Division of Neonatology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA.
Pediatr Crit Care Med. 2012 Jul;13(4):e262-8. doi: 10.1097/PCC.0b013e3182455586.
To determine the accuracy of measures of respiratory mechanics derived from neonatal ventilators using an in vitro passive physical lung model to simulate newborn pulmonary conditions.
Test lung models.
Laboratory-based measurements.
Three test lungs were constructed to simulate three severities of neonatal lung disease, with ranges of compliance from 0.5 to 2.0 mL/cm H2O and resistance from 25 to 150 cm H2O/(L/sec). Each ventilator was tested using 27 combinations of peak inspiratory pressure (15-25 cm H2O), positive end-expiratory pressure (5-7 cm H2O), and rate settings (20-60 B/min). Data were compared for five different ventilators across simulated lung severity as the ratio of ventilator readout to test lung reference value. A ratio of 1.0 indicated a completely unbiased result.
Overall, four of the five ventilators under-read expired tidal volume by about 1%-12% across all lung conditions, whereas the VIP Bird readout ranged from -4% to +4% bias. Changes in ventilator settings had only a modest effect on mechanics readout. As peak inspiratory pressure progressed from 15 to 25 cm H2O, bias in tidal volume readout changed from +5.0% to -2.5% (p < .001) in the VIP Bird, and from -11% to -9% (p < .001) in the Draeger Babylog VN500. Between positive end-expiratory pressure levels of 5 and 7 cm H2O, tidal volume bias in the Babylog varied between -13% and -7% (p < .001). In progressing from simulated normal to severely ill lung condition, bias in compliance measurements by the Avea and SLE5000 increased from -18% to -40% whereas in the VIP Bird it remained between -17% to -13%, and in the Draeger Evita XL-neo it changed from +17% to -13% and from -8% to -16% in the Babylog. Ratio of ventilator resistance readout to reference value with progressing simulated lung condition changed from 2.0 to 1.0 for the Draeger Evita, 1.6 to 1.1 for the Babylog, 4.2 to 2.0 for the SLE, and from 11.7 to 5.6 for the VIP Bird. The Avea, by design, did not display resistances >100 cm H2O/(L/sec), but overestimated the simulated normal lung resistance of 25 cm H2O/(L/sec) by a factor of 2.5.
Neonatal ventilator respiratory mechanics measurements and computation methods need further standardization to be useful in clinical settings.
使用体外被动物理肺模型来模拟新生儿肺部条件，以确定源自新生儿呼吸机的呼吸力学测量值的准确性。
测试肺模型。
基于实验室的测量。
构建了三个测试肺，以模拟三种严重程度的新生儿肺部疾病，顺应性范围为 0.5 至 2.0 毫升/厘米 H2O，阻力范围为 25 至 150 厘米 H2O/（升/秒）。使用 27 种组合的峰吸气压（15-25 厘米 H2O）、呼气末正压（5-7 厘米 H2O）和速率设置（20-60 次/分钟）对每个呼吸机进行了测试。根据模拟肺严重程度，将数据与五种不同呼吸机的参考值进行了比较，作为呼吸机读数与测试肺参考值的比值。1.0 的比值表示完全无偏的结果。
总体而言，五种呼吸机中的四种在所有肺条件下都将呼气潮气量低估了约 1%-12%，而 VIP Bird 的读数范围在-4%到+4%的偏差范围内。呼吸机设置的变化对力学读数的影响仅适度。随着峰吸气压从 15 厘米 H2O 增加到 25 厘米 H2O，VIP Bird 中的潮气量读数偏差从+5.0%变为-2.5%（p<.001），而在 Draeger Babylog VN500 中则从-11%变为-9%（p<.001）。在 5 厘米 H2O 和 7 厘米 H2O 的呼气末正压水平之间，Babylog 中的潮气量偏差在-13%到-7%之间（p<.001）。随着从模拟正常到严重疾病的肺条件进展，Avea 和 SLE5000 的顺应性测量偏差从-18%增加到-40%，而在 VIP Bird 中则保持在-17%至-13%之间，在 Draeger Evita XL-neo 中则从+17%变为-13%，在 Babylog 中则从-8%变为-16%。随着模拟肺条件的进展，呼吸机阻力读数与参考值的比值从 Draeger Evita 的 2.0 变为 1.0，从 Babylog 的 1.6 变为 1.1，从 SLE 的 4.2 变为 2.0，从 VIP Bird 的 11.7 变为 5.6。Avea 由于设计原因，没有显示>100 厘米 H2O/（升/秒）的阻力，但将模拟正常肺的 25 厘米 H2O/（升/秒）的阻力高估了 2.5 倍。
新生儿呼吸机呼吸力学测量和计算方法需要进一步标准化，才能在临床环境中有用。
