title: Conditions associated with severe carbon monoxide diffusion coefficient reduction.
abstract: OBJECTIVE
  To identify conditions associated with severe carbon monoxide transfer coefficient reduction (Kco < 40% of predicted values).
  
  
  METHODS
  We retrospectively reviewed pulmonary function tests, such as Kco measurement, in consecutive patients evaluated in the physiology unit of a University hospital over a 6-year period. Patients were included if they had at least 1 measure of severe Kco reduction, with further detailed pulmonary function tests, clinical data, and diagnostic procedures conducted within 6 months.
  
  
  RESULTS
  5576 patients underwent 9061 Kco measurements. 195 patients (3.5%) with Kco < 40% were investigated (156 males; mean age 62 ± 12 years). Mean Kco was 29 ± 9% of predicted values. The main conditions associated with severe Kco reduction were: emphysema (46%); interstitial lung disease (28%); combined pulmonary fibrosis and emphysema (16%); and pre-capillary pulmonary hypertension (8%). Systolic pulmonary artery pressure was ≥ 35 mmHg at echocardiography in 88% of patients. Right heart catheterization performed in 97 patients showed pre-capillary pulmonary hypertension in 86 of 195 patients (44%). Pulmonary hypertension was the most frequent condition associated with Kco severe reduction. Pulmonary hypertension was present in 29%, 53%, and 48% of patients with chronic obstructive pulmonary disease, interstitial lung disease, and combined pulmonary fibrosis and emphysema, respectively, and was disproportionate to the parenchymal lung disease (mean pulmonary artery pressure > 35 mmHg) in 63% of cases.
  
  
  CONCLUSIONS
  Severe Kco reduction is frequently related to pulmonary hypertension, especially when associated with emphysema and/or interstitial lung disease. Systematic echocardiography is thus warranted in any patient with severe Kco diminution.
authors: Hôpital Louis Pradel, Service de Pneumologie - Centre de Référence des Maladies Rares Pulmonaires, France. kiaslili@yahoo.fr
authors: Lize
authors: L
authors: Kiakouama
authors: Vincent
authors: V
authors: Cottin
authors: Jean-Charles
authors: JC
authors: Glerant
authors: Jean-Yves
authors: JY
authors: Bayle
authors: Jean-François
authors: JF
authors: Mornex
authors: Jean-François
authors: JF
authors: Cordier
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000403:Airway Resistance / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D002248:Carbon Monoxide / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011650:Pulmonary Alveoli / Q000503:physiopathology; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D002248:Carbon Monoxide