End-inspiratory pause prolongation in acute respiratory distress syndrome patients: effects on gas exchange and mechanics

Annals of Intensive Care

Table 2 Respiratory system mechanics, gas exchange and hemodynamic data during the study

	Phase 1 (baseline)	Phase 2 (EIP prolongation)	Phase 3 (Vt reduction)	Overall p value	Intergroup differences
EIP (s)	0.12 ± 0.04	0.7 ± 0	0.7 ± 0	<0.001	a, b
Ppeak (cmH₂O)	38 ± 6	38 ± 6	35 ± 5	<0.001	b, c
Pmean (cmH₂O)	15 ± 3	18 ± 2	17 ± 2	<0.001	a, b, c
Pplat (cmH₂O)	24 ± 3	24 ± 3	22 ± 3	<0.001	b, c
PEEPi (cmH₂O)	0.2 ± 0.2	0.5 ± 0.4	0.5 ± 0.4	0.06
Vt (mL)	378 ± 73	378 ± 73	336 ± 61	<0.001	b, c
Vt (PBW; mL/Kg)	6.3 ± 0.8	6.3 ± 0.8	5.6 ± 0.8	<0.001	b, c
Vd_phys (mL)	267 ± 71	244 ± 65	216 ± 58	<0.001	a, b, c
Vd/Vt	0.70 ± 0.07	0.64 ± 0.08	0.64 ± 0.08	<0.001	a, b
Crs (mL/cmH₂O)	29 ± 9	29 ± 9	32 ± 11	0.001	b, c
∆ Paw (cmH₂O)	13.6 ± 3.6	13.4 ± 3.6	10.9 ± 3.1	<0.001	a, b, c
R_aw (cmH₂O/L/s)	14 ± 5	13 ± 5	13 ± 4	0.28
pH	7.31 ± 0.07	7.34 ± 0.09	7.31 ± 0.08	<0.001	a, c
PaO₂ (mmHg)	102 ± 23	98 ± 23	105 ± 29	0.35
PaCO₂ (mmHg)	54 ± 9	50 ± 8	54 ± 10	<0.001	a, c
EtCO₂ (mmHg)	41 ± 6	39 ± 6	43 ± 7	0.002	a, c
P(a-et)CO₂ (mmHg)	13 ± 6	12 ± 8	12 ± 9	0.27
MAP (mmHg)	80 ± 12	76 ± 9	77 ± 12	0.08
HR (beats/min)	87 ± 19	83 ± 20	86 ± 21	0.14
Temperature (°C)	36.7 ± 0.9	36.7 ± 0.9	36.6 ± 0.8	0.61

Data are presented as number (%) or mean ± SD
Intergroup differences (p < 0.05): a, phase 1 versus phase 2; b, phase 1 versus phase 3; c, phase 2 versus phase 3
Crs static compliance of the respiratory system, EIP end-inspiratory pause, EtCO ₂ end-tidal carbon dioxide concentration in the expired air, FiO ₂ fraction of inspired oxygen, HR heart rate, MAP mean arterial pressure, PaO ₂ partial pressure of oxygen in arterial blood, PaCO ₂ partial pressure of carbon dioxide in arterial blood, PBW predicted body weight, PEEPi intrinsic positive end-expiratory pressure, Pmean mean airway pressure, Ppeak peak airway pressure, Pplat plateau airway pressure, P(a-et)CO₂ arterial to end-tidal CO₂ gradient, Raw airway resistance, Vd _phys physiological dead space, Vd/Vt dead space-to-Vt ratio, Vt tidal volume, ∆Paw driving airway pressure