Effect of Hypothermia on BIS and PSI Correlation During Cardiopulmonary Bypass

Official title

Effect of Hypothermia on the Correlation Between Bispectral Index (BIS) and Patient State Index (PSI) During Cardiopulmonary Bypass

Overview

The goal of this observational study is to evaluate whether hypothermia affects the relationship between electroencephalography-derived indices during cardiac surgery in adult patients undergoing cardiopulmonary bypass. The main questions it aims to answer are: Does the correlation between Bispectral Index (BIS) and Patient State Index (PSI) change between normothermic and hypothermic phases during cardiopulmonary bypass? How do BIS and PSI values change in response to decreasing body temperature? Participants will: Undergo standard general anesthesia for elective on-pump coronary artery bypass surgery Be monitored simultaneously with BIS and PSI devices during surgery Have data recorded at predefined temperature-based time points during cardiopulmonary bypass

Detailed description

Hypothermia during cardiopulmonary bypass (CPB) is known to influence cerebral metabolism and electroencephalographic activity. Processed electroencephalography-derived indices such as the Bispectral Index (BIS) and Patient State Index (PSI) are commonly used to monitor anesthetic depth; however, these indices are generated using different proprietary algorithms. While previous studies have demonstrated moderate to high correlation between BIS and PSI under normothermic conditions, it remains unclear whether this relationship is preserved during hypothermic CPB.

This prospective observational study aims to evaluate the effect of hypothermia on the relationship between BIS and PSI in adult patients undergoing elective on-pump coronary artery bypass grafting. Both indices will be monitored simultaneously throughout the intraoperative period using standard sensor placement.

Data will be collected at predefined time points representing normothermic, hypothermic, and rewarming phases of CPB. The primary analysis will focus on comparing the correlation between BIS and PSI at a normothermic reference point (36°C) and a hypothermic reference point (32°C).

To minimize confounding effects, anesthetic management and physiological parameters will be maintained within routine clinical target ranges, and relevant variables will be recorded throughout the procedure. Secondary analyses will explore temperature-dependent changes in each index and agreement between clinically relevant depth-of-anesthesia categories.

This study is designed to clarify whether hypothermia alters the relationship between commonly used processed EEG indices, which may have implications for intraoperative neuromonitoring and anesthetic management during cardiac surgery.

Interventions

• Other Simultaneous BIS and PSI Monitoring
  This observational study does not involve any experimental intervention. All participants will receive standard anesthesia and surgical care according to institutional protocols. The study focuses on simultaneous intraoperative monitoring using Bispectral Index (BIS) and Patient State Index (PSI) devices. Sensors for both monitors will be applied prior to induction of anesthesia, and values will be recorded at predefined time points during normothermic, hypothermic, and rewarming phases of cardi

Primary outcome measures

• Difference in Correlation Between Bispectral Index (BIS) and Patient State Index (PSI) Under Normothermic and Hypothermic Conditions [Time frame: Intraoperative (during cardiopulmonary bypass at predefined time points)]

Secondary outcome measures (3)

• Change in Bispectral Index (BIS) and Patient State Index (PSI) per Degree Celsius During Cooling and Rewarming [Time frame: Intraoperative (during cooling and rewarming phases of cardiopulmonary bypass)]
• Effect of CPB Initiation on the Relationship Between Bispectral Index (BIS) and Patient State Index (PSI) [Time frame: Intraoperative (comparison of pre-CPB and post-CPB initiation time points)]
• Agreement in Clinical Depth Categories Between Bispectral Index (BIS) and Patient State Index (PSI) [Time frame: Intraoperative (during predefined normothermic and hypothermic phases of cardiopulmonary bypass)]

Eligibility criteria

Inclusion criteria

• Age ≥18 years
• Elective on-pump Coronary Artery Bypass Grafting (CABG) surgery
• Planned use of general anesthesia
• Written informed consent

Exclusion criteria

• Preexisting neurological disease
• Use of medications affecting Electroencephalography (e.g., antiepileptics)
• Severe hepatic dysfunction
• Emergency surgery
• Inadequate signal quality for anesthesia depth monitoring

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Cohort

Study locations

Turkey (Türkiye) · 1 center

• Sakarya University Training and Research Hospital, Department of Anesthesiology and Reanim — Sakarya

Publications

• Meybohm P, Gruenewald M, Hocker J, Renner J, Graesner JT, Ilies C, Scholz J, Bein B. Correlation and agreement between the bispectral index vs. state entropy during hypothermic cardio-pulmonary bypass. Acta Anaesthesiol Scand. 2010 Feb;54(2):169-75. doi: 10.1111/j.1399-6576.2009.02138.x. Epub 2009 Oct 15. PMID 19839944
• Belletti A, Lee DK, Yanase F, Naorungroj T, Eastwood GM, Bellomo R, Weinberg L. Changes in SedLine-derived processed electroencephalographic parameters during hypothermia in patients undergoing cardiac surgery with cardiopulmonary bypass. Front Cardiovasc Med. 2023 Jul 4;10:1084426. doi: 10.3389/fcvm.2023.1084426. eCollection 2023. PMID 37469479

Identifiers

NCT: NCT07508579 · SEAH-DOAonCPB-2026

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