Table 4—

Correlation coefficients of linear regression between changes (Δ) in arterial carbon dioxide tension (P_a,CO₂) and in dynamic intrinsic positive end-expiratory pressure (PEEPi) with changes in various lung function tests

	ΔP_a,CO₂ mmHg		ΔPEEPi,_dyn cmH₂O
	r	p	r	p
ΔP_I/V_T/t_I cmH₂O·L⁻¹·s⁻¹	0.69	<0.0001	0.77	<0.0001
ΔV_T L	−0.69	<0.0001	−0.53	<0.005
ΔTTI	0.69	<0.0001	0.69	<0.0001
ΔFEV₁ L	−0.62	<0.0001	−0.39	<0.05
ΔP_I/P_I,max	0.62	<0.0001	0.64	<0.0001
ΔE_L,dyn _{cmH₂O·L⁻¹}	0.62	<0.0001	0.40	<0.05
ΔP_I, cmH₂O	0.59	<0.0001	0.72	<0.0001
ΔFEF_25–75% L·s⁻¹	−0.57	<0.0001	−0.31	ns
ΔFRC L	0.56	<0.001	0.46	<0.01
ΔIC L	−0.55	<0.001	−0.43	<0.02
ΔR_L cmH₂O·L⁻¹·s⁻¹	0.54	<0.005	0.65	<0.0001
ΔP_0.1/V_T/t_I cmH₂O·L⁻¹·s⁻¹	0.53	<0.005	0.38	<0.05

PEEPi,_dyn: dynamic intrinsic positive end-expiratory pressure
P_I: mean inspiratory pressure swing
P_I/V_T/t_I: effective inspiratory impedance of the lung
V_T: tidal volume
TTI: tension/time index of the inspiratory muscles
FEV₁: forced expiratory volume in one second
P_I,max: maximal inspiratory pressure
E _{L,dyn: dynamic lung elastance}
FEF_25–75%: forced mid-expiratory flow
FRC: functional residual capacity
IC: inspiratory capacity
R_L: inspiratory lung resistance
P_0.1/V_T/t_I: effective impedance of the respiratory system
ns: nonsignificant