Nocturnal hypoxemia and prognosis in patients with acute symptomatic pulmonary embolism

Background: Nocturnal hypoxemia has been associated with cardiovascular and non-cardiovascular morbidity and mortality. This study aimed to investigate the prognostic value of nocturnal hypoxemia among patients with hemodynamically stable acute symptomatic pulmonary embolism (PE).

Methods: We performed an ad hoc secondary analysis of clinical data from a prospective cohort study. Nocturnal hypoxemia was measured by the percent sleep registry with oxygen saturation <90% [TSat90]). Outcomes assessed over the 30-days after the diagnosis of PE included PE-related death, other cardiovascular deaths, clinical deterioration requiring an escalation of treatment, recurrent venous thromboembolism (VTE), acute myocardial infarction [AMI], or stroke.

Results: Of the 221 hemodynamically stable patients with acute PE from which the TSat90 could be calculated and did not receive supplemental oxygen, the primary outcome occurred in 11 (5.0%; 95% confidence interval [CI], 2.5% to 8.7%) within 30-days after the diagnosis of PE. When categorized by quartiles, TSat90 was not significantly associated with the occurrence of the primary outcome in unadjusted Cox regression analysis (hazard ratio, 0.96; 95% CI, 0.57 to 1.63; P = 0.88), or after adjustment for body mass index (adjusted hazard ratio, 0.97; 95% CI, 0.57 to 1.65; P = 0.92). When examined as a completely continuous variable (between 0 and 100), TSat90 was not associated with a significant increase in the adjusted hazard of 30-day primary outcome rates (hazard ratio, 0.97; 95% CI, 0.86 to 1.10; P = 0.66).

Conclusions: In this study, nocturnal hypoxemia did not identify stable patients with acute symptomatic PE at increased risk for adverse cardiovascular events.