Masimo has announced the findings of a retrospective study published in the Journal of Cardiothoracic and Vascular Anesthesia in which Dr André Denault and colleagues at the Montreal Heart Institute and Centre Hospitalier de l’Université de Montréal investigated the impact of anaesthesia during cardiac surgery guided by Masimo SedLine® Brain Function Monitoring, in particular by SedLine’s processed electroencephalography (pEEG) feature, the Patient State Index (PSi).
This study is the first to primarily explore the impact of pEEG-guided anaesthesia on vasoactive and inotropic drugs—drugs that affect the diameter of blood vessels and that modify the force of the heart’s contractions, respectively—in the ICU.
The researchers found that pEEG-guided anaesthesia was associated with a reduction in the use of such drugs, as well as less use of anaesthetic agents and opioids in the OR, lower central venous pressure (CVP), less fluid administration, less intraoperative bleeding, and shorter duration on mechanical ventilation.
Noting that pEEG-guided anaesthesia may improve hemodynamic stability and that high postoperative doses of vasoactive and inotropic drugs have been associated with mortality and renal dysfunction, the researchers sought to determine whether use of pEEG-guided anaesthesia might improve outcomes by reducing use of such agents during cardiac surgery and at arrival in the ICU.
Their primary goal was to determine whether pEEG-guided anaesthesia would be associated with reduced hemodynamic instability during cardiopulmonary bypass (CPB) separation, measured by stratifying the operation into three categories: ‘easy’ (use of only one vasoactive or one inotropic agent), ‘difficult’ (use of at least two different classes of agents) or ‘complex’ (requiring a return to CPB or use of mechanical circulatory support). Their secondary goal was to determine if pEEG-guided anaesthesia would lead to the hypothesized reduction in vasoactive and inotropic drug administration in the ICU, measured by vasoactive and inotropic score (VIS).
The researchers compiled a retrospective cohort of 300 adults who underwent cardiac surgery using CPB between 2013 and 2020 at the Montreal Heart Institute.
The patients were divided into two groups, depending on whether anaesthesia was guided by pEEG, which became a standard of care in 2017. Patients in the pEEG group (n=150) had their brain function monitored, from the moment they entered the OR to arrival in the ICU, using Masimo SedLine.
In the pEEG group, patients received fewer vasoactive and inotropic drugs in the first hour after ICU admission, resulting in lower VIS scores (pEEG: 5 [0-10], control: 8 [2-15], p=0.003). Being in the pEEG group reduced the odds of being in a higher VIS category by 57% (OR=0.43; 95% confidence interval: 0.26-0.73; p=0.002).
In addition, in the pEEG group, several additional outcomes were lower: duration of mechanical ventilation (pEEG: 3 hours [2-4 hours], control: 4 hours [3-7 hours], p<0.001), intraoperative fluid balance (pEEG: 758 mL [351-1329 mL], control: 500 mL [300-700 mL], p=0.002), and the amount of bleeding (pEEG: 400 mL [282-500 mL], control: 500 mL [300-700 mL], p=0.002).
A lower proportion of patients experienced unsuccessful (difficult or complex) CPB separation in the pEEG group than the control group (60% vs. 72%, p=0.028).
However, after adjusting for other parameters using multiple logistic regression, use of pEEG-guided anaesthesia was not independently associated with successful CPB separation; instead, as the researchers note, unsuccessful separation was associated with several independent known predictors of hemodynamic complications.
The researchers concluded: “pEEG-guided anaesthesia is associated with a reduction in the use of inotropic or vasoactive drugs at arrival in the ICU. In addition, its implementation was associated with lower requirements of anaesthetic agents and opioids in the OR, lower CVP, fluid requirements, intraoperative bleeding, and shorter duration of mechanical ventilation. However, its use did not facilitate weaning from CPB compared to a group where pEEG was unavailable. Future research is needed to confirm these results in prospective randomized clinical trials.”
