Mecikalski M, Shigeoka J W
Chest. 1984 Nov;86(5):667-70. doi: 10.1378/chest.86.5.667.
Demand valves conserve oxygen by limiting delivery to the inspiratory phase of respiration and reducing the waste which occurs during expiration with conventional, constant flow therapy. However, arterial oxygen tensions (PaO2) achieved in past evaluations were frequently higher than recommended for treating chronic hypoxemia. We wondered if excessive amounts of oxygen were used which would exaggerate waste with conventional therapy, and, in turn, apparent savings with demand valves. Oxygen savings were evaluated with a demand valve in ten stable COPD patients who had recommended levels of PaO2 (55 to 65 mm Hg, SaO2 90 percent to 92 percent). The valve reduced oxygen use significantly compared to conventional therapy (average savings 28 percent, range 14 percent to 49 percent). The greatest savings were found in subjects who used the highest conventional flows.
按需阀通过将氧气输送限制在呼吸的吸气阶段并减少传统恒流疗法在呼气期间产生的浪费来节约氧气。然而，过去评估中所达到的动脉血氧分压（PaO2）常常高于治疗慢性低氧血症的推荐水平。我们想知道是否使用了过量的氧气，这会夸大传统疗法的浪费，进而夸大按需阀的明显节省效果。在十名稳定的慢性阻塞性肺疾病（COPD）患者中使用按需阀评估氧气节省情况，这些患者的PaO2（55至65毫米汞柱，血氧饱和度[SaO2] 90%至92%）处于推荐水平。与传统疗法相比，该阀显著减少了氧气使用（平均节省28%，范围为14%至49%）。在使用最高传统流量的受试者中发现节省最多。
