Laurent Gergelé1, Younes Khadraoui2, Romain Manet3, Olivier Desebbe4. 1. Department of Intensive Care, Ramsay Santé, Hôpital Privé de la Loire, Saint Etienne, France. laurentgergele@yahoo.fr. 2. Independent Data Scientist, Sophia Antipolis, France. 3. Department of Neurosurgery B, Hôpital P. Wertheimer, Hospices Civiles de Lyon, Lyon, France. 4. Department of Anaesthesiology and Intensive Care, Ramsay Santé, Sauvegarde Clinic, Lyon, France.
Abstract
INTRODUCTION: Assessment of the individual safest minimal mean arterial pressure (MAP) during cardiac surgery remains empirical. The objective of this study was to evaluate the lower limit of autoregulation (LLA) within a short period (15 min). METHODS: After developing autoregulation software (OptiMAP) incorporated into transcranial Doppler ultrasound (Waki-Atys®, Lyon, France), we monitored the mean blood flow velocity (MV) and MAP. Thirty successive values of MV and MAP were automatically analysed to calculate the correlation (Mx) between the two parameters. We compared two methods of Mx sampling during a period of 15 min: Mx10s = long averaging windows (one MAP/MV pair recorded every 10 s), and Mx2s = short averaging windows (one MAP/MV pair recorded every 2 s). The LLA value calculated from the whole recording (Mx10s) was used as the reference. Autoregulation was considered impaired at an Mx value >0.35. RESULTS: Five patients were included in the study. The surgery lasted for 138 ± 32 min and cardiopulmonary bypass lasted for 72 ± 33 min. MAP and MV were recorded for 117 ± 24 min. MAP varied from 33 ± 10 to 92 ± 10 mmHg. LLA calculated from the whole recording (Mx10s) was similar to LLA calculated from the 15-min recording (Mx2s): 70 ± 2.5 versus 73 ± 3.5 mmHg. MAP remained below LLA during 48 ± 12% of the recording. During the 15-min recording, Mx10s was not able to calculate the LLA value. CONCLUSION: In cases of haemodynamic instability, decreasing the Mx sampling window seems to accurately detect LLA.
INTRODUCTION: Assessment of the individual safest minimal mean arterial pressure (MAP) during cardiac surgery remains empirical. The objective of this study was to evaluate the lower limit of autoregulation (LLA) within a short period (15 min). METHODS: After developing autoregulation software (OptiMAP) incorporated into transcranial Doppler ultrasound (Waki-Atys®, Lyon, France), we monitored the mean blood flow velocity (MV) and MAP. Thirty successive values of MV and MAP were automatically analysed to calculate the correlation (Mx) between the two parameters. We compared two methods of Mx sampling during a period of 15 min: Mx10s = long averaging windows (one MAP/MV pair recorded every 10 s), and Mx2s = short averaging windows (one MAP/MV pair recorded every 2 s). The LLA value calculated from the whole recording (Mx10s) was used as the reference. Autoregulation was considered impaired at an Mx value >0.35. RESULTS: Five patients were included in the study. The surgery lasted for 138 ± 32 min and cardiopulmonary bypass lasted for 72 ± 33 min. MAP and MV were recorded for 117 ± 24 min. MAP varied from 33 ± 10 to 92 ± 10 mmHg. LLA calculated from the whole recording (Mx10s) was similar to LLA calculated from the 15-min recording (Mx2s): 70 ± 2.5 versus 73 ± 3.5 mmHg. MAP remained below LLA during 48 ± 12% of the recording. During the 15-min recording, Mx10s was not able to calculate the LLA value. CONCLUSION: In cases of haemodynamic instability, decreasing the Mx sampling window seems to accurately detect LLA.
Entities:
Keywords:
Cardiac surgery; Cardiopulmonary bypass; Cerebral autoregulation; LLA; Lower limit of autoregulation; Mean arterial pressure; Mx
Authors: Charles H Brown; Karin J Neufeld; Jing Tian; Julia Probert; Andrew LaFlam; Laura Max; Daijiro Hori; Yohei Nomura; Kaushik Mandal; Ken Brady; Charles W Hogue; Ashish Shah; Kenton Zehr; Duke Cameron; John Conte; O Joseph Bienvenu; Rebecca Gottesman; Atsushi Yamaguchi; Michael Kraut Journal: JAMA Surg Date: 2019-09-01 Impact factor: 14.766