title: Prognostic significance of PaO2/PaCO2 ratio in normotensive patients with pulmonary embolism.
abstract: BACKGROUND
  Risk stratification remains controversial in patients with normotensive pulmonary embolism (PE). The debate has recently focused right ventricular dysfunction detected by echocardiography or spiral computed tomography (CT) and cardiac biomarkers.
  
  
  OBJECTIVE
  The utility of the PaO(2)/PaCO(2) ratio to predict the short-term prognosis of PE is not currently known and that is the aim of the present study.
  
  
  METHODS
  This study retrospectively enrolled 99 (34 males, 65 females, 67 ± 15 years) consecutive patients with acute PE, diagnosed by spiral chest tomography pulmonary angiography (CTPA). On admission, cardiac troponin T (cTn-T) was measured and on CTPA both right ventricle diameter and left ventricle diameter was calculated (RV/LV ratio). During the first 24 h after admission, all the patients had initial arterial blood gas collected under room air. Receiver-operating characteristic (ROC) analysis was performed to determine the optimal PaO(2)/PaCO(2), RV/LV ratio and cTn-T cutoff level with regard to prognosis.
  
  
  RESULTS
  In-hospital mortality was 12.1% and all-cause 90-day mortality was 15.2%. Ten of 15 patients who died had a PaO(2)/PaCO(2) ≤ 1.8 based on ROC analysis (P < 0.014).The cutoff level of PaO(2)/PaCO(2) ≤ 1.8 had a high negative predictive value of 93% for mortality. Multivariable analysis revealed that PaO(2)/PaCO(2) ≤ 1.8 Hazard Ratio (HR): 16.8 [95% CI: 2.6-108, P < 0.003] was the most significant independent predictor, whereas cTn-T, pO(2) < 60 mmHg and cardiac failure were nonsignificant factors. In addition, PaO(2)/PaCO(2) ≤ 1.8 showed significant survival differences for overall mortality rates in Kaplan-Meier analysis (P < 0.012).
  
  
  CONCLUSIONS
  The PaO(2)/PaCO(2) measurement is a highly useful and practical measurement to predict prognosis in patients with acute PE. Moreover, it appears to be a more accurate predictor than RV/LV ratio and cTn-T levels in patients with normotensive PE.
authors.affiliation: Department of Pulmonary Medicine, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Savas
authors.initials: S
authors.lastname: Ozsu
authors.forename: Yasin
authors.initials: Y
authors.lastname: Abul
authors.forename: Ismail
authors.initials: I
authors.lastname: Yilmaz
authors.forename: Asiye
authors.initials: A
authors.lastname: Ozsu
authors.forename: Funda
authors.initials: F
authors.lastname: Oztuna
authors.forename: Yilmaz
authors.initials: Y
authors.lastname: Bulbul
authors.forename: Tevfik
authors.initials: T
authors.lastname: Ozlu
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011237:Predictive Value of Tests; D011379:Prognosis; D011655:Pulmonary Embolism / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology*; D012189:Retrospective Studies; D016277:Ventricular Function, Left / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen