Patients alter power of breathing as the primary response to changes in pressure support ventilation

Introduction: The patient-ventilator relationship is dynamic as the patient's health fluctuates and the ventilator settings aremodified. Spontaneously breathing patients respond tomechanical ventilation by changing their patterns of breathing. This studymeasured the physiologic responsewhen pressure support (PS) settingsweremodified during mechanical ventilation. Methods: Subjects were instrumented with a non-invasive pressure, flow, and carbon dioxide airway sensor to estimate tidal volume, respiratory rate, minute ventilation, and end-tidal CO2. Additionally, a catheter was used to measure esophageal pressure and estimate effort exerted during breathing. Respiratory function measurements were obtained while PS settings were adjusted 569 times between 5 and 25 cmH2O. Results: Data was collected on 248 patients. The primary patient response to changes in PSwas to adjusting effort (power of breathing) followed by adjusting tidal volume. Changes in respiratory rate were less definite while changes in minute ventilation and end-tidal CO2 appeared unrelated to the change in PS. Conclusion: The data indicates that patients maintain a set minute ventilation by adjusting their breathing rate, volume, and power. The data indicates that the subjects regulate their Ve and PetCO2 by adjusting power of breathing and breathing pattern. (c) 2020 Elsevier Inc. All rights reserved.