The single-breath nitrogen test, mortality, and cancer

Previous studies have demonstrated a relationship between mortality from lung diseases, such as chronic obstructive pulmonary disease, and impaired lung function. In these studies, lung function was determined by measuring the forced expiratory volume (FEV). FEV refers to the amount of air that can be forcefully exhaled from the lungs during a specified time interval (usually 30 seconds or 1 minute). Previous studies concluded that a reduced FEV was directly related to impaired lung function and mortality from lung disease. The single-breath nitrogen test (SBNT) is another test that is used to evaluate lung function. This test involves inhaling pure oxygen in a deep breath and then exhaling fully at a steady rate. The amount of nitrogen present in the exhaled air is measured and related to the total volume of air exhaled. This gives a measure of how well the lung membranes can exchange gases between the air and the blood. If lung function is impaired, then the ability to exchange gases across the lung membranes will be reduced. Previous studies have come to different conclusions as to whether the results of an SBNT are related to overall mortality or mortality from lung disease. To investigate this further, 876 men (521 were smokers) were evaluated for lung function using FEV and SBNT. The men were aged 46 to 69 when the study began in 1974, and they were followed for the next 10 years. The study showed that FEV was related to mortality from lung disease, but was not related to cancer. No relationship was found between SBNT and overall mortality, overall cancer risk, or lung cancer. It is concluded that SBNT has no predictive value concerning overall mortality or risk of cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)