A study on visualization of nitriic oxide in humans

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In order to measure nitric oxide (NO) in human subjects, we have developed a realtime monitoring system especially design for a measurement of human exhaled NO.The system can exhibit not only the traces of exhaled NO (ppb) and CO2 but also air flow, VCO2, and VNO on the computer display. We can monitor the changes of exhlaed NO in a real time fashion. Visualization of NO is thus performed on the computer screen. This system consists of a chemiluminescence NO analyzer, an O2-CO2 analyzer, a gas flow meter, an AD/DA converting apparatus, signal delaying soft wear, a DA/AD converting apparatus, and the signal acquisition device (MacLab). The whole system was tested in the measurements of human exhaled NO and human nasal NO and turned out to be useful for the estimation of exhaled NO as well as nasal NO.We attempted to clarify the origin of exhaled NO in the human lower airway by using this device. The results demonstrated that the exhaled NO is likely to be produced in the peripheral airway, probably, terminal bronchioles. Because the exhaled NO increases when the expiration time and/or breath-hold time prolong and the alveolar ventilation increases. It was almost impossible to wash out NO in the airway by hyperventilation, suggesting that the NO is produced in the airway epithelia and continuously diffuses toward the airway cavity by its own high partial pressure within the epilthelia. Nasal NO was found to decrease by physical exercise along with a decrease in nasal airway resistance. In the clinical study, the exhaled NO from the patients with diffuse panbronchiolitis was measured to be very low. These patients exhibited low nasal NO as well. By using our device, accurate and quick measurement of exhaled NO was possible.