Abstract
An automatic pressure regulator for the endotracheal tube cuff was developed, which can maintain cuff pressure constantly at any pre-set level regardless of the ambient（chamber）pressure change during OHP therapy and of the diffusion of N2O into the cuff during anesthesia.
This device consists of a pressure reducing valve a pressure, setting dial and a fail-safe system.
This device is placed between the hospital piping system and the inflating line of the endotracheal tube and can continuously supply low pressure, low flow gas to the cuff to maintain cuff pressure at any desired level. Excess gas is released from the system simultaneously.
When the ambient pressure increases, the pressure regulator of this system senses the change and supplies extra gas to the cuff, so that relative gradient between the intra-cuff pressure and ambient pressure is kept constant. This device has the fail-safe system which works when pressure of the hospital piping system decreases abnormally.
So far no trouble has been encountered in using the pressure regulator during OHP therapy.
