Department of Adult Intensive Care, Erasmus Medical Center, Rotterdam, The Netherlands.
Department of Neonatal and Pediatric Intensive Care, Erasmus Medical Center-Sophia Children's Hospital, Rotterdam, The Netherlands.
Physiol Meas. 2024 Jun 4;45(5). doi: 10.1088/1361-6579/ad3c0e.
. The respiratory rate (RR) is considered one of the most informative vital signals. A well-validated standard for RR measurement in mechanically ventilated patient is capnography; a noninvasive technique for expiratory COmeasurements. Reliable RR measurements in spontaneously breathing patients remains a challenge as continuous mainstream capnography measurements are not available. This study aimed to assess the accuracy of RR measurement using electrical impedance tomography (EIT) in healthy volunteers and intensive care unit (ICU) patients on mechanical ventilation and spontaneously breathing post-extubation. Comparator methods included RR derived from both capnography and bioimpedance electrocardiogram (ECG) measurements.. Twenty healthy volunteers wore an EIT belt and ECG electrodes while breathing through a capnometer within a 10-40 breaths per minute (BPM) range. Nineteen ICU patients underwent similar measurements during pressure support ventilation and spontaneously breathing after extubation from mechanical ventilation. Stable periods with regular breathing and no artefacts were selected, and agreement between measurement methods was assessed using Bland-Altman analysis for repeated measurements.. Bland-Altman analysis revealed a bias less than 0.2 BPM, with tight limits of agreement (LOA) ±1.5 BPM in healthy volunteers and ventilated ICU patients when comparing EIT to capnography. Spontaneously breathing ICU patients had wider LOA (±2.5 BPM) when comparing EIT to ECG bioimpedance, but gold standard comparison was unavailable. RR measurements were stable for 91% of the time for capnography, 68% for EIT, and 64% of the ECG bioimpedance signals. After extubation, the percentage of stable periods decreased to 48% for EIT signals and to 55% for ECG bioimpedance.. In periods of stable breathing, EIT demonstrated excellent RR measurement accuracy in healthy volunteers and ICU patients. However, stability of both EIT and ECG bioimpedance RR measurements declined in spontaneously breathing patients to approximately 50% of the time.
呼吸频率（RR）被认为是最具信息量的生命体征之一。机械通气患者中 RR 测量的一个经过良好验证的标准是呼气末二氧化碳分压（CO）测量的二氧化碳描记法；这是一种用于呼气 CO 测量的非侵入性技术。在自主呼吸的患者中，RR 的可靠测量仍然是一个挑战，因为没有连续的主流二氧化碳描记法测量。本研究旨在评估在健康志愿者和接受机械通气和拔管后自主呼吸的重症监护病房（ICU）患者中使用电阻抗断层成像（EIT）测量 RR 的准确性。比较方法包括来自二氧化碳描记法和生物阻抗心电图（ECG）测量的 RR。二十名健康志愿者在每分钟 10-40 次呼吸（BPM）范围内通过二氧化碳描记仪呼吸时佩戴 EIT 带和 ECG 电极。十九名 ICU 患者在压力支持通气期间和从机械通气拔管后自主呼吸期间接受了类似的测量。选择具有规则呼吸且无伪影的稳定期，并使用重复测量的 Bland-Altman 分析评估测量方法之间的一致性。 Bland-Altman 分析显示，在健康志愿者和通气 ICU 患者中，当将 EIT 与二氧化碳描记法进行比较时，偏差小于 0.2 BPM，且一致性界限（LOA）为±1.5 BPM。当将 EIT 与 ECG 生物阻抗进行比较时，自主呼吸的 ICU 患者的 LOA 更宽（±2.5 BPM），但无法进行金标准比较。二氧化碳描记法的 RR 测量稳定时间为 91%，EIT 为 68%，ECG 生物阻抗为 64%。拔管后，EIT 信号稳定期的百分比下降至 48%，ECG 生物阻抗的百分比下降至 55%。在稳定呼吸期间，EIT 在健康志愿者和 ICU 患者中表现出出色的 RR 测量准确性。然而，EIT 和 ECG 生物阻抗 RR 测量的稳定性在自主呼吸的患者中下降到大约 50%的时间。
