title: Postural variations of pulmonary diffusing capacity in insulin-dependent diabetes mellitus.
abstract: OBJECTIVE
  To assess whether posture-related changes of diffusing capacity could be considered as an early sensitive marker of pulmonary abnormalities in patients with insulin-dependent diabetes mellitus (IDDM) and whether the postural variations of pulmonary capillary blood volume (Vc) could reflect the lung capillary damage that characterizes the diabetic microangiopathy.
  
  
  METHODS
  Carbon monoxide diffusing capacity (DCO) was measured by the single-breath method. Four DCO measurements, two in sitting and two in supine position, were performed in each subject using gas mixtures containing different oxygen concentrations. Membrane and capillary volume components of the diffusion capacity were calculated and both were expressed as absolute value and corrected by alveolar volume (VA).
  
  
  METHODS
  Twenty IDDM patients and 20 normal subjects matched for age and sex were studied.
  
  
  RESULTS
  The IDDM patients showed normal pulmonary volumes and flows. No significant differences between the two groups were found for DCO, coefficient of diffusion, Vc, and pulmonary capillary blood volume corrected by alveolar volume in sitting position. All these indexes significantly increased in normal subjects but not in diabetics, by changing the posture of the subject from sitting to supine position. In a multivariate analysis, the presence of diabetes mellitus and the age of the subjects were the only significant predictors of Vc postural changes.
  
  
  CONCLUSIONS
  This postural test, adjusted for age, could be included in a screening diagnostic procedure for an early assessment of pulmonary abnormalities in diabetic patients. The lack of Vc postural increase in diabetics could reflect the presence of a microangiopathy involving the pulmonary small vessels.
authors.affiliation: Department of Respiratory Physiology, Catholic University, Rome, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Fuso
authors.forename: P
authors.initials: P
authors.lastname: Cotroneo
authors.forename: S
authors.initials: S
authors.lastname: Basso
authors.forename: M
authors.initials: M
authors.lastname: De Rosa
authors.forename: A
authors.initials: A
authors.lastname: Manto
authors.forename: G
authors.initials: G
authors.lastname: Ghirlanda
authors.forename: R
authors.initials: R
authors.lastname: Pistelli
mesh_terms: D000328:Adult; D015415:Biomarkers; D001810:Blood Volume; D002196:Capillaries / Q000502:physiology; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008168:Lung / Q000098:blood supply; D008297:Male; D015999:Multivariate Analysis; D011187:Posture; D011652:Pulmonary Circulation; D011653:Pulmonary Diffusing Capacity; D012129:Respiratory Function Tests
chemical_list: D015415:Biomarkers