CBR - Center of Breath Research, Department of Anaesthesiology, Intensive Care and Pain Therapy, Faculty of Medicine, Saarland University Medical Center, Saarland University, 66421, Homburg, Saar, Germany.
Department of OUTCOMES RESEARCH, Anaesthesiology Institute, Cleveland Clinic, Cleveland, OH, USA.
J Clin Monit Comput. 2023 Apr;37(2):493-500. doi: 10.1007/s10877-022-00907-0. Epub 2022 Sep 21.
The bedside Exhaled Drug MONitor - EDMON measures exhaled propofol in ppb every minute based on multi-capillary column - ion mobility spectrometry (MCC-IMS). The MCC pre-separates gas samples, thereby reducing the influence of the high humidity in human breath. However, preliminary analyses identified substantial measurement deviations between dry and humid calibration standards. We therefore performed an analytical validation of the EDMON to evaluate the influence of humidity on measurement performance. A calibration gas generator was used to generate gaseous propofol standards measured by an EDMON device to assess linearity, precision, carry-over, resolution, and the influence of different levels of humidity at 100% and 1.7% (without additional) relative humidity (reference temperature: 37°C). EDMON measurements were roughly half the actual concentration without additional humidity and roughly halved again at 100% relative humidity. Standard concentrations and EDMON values correlated linearly at 100% relative humidity (R²=0.97). The measured values were stable over 100min with a variance ≤ 10% in over 96% of the measurements. Carry-over effects were low with 5% at 100% relative humidity after 5min of equilibration. EDMON measurement resolution at 100% relative humidity was 0.4 and 0.6 ppb for standard concentrations of 3 ppb and 41 ppb. The influence of humidity on measurement performance was best described by a second-order polynomial function (R²≥0.99) with influence reaching a maximum at about 70% relative humidity. We conclude that EDMON measurements are strongly influenced by humidity and should therefore be corrected for sample humidity to obtain accurate estimates of exhaled propofol concentrations.
床边呼气药物监测仪 - EDMON 基于多毛细管柱 - 离子迁移谱（MCC-IMS），每分钟测量 ppb 级别的呼出的丙泊酚。MCC 预先分离气体样本，从而降低了人体呼吸中高湿度的影响。然而，初步分析表明，干燥和湿润校准标准之间存在显著的测量偏差。因此，我们对 EDMON 进行了分析验证，以评估湿度对测量性能的影响。使用校准气体发生器生成通过 EDMON 设备测量的气态丙泊酚标准品，以评估线性度、精密度、携带效应、分辨率以及在 100%和 1.7%（无额外）相对湿度（参考温度：37°C）下不同湿度水平的影响。在没有额外湿度的情况下，EDMON 测量值大约是实际浓度的一半，而在 100%相对湿度下则再次减半。在 100%相对湿度下，标准浓度和 EDMON 值呈线性相关（R²=0.97）。在超过 96%的测量中，测量值在 100min 内保持稳定，方差≤10%。在 5min 的平衡后，在 100%相对湿度下的携带效应为 5%。EDMON 在 100%相对湿度下的测量分辨率为 0.4 和 0.6 ppb，标准浓度分别为 3 ppb 和 41 ppb。湿度对测量性能的影响可以通过二次多项式函数（R²≥0.99）来最佳描述，影响在相对湿度约为 70%时达到最大值。我们得出结论，EDMON 测量值受湿度影响较大，因此应校正样品湿度以获得准确的呼出丙泊酚浓度估计值。
