Berve Per Olav, Irusta Unai, Kramer-Johansen Jo, Skålhegg Tore, Kongsgård Håvard Wahl, Brunborg Cathrine, Aramendi Elisabete, Wik Lars
National Advisory Unit for Prehospital Emergency Medicine (NAKOS), Oslo University Hospital-Ullevål and University of Oslo, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway.
Prehospital Clinic, Ambulance Department, Oslo University Hospital-Ullevål, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway.
J Clin Med. 2019 May 22;8(5):724. doi: 10.3390/jcm8050724.
Compressions during the insufflation phase of ventilations may cause severe pulmonary injury during cardiopulmonary resuscitation (CPR). Transthoracic impedance (TTI) could be used to evaluate how chest compressions are aligned with ventilations if the insufflation phase could be identified in the TTI waveform without chest compression artifacts. Therefore, the aim of this study was to determine whether and how the insufflation phase could be precisely identified during TTI. We synchronously measured TTI and airway pressure (Paw) in 21 consenting anaesthetised patients, TTI through the defibrillator pads and Paw by connecting the monitor-defibrillator's pressure-line to the endotracheal tube filter. Volume control mode with seventeen different settings were used (5-10 ventilations/setting): Six volumes (150-800 mL) with 12 min frequency, four frequencies (10, 12, 22 and 30 min) with 400 mL volume, and seven inspiratory times (0.5-3.5 s ) with 400 mL/10 min volume/frequency. Median time differences (quartile range) between timing of expiration onset in the Paw-line (Paw) and the TTI peak and TTI maximum downslope were measured. TTI peak and Paw time difference was 579 (432-723) m s for 12 min, independent of volume, with a negative relation to frequency, and it increased linearly with inspiratory time (slope 0.47, R 2 = 0.72). Paw and TTI maximum downslope time difference was between -69 and 84 m s for any ventilation setting (time aligned). It was independent ( R 2 < 0.01) of volume, frequency and inspiratory time, with global median values of -47 (-153-65) m s , -40 (-168-68) m s and 20 (-93-128) m s , for varying volume, frequency and inspiratory time, respectively. The TTI peak is not aligned with the start of exhalation, but the TTI maximum downslope is. This knowledge could help with identifying the ideal ventilation pattern during CPR.
通气吹入阶段的按压可能会在心肺复苏（CPR）期间导致严重的肺损伤。如果能在无胸外按压伪迹的经胸阻抗（TTI）波形中识别出吹入阶段，那么TTI可用于评估胸外按压与通气的同步情况。因此，本研究的目的是确定在TTI期间能否以及如何精确识别吹入阶段。我们同步测量了21名同意参与的麻醉患者的TTI和气道压力（Paw），通过除颤电极片测量TTI，通过将监护除颤仪的压力线连接到气管导管过滤器来测量Paw。使用了17种不同设置的容量控制模式（每种设置5 - 10次通气）：六种容量（150 - 800 mL），频率为12次/分钟；四种频率（10、12、22和30次/分钟），容量为400 mL；七种吸气时间（0.5 - 3.5秒），容量/频率为400 mL/10次/分钟。测量了Paw曲线（Paw）中呼气开始时间与TTI峰值和TTI最大下降斜率之间的中位时间差（四分位间距）。对于12次/分钟的情况，TTI峰值与Paw时间差为579（432 - 723）毫秒，与容量无关，与频率呈负相关，且随吸气时间呈线性增加（斜率0.47，R² = 0.72）。对于任何通气设置（时间对齐），Paw与TTI最大下降斜率时间差在 - 69至84毫秒之间。它与容量、频率和吸气时间无关（R² < 0.01），对于不同的容量、频率和吸气时间，全局中位数值分别为 - 47（ - 153 - 65）毫秒、 - 40（ - 168 - 68）毫秒和20（ - 93 - 128）毫秒。TTI峰值与呼气开始不同步，但TTI最大下降斜率与呼气开始同步。这一知识有助于确定CPR期间的理想通气模式。
