A breathing assistance device with improved pressure characteristics is disclosed. The device is capable of providing a high level of CPAP per unit of supplementary respirable gas consumed while maintaining low CPAP fluctuations throughout the breath cycle. The invention further optionally comprises a manometer for monitoring pressure and a safety pressure relief valve as additional safety measures against overpressure delivered to a patient. The device may be made to be completely disposable for one-time or single patient use.
