Hardman Jonathan G, Aitkenhead Alan R
From the University Department of Anesthesia, University Hospital, Nottingham, UK.
Anesth Analg. 2003 Dec;97(6):1840-1845. doi: 10.1213/01.ANE.0000090315.45491.72.
We present an original, mathematical model of ventilation and gas-exchange. Our aim was to validate it using data from previous clinical investigations, allowing our use of it in future investigations. The first previous investigation used a low-dead space, double-lumen, tracheal tube (DLT). We matched the model's PaCO(2) and airway pressures (P(AW)) to the patient mean during use of the DLT and a single-lumen tube (SLT). The model's resulting PaCO(2), PECO(2) and P(AW) were compared with the patients' as tidal volume (VT) changed with constant minute volume. The second investigation examined dead space during anesthesia. The model's VT, respiratory rate, CO(2) production, temperature, and alveolar and anatomical dead spaces were matched to each mechanically ventilated subject. Bias and precision in predictions of PaCO(2) and PECO(2) were calculated. The model's bias in prediction of dead space reduction by the DLT was 6.9%. Bias in prediction of P(AW) was 0.1% (peak) and -5.13% (mean), of PaCO(2) was 1.2% (DLT) and 1.5% (SLT) and of PECO(2) was 1.7% (DLT) and 1.3% (SLT). Prediction of PaCO(2) and PECO(2) in the second investigation (as 95% confidence interval of bias): PaCO(2) -2.6% to 0.8% and PECO(2) -4.9% to 1.2%. This validation allows future application of our model in appropriate theoretical investigations.
We present an original, mathematical model of ventilation and gas exchange. We validate it against previously published clinical data to allow its use in future theoretical investigations where data may be unavailable from patients.
我们提出了一个原创的通气与气体交换数学模型。我们的目的是使用先前临床研究的数据对其进行验证，以便在未来的研究中使用该模型。先前的第一项研究使用了低死腔双腔气管导管（DLT）。我们将模型的动脉血二氧化碳分压（PaCO₂）和气道压力（P(AW)）与使用DLT和单腔气管导管（SLT）期间的患者平均值进行匹配。随着潮气量（VT）在分钟通气量恒定的情况下发生变化，将模型得出的PaCO₂、呼气末二氧化碳分压（PECO₂）和P(AW)与患者的相应值进行比较。第二项研究考察了麻醉期间的死腔。将模型的VT、呼吸频率、二氧化碳产生量、体温以及肺泡和解剖死腔与每个机械通气受试者进行匹配。计算了PaCO₂和PECO₂预测的偏差和精密度。该模型对DLT减少死腔的预测偏差为6.9%。P(AW)预测偏差为0.1%（峰值）和 -5.13%（平均值），PaCO₂预测偏差为1.2%（DLT）和1.5%（SLT），PECO₂预测偏差为1.7%（DLT）和1.3%（SLT）。第二项研究中PaCO₂和PECO₂的预测（作为偏差的95%置信区间）：PaCO₂为 -2.6%至0.8%，PECO₂为 -
