Monitoring cardiac output (CO) is important for the management of patient circulation in an operation room (OR) or intensive care unit (ICU). We assumed that the change in pulse wave transit time (PWTT) obtained from an electrocardiogram (ECG) and a pulse oximeter wave is correlated with the change in stroke volume (SV), from which CO is derived. The present study reports the verification of this hypothesis using a hemodynamic analysis theory and animal study. PWTT consists of a pre-ejection period (PEP), the pulse transit time through an elasticity artery (T(1)), and the pulse transit time through peripheral resistance arteries (T(2)). We assumed a consistent negative correlation between PWTT and SV under all conditions of varying circulatory dynamics. The equation for calculating SV from PWTT was derived based on the following procedures. 1. Approximating SV using a linear equation of PWTT. 2. The slope and y-intercept of the above equation were determined under consideration of vessel compliance (SV was divided by Pulse Pressure (PP)), animal type, and the inherent relationship between PP and PWTT. Animal study was performed to verify the above-mentioned assumption. The correlation coefficient of PWTT and SV became r = -0.710 (p 〈 0.001), and a good correlation was admitted. It has been confirmed that accurate continuous CO and SV measurement is only possible by monitoring regular clinical parameters (ECG, SpO2, and NIBP).
BackgroundExhaled volatile organic compounds (VOC) are being considered as biomarkers for various lungs diseases, including cancer. However, the accurate measurement of extremely low concentrations of VOC in expired air is technically challenging. We evaluated the clinical contribution of exhaled VOC measured with a new, double cold-trap method in the diagnosis of lung cancer.MethodsBreath samples were collected from 116 patients with histologically confirmed lung cancer and 37 healthy volunteers (controls) after inspiration of purified air, synthesized through a cold-trap system. The exhaled VOC, trapped in the same system, were heat extracted. We analyzed 14 VOC with gas chromatography.ResultsThe concentrations of exhaled cyclohexane and xylene were significantly higher in patients with lung cancer than in controls (p = 0.002 and 0.0001, respectively), increased significantly with the progression of the clinical stage of cancer (both p < 0.001), and decreased significantly after successful treatment of 6 patients with small cell lung cancer (p = 0.06 and 0.03, respectively).ConclusionMeasurements of exhaled VOCs by a double cold-trap method may help diagnose lung cancer and monitor its progression and regression.
Total hemoglobin (tHb), carboxyhemoglobin (COHb), and methemoglobin (MetHb) are usually measured with a CO-oximeter. Noninvasive and continuous measurement of these blood components is expected to decrease the pain of a patient. Therefore, we developed an instrument to measure oxygen saturation (SpO(2), tHb, COHb, and MetHb non invasively. Multiwavelength LED (600, 625, 660, 760, 800, 940, and 1300 nm) and a combined detector (Si, InGaAs) were built into the instrument (Seven wavelengths transparent pulse spectrophotometer). We used the Waseda mock circulatory system, which can simulate blood circulation in tissues and generate a pulse wave mechanically, to estimate the instrument's performance. Furthermore we proposed new calculation formula including DC components of optical density (this method). Under conditions without any change of other components, the mean error +/- standard deviation between this method and the CO-oximetry were SaO(2)=0.0 +/- 1.4%, tHb=0.0 +/- 0.0 g/dl, COHb=0.0 +/- 2.0%, and MetHb=0.0 +/- 0.3%. When the concentration of other components was changed, this method showed mean errors and standard deviations of SaO(2)=0.2 +/- 1.6%, tHb=0.0 +/- 0.4 g/dl, COHb=0.5 +/- 4.1%, and MetHb=0.0 +/- 0.3%
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