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Table 2 Lung density, total lung volume, normally aerated, poorly aerated, non-aerated and over aerated lung tissue

From: High-frequency oscillatory ventilation guided by transpulmonary pressure in acute respiratory syndrome: an experimental study in pigs

   ARDS PEEP 5 ARDS PEEP 10 ARDS PEEP 20
Hounsfield units HU Median 25% 75% Median 25% 75% Median 25% 75%
 VCV expiration   − 313.6 − 379.0 − 266.0 −379.2 − 452.6 − 331.1 − 479.5©£ − 554.7 − 439.5
 ARDS HFOV con   − 418.1 −517.5 − 398.9 − 535.4 Ω − 580.3 − 484.6
 ARDS HFOV PL mean   −338.6 − 477.2 − 238.9 − 447.1 − 549.4 − 399.0
Total lung volume ml          
 VCV   1351.6 1197.8 1480.9 1619.3^ 1553.5 1765.6 2349.2© 2230.8 2435.9
 ARDS HFOV con   1976.6 1870.1 2249.7 2582.1 Ω 2468.3 2734.3
 ARDS HFOV PL mean   1817.4 1464.8 1955.6 2256.0 2159.2 2388.3
Normally aerated tissue ml          
 VCV expiration   484.3 387.5 509.9 647.9 591.8 725.6 1112.9£ 1016.3 1157.6
 ARDS HFOV con   855.4 812.7 937.7 1292.6 Ω 1196.9 1424.4
 ARDS HFOV PL mean   593.3 418.5 881.7 979.0 885.3 1166.5
Poorly aerated tissue ml          
 VCV expiration   225.1 217.2 246.3 306.1^ 283.7 341.6 621.6£ 509.5 818.3
 ARDS HFOV con   447.9 390.5 507.2 685.9 Ω 596.9 776.6
 ARDS HFOV PL mean   336.1 221.4 413.1 557.2 500.1 614.5
Non-aerated tissue ml          
 VCV expiration   628.3 447.0 725.3 608.4 448.8 705.6 409.3©£ 325.5 459.0
 ARDS HFOV con   567.9 450.5 610.9 350.2 Ω 250.6 367.5
 ARDS HFOV PL mean   736.5 484.1 775.7 518.6 391.6 642.4
Over aerated tissue ml          
 VCV expiration   26.3 19.3 32.2 59.5^ 47.2 68.0 124.8© 71.1 218.0
 ARDS HFOV con   106.1 72.1 167.7 180.7 Ω 113.7 390.7
 ARDS HFOV PL mean   72.9 23.6 107.4 121.0 63.6 208.4
  1. Values are medians (25th and 75th quartiles) in eight animals. See text or Table 1 for description of groups
  2. ARDS acute respiratory distress syndrome, VCV volume controlled ventilation, HFOV con conventional high frequency oscillatory ventilation, HFOV P L mean HFOV guided by mean transpulmonary pressure, PEEP positive end-expiratory pressure
  3. ^p < 0.05 VCV ARDS PEEP 10 expiration vs. HFOV con “PEEP 10”; p < 0.05 VCV ARDS PEEP 10 expiration vs. HFOV PL mean “PEEP 10”; p < 0.05 HFOV con ARDS “PEEP 10” vs. HFOV PL mean ARDS “PEEP 10”; ©p < 0.05 VCV ARDS PEEP 20 expiration vs. HFOV con “PEEP 20”; £p < 0.05 VCV ARDS PEEP 20 expiration vs. HFOV PL mean “PEEP 20”; Ωp < 0.05 HFOV con ARDS “PEEP 20” vs. HFOV PL mean ARDS “PEEP 20”; p < 0.05 (p values were determined using the Wilcoxon test for paired samples)