Non-invasive assessment of pulmonary blood flow using an inert gas rebreathing device in fibrotic lung disease
- Tamera J Corte1,
- Athol U Wells1,
- Michael A Gatzoulis1,
- Derek Cramer1,
- Simon Ward1,
- Peter S Macdonald2,
- Konstantinos Dimopoulos1,
- Stephen J Wort1
- 1Royal Brompton Hospital and National Heart and Lung Institute, London, UK
- 2University of New South Wales, Sydney, Australia
- Correspondence to Dr Stephen John Wort, Pulmonary Hypertension Unit, Royal Brompton Hospital, Sydney St, London SW3 6NP, UK;
- Received 5 June 2009
- Accepted 30 January 2010
Background and aims Pulmonary hypertension (PH) is increasingly recognised in patients with diffuse lung disease, and is associated with increased mortality. Cardiac output (CO) is a prognostic marker in PH. Non-invasive assessment of pulmonary blood flow (PBFINNOCOR) with the inert gas rebreathing Innocor device has been validated against CO in PH, but not in PH associated with parenchymal lung disease. PBFINNOCOR may be less accurate in patients with lung disease because of intrapulmonary shunting and/or incomplete gas mixing. Our aim was to determine the variability of PBFINNOCOR in normal subjects, before evaluating PBFINNOCOR in diffuse lung disease against CO measured by the indirect Fick method (COFICK) at right heart catheterisation (RHC).
Methods and results 23 normal subjects had lung volume measurements by a constant-volume body plethysmograph and three consecutive PBFINNOCOR measurements on the same day. 20 subjects returned for repeat assessment. PBFINNOCOR had good intrasession repeatability (coefficient of variation (CV)=6.57%) and intersession reproducibility (mean CO difference=0.13; single determinant SD=0.49; CV=9.7%). 28 consecutive patients with lung fibrosis referred for RHC had PBFINNOCOR measured within 24 h of RHC. There was good agreement between COFICK and PBFINNOCOR, with no evidence of systematic bias (mean COFICK 4.3±1.0; PBFINNOCOR 4.0±1.2l/ min; p=0.07). Bland–Altman analysis revealed a mean difference of −0.32 and limits of agreement of −2.10 to +1.45.
Conclusion Non-invasive PBF measured by the inert gas rebreathing Innocor device has good intrasession repeatability and intersession reproducibility. In diffuse lung disease, CO can be accurately and non-invasively measured by the Innocor device.
- Cardiac output
- interstitial fibrosis
- pulmonary artery pressure
- pulmonary blood flow
- pulmonary fibrosis
- pulmonary hypertension
Funding Actelion Pharmaceuticals-Educational Grant.
Competing interests None.
Ethics approval This study was conducted with the approval of the Brompton, Harefield and NHLI Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.