Using the airway pressure (AP, yellow) and its first derivative (dAP/dt, grey) the following time points were identified as follows: “A” constitutes the beginning of the MM when patient is starting to inspire against an obstructed airway (AP decreases to at least to -5 mmHg, and dAPp/dt turns negative). “B” occurs when inspiratory efforts level off as the patient maintains stable negative intra-thoracic pressure (AP curve stops decreasing, and dAP/dt starts turning positive). “C” constitutes the end of breath as the patient expires with an open airway (AP curve increases by 5 mmHg or more from the maximum negative value; dAP/dt values are positive). “D” defines the end of the MM, when intra-thoracic pressure values return to baseline. “E” stands for the end of one breathing experiment, and was set at 3-5 seconds after point “D.” The interval of interest for the main analysis is depicted as a gray arrow.