Resp Care
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We determined the minimum systolic pressures required for blood to enter and begin to displace the plungers of four brands of 3-ml and 5-ml plastic and glass arterial blood gas syringes by combining samples of each syringe size with three sizes of short-beveled needles--25 gauge, 5/8"; 22-gauge, 1"; and 20-gauge, 1 1/2". We measured pressures by use of an arterial-vessel model that incorporated whole human blood and simulated the conditions of a percutaneous arterial puncture. ⋯ Because we found no clinical or statistical differences between 20- and 22-gauge needles, we do not recommend use of the larger 20-gauge needle. The syringe-needle combinations that we do recommend should negate the need for, and the potential trauma of, manual aspiration of the syringe plunger.
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To determine the fractional delivered oxygen concentrations (FDO2) and the proper functioning of patient valves in adult resuscitation bags, we studied the Laerdal, the PMR 1, the PMR 2, and the Vitalograph resuscitators at various oxygen flowrates and ventilation patterns, with and without reservoirs. The Vitalograph, with new or old reservoir, and the PMR 1 cannot deliver high oxygen concentrations (FDO2 greater than 0.90) and should not be used when high FDO2 is important. The PMR 2 and the Laerdal cannot deliver high oxygen concentrations without reservoirs attached; with reservoirs attached the Laerdal achieves FDO2 greater than 0.98 at a flowrate of 10 l/min, and the PMR 2 achieves FDO2 greater than 0.90 at a flowrate of 15 l/min.