. 1999 Jul 30;3(4):111–116. doi: 10.1186/cc352

Table 1.

Frequency of normal arterial blood gas tests in patients with and without pulmonary embolism (PE)

	PE present		PE absent

			abnormal scan*		Normal/near-normal scan

	n	%	n	%	n	%
P(A–a)O₂ < 20 mmHg	37/312	12^‡	21/191	11^¶	53/270	20
P(A–a)O₂ age corrected^†	22/312	7^‡§	23/191	12	43/270	16
PaO₂ > 80 mmHg	44/312	14^‡	25/191	13^¶	68/270	25
PaCO₂ > 35 mmHg	110/312	35^§	105/191	55^¶	99/270	37

*Patients in whom PE was excluded by angiography. ^†Normal values adjusted for age. ^‡Different from those with normal/near-normal scan and ^§different from those with abnormal scan. ^¶Different from those with normal/near-normal scan.