PURPOSE:Isolated abnormalities in DLCO are often seen during pulmonary function testing (PFT). There are very few studies evaluating the significance of these abnormalities.
METHODS:All pfts done from January 2006 to March 2008 were analyzed retrospectively. Studies with normal flow rates and lung volumes were excluded. Demographic data,Chest CT scans, and echocardiographic reports of the patients with isolated DLCO abnormalities were reviewed. The frequency procedure was used to analyze the data.
RESULTS:1777 complete PFTs (spirometry, lung volumes and DLCO) were performed during this period. 124 patients had isolated reduction in DLCO. Average DLCO was 53% of predicted, with normal flow rates and lung volumes. The study group included 31 of these patients in whom Chest CT scan and Echocardiography were available. Mean age was 60 yrs; 65% were females (21); 56% were smokers (18). There was no significant corelation with age, race or BMI. The clinical indication for doing PFTs were Obstructive Airway Disease (OAD) in 15, (46%), Interstitial lung disease (ILD) in 8 pts (25%), unexplained dyspnea in 5 (15%) and miscellaneous in 3 pts. Chest CT findings were as follows: Interstitial infiltrates in all the pts with ILD; Pts with OAD had interstitial disease in 7, emphysema in 3 pts and normal in 5 pts. In pts with unexplained dyspnea 3 out of 5 pts had interstitial abnormalities on Chest CT scan. Plain Chest X-Ray did not reveal these changes in pts with OAD and unexplained dyspnea. Echocardiography revealed Diastolic dysfunction in 60% and elevated Right Ventricular Systolic Pressure (above 35 mm of Hg) in 38%. Pulse oximetry was above 90% in all with a mean of 95.2%.
CONCLUSION:Isolated DLCO abnormalities can be seen in patients with interstitial lung disease, OAD, and unexplained dyspnea without alterations in flow rates and lung volumes. Pulmonary hypertension or Diastolic dysfunction may also be seen in association..
CLINICAL IMPLICATIONS:Isolated reductions in DLCO in patients suspected to have OAD, and unexplained dyspnea, should alert the physician of additional lung and cardiac pathology and prompt radiographic evaluation such as HRCT and Echocardiography.
DISCLOSURE:Ibrahim Abou Daya, No Financial Disclosure Information; No Product/Research Disclosure Information