Arterial base deficit in pulmonary embolism is an index of severity and diagnostic delay

In acute pulmonary embolism, patients free from circulatory failure usually present a blood gas pattern consistent with respiratory alkalosis. We investigated whether the appearance of arterial base deficit in these patients indicates disease severity and diagnostic delay. Twenty-four consecutive patients with pulmonary embolism were retrospectively evaluated. Twelve patients had arterial base excess or =0 mmol/L (Group 1), and 12 patients arterial base deficit 0 mmol/L (Group 2). No patient showed signs of circulatory failure. Group 1 was characterized by a mean base excess of 2.2 +/- 1.7 mmol/L, while in Group 2, the mean base deficit was -1.9 +/- 0.7 mmol/L (p 0.0001). At 1 week since the embolism, 11 patients of Group 1 and 6 of Group 2 received a PE diagnosis (p 0.05). The vascular obstruction index was more severe in Group 2 than in Group 1 (48 +/- 12 vs. 36 +/- 17%, respectively, p 0.05). In Group 2, the PaCO(2) was lower (33 +/- 3 vs. 36 +/- 5 mmHg, respectively, p 0.05), the arterial pH was decreased (7.442 +/- 0.035 vs. 7.472 +/- 0.050, respectively, p