Welcome to Cross-Canada Paediatric - Respiratory Residency Rounds
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Latent PFT findings in the absence of clinical or radiological lung disease
– Normal
– Reduced transfer factor for CO (DLco)
– Airway obstruction
– Hyperinflation
– Restrictive pattern

Studies investigating latent PFT findings
– Abnormal PFTS (restrictive/obstructive) 9, 10
– No impairment in PFTs 2, 11
– Reduced FEV1 3
– Reduced DLco 1, 4, 7, 10, 11
– Increased bronchial responsiveness 12

Effect of treatment on latent PFT findings:
Normal PFTs were found in subjects with IBD. DLco was decreased in active disease. Dysfunction of small airways, measured by density dependence to calculate maximal expiratory flow rates, was shown.13 Normalization of this small airway dysfunction occurred with steroid treatment.

Additional points to be make note of:
– Role of treatment side-effects e.g. hypersensitivity pneumonitis is seen with Sulfasalazine up to 7 months after start date. Abnormalities improve with cessation of drug.
– TNFalpha and IL6 are elevated in crohns disease and have also been shown to play a role in sarcoid.
– Raised CD4/CD8 levels have been shown in active disease. Abnormally high CD4/CD8 have also been shown in induced sputum in active disease compared with remission. 14, 15
– Expired nitric oxide (eNO) is increased in active disease and correlates with disease activity in 55 adults with IBD (31 CD). eNO was obtained from aspirated colonic gas. A negative correlation was shown between disease activity and spirometry. Findings were stronger for UC than for CD. 16

Published cases of pulmonary crohns disease in children
– 13 year old girl with CD and recent onset asthma 17
– 15 year old girl with exercise dyspnea, abdominal pain, ÆRML 18
– 3 year old boy swollen gums and CXR changes 19
– 17 year old boy with abdominal symptoms and consolidation LLL 20

Munck A et al "Latent pulmonary function abnormalities in children with Crohns disease. ERJ 1995
1 This is the main published study of pulmonary involvement of Crohns disease in children.
– 26 children with CD (mean 14 years)
– None with pulmonary symptoms
– 20 acute, 10 remission (using LLoyd-Still index)
– CXR, PFT, DLco on all
– CXR normal in all
– Lung volumes not different overall (3/20 acute showed restrictive pattern)
– (DLco in acute disease (53±15%)
– Higher DLco in remission (81±19%) although some DLco levels still abnormally low.
– No relationship between DLco and disease severity
– Study suggests latent pulmonary involvement in children with crohns disease


Pulmonary symptoms are found in Crohns disease
– Pulmonary symptoms usually follow the onset of GI disease by days to decades
– Subclinical pulmonary dysfunction is common, as measured by DLco and PFTs
– This dysfunction persists even during remission
– Unclear whether DLco/PFTs are dependent on disease severity

Bibliography on the next page.

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