Determinants of skin contact pressure formation during non-invasive ventilation.

There is no published data about mask features that impact skin contact pressure during mask ventilation. To investigate the physical factors of skin contact pressure formation. We measured masks with original and reduced air cushion size and recorded contact pressure. We determined cushion contact and mask areas by planimetric measurements. Contact pressures necessary to prevent air leakage during inspiration exceed inspiratory pressure by 1.01+/-0.41 hPa independent of cushion size. Contact area, ventilator pressure and mask area during inspiration and expiration impact contact pressure. Mask contact pressures are higher during expiration. The contact pressure increases with increase in inspiratory pressures independent of the ventilator cycle. During expiration, the contact pressure will increase in proportion to the expiratory pressure reduction of the ventilator. The mask with reduced air cushion size developed higher contact pressures. Contact pressure can be reduced by selecting masks with a small mask area in combination with a large mask cushion.