Section of Hospital Medicine, University of Chicago, Chicago, USA; Emergency Resuscitation Center, University of Chicago, Chicago, IL 60637, USA.
Resuscitation. 2010 Mar;81(3):317-22. doi: 10.1016/j.resuscitation.2009.11.003. Epub 2009 Dec 29.
Hyperventilation is both common and detrimental during cardiopulmonary resuscitation (CPR). Chest-wall impedance algorithms have been developed to detect ventilations during CPR. However, impedance signals are challenged by noise artifact from multiple sources, including chest compressions. Capnography has been proposed as an alternate method to measure ventilations. We sought to assess and compare the adequacy of these two approaches.
Continuous chest-wall impedance and capnography were recorded during consecutive in-hospital cardiac arrests. Algorithms utilizing each of these data sources were compared to a manually determined "gold standard" reference ventilation rate. In addition, a combination algorithm, which utilized the highest of the impedance or capnography values in any given minute, was similarly evaluated.
Data were collected from 37 cardiac arrests, yielding 438min of data with continuous chest compressions and concurrent recording of impedance and capnography. The manually calculated mean ventilation rate was 13.3+/-4.3/min. In comparison, the defibrillator's impedance-based algorithm yielded an average rate of 11.3+/-4.4/min (p=0.0001) while the capnography rate was 11.7+/-3.7/min (p=0.0009). There was no significant difference in sensitivity and positive predictive value between the two methods. The combination algorithm rate was 12.4+/-3.5/min (p=0.02), which yielded the highest fraction of minutes with respiratory rates within 2/min of the reference. The impedance signal was uninterpretable 19.5% of the time, compared with 9.7% for capnography. However, the signals were only simultaneously non-interpretable 0.8% of the time.
Both the impedance and capnography-based algorithms underestimated the ventilation rate. Reliable ventilation rate determination may require a novel combination of multiple algorithms during resuscitation.
在心肺复苏（CPR）期间，过度通气既常见又有害。已经开发出胸壁阻抗算法来检测 CPR 期间的通气。然而，阻抗信号受到来自多个来源的噪声伪影的挑战，包括胸部按压。呼气末二氧化碳描记法已被提议作为测量通气的替代方法。我们试图评估和比较这两种方法的充分性。
在连续的院内心脏骤停期间记录连续的胸壁阻抗和呼气末二氧化碳描记法。将利用这些数据源中的每一个的算法与手动确定的“金标准”参考通气率进行比较。此外，还评估了一种组合算法，该算法在任何给定分钟内使用阻抗或呼气末二氧化碳描记法中的最高值。
从 37 例心脏骤停中收集数据，得到 438 分钟的连续胸部按压和同时记录阻抗和呼气末二氧化碳描记法的数据。手动计算的平均通气率为 13.3+/-4.3/min。相比之下，除颤器的基于阻抗的算法产生的平均速率为 11.3+/-4.4/min（p=0.0001），而呼气末二氧化碳描记法的速率为 11.7+/-3.7/min（p=0.0009）。两种方法的灵敏度和阳性预测值没有显著差异。组合算法的速率为 12.4+/-3.5/min（p=0.02），这使得呼吸频率与参考值相差 2/min 的分钟数比例最高。阻抗信号不可解释的时间为 19.5%，而呼气末二氧化碳描记法的时间为 9.7%。然而，信号仅同时不可解释的时间为 0.8%。
基于阻抗和呼气末二氧化碳描记法的算法都低估了通气率。在复苏过程中，可靠的通气率确定可能需要多种算法的新型组合。
