## 3 Results
### The V/A-C Asynchronous Events  
The maximum inhalation and exhalation peaks for flow and pressure values were analyzed for the breathing cycles where the lung simulator interacts with the mechanical ventilator in phase (synchronous) as shown in Table 3. Additionally, the values were calculated for breathing cycles where the lung simulator and the mechanical ventilator are out of phase (asynchronous), which is characterized by the occurrence of double triggering. This asynchrony caused a significant increase of peak inspiratory pressure (\(7.96\pm 6.38\) vs. \(11.09\pm 0.49\) cmH\({}_{2}\)O, \(p<\)0.01)) and peak expiratory flow (\(-25.57\pm 8.93\) vs. \(32.90\pm 0.54\) L/min, \(p<\)0.01) when compared to synchronous phases of the breathing simulation. The differentiation resulted in a decrease of \(\sigma_{\rm FLOW}\) and \(\sigma_{\rm PRESSURE}\) during synchronous and asynchronous simulator-ventilator interaction in comparison to the nondifferentiated event analysis (see Tables 2 and 3).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{3}{*}{
\begin{tabular}{c} **Ventilator** \\ **Mode** \\ \end{tabular} } & \multirow{3}{*}{**Phase**} & **Peak** & **Peak** & **Peak** & **Peak** \\  & & **Inspiratory** & **Inspiratory** & **Expiratory** & **Expiratory** \\  & & **Flow** & **Pressure** & **Flow** & **Pressure** \\  & & **(\(\pm\sigma_{\rm FLOW}\))** & **(\(\pm\sigma_{\rm PRESSURE}\))** & **(\(\pm\sigma_{\rm FLOW}\))** & **(\(\pm\sigma_{\rm PRESSURE}\))** \\  & & **[L/min]** & **[cmH\({}_{2}\)O]** & **[L/min]** & **[cmH\({}_{2}\)O]** \\ \hline V/A-C & SB & 25.56 (\(\pm 1.34\)) & 7.96 (\(\pm 6.38\)) & \(-25.57\) (\(\pm 8.93\)) & 0.14 (\(\pm 0.20\)) \\  & SA & 26.43 (\(\pm 0.57\)) & 11.09 (\(\pm 0.49\)) & \(-32.9\) (\(\pm 0.54\)) & 0 (\(\pm 0.03\)) \\ \hline PSV & SB & 43.96 (\(\pm 0.01\)) & 10.18 (\(\pm 0.04\)) & \(-27.5\) (\(\pm 0.97\)) & 0.24 (\(\pm 0.08\)) \\  & SA & 41.19 (\(\pm 0.31\)) & 10 (\(\pm 0.02\)) & \(-32.16\) (\(\pm 0.51\)) & 0 (\(\pm 0.03\)) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Patient–ventilator interaction. Differentiation between phases: (1) spontaneous sinusoidal breathing (SB) and (2) simulated apnea (SA) for both V/A-C and PSV mode with a breathing frequency of 12 bpm.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & **Peak Inspiratory** & **Peak Inspiratory** & **Peak Expiratory** & **Peak Expiratory** \\
**Phase** & **Triggered** & **Flow** & **Pressure** & **Flow** & **Pressure** \\
**(V/A-C)** & **Event** & **(\(\pm\sigma_{\rm FLOW}\))** & **(\(\pm\sigma_{\rm PRESSURE}\))** & **(\(\pm\sigma_{\rm FLOW}\))** & **(\(\pm\sigma_{\rm PRESSURE}\))** \\  & & **[L/min]** & **[cmH\({}_{2}\)O]** & **[L/min]** & **[cmH\({}_{2}\)O]** \\ \hline SB & Synchronous & 25.06 (\(\pm 1.38\)) & 3.68 (\(\pm 1.21\)) & \(-19.53\) (\(\pm 0.45\)) & 0.24 (\(\pm 0.15\)) \\  & Asynchronous & 26.54 (\(\pm 0.49\)) & 16.48 (\(\pm 0.17\)) & \(-37.66\) (\(\pm 0.68\)) & \(-0.07\) (\(\pm 0.07\)) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Comparison of peak flow and pressure values for the recorded spontaneous sinusoidal breathing phase (SB) of the V/A-C mode. The mode introduced a forced inspiratory cycle (double triggering) based on the trigger event. The inspiratory and expiratory peaks are differentiated based on the trigger event. Synchronous: the lung simulator’s spontaneous breathing is in phase with the mechanical ventilator during V/A-C mode; asynchronous: the lung simulator and the mechanical ventilator are out of phase during V/A-C mode.