Investigation of Sedation Depth Via BIS Monitoring in ICU After Cardiac Surgery (BISICU)

An Explorative Prospective Non-interventional Study on Sedation Depth in Postoperative Cardiac Surgery Patients Using Blinded BIS Monitoring

This study is a non-interventional, observational research project focused on monitoring sedation levels in patients who have undergone cardiac surgery. It uses a tool called Bispectral Index (BIS), which measures brain activity to assess sedation depth. The goal is to understand how often patients experience deep sedation (BIS <50) during the first 48 hours in the ICU and to explore its impact on clinical outcomes like ventilation duration, ICU stay length, and complications such as infections or delirium.

The study is conducted at two hospitals in Austria and involves patients who require mechanical ventilation and continuous sedation for more than six hours after surgery. BIS data will be collected continuously, but the readings will be blinded to the clinical team, meaning they will not influence patient care. Sedation will be managed using standard clinical practices.

The findings aim to improve sedation management in ICUs.

Study Overview

• Status: Completed
• Conditions: Sedation After Cardiac Surgery

• Study Type: Observational
• Enrollment (Actual): 50

Contacts and Locations

Study Locations

• Austria
  • Styria
    • Graz, Styria, Austria, 8010
      • Medical University Graz
  • Upper Austria
    • Wels, Upper Austria, Austria, 4600
      • Klinikum Wels

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

patients admitted to the ICU following cardiac surgery. These patients are expected to require invasive mechanical ventilation and continuous sedation for more than 6 hours postoperatively.

Description

Inclusion Criteria:

• Age ≥ 18 years.
• Undergoing cardiac surgery with subsequent admission to the ICU
• expected duration of invasive mechanical ventilation > 6 hours postop.
• Written informed consent obtained from the patient or legal representative (if the patient is not capable of consent).

Exclusion Criteria:

• Pre-existing neurological disorders affecting consciousness or sedation assessment (e.g., severe dementia, epileptic encephalopathy).
• Acute neurological events in the perioperative period (e.g., stroke, intracranial hemorrhage).
• Severe hepatic dysfunction (Child-Pugh Class C).
• Participation in another interventional study potentially affecting sedation or cognitive outcomes.
• Pregnancy or lactation.
• Patients in whom short-term survival is deemed unlikely due to clinical course

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
study group; adult patients who have undergone cardiac surgery expected to require invasive mechanical ventilation and continuous sedation for more than six hours postoperatively

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of time spent in deep sedation	BIS <50	immediately after extubation or up to 48 hours of ICU sedation - whichever comes first

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Duration of mechanical ventilation		immediately after extubation
Incidence of pulmonary infection	any kind of pulmonary infection, including tracheobronchitis, pneumonia	immediately after ICU discharge
Incidence of ICU delirium	assessed using CAM-ICU or ICDSC	immediately after extubation
Time average of vasopressor dose	Time average of Noradrenaline dose	immediately after extubation or after 48 hours of invasive ventilation
ICU and hospital LOS	in days	immediately after hospital discharge
in hospital mortality		immediately after hospital discharge
Incidence of BIS suppression events	episodes where the suppression ratio exceeds 10%, indicating potential over-sedation or EEG suppression	immediately after extubation or after 48 hours of invasive ventilation

Collaborators and Investigators

• Sponsor: Medical University of Graz

Study record dates

Study Major Dates

• Study Start (Actual): November 22, 2025
• Primary Completion (Actual): March 25, 2026
• Study Completion (Actual): March 26, 2026

Study Registration Dates

• First Submitted: November 24, 2025
• First Submitted That Met QC Criteria: January 13, 2026
• First Posted (Actual): January 20, 2026

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 28, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: 1368

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No