The Hope I, Hope II, and Vitalograph bag resuscitators were studied at various oxygen flowrates and ventilation patterns, with and without oxygen reservoirs to determine fractional delivered oxygen (FDO₂) and function of patient valves. The Hope I cannot deliver high oxygen concentrations (FDO2 >0.90) in any configuration and should not be used when high FDO2 is important. The Hope II cannot deliver high oxygen without a reservoir; but with a reservoir and oxygen flowrates of 10 l/min or greater, it does achieve FDO2 >0.90. The Vitalograph requires both an oxygen reservoir and an oxygen flowrate of 20 1/min to achieve high oxygen concentrations. To use the Vitalograph in this technique one should employ a backpressure-calibrated oxygen flowmeter capable of accurately delivering 20 1/min; otherwise there is a risk that the patient valve may stick at oxygen flowrates >25 1/min.
Fitzmaurice et al. (1980) studied this question.