Correlation between 6-minutes Walking Test and DLCO in patients with Idiopathic Interstitial Pneumonitis as an Indicator for Arterial Deoxygenation

Abstract

Idiopathic interstitial pneumonias (IIPs) are interstitial lung diseases of unknown etiology that share similar clinical and radiological features and are distinguished primarily by the histopathologic patterns on lung biopsy. Diagnosis is based on history, physical examination, high-resolution CT imaging, pulmonary function tests, and lung biopsy. Treatment varies by subtype. Prognosis varies by subtype and ranges from excellent to nearly always fatal(ATS and ERS, 2002). Measurements that can be made periodically to objectively assess changes in physiologic function over time include formal dyspnea assessment tools, the forced vital capacity (FVC), diffusion capacity of the lung for carbon monoxide (DLCO), and the 6-minute walk test (6-MWT) distance and oxyhemoglobin saturation change. A test of the diffusing capacity of the lungs for carbon monoxide (DLCO) is one of the most clinically valuable tests of lung function. DLCO measures the ability of the lungs to transfer gas from inhaled air to the red blood cells in pulmonary capillaries reflecting arterial deoxygenation(Macintyre et al., 2005). This prospective study was done to study the correlation between 6 minutes walking test and DlCO in patients with Idiopathic Interstitial Pneumonitis admitted at Ain Shams Hospital as an indicator for arterial deoxygenation. The study group consisted of 25 outpatients (13 were males &12 females), with mean age 52.2 ± 12.39. The following parameters were fulfilled for all the patients: 1. Full history taking. 2. Thorough clinical examination. 3. Chest X-ray 4. High Resolution Computerized Tomography (HRCT) 5. Full Spirometric study 6. DLCO before 6 minutes walk test 7. Oxygen Saturation using Pulse Oximetry before and after 6 -MWT 8. 6 minutes walk test (6 -MWT) The results of this study were: 1- There was a +ve correlation between DLCO defect and resting Spo2 in a group of patients with mild DLCO defect, there was a +ve correlation between DLCO defect and post exertion Spo2 in a group of patients with mild DLCO defect, there was a –ve correlation between DLCO defect and difference saturation Spo2 in a group of patients with mild DLCO defect. 2-There was a +ve correlation between DLCO defect and Resting Spo2 in a group of patients with moderate DLCO defect, There was ws a +ve correlation between DLCO defect and Post exertion Spo2 in a group of patients of moderate DLCO defect, there was a –ve correlation between DLCO and Difference saturation ( resting and post exertion Spo2 ) in a group of patients with Moderate DLCO defect. 3-There was a + ve correlation between DLCO defect and Resting Spo2 in a group of patients with severe DLCO