End-tidal to arterial PCO2 ratio: a bedside meter of the overall gas exchanger performance

Intensive Care Medicine Experimental

Table 2 Computed tomography quantitative variables at 5 cmH₂O of end-expiratory pressure among the P_ETCO₂/PaCO₂ ratio quartiles

P_ETCO₂/PaCO₂ quartiles	I	II	III	IV	p value
Ranges	[0.416,0.709]	[0.709,0.796]	[0.796,0.886]	[0.886,1.16]
Number of patients	N = 52	N = 51	N = 48	N = 49
Not aerated lung tissue, g	864 [534; 1321]	570 [417; 824]	510 [343; 692]	459 [314; 664]	< 0.001
Poorly aerated lung tissue, g	545 [342; 761]	398 [271; 552]	423 [284; 584]	356 [264; 440]	0.001
Normally aerated lung tissue, g	281 [189; 414]	288 [220; 452]	363 [243; 487]	356 [260; 500]	0.021
Hyperinflated lung tissue, g	0.32 [0.02; 2.72]	0.16 [0.01; 1.10]	0.24 [0.02; 2.47]	0.19 [0.01; 1.05]	0.739
Inhomogeneity index	0.20 [0.15; 0.24]	0.16 [0.13; 0.23]	0.15 [0.12; 0.18]	0.14 [0.12; 0.20]	0.007
Possibly recruitable tissue, g	336 [168; 583]	253 [109; 462]	171 [89.8; 295]	117 [54.4; 219]	< 0.001