In COPD patients on prolonged mechanical ventilation heart rate variability during the T-piece trial is better after pressure support plus PEEP: A pilot physiological study

Abstract Objectives To evaluate heart rate variability (HRV), hemodynamics, mechanics, dyspnea and blood gases following different mechanical ventilation (MV) settings. Background No study has evaluated physiological changes during T-piece trials following different MV settings. Methods In 8 COPD patients on prolonged MV we applied in random order two MV settings: i) pressure support (PS) 20 cm H 2 O + positive end-expiratory pressure(PEEP) 0 cm H 2 O (setting-1) and ii) PS 15 cm H 2 O + PEEP 5 cm H 2 O (setting-2), each followed by a 30 min T-piece trial. Results Setting-1 induced greater minute ventilation, tidal volume/inspiratory time and lower pulmonary artery occlusion pressure; setting-2 reduced intrinsic PEEP. Mechanics and hemodynamics data did not differ, but all HRV time domain indices were reduced only after setting-1, suggesting a decreased parasympathetic and increased sympathetic cardiac modulation. Conclusions The T-piece trial following setting-2 seems less stressful on neural control of HRV. Future studies on T-piece trials should consider the residual effect of the MV setting.