Ventriculo–arterial interaction may be assessed by Oscillatory Power Fraction

• Published in: Clinical physiology and functional imaging 2019-09, Vol.39 (5), p.308-314
• Main Authors: Tannvik, Tomas Dybos, Rimehaug, Audun Eskeland, Wigen, Morten Smedsrud, Løvstakken, Lasse, Kirkeby‐Garstad, Idar
• Format: Article
• Language: English
• Subjects: Acceleration; Aged; Anesthesia; Aorta; Aorta - diagnostic imaging; Aorta - physiopathology; Arterial Pressure; Blood circulation; Blood flow; Blood Flow Velocity; Blood pressure; Cardiac Output; cardiac power; Coronary artery; Coronary Artery Bypass - adverse effects; coronary artery bypass graft surgery; Coronary Artery Disease - diagnostic imaging; Coronary Artery Disease - physiopathology; Coronary Artery Disease - surgery; Echocardiography, Doppler, Pulsed; energetics; Energy transfer; Extubation; Head-Down Tilt; Heart; Heart surgery; Heart Ventricles - diagnostic imaging; Heart Ventricles - physiopathology; Humans; Mathematical analysis; Middle Aged; oscillations; Patient Positioning - methods; Position measurement; Predictive Value of Tests; Pressure curve; Prospective Studies; Pulsatile Flow; Time Factors; Treatment Outcome; Ventricle; Ventricular Function, Left
• ISSN: 1475-0961; 1475-097X
• DOI: 10.1111/cpf.12573

Summary The rate of energy transfer from the left ventricle to the aorta is viewed in terms of mean power (MP) and total power (TP). The difference between MP and TP is due to the pulsatility of the circulation and is known as oscillatory power (OP). OP is considered the energy spent to accelerate the blood flow. The aim of this study was to investigate the baseline left ventricular oscillatory power fraction (OP/TP) and how this was affected by acute cardiovascular dysfunction and altered preload. Twenty‐eight patients undergoing elective coronary artery bypass graft surgery were included. Before administration of anaesthesia, we simultaneously recorded an arterial pressure curve and instantaneous cardiac outflow with pulsed wave Doppler. Postoperatively, prior to extubation, these measurements were repeated in neutral, Trendelenburg and reverse‐Trendelenburg position. The final measurements were taken on the awake patient the day after the operation. TP is the mean of the instantaneous product of the flow and pressure curves. MP was calculated by multiplying mean arterial pressure with mean cardiac output. The oscillatory power fraction is therefore calculated as (TP‐MP)/TP. The oscillatory power fraction in neutral position decreased from 23% preoperatively to 16% immediately postoperatively (P