Validation of the PRST Score Against Bispectral Index

Validation of the PRST Score Against Bispectral Index During General Anesthesia: A Randomized Controlled Trial

The goal of this randomized controlled trial is to evaluate whether the PRST (Evans) score is a valid method for monitoring the depth of general anesthesia in adult surgical patients. It will also assess whether combining the PRST score with Bispectral Index (BIS) monitoring improves anesthetic depth assessment compared with PRST-guided monitoring alone.

The main questions it aims to answer are:

1. Does the PRST score correlate with BIS values during general anesthesia?
2. Does visible BIS-guided monitoring improve anesthetic depth assessment compared with PRST-guided monitoring alone?

Researchers will compare patients managed using PRST-guided monitoring alone with patients managed using PRST plus visible BIS-guided monitoring.

Participants will:

1. Undergo elective surgery under general anesthesia
2. Receive intraoperative anesthetic depth monitoring using PRST score alone or PRST combined with BIS monitoring
3. Have PRST score, BIS, heart rate, and blood pressure recorded at predefined intraoperative timepoints
4. Complete a postoperative interview assessing recall, dreaming, and anesthesia-related discomfort

Study Overview

• Status: Completed
• Conditions: General Anesthesia; Elective Surgeries; BIS
• Intervention / Treatment: Device: PRST Monitoring; Device: PRST + BIS Monitoring

Detailed Description

This single-center, parallel-group randomized controlled trial (RCT) aims to evaluate the validity of the PRST (Evans) score for monitoring the depth of general anesthesia and to assess its relationship with Bispectral Index (BIS) monitoring in adult surgical patients undergoing elective procedures under general anesthesia.

Intraoperative awareness remains a clinically important complication during general anesthesia. Traditional clinical assessment methods such as the PRST score evaluate autonomic responses including systolic blood pressure, heart rate, sweating, and lacrimation, whereas BIS provides an electroencephalography-based objective assessment of hypnotic depth. This study investigates whether combining PRST assessment with BIS monitoring may improve anesthetic depth evaluation compared with PRST-guided monitoring alone.

Eligible participants are randomized into either a PRST-guided monitoring group or a PRST plus visible BIS-guided monitoring group. Standard anesthetic induction and maintenance protocols are applied in both groups. In the intervention group, BIS monitoring is used as an adjunctive tool to guide anesthetic depth management, with a target BIS range of 40-60.

PRST score, BIS values, heart rate (HR), and mean arterial pressure (MAP) are recorded at predefined intraoperative timepoints including T0 (baseline before induction), T1 (after induction before laryngoscopy), T2 (1-3 minutes after airway instrumentation), T3 (before skin incision), T4 (5 minutes after incision), and T5-T6 (15 and 30 minutes during the maintenance phase). Postoperative interviews are conducted to evaluate recall, dreaming, and anesthesia-related discomfort.

The primary objective is to determine the association between PRST score and BIS values during general anesthesia. Secondary objectives include evaluation of hemodynamic responses, anesthetic delivery variables, postoperative recall-related events, and the diagnostic performance of PRST score in identifying BIS-defined light anesthesia.

• Study Type: Interventional
• Enrollment (Actual): 183
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Indonesia
  • Special Region of Yogyakarta
    • Yogyakarta, Special Region of Yogyakarta, Indonesia, 55281
      • RSUP Dr. Sardjito

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Scheduled for elective surgery under general anesthesia

Exclusion Criteria:

