(3)
The log-normal distribution uses the following parameters,
μ: mean of the natural logarithm of the data.
σ: standard deviation of the natural logarithm of the data.
The BSDs of the MBs generated by each manual operation ten times are
shown in Figure 6 (a, b, c, d).
The
results indicate that the size
distribution of microbubbles varied with the number of operations,
especially between 20-60 µm. The diameter of the bubbles is mainly
distributed in the range of 10-100 µm, with a wide distribution range.
These bubbles may affect the detection results of c-TCD after entering
the vein because the lifetime of the bubbles decreases as the bubble
size decreases, and large bubbles cannot pass through the capillaries
and fail to reach the foramen ovale. Eventually, the inhomogeneous
mixture of gas-liquid will cause hemodynamic changes.
Figure 7a compares the bubble size distribution averaged of 10
experiments performed by each person, with the curves being messy
between 15-80 μm, which also shows that the difference in results
between each individual is particularly obvious. In addition, the mean
bubble size, Sauter mean
diameter, and standard deviation value of 10 manual operations for each
volunteer are shown graphically
in Figure 7(b, c, and d). As can be seen, the reproducibility is
relatively poor. The mean bubble
size is between 21-34
μm,
the D32 is mainly
between 50-300 μm, and the maximum
standard deviation was close to
17 μm in 60 experiments. This initial inference has been strongly
validated that the velocity and strength of each manual operation vary
when pushing with the syringe leading to this phenomenon, especially
between individuals. Through the analysis of Figure 7 and Table 2, the
results show that the stronger the gas-liquid mixing, the more uniform
the state, and the mean bubble size and standard deviation of the
bubbles may decrease. These values are unstable with large fluctuations,
which provides a more accurate basis for the instability of the manual
method.