.54 (5.47, 8.91)a 7.05 (5.67, 9.02)a 7.07 (5.70, 11.62)a <0.001
  PSN 6.43 (5.31, 9.54)x 6.92 (5.53, 9.98)a 7.14 (5.50, 9.20)a 7.79 (5.74, 9.66)a  
VT/TiP (ml/s) PSP 424 (390, 446)z 429 (389, 472) 436 (386, 458) 438 (396, 466) 0.013
  PSN 414 (302, 491)x 443 (334, 508)a 452 (338, 526)a 479 (361, 513)a  
TiN (s) PSP 0.90 (0.72, 1.03) 0.90 (0.74, 0.94) 0.84 (0.73, 0.98) 0.87 (0.69, 0.93) NS
  PSN 0.84 (0.71, 0.96) 0.77 (0.71, 0.86) 0.81 (0.74, 0.86) 0.84 (0.73, 0.95)  
TeN (s) PSP 2.12 (1.43, 2.60)z 2.22 (1.45, 2.93) 2.17 (1.58, 3.14)z 2.13 (1.53, 2.58) 0.050
  PSN 1.76 (1.16, 2.66)x 2.09 (1.20, 2.77)a 2.02 (1.24, 2.59)a 2.14 (1.33, 2.92)a  
TiN/TtN (%) PSP 29.6 (27.5, 36.5) 28.7 (24.5, 39.0) 27.1 (23.4, 36.3) 26.1 (23.0, 36.7) NS
  PSN 31.4 (25.6, 37.8) 29.4 (23.9, 38.5) 29.7 (24.6, 38.3) 30.6 (22.5, 36.8)  
pH PSP 7.36 (7.33, 7.41) 7.38 (7.36, 7.41)a 7.39 (7.34, 7.44)a 7.39 (7.33, 7.42)a 0.009
  PSN 7.37 (7.33, 7.40)x 7.39 (7.34, 7.42)a 7.38 (7.32, 7.45)a 7.38 (7.35, 7.42)a  
PaCO2 (mm Hg) PSP 37.9 (32.0, 48.6) 35.9 (31.2, 46.1) 36.3 (32.1, 46.8) 33.5 (32.9, 43.3) NS
  PSN 40.4 (29.8, 47.5) 34.2 (31.2, 42.1) 35.4 (32.8, 41.8) 36.5 (30.7, 41.9)  
PaO2 (mm Hg) PSP 84.0 (79.9, 113.9) 94.8 (84.9, 116.7) 98.7 (90.0, 124.3) 103.9 (84.0, 117.2) NS
  PSN 89.7 (83.5, 122.9) 106.6 (81.2, 124.1) 99.4 (91.0, 123.9) 109.0 (95.0, 125.8)  
MAP (mm Hg) PSP 89.0 (76.0, 92.7) 88.0 (77.0, 92.7) 86.7 (77.7, 91.7) 89.3 (79.0, 91.3) NS
  PSN 88.3 (75.7, 91.3) 88.0 (75.3, 90.4) 88.7 (78.3, 91.0) 86.7 (80.3, 92.0)  
  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, P̅aw mean airway pressure (including PEEPe), PEEPe extrinsic PEEP, VT tidal volume, VE minute ventilation, TiN neural inspiratory time, TeN neural expiratory time, Ti/TtotN neural duty cycle, BfN neural breathing frequency, PEEPiSTAT static intrinsic positive end-expiratory pressure, MAP mean arterial pressure, NS not significant