• Unstable hemodynamic conditions
• Contraindications to specific anesthetic agents or significant neurological disorders (e.g., Parkinson's disease, stroke, or dementia)
• Receiving medications known to influence EEG activity, such as anticonvulsants
• Unable to provide informed consent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Control (PRST group); Participants in this group will undergo elective surgery under general anesthesia with anesthetic depth managed using standard clinical monitoring and PRST-guided assessment. PRST components, including systolic blood pressure response, heart rate response, sweating, and lacrimation, will be assessed at predefined intraoperative timepoints.	Device: PRST Monitoring; Clinical anesthetic depth monitoring using PRST score assessment without visible BIS-guided titration.
Experimental: Intervention (PRST + BIS group); Participants in this group will undergo elective surgery under general anesthesia with anesthetic depth managed using standard clinical monitoring, PRST-guided assessment, and visible BIS monitoring. BIS monitoring will be initiated after induction and used as an adjunct to guide hypnotic depth titration, with a typical target BIS range of 40-60. PRST score, BIS values, and hemodynamic parameters will be recorded at predefined intraoperative timepoints.	Device: PRST + BIS Monitoring; Clinical anesthetic depth monitoring using PRST score combined with visible BIS-guided anesthetic titration targeting BIS 40-60.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
PRST score	PRST components were assessed as follows: SBP response (increase from baseline <15 mmHg = 0; 15-30 mmHg = 1; >30 mmHg = 2), HR response (increase from baseline <15 bpm = 0; 15-30 bpm = 1; >30 bpm = 2), sweating (absent = 0; present = 1), and lacrimation (absent = 0; present = 1). The total PRST score ranged from 0 to 6 with higher scores indicating greater autonomic response to nociceptive stimuli.	T0 (baseline before induction), T1 (after induction before laryngoscopy), T2 (1-3 minutes after airway instrumentation), T3 (before skin incision), T4 (5 minutes after incision), and T5-T6 (15 and 30 minutes during the maintenance phase).
BIS Score	Bispectral Index (BIS) monitoring is an electroencephalography-based anesthetic depth monitoring system used to assess the hypnotic state during general anesthesia. In this study, BIS monitoring is initiated after anesthetic induction and used as an adjunctive tool to guide anesthetic depth management, with a target BIS range of 40-60 during maintenance of general anesthesia. Continuous BIS values are recorded throughout the intraoperative period to evaluate anesthetic depth and correlation with PRST score measurements.	T0 (baseline before induction), T1 (after induction before laryngoscopy), T2 (1-3 minutes after airway instrumentation), T3 (before skin incision), T4 (5 minutes after incision), and T5-T6 (15 and 30 minutes during the maintenance phase).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Heart Rate		T0 (baseline before induction), T1 (after induction before laryngoscopy), T2 (1-3 minutes after airway instrumentation), T3 (before skin incision), T4 (5 minutes after incision), and T5-T6 (15 and 30 minutes during the maintenance phase).
Mean Arterial Pressure		T0 (baseline before induction), T1 (after induction before laryngoscopy), T2 (1-3 minutes after airway instrumentation), T3 (before skin incision), T4 (5 minutes after incision), and T5-T6 (15 and 30 minutes during the maintenance phase).
Sevoflurane dial setting	Sevoflurane dial setting refers to the vaporizer concentration setting used to deliver inhaled sevoflurane during maintenance of general anesthesia. In this study, sevoflurane concentration is adjusted intraoperatively according to anesthetic depth assessment and clinical monitoring parameters, including PRST score and BIS monitoring when applicable.	T3 (before skin incision), T4 (5 minutes after incision), and T5-T6 (15 and 30 minutes during the maintenance phase).
End-tidal minimum alveolar concentration (MAC) values	End-tidal minimum alveolar concentration (MAC) values represent the measured concentration of inhaled anesthetic agent in exhaled gas and are used as an indicator of anesthetic potency during general anesthesia. In this study, end-tidal MAC values are continuously monitored intraoperatively and recorded at predefined timepoints to evaluate anesthetic delivery and depth of anesthesia in relation to PRST score and BIS monitoring.	T3 (before skin incision), T4 (5 minutes after incision), and T5-T6 (15 and 30 minutes during the maintenance phase).
Postoperative discomfort	Postoperative discomfort refers to patient-reported unpleasant physical or psychological experiences following general anesthesia and surgery. Assessment is performed postoperatively using structured interview questions evaluating discomfort related to anesthesia, intraoperative experience, or recovery period. Responses are recorded and compared between study groups.	Immediately after recovery from general anesthesia
Dreaming	Dreaming refers to patient-reported dream experiences occurring during the peri-anesthetic period under general anesthesia. Assessment is performed postoperatively using structured interview questions adapted from the modified Brice interview to identify the presence or absence of dreaming during anesthesia and recovery. Responses are recorded and compared between study groups.	Immediately after recovery from general anesthesia

Collaborators and Investigators

• Sponsor: Gadjah Mada University

Study record dates

Study Major Dates

• Study Start (Actual): October 26, 2025
• Primary Completion (Actual): January 5, 2026
• Study Completion (Actual): January 5, 2026

Study Registration Dates

• First Submitted: May 11, 2026
• First Submitted That Met QC Criteria: May 11, 2026
• First Posted (Actual): May 15, 2026

Study Record Updates

• Last Update Posted (Actual): May 15, 2026
• Last Update Submitted That Met QC Criteria: May 11, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: general anesthesia; bispectral index; Depth of Anesthesia; PRST score
• Other Study ID Numbers: PRST-BIS-RCT-2026

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