Potential hazard of East-Radcliffe ventilator. Failure to entrain adequate oxygen.

Reports of two hypoxic episodes which occurred during the use of the East Radcliffe PNA 1 ventilator in the 'complete rebreathing' mode led to the study of the efficiency of the emergency air entrainment system. The inability of this system to maintain adequate oxygen concentrations during interruption of the fresh gas supply results in the development of a hypoxic gas mixture despite patency of the entrainment valve. The reasons for this, and their clinical implications during intermittent positive pressure ventilation in the 'complete rebreathing' mode, are discussed.