# Determining Obstruction in Endotracheal Tubes Using Physical Respiratory Signals
## 3 Results
### Feature Extraction Results
#### 3.2.2 Texture Analysis Results  
Texture analysis of Phases A, B, and C for flow revealed that only Phase C showed significant results. The texture analysis of average data revealed that the control data for flow showed significant differences except for the 20% obstruction case of Section 2  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Control** & **Section** & **Trial** \\ \hline \multirow{6}{*}{0.021} & & 20\% & 0.021 \(\pm\) 0.0025 \\  & 1 & 40\% & 0.025 \(\pm\) 0.0024 *** \\  & & 50\% & 0.03 \(\pm\) 0.0029 *** \\  & & 20\% & 0.016 \(\pm\) 0.0017 *** \\  & 2 & 40\% & 0.017 \(\pm\) 0.0017 *** \\  & & 50\% & 0.015 \(\pm\) 0.0015 *** \\  & & 20\% & 0.015 \(\pm\) 0.0017 *** \\  & 3 & 40\% & 0.014 \(\pm\) 0.0014 *** \\  & & 50\% & 0.014 \(\pm\) 0.0013 *** \\ \hline \hline \end{tabular} M \(\pm\) SD, *** \(p\) \(<\) 0.001.  
\end{table}
Table 1: Statistical significance test results of absolute average analysis for all Sections and degrees of obstruction compared to flow rate control conditions.  
Figure 8: Graph of absolute average analysis result for Phase C of flow.  
(\(p\) = 0.806) and 40% obstruction case of Section 3 (\(p\) = 0.134) (Table 3). Analysis of the degree of obstruction between all Sections and by Section indicated significant differences in all cases (\(p\) < 0.05) except for between 40% and 50% obstruction cases of Section 2 (\(p\) = 0.337). Both the location and degree of obstruction were significant in the combined microphone and flow sensor signal.  
Figure 9 shows the texture analysis results. Figure 9a shows the average results of the texture analysis. The combined microphone and flow rate data showed the largest values compared to all other degrees and locations of obstruction. The averaged flow data results of the texture analysis showed a trend similar to that of the absolute average analysis results. Figure 9b,c show the skewness and kurtosis of the texture analysis, respectively. The combined microphone and flow sensor data showed the smallest value compared with all other degrees and locations of obstruction. The degree of obstruction results for Section 1 showed that the value was lower with a higher degree of obstruction and the value at 20% obstruction was similar to that of the control. In Section 2, no trend was observed. In Section 3, unlike in Section 1, the value increased with an increase in the degree of obstruction. Table 4 shows the linear model results for the degree of obstruction according to the location of obstruction. The location of obstruction results showed that the value increased as the location of obstruction moved away from the mouth, regardless of the degree of obstruction.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Control** & **Section** & & **Trial** \\ \hline \multirow{5}{*}{54.76} & \multirow{5}{*}{2} & 20\% & 55.73 \(\pm\) 4.632 \({}^{*}\) \\  & & 40\% & 59.24 \(\pm\) 4.719 *** \\  & & 50\% & 63.31 \(\pm\) 4.746 *** \\  & & 20\% & 54.67 \(\pm\) 4.502 \\  & & 40\% & 56 \(\pm\) 4.518 ** \\  & & 50\% & 56.36 \(\pm\) 4.523 *** \\  & & 20\% & 52.56 \(\pm\) 4.56 *** \\  & & 40\% & 54.2 \(\pm\) 4.525 \\  & & 50\% & 56.34 \(\pm\) 4.423 *** \\ \hline \end{tabular} M \(\pm\) SD, \({}^{*}\)\(p\) < 0.05, \({}^{**}\)\(p\) < 0.01, \({}^{***}\)\(p\) < 0.001.  
\end{table}
Table 3: Statistical significance test results of texture analysis for average by all Sections and degrees of obstruction against flow control conditions.  
Figure 9: Texture analysis result graph for Phase C of flow and microphone + flow. (**a**) Average result graph, (**b**) skewness result graph, and (**c**) kurtosis result graph.