Markhorst D G, Leenhoven T, van Genderingen H R, Uiterwijk J W, van Vught A J
Department of Pediatrics, University Hospital Vrije Universiteit, Amsterdam, The Netherlands.
J Clin Monit. 1997 Nov;13(6):349-55. doi: 10.1023/a:1007476223906.
The objective of this study is to determine the accuracy and precision of chemiluminescence and electrochemical nitric oxide (NO) measurements and accuracy of NO dosage with electronic mass flow controllers (MFC) versus rotameters during NO inhalational therapy.
NO flow was delivered to a high frequency oscillator and mixed with ventilator flow. NO and NO2 concentrations were measured simultaneously with a standard chemiluminescence analyzer and a modified electrochemical analyzer. Dosage accuracy was assessed with gas flows adjusted with either MFC's or rotameters. Accuracy of both analyzers was validated with both NO and ventilator flow regulated with a MFC.
In dry air, without pulsatile pressure, MFC controlled NO and ventilator flow resulted in an accuracy expressed as the ratio of calculated concentration to measured concentration (RCM) of 0.995 (CI: 0.983-0.988) when measured with chemiluminescence. When the ventilator rotameter was used instead of a MFC, RCM was 0.856 (CI: 0.835-0.877). With a rotameter for both NO and ventilator flow, RCM increased to 1.175 (CI: 0.793-1.740) with an increase of confidence interval limits. Chemiluminescence was sensitive to humidification of the ventilatory gases (p < 0.05), slightly sensitive to the addition of oxygen and to pulsatile pressure (not significant). RCM obtained with the modified electrochemical analyzer was in close agreement with chemiluminescence RCM, although 95% CI were wider with electrochemical analysis.
During high frequency oscillatory ventilation (HFOV), standard rotameter flow control of both NO and ventilator flow results in unpredictable NO concentrations that would be clinically unacceptable. When one MFC was used for NO flow control, with ventilator flow controlled with a rotameter, this resulted in moderate dosage accuracy. To achieve a still higher accuracy, MFC flow control for both NO and ventilator flow is indicated. During HFOV, standard chemiluminescence analyzers cannot be considered to be the gold standard for determination of the NO concentration delivered. Measurement of NO concentration may not be mandatory for determination of inhaled NO dose during HFOV, but may be used to monitor for unsafe or unwanted events.
本研究的目的是确定在一氧化氮（NO）吸入治疗期间，化学发光法和电化学法测量NO的准确性和精密度，以及使用电子质量流量控制器（MFC）与转子流量计进行NO给药的准确性。
将NO流量输送至高频振荡器并与呼吸机气流混合。使用标准化学发光分析仪和改良型电化学分析仪同时测量NO和NO₂浓度。通过用MFC或转子流量计调节气流来评估给药准确性。在MFC调节NO和呼吸机气流的情况下，对两种分析仪的准确性进行验证。
在干燥空气中，无脉动压力时，用化学发光法测量，MFC控制NO和呼吸机气流时，计算浓度与测量浓度之比（RCM）的准确性为0.995（CI：0.983 - 0.988）。当使用呼吸机转子流量计而非MFC时，RCM为0.856（CI：0.835 - 0.877）。对于NO和呼吸机气流均使用转子流量计时，随着置信区间上限增加，RCM增至1.175（CI：0.793 - 1.740）。化学发光法对通气气体的湿度敏感（p < 0.05），对添加氧气和脉动压力略有敏感（不显著）。改良型电化学分析仪获得的RCM与化学发光法RCM密切一致，尽管电化学分析的95%CI更宽。
在高频振荡通气（HFOV）期间，对NO和呼吸机气流均采用标准转子流量计流量控制会导致不可预测的NO浓度，这在临床上是不可接受的。当使用一个MFC控制NO流量，而用转子流量计控制呼吸机气流时，这会导致中等程度的给药准确性。为达到更高的准确性，建议对NO和呼吸机气流均采用MFC流量控制。在HFOV期间，标准化学发光分析仪不能被视为测定输送的NO浓度的金标准。在HFOV期间，测定吸入NO剂量可能并非必须测量NO浓度，但可用于监测不安全或不良事件。
