Supplementum 282: Abstracts Swiss Anaesthesia 2024, joint annual congress of the Swiss Society for Anaesthesiology and Perioperative Medicine and the Swiss Association for Anaesthesia Care (Interlaken, Switzerland, November 7−9, 2024)

Background:The induction of general anaesthesia (GA) is known to have considerable haemodynamic effects, which can lead to perioperative complications.These effects are often assessed by arterial blood pressure or ejection fraction, but these measures do not provide a complete picture of what occurs across the heart.While the aorta, pulmonary artery, and left and right atria and ventricles form an integrative unit, they all have different underlying haemodynamics.Yet the impact of GA on each of the chambers and great vessels is rarely investigated at the same time due to limitations in measuring techniques.Therefore, to comprehensively understand this effect, we applied advanced cardiovascular magnetic resonance (CMR) 4D flow imaging to simultaneously and non-invasively quantify whole heart haemodynamics at both an awake baseline state and after the induction of GA.Methods: Six patients (ASA I-III), scheduled for elective surgery were enrolled to undergo GA induction in an MRI.A 4D flow image of the thoracic cavity was acquired pre-induction and repeated 15minutes after the induction of GA maintained by sevoflurane.Images were blinded and analysed for whole-heart haemodynamics.Results: Induction of GA decreased mean arterial pressure (98 6 vs 66 2 mmHg, p <0.01).Pre-load defined by end-diastolic volume dropped in the left ventricle (-16%, 148 12 vs 125 11ml, p <0.01), with a non-significant drop in the right ventricle (-7%, 176 18 vs 165 20ml, p = 0.08).Reflecting afterload, systemic resistance dropped by -32% (28 5 vs 19 3dynes*cm-5, p = 0.03) while resistance in the pulmonary system did not change (23%, 13 1 vs 16 3dynes*cm-5, p = 0.29).Transmitral blood flow velocity decreased by -24% (80 17 vs 58+12 cm/s, p = 0.05) during early diastole and by -32% (62 33 vs 43 25 cm/s, p = 0.02) during the atrial kick in late diastole.Conversely, for the right side of the heart tricuspid blood flow velocity did not change for early (-14%, 63 23 vs 49 9 cm/s, p = 0.24) or late diastole (-14%, 51 14 43 16 cm/s, p = 0.23). Conclusion:This novel approach of applying 4D flow CMR in a perioperative environment provides new insights into how GA influences haemodynamics uniquely across the cardiovascular chambers and vessels.By understanding which individual cardiovascular structures are more susceptible to significant haemodynamic fluctuations, anaesthetists may be able to target therapies to mitigate perioperative complications associated with GA haemodynamic instabilities.