title: Association of Anemic Hypoxia and Increased Pulmonary Artery Systolic Pressure in Patients With Systemic Lupus Erythematosus.
abstract: OBJECTIVE
  Pulmonary arterial hypertension (PAH) is a rare but serious complication of systemic lupus erythematosus (SLE). Chronic hypoxia is known to cause PAH resulting from pulmonary vascular remodeling. We investigated the association between anemic hypoxia and PAH in SLE patients.
  
  
  METHODS
  Systolic pulmonary artery pressure (PAP) was measured in 132 SLE patients by echocardiography. Increased PAP was defined as resting PAP > 40 mm Hg. Oxygen delivery (DO2) was estimated as the product of cardiac output and arterial oxygen content.
  
  
  RESULTS
  Of 132 patients, 17 (12.9%) had increased PAP, and these patients had significantly lower DO2 values than patients with normal PAP (P = 0.002). The DO2 values inversely correlated with PAP values (γ = -0.308, P < 0.001) and plasma N-terminal pro-brain natriuretic peptide levels (γ = -0.323, P = 0.001), but positively correlated with hemoglobin levels (γ = 0.402, P < 0.001). Compared to those with normal PAP, patients with increased PAP had significantly longer durations of anemia over the preceding 6-24 months. Patients with anemia of longer durations (≥3 months) in the preceding 6 months had a higher risk of increased PAP compared to those with shorter durations (P < 0.001). When SLE patients were divided into 3 groups according to hemoglobin and PAP, serum interleukin-6 (IL-6) levels increased across groups with higher PAP (P = 0.001 for trend), but decreased across tertiles of hemoglobin levels (P = 0.008 for trend).
  
  
  CONCLUSIONS
  Our data indicate an association between chronic anemic hypoxia and increased PAP in SLE patients and suggest that increased IL-6 might participate in this process.
authors.affiliation: St. Vincent Hospital, The Catholic University of Korea, Suwon, Republic of Korea.
authors.forename: Ki-Jo
authors.initials: KJ
authors.lastname: Kim
authors.affiliation: Yeouido St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: In-Woon
authors.initials: IW
authors.lastname: Baek
authors.affiliation: Uijeongbu St. Mary's Hospital, The Catholic University of Korea, Uijeongbu, Republic of Korea.
authors.forename: Chong-Hyeon
authors.initials: CH
authors.lastname: Yoon
authors.affiliation: Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Wan-Uk
authors.initials: WU
authors.lastname: Kim
authors.affiliation: Yeouido St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Chul-Soo
authors.initials: CS
authors.lastname: Cho
mesh_terms: D000740:Anemia / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D062186:Arterial Pressure; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D015150:Echocardiography, Doppler; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D000860:Hypoxia / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D015850:Interleukin-6 / Q000097:blood; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D010100:Oxygen / Q000097:blood; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D056910:Republic of Korea; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D006454:Hemoglobins; C508600:IL6 protein, human; D015850:Interleukin-6; D010100:Oxygen