Table 3.

Correlation analysis of PETCO₂ and PaCO₂ in different disease types.

Disease types	Cases	PETCO2 (mm Hg)	PaCO2 (mm Hg)	PaCO2- PETCO2 gap (mm Hg)	r	P
COPD	70	42.81 ± 12.04	48.16 ± 13.14	5.35 ± 7.97	0.80	<.001
Multiple trauma	23	41.30 ± 8.14	38.75 ± 5.50	–2.55 ± 6.25	0.64	.001
Severe pneumonia	55	32.05 ± 7.39	35.13 ± 8.13	3.08 ± 6.97	0.60	<.001
Gastrointestinal surgery	73	36.77 ± 7.53	36.13 ± 7.22	–0.64 ± 6.82	0.57	<.001
Cerebrovascular disease	56	34.79 ± 7.37	35.01 ± 7.85	0.22 ± 7.36	0.53	<.001
Others	21	32.52 ± 6.65	33.71 ± 6.77	1.19 ± 6.95	0.46	.06

COPD = chronic obstructive pulmonary disease, PaCO₂ = arterial carbon dioxide tension, PETCO₂ = end-expiratory carbon dioxide partial pressure.