During the past 5 years many manufacturers of adult manual resuscitators have designed completely new resuscitators or have modified the reservoir on their original devices. The purpose of this study was to evaluate resuscitators with new designs to determine whether their fractional delivered oxygen concentration (FDO2) was signif-icantly improved over that of older resuscitators. The resuscitators were tested in three patterns of ventilation with oxygen flowrates of 5, 10, 15, and 20 l/min. The FDO2 capability of three resuscitator models without oxygen reservoir (Laerdal, Vitalo-graph, and AMBU Model R) was low (0.28 to 0.56). Of the new configurations, the Vitalograph with new 400-ml reservoir and the AMBU Model R (with reservoir) were unable to provide an FDO2 >0.90 in any ventilation pattern and should not be used when a higher FDO2 is important. The Laerdal with its 800-ml reservoir achieved an FDO2 between 0.88 and 0.97, depending on the ventilation pattern, at an oxygen flow of 15 l/min. The Laerdal with 2,600-ml reservoir and the AMBU MS 30 with reservoir achieved an FDO2 >0.96 at an oxygen flowrate of 15 l/min in all three ventilation patterns. The Vitalograph with its new 800-ml reservoir achieved an FDO2 of 0.90 with an oxygen flow of 15 l/min at the lowest minute volume studied (7.21). The AMBU MS 30 was the only resuscitator without a reservoir that was able to deliver a high oxygen concentration (>0.90) in all three ventilation patterns, provided that the oxygen flow was 20 l/min. At an oxygen flow of 25 l/min, the patient valve on the Vitalograph with no reservoir and with its old 400-ml reservoir chattered and stuck in the inspiratory position, as did the patient valve on the AMBU Model NR at an oxygen flowrate of 20 l/min. (Barnes TA, Watson ME. Oxygen Delivery Performance of Old and New Designs of the Laerdal, Vitalograph, and AMBU Adult Manual Resuscitators. Respir Care 1983;28:1121-1128.
