 Cardioventilatory coupling analysis Phase synchronization method for quantification of coupling between weakly coupled self-sustained oscillators here heart and ventilator will be implemented. The idea behind is that a good ventilatory mode should produce cardio-respiratory coordination indistinguishable from that observed in healthy subject during spontaneous breathing at the same frequency and amplitude. Phase synchronization technique is complemented with joint symbolic analysis and cross-conditional entropy assessing of cardio-respiratory coupling in terms of degree of repeatability of coordination schemes between heart rate signal and ventilation. These approaches have the main advantages that they are less sensitive to non-stationarities and they are capable of capturing nonlinear couplings over shorter data sequences. 