The secretion clearance mode (SCM) provided by a biphasic cuirass ventilator (RTX^®) promotes airway clearance. SCM affects intrathoracic pressure and can change central hemodynamics. However, its effect on brain hemodynamics remains unknown. Hence, to investigate the effect of SCM on cerebral blood flow, the regional oxygen saturation (rSO₂) of the frontal lobe during SCM was measured using near-infrared spectroscopy. In three cases where SCM was used to improve pneumonia, the average amount of change in the rSO₂ during SCM was－2.1 to + 5.1% and did not correlate with the MAP, SpO₂, or PaCO₂. The findings suggested no abnormal changes in cerebral blood flow during the SCM.