Department of Medicine, Universidade Federal de São Paulo, São Paulo, Brazil.
Respir Care. 2012 Jul;57(7):1071-5. doi: 10.4187/respcare.01230. Epub 2012 Jan 23.
Oxygen therapy is an important therapeutic resource for patients with hypoxemia. When changing oxygen flow meters, we have observed that sometimes, even with the same oxygen flow setting as before, a different S(pO(2)) is obtained.
To analyze the precision and accuracy of flow meters used in hospital settings.
An experimental study was performed to test oxygen flow meters from a tertiary hospital, by using a calibrated flow analyzer. Used and new flow meter accuracy was tested by reading in the gas analyzer a single measurement at flow rates of 1, 3, 5, and 10 L/min in 91 flow meters, and they were compared using the Student t test or Mann-Whitney U test. Flow meter precision was tested by reading in the flow analyzer 3 repetitive measurements set at flow rates of 1, 3, 5, and 10 L/min in 11 flow meters, and the reproducibility of these measurements was conducted by using the intraclass correlation coefficient and the Friedman test.
The mean measured flow rates were slightly lower than the stipulated flow rate at 1 L/min, very close for 3 L/min, and higher for the 5 and 10 L/min flow rates. There was a large variability among the measurements from different flow meters, mainly at low flow rates (1 and 3 L/min). There was no difference between new and used flow meters at the flow rates measured, except at 10 L/min. Flow meters precision analysis showed a good reproducibility in 3 repetitive measurements for each flow rate (minimum 0.95, maximum 0.99 intraclass correlations).
The flow meters tested showed good precision and poor accuracy.
氧气疗法是低氧血症患者的重要治疗资源。在更换氧气流量计时，我们观察到，即使氧气流量设置与之前相同，有时也会得到不同的 SpO2。
分析医院环境中使用的流量计的精度和准确度。
通过使用校准的流量分析仪，对一家三级医院的氧气流量计进行了实验研究。通过在气体分析仪上读取单个测量值，测试了使用中和新的流量计的准确度，在 91 个流量计中，分别在 1、3、5 和 10 L/min 的流速下进行测试，使用学生 t 检验或曼-惠特尼 U 检验进行比较。通过在流量分析仪上读取 3 次重复测量，测试了流量计的精度，在 1、3、5 和 10 L/min 的流速下进行了测试，使用组内相关系数和 Friedman 检验来评估这些测量值的可重复性。
在 1 L/min 时，测量的平均流速略低于规定流速，在 3 L/min 时非常接近，而在 5 和 10 L/min 时则较高。不同流量计的测量值之间存在较大的差异，主要在低流速（1 和 3 L/min）时。新的和使用过的流量计在测量的流速上没有差异，除了在 10 L/min 时。流量计精度分析显示，每个流速的 3 次重复测量具有良好的可重复性（最小 0.95，最大 0.99 组内相关系数）。
测试的流量计具有良好的精度和较差的准确度。
