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Table 3 Ventilatory pressures during continuous positive-pressure ventilation and continuous external negative-pressure ventilation at inspiration and expirationa

From: Negative- versus positive-pressure ventilation in intubated patients with acute respiratory distress syndrome

  Airway pressure (cmH2O) Tank pressure (cmH2O) Transrespiratory
pressure (cmH2O)
Oesophageal pressure
(cmH2O)
Transpulmonary pressure (cmH2O)
Patient CPPV CENPV CENPV CENPV CPPV CENPV CPPV CENPV
1         
Inspiration 33 -3 (27) -30 27 20 -9 (21) 13 6
Expiration 16 5 (20) -15 20 15 4 (19) 1 1
2         
Inspiration 36 -2 (31) -33 31 22 -9 (24) 14 7
Expiration 16 5 (20) -15 20 15 5 (20) 1 0
3         
Inspiration 30 0 (31) -31 31 19 -8 (23) 11 8
Expiration 16 2 (17) -15 17 15 2 (17) 1 0
4         
Inspiration 33 -1 (31) -32 31 25 -9 (23) 8 8
Expiration 16 4 (19) -15 19 16 4 (19) 0 0
5         
Inspiration 39 -2 (38) -40 38 23 -10 (30) 16 8
Expiration 16 4 (19) -15 19 16 3 (18) 0 1
6         
Inspiration 47 0 (43) -43 43 32 -10 (33) 15 10
Expiration 23 5 (24) -19 24 22 5 (24) 1 0
Mean ± SD         
Inspiration 36 ± 6 -1.3 ± 1.2*
(33.5 ± 5.9)
-35 ± 5 34 ± 6 24 ± 5 -9 ± 0.8*
(25.7 ± 4.7)
13 ± 3 8 ± 1.3
Expiration 17 ± 3 4.2 ± 1.2*
(19.5 ± 2.3)
-16 ± 1.6 20 ± 2* 17 ± 3 4 ± 1.2*
(19.5 ± 2.4)
1 ± 0.5 0 ± 0.5
  1. aIn parentheses, both airway and oesophageal pressures are shown in reference to tank pressure to enable calculation of transpulmonary pressures (airway pressure - oesophageal pressure) in reference to both atmospheric and body surface pressure inside the tank. Transrespiratory system pressures during CENPV (airway pressure - tank pressure) were compared to airway pressures during CPPV. CENPV, continuous external negative-pressure ventilation; CPPV, continuous positive-pressure ventilation. *P = 0.03 and P = 0.04 compared to the corresponding inspiratory or expiratory value during CPPV.