Abstracts
Effect of anaesthesia depth monitored using Bispectral Index on time to extubation in cardiothoracic surgery patients
Inhoud:

    Auteur(s):

    Martijn Vrouenraets1, Tom den Ridder2,  Anouk Lindelauf3, Yorinde Kishna1, Carine Vossen2, Marc Buise2, Iwan van der Horst1, Marcel Aries1

     

    1Departement of Intensive Care Medicine, Maastricht University Medial Centre+, Maastricht University, Maastricht, the Netherlands

    2Departement of Anesthesiologie, Maastricht University Medial Centre+, Maastricht University, Maastricht, the Netherlands

    3Departement of Perfusie, Maastricht University Medial Centre+, Maastricht University, Maastricht, the Netherlands
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    Abstracts

    Effect of anaesthesia depth monitored using Bispectral Index on time to extubation in cardiothoracic surgery patients

    Teaser: In deze observationele studie onderzochten we de relatie tussen anesthesiediepte - gemeten met de BiSpectral Index (BIS) neuromonitor - en de postoperatieve tijd tot detubatie na electieve cardiothoracale chirurgie in 34 patiënten. We vonden dat het aantal cumulatieve minuten doorgebracht in diepe anesthesie (gedefinieerd als een BIS waarde < 20) significant gecorreleerd was met tijd tot detubatie op de IC.

    Background: A prolonged time to waking up and extubation in the intensive care unit (ICU) following cardiothoracic surgery can have negative effects on postoperative recovery. A prolonged time to extubation may be caused by certain surgical, anaesthesiologic or neurological complications. The depth of general anaesthesia may affect both the time to extubation and the occurrence of postoperative delirium. Intraoperative non-invasive neuromonitoring, such as the BiSpectral Index (BIS) monitor, can be used to estimate the general anaesthesia depth. We hypothesized that patients with deep anaesthesia levels during surgery experience a prolonged postoperative time to extubation.

    Methods: In this observational, prospective, single-centre study, 34 patients were included undergoing cardiopulmonary bypass (CPB) for coronary artery bypass grafting (CABG) and/or aortic valve replacement (AVR). No intra-operative anaesthesia protocol based on BIS monitoring is present in our hospital. Patients with major perioperative complications (tamponade, cardiac ischemia, cardiac arrest) were excluded. Besides the mean, minimum and maximum BIS value, the so called ‘anaesthesia depth’ variable was calculated for each intra-operative BIS range from 0 to 100 with portions of 10. This variable corresponds to the cumulative number of minutes the patient has spent within a certain BIS range. The moment of extubation in the ICU was determined using the disappearance of the end-tidal CO2 signal.

    Results: The majority of patients were male (91%) and underwent CABG (79%). The mean age was 67.0 ± 9.2. Patients were categorized into a group with a time to extubation of less than 8 hours (n=20, 8- group) or more than 8 hours (n=14, 8+ group). The BIS parameters for both subgroups are shown in Fig. 1. The amount of time spent in deep levels of anaesthesia (BIS < 20) was significantly greater in the 8+ group compared to the 8- group (14.2 ± 21.5 versus 1.2 ± 5.2 minutes, p < 0.05) (Fig. 1B). In a multiple regression analyses, the variables age, type of surgical procedure, surgery duration and CPB duration did not significantly affect the time to extubation.

    Conclusion: In this ongoing project we found that the amount of time spent in deep anaesthesia  (BIS < 20) was significantly correlated with time to extubation. Future research should evaluate the overall impact of anaesthesia levels lower than the recommended BIS range of 40 to 60 on relevant patient outcomes, including anaesthesia awareness, postoperative delirium, postoperative pain, duration of the ICU and hospital stay, and longer-term clinical outcomes.