Are Transcutaneous Oxygen and Carbon Dioxide Determinations of Value in Pulmonary Arterial Hypertension?

Background We hypothesized that transcutaneous gas determinations of O 2 and CO 2 (TcPO 2 and TcPCO 2 ) are associated with the severity of PAH . Methods In this cross‐sectional study, we included consecutive patients with PAH (group 1 PH ; n  = 34). Transcutaneous gas determinations were compared to those of age‐ and gender‐matched healthy controls ( n  = 14), nongroup 1 PH ( n  = 19) or patients with high estimated RVSP on echocardiography but without hemodynamic evidence of PH ( n  = 12). Results In patients with PAH , TcPO 2 , and TcPCO 2 were significantly associated with PaO 2 ( R  = 0.44, p  = 0.03) and PaCO 2 ( R  = 0.77, p  < 0.001), respectively. TcPO 2 /FiO 2 (mean difference: −65.0 [95% CI : −121.3, −8.7]) and TcPCO 2 (mean difference: −7.4 [95% CI : −11.6, −3.1]) were significantly lower in patients with PAH than healthy controls. TcPCO 2 was useful in discriminating PAH patients from other individuals ( AUC : 0.74 [95% CI : 0.62, 0.83]). TcPO 2 /FiO 2 ratio was significantly associated with mean PAP , TPG , PVR , CI , SVI , DLCO , six‐minute walk distance and components of the CAMPHOR questionnaire. Conclusions Transcutaneous pressure of CO 2 was lower in patients with PAH . Transcutaneous pressure of O 2 over inspired fraction of O 2 ratio was inversely associated with severity of disease in patients with PAH .