Historical REVIEW-
Hard Hat Divers received positive mask pressures with air exchange to compensate for the increasing positive baro pressures during deep sea diving.
Barach et al in the 1940's employed mechanical devices to retard physiological expiratory flow by means of mechanical expiratory flow metering. As a method directed toward decreasing the left ventricular pressure by impairing venous return to the right heart, these devices were employed to increase the mean intrathoracic pressure in spontaneously breathing patients with advanced left sided heart failure.
During WWII, US ARMY AIR FORCES employed a form of a mechanical inspiratory physiological demand oxygen flow generation with a positive expiratory pressure to increase altitude tolerance in pilots flying at higher altitudes with a critical reduced oxygen partial pressure.
Petty et al in the 1960's employed a positive end expiratory pressure (PEEP) in apneic patients receiving continuous mechanical ventilation to mechanically increase the Functional Residual Capacity (FRC) as a means of enhancing the pulmonary blood gas interface.
F. M. Bird introduced in 1975 a selectable semi automatic mechanical form of continuous positive airway pressure (CPAP) during spontaneous respiration in his IMVbird®.
In 1985 F. M. Bird introduced an advanced form of a selectable automatic DEMAND continuous positive airway pressure (D-CPAP) with "precise, near instantaneous proximal airway flow servoing" during spontaneous ventilation.
In 1986 F. M. Bird, introduced OSCILLATORY DEMAND CONTINUOUS POSITIVE AIRWAY PRESSURE (OD-CPAP/PEEP) in apneic or spontaneously breathing patients receiving mechanical ventilation.
DEFINITIONS:
HARD HAT DIVING PRESSURES- employed a form of vented Continuous Positive Pressure Breathing (CPPB) in the divers hard hat suit during deep sea diving operations.
PHYSIOLOGICAL EXPIRATORY FLOW RETARD- can be used to maintain an increased mean intrathoracic pressure as well as to maintain an increased endobronchial airway patency toward end expiration in spontaneously breathing COPD patients.