Fig. 5.

Correlation sum (left) and correlation dimension (right) from dimension 2 to 6 for RI (top) and RE coupling (bottom) during ACV (black curves), IPS (green curves), and USB (red curves) in one patient. Ventilatory mode and respiratory timing have different effects on the correlation dimension of the coupling interval. In this example, during both ACV and IPS, the curves of the RI coupling converge to a single value that gives the value of the correlation dimension. For statistical analysis, an embedding dimension of 3 was chosen to estimate the correlation dimension of the experimental data. The RE coupling exhibits different correlation curves with curves converging to a single value only in the ACV mode. The black arrow shows the point of convergence during ACV and green arrow, during IPS.