Evaluation of acquired antithrombin deficiency in paediatric patients supported on extracorporeal membrane oxygenation.

AIMS: There remains a paucity of literature regarding best practice for antithrombin (AT) monitoring, dosing and dose-response in paediatric extracorporeal membrane oxygenation (ECMO) patients. METHODS: We conducted a retrospective cohort study at a quaternary care paediatric intensive care unit in all patients <18 years of age supported on ECMO from 1 June 2011 to 30 April 2020. Adverse events and outcomes were characterized for all ECMO runs. AT activity and replacement were characterized and compared between two clinical protocols. AT activities measured post- vs. pre-AT replacement were compared in order to characterize a dose-response relationship. RESULTS: The final cohort included 191 patients with 201 ECMO runs and 2028 AT activity measurements. The median AT activity was 65% (interquartile range [IQR], 51-82) and 879 (43.3%) measurements met the criteria of deficient. The overall median AT dose and increase in AT activity were 50.6 units/kg/dose (IQR, 39.5-67.2) and 23.5% (IQR, 9.8-36.0), respectively. In the protocol that restricted AT activity measurements to clinical scenarios concerning for heparin resistance, there was significantly higher dosing in conjunction with significantly fewer overall administrations. Approximately one third of AT activity remained deficient after repletion. There was no difference in mechanical complications, reasons for discontinuation of ECMO support, time on ECMO or survival between protocols. CONCLUSIONS: There was a high prevalence of AT deficiency in paediatric ECMO patients. An AT replacement protocol based on evaluating heparin resistance is associated with fewer AT administrations, with similar circuit and patient outcomes. Further data are needed to identify optimal dosing strategies.

Hypotension After Cardiac Operations Based on Autoregulation Monitoring Leads to Brain Cellular Injury.

BACKGROUND: Individualizing blood pressure targets could improve organ perfusion compared with current practices. In this study we assess whether hypotension defined by cerebral autoregulation monitoring vs standard definitions is associated with elevation in the brain-specific injury biomarker glial fibrillary acidic protein plasma levels (GFAP). METHODS: Plasma GFAP levels were measured in 121 patients undergoing cardiac operations after anesthesia induction, at the conclusion of the operation, and on postoperative day 1. Cerebral autoregulation was monitored during the operation with the cerebral oximetry index, which correlates low-frequency changes in mean arterial pressure (MAP) and regional cerebral oxygen saturation. Blood pressure was recorded every 15 minutes in the intensive care unit. Hypotension was defined based on autoregulation data as an MAP below the optimal MAP (MAP at the lowest cerebral oximetry index) and based on standard definitions (systolic blood pressure decrement >20%, >30% from baseline, or <100 mm Hg, or both). RESULTS: MAP (mean ± standard deviation) in the intensive care unit was 74 ± 7.3 mm Hg; optimal MAP was 78 ± 12.8 mm Hg (p = 0.008). The incidence of hypotension varied from 22% to 37% based on standard definitions but occurred in 54% of patients based on the cerebral oximetry index (p < 0.001). There was no relationship between standard definitions of hypotension and plasma GFAP levels, but MAP of less than optimal was positively related with postoperative day 1 GFAP levels (coefficient, 1.77; 95% confidence interval, 1.27 to 2.48; p = 0.001) after adjusting for GFAP levels at the conclusion of the operation and low cardiac output syndrome. CONCLUSIONS: Individualizing blood pressure management using cerebral autoregulation monitoring may better ensure brain perfusion than current practice.