15 Mar

Effects of Injection Site on the Accuracy of Thermal Washout: Methods and Materials (5)

Due to the relatively small diameter of the circuit (internal diameter, 20 mm), outflow resistance of the chamber was apparent; however, the power of the motor was sufficient to eject stroke volume forcefully, and no regurgitation or leakage was observed. birth control yasmin
Measurement Principles
We adopted the thermal washout technique of Holt for the measurement of right ventricular end diastolic volume (KVEDV) and RVEF. When the cold water was injected into the RV or RA, the thermal washout curve of RV could be obtained for the pulmonary artery with the aid of the rapid response thermistor shown in Figure 2. Four successive end-diastolic plateaus were detected and the three serial EFs were calculated (EF1, EF2, and EF3), as well as EFmean (mean of three EFs) (Fig 2). Clinically, end-diastolic plateaus in the thermal washout curve were determined by the method described previously, briefly outlined as follows: the radial arterial pressure wave, the electrocardiogram, and the thermal washout curve were recorded simultaneously on a microcomputer (PC9801, NEC, Tokyo, Japan) via a commercially available AD converter, and the four successive end-diastolic plateaus were determined by calculating the mean values of the thermal change recorded every 20 ms between the end of QRS and the start of the rapid deflection of arterial systolic wave, starting with the first R-wave occurring after the peak deviation on the thermodilution curve.


Figure 2. Principles in measuring ejection fraction.

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