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Open AccessArticle

Transthoracic Impedance Measured with Defibrillator Pads—New Interpretations of Signal Change Induced by Ventilations

1
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
2
Prehospital Clinic, Ambulance Department, Oslo University Hospital—Ullevål, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway
3
Communications Engineering Department, University of the Basque Country UPV/EHU, Alameda Urquijo S/N, 48013 Bilbao, Spain
4
Prehospital Clinic, Airambulance Department, Oslo University Hospital—Ullevål, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway
5
Oslo Centre for Biostatistics and Epidemiology, Research Support Services, Oslo University Hospital—Ullevål, P.O. Box 4956 Nydalen, N-0424 Oslo, Norway
*
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
J. Clin. Med. 2019, 8(5), 724; https://doi.org/10.3390/jcm8050724
Received: 11 April 2019 / Revised: 14 May 2019 / Accepted: 17 May 2019 / Published: 22 May 2019
(This article belongs to the Special Issue Cardiovascular and Neurological Emergency)
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−1 frequency, four frequencies (10, 12, 22 and 30 min−1) with 400 mL volume, and seven inspiratory times (0.5–3.5 s ) with 400 mL/10 min−1 volume/frequency. Median time differences (quartile range) between timing of expiration onset in the Paw-line (PawEO) and the TTI peak and TTI maximum downslope were measured. TTI peak and PawEO time difference was 579 (432–723) m s for 12 min−1, independent of volume, with a negative relation to frequency, and it increased linearly with inspiratory time (slope 0.47, R 2 = 0.72). PawEO 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. View Full-Text
Keywords: transthoracic impedance; ventilation; peak inspiration pressure; cardiopulmonary resuscitation (CPR); pulmonary injury; pulmonary barotrauma; ventilation pattern transthoracic impedance; ventilation; peak inspiration pressure; cardiopulmonary resuscitation (CPR); pulmonary injury; pulmonary barotrauma; ventilation pattern
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MDPI and ACS Style

Berve, P.O.; Irusta, U.; Kramer-Johansen, J.; Skålhegg, T.; Kongsgård, H.W.; Brunborg, C.; Aramendi, E.; Wik, L. Transthoracic Impedance Measured with Defibrillator Pads—New Interpretations of Signal Change Induced by Ventilations. J. Clin. Med. 2019, 8, 724. https://doi.org/10.3390/jcm8050724

AMA Style

Berve PO, Irusta U, Kramer-Johansen J, Skålhegg T, Kongsgård HW, Brunborg C, Aramendi E, Wik L. Transthoracic Impedance Measured with Defibrillator Pads—New Interpretations of Signal Change Induced by Ventilations. Journal of Clinical Medicine. 2019; 8(5):724. https://doi.org/10.3390/jcm8050724

Chicago/Turabian Style

Berve, Per O.; Irusta, Unai; Kramer-Johansen, Jo; Skålhegg, Tore; Kongsgård, Håvard W.; Brunborg, Cathrine; Aramendi, Elisabete; Wik, Lars. 2019. "Transthoracic Impedance Measured with Defibrillator Pads—New Interpretations of Signal Change Induced by Ventilations" J. Clin. Med. 8, no. 5: 724. https://doi.org/10.3390/jcm8050724

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