Behrends M, Kernbach M, Bräuer A, Braun U, Peters J, Weyland W
Abteilung für Anästhesiologie und Intensivmedizin, Univerversitätsklinkum Essen, Germany.
Intensive Care Med. 2001 Jan;27(1):228-35. doi: 10.1007/s001340000708.
To evaluate the Datex Deltatrac II for measurements in neonates requiring mechanical ventilation.
Prospective laboratory evaluation, using a ventilated lung model and gas injection. During simulation of 79 neonatal respiratory settings, assessment of oxygen consumption (VO2), carbon dioxide production (VCO2) and respiratory quotient (RQ) was compared to a reference method (mass spectrometry, wet gas spirometry) using the statistical method of Bland and Altman.
Respiratory variables, which may influence the accuracy and precision of gas exchange measurements, were varied within the following ranges: inspired oxygen fraction (FIO2): 0.21-0.8, expired carbon dioxide fraction (FECO2) and inspiratory-expiratory oxygen fraction (DFO2): 0.0032-0.0256, expiratory flow rate: 1.0-2.5 l/min, inspiratory pressure: 10-55 mbar, respiratory rate 25-60/min, constant RQ of 1. This resulted in 79 tests with VCO2 and VO2 ranging from 8-64 ml/min.
The coefficient of repeatability for ten single subsequent Deltatrac measurements was 8.09 ml/min for VO2 and 9.17 ml/min for VCO2 compared to 2.02 ml/min and 0.90 ml/min for VO2 and VCO2 with repeated reference measurements. The coefficient of repeatability of the Deltatrac measurements improved considerably when means of subsequent 5 min intervals were compared: 0.68 ml/min for VO2 and 0.28 ml/ min for VCO2. The difference between the two methods (Deltatrac-reference) was -3.8 % (2 s: 11.4%) for VO2, 13.2% (2s: 7.9%) for VCO2 and 17.6% (2s: 16.7%) for RQ. The agreement between methods deteriorated with smaller (FECO2) or DFO2 and increasing FIO2.
Considering limits of agreement of less than +/- 20% as clinically acceptable, results for VO2 assessment indicate acceptable accuracy and precision whereas VCO2 and RQ assessments exceed this limit. Limited accuracy and precision result from detection of CO2 following dilution of expiratory gases and increased sensitivity to error propagation by Haldane equations due to the small differences between inspiratory and expiratory gas fractions.
评估Datex Deltatrac II在需要机械通气的新生儿中的测量性能。
采用通气肺模型和气体注入法进行前瞻性实验室评估。在模拟79种新生儿呼吸设置时，使用Bland和Altman统计方法，将氧耗量（VO2）、二氧化碳产生量（VCO2）和呼吸商（RQ）的评估结果与参考方法（质谱法、湿式气体肺量计）进行比较。
对可能影响气体交换测量准确性和精密度的呼吸变量在以下范围内进行变化：吸入氧分数（FIO2）：0.21 - 0.8，呼出二氧化碳分数（FECO2）和吸入 - 呼出氧分数差（DFO2）：0.0032 - 0.0256，呼气流量：1.0 - 2.5升/分钟，吸气压力：10 - 55毫巴，呼吸频率25 - 60次/分钟，恒定呼吸商为1。这导致进行了79次测试，VCO2和VO2范围为8 - 64毫升/分钟。
与重复参考测量时VO2的2.02毫升/分钟和VCO2的0.90毫升/分钟相比，十次连续的Deltatrac单次测量的重复性系数VO2为8.09毫升/分钟，VCO2为9.17毫升/分钟。当比较随后5分钟间隔的平均值时，Deltatrac测量的重复性系数有显著改善：VO2为0.68毫升/分钟，VCO2为0.28毫升/分钟。两种方法（Deltatrac - 参考方法）之间的差异对于VO2为 - 3.8%（2s：11.4%），对于VCO2为13.2%（2s：7.9%），对于RQ为17.6%（2s：16.7%）。随着（FECO2）或DFO2变小以及FIO2增加，两种方法之间的一致性变差。
将临床可接受的一致性界限设定为小于±20%，VO2评估结果表明具有可接受的准确性和精密度；而VCO2和RQ评估超出了该界限。准确性和精密度受限是由于呼气气体稀释后二氧化碳的检测以及由于吸入和呼出气体分数差异较小，Haldane方程对误差传播的敏感性增加所致。
