Mixed Venous Oxygen Tension important prognostic factor for Pulmonary Hypertension

A recent study found that mixed venous oxygen tension (PvO2) is an important prognostic factor for pulmonary hypertension. The study was published in the journal "BMC Pulmonary Medicine, 2022." 

Pulmonary hypertension (PH) is a progressive disease that can lead to right ventricular dysfunction and death. It is characterized by abnormal remodeling of small pulmonary arteries, elevated pulmonary arterial pressure, and increased pulmonary vascular resistance. Much research has not been carried out on the prognostic value of mixed venous oxygen tension (PvO2) at pulmonary hypertension diagnosis treated with selective pulmonary vasodilators. Hence, researchers from Japan conducted a study to investigate the association of PvO2 with long-term prognosis in pulmonary arterial hypertension (PAH) and medically treated chronic thromboembolic pulmonary hypertension (CTEPH) and to identify the various mechanisms causing tissue hypoxia in patients with CTEPH or PAH.

A retrospective analysis was conducted from 1983 to 2018. There were 138 and 268 patients with PAH and CTEPH respectively. The mean age of patients with PAH was 50.2 ± 16.6 years with 81.9% women and in CTEPH patients was 57.4 ± 13.1 years with 72.8% women. The survival rates of patients with/without tissue hypoxia (PvO2 < 35 mmHg) and their prognostic factors based on the pulmonary hypertension risk stratification guidelines were analyzed.

Results: 

• Survival was significantly poorer in patients with tissue hypoxia than in those without it for PAH (P = 0.001) and CTEPH (P = 0.017) treated with selective pulmonary vasodilators.
• In patients with PAH, PvO2 was more strongly correlated with prognosis than other hemodynamic prognostic factors regardless of selective pulmonary vasodilators usage.
• PvO2 was the only significant prognostic factor in patients with CTEPH treated with pulmonary hypertension medication.
• Patients with CTEPH experiencing tissue hypoxia exhibited significantly poorer survival than those in the intervention group (P < 0.001).
• PvO2 was more strongly correlated with the cardiac index (CI) than the alveolar-arterial oxygen gradient (A-aDO2) in PAH, whereas in CTEPH, PvO2 was more strongly correlated with A-aDO2 than with CI. 

Thus, the researchers concluded that PvO2 may be an important prognostic factor for pulmonary hypertension. Tissue hypoxia has a prognostic impact on different aspects of PAH and CTEPH, reflecting their distinct pathogenesis. 

For the full article, click here: https://doi.org/10.1186/s12890-022-02073-0 

Nagata, J., Sekine, A., Tanabe, N. et al. Mixed venous oxygen tension is a crucial prognostic factor in pulmonary hypertension: a retrospective cohort study. BMC Pulm Med 22, 282 (2022).