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Aim: We performed a stress assessment of noninvasive positive pressure ventilation (NPPV) using the salivary biomarkers chromogranin A. Materials & methods: Twenty healthy volunteers were subjected to NPPV for 30 min. We collected saliva samples before and after NPPV and evaluated chromogranin A. Results: We collected saliva samples from 13 volunteers for enzyme measurement. Of the 13 volunteers, 11 showed elevated chromogranin A levels, which were significantly higher after NPPV than before NPPV (p < 0.01). The chromogranin A increase group displayed significantly increased leak flow and reduced respiratory rate and absolute humidity compared with the chromogranin A reduction group. Conclusion: The increase of leak volume might be a stress factor in patients receiving NPPV.

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Hepatitis C virus infects and causes inflammation in extrahepatic organs and the liver. Patients with chronic hepatitis C disease receive interferon-based treatment, and both interferon and interferon-free therapies are expensive. We attempted to eliminate hepatitis C virus-infected cells using extracorporeal circulation with a unique filter. We created two types of the filters with syndiotactic polystyrene (SPS) resin sheets in a solution that dissolved hydroxypropyl cellulose (HPC) and cellulose acetate (CA) in oleyl alcohol, respectively. First, hepatitis C virus-positive cells were confirmed in the blood and mononuclear cells of hepatitis C virus-infected volunteers, showing that mononuclear cells phagocytosed the hepatitis C virus. Next, we extracted blood from three healthy volunteers and examined the blood cell removal rate using various filters. The HPC-SPS (fiber diameter, 3.5 µm) showed the highest mononuclear cell removal rate and the lowest platelet removal rate. HPC-SPS reduced hepatitis C virus-positive cells in patients with the hepatitis C virus, and the removal rate of monocytes containing the hepatitis C virus was 77.2%. Thus, HPC-SPS may serve as filter to remove mononuclear cells and granulocytes from blood. Although a technique using extracorporeal circulation is required to apply HPC-SPS, the technical cost is lower than IFN-free drug therapy. We believe that HPC-SPS can be utilized for the treatment of HCV-and leukocyte-related diseases.

Noninvasive ventilator connects a one-way circuit with leak and delivers inspired gas via the upper airway tract. A heated humidifier don't have to connect to contain heat and moisture exchange humidity in the upper airway functions. However, there are many case connecting a heated humidifier to be inadequate humidity in the upper airway. The purpose of this study was to clarify the influence of absolute humidity on leak and inspiratory positive airway pressure during noninvasive positive pressure ventilation. We connected respiratory machine, a heated humidifier and a model lung via two type circuits. One circuit was a single-limb breathing with an exhalation port and another was two-way circuits to distinguish the inspiratory from the expiratory via Y-piece. Two heated humidifiers were included in both inspiratory and expiratory circuits to simulate the physical lung. Relative humidity, temperature and flow rate were measured for 30 minutes. Absolute humidity was calculated using the Teten's equation and a gas state equation with relative humidity and temperature. In results, flow rate increased and absolute humidity decreased, when leak volume increased. We presumed that warmer humidified gas was discharged through the leak port with increasing flow rate to compensate leak. However, absolute humidity slightly was not associated with higher inspiratory positive airway pressure at the steady leak. We supposed that expiratory gas was not capable to discharge due to increasing flow rate and might be accumulated into the mask. The expired gas temperature accumulated in the mask might affect the inspired absolute humidity. Consequently, we are desirable to measure the inspired gas temperature and absolute humidity. In conclusion, absolute humidity would depend on leak during noninvasive positive pressure ventilation.