Equivalent MAC in General Anesthesia

Not yet recruiting

• Conditions: General Anesthesia; Intraoperative Monitoring; Anesthetic Depth
• Interventions: Drug: Sevoflurane + Remifentanil; Drug: Propofol + Remifentanil; Drug: Sevoflurane + Propofol + Remifentanil

• Registration Number: NCT07197567
• Lead Sponsor: Sakarya University

Brief Summary

This observational study aims to evaluate the clinical applicability of the Equivalent Minimum Alveolar Concentration (eMAC) parameter during general anesthesia. eMAC is a recently developed index that combines the effects of both inhalational and intravenous anesthetics, providing a unified measure of anesthetic depth. While the traditional Minimum Alveolar Concentration (MAC) is widely used for inhalational agents, it does not reflect intravenous anesthetics or combined techniques such as Combined Intravenous and Inhalational Anesthesia (CIVIA).

In this study, adult patients undergoing elective surgery under general anesthesia will be observed. Standard clinical practice will not be altered. Demographic and clinical parameters, including eMAC, MAC, Bispectral Index (BIS), and hemodynamic variables, will be recorded at defined perioperative time points. No experimental drugs or additional procedures will be administered.

The primary aim is to investigate the correlation between eMAC and MAC values obtained during anesthesia. Secondary objectives include assessing the relationship between eMAC and BIS values, comparing eMAC, MAC, and BIS across different anesthetic techniques, and evaluating hemodynamic stability in relation to anesthetic depth.

The results of this study may contribute to a better understanding of eMAC and its potential role in clinical anesthesia practice.

Detailed Description

This is a prospective, observational study designed to evaluate the Equivalent Minimum Alveolar Concentration (eMAC) parameter during general anesthesia. eMAC is a composite index that incorporates the anesthetic effects of both inhalational agents and intravenous anesthetics, such as propofol and remifentanil, allowing assessment of anesthetic depth under combined techniques (CIVIA). While the traditional Minimum Alveolar Concentration (MAC) is well established for inhalational agents, its applicability is limited in cases where intravenous agents are administered. eMAC has been proposed as a more comprehensive measure, but clinical validation is lacking.

Adult patients (ages 18-65, ASA I-III) scheduled for elective surgical procedures under general anesthesia will be enrolled. No experimental interventions will be performed; anesthetic management will follow routine clinical practice. Participants will be observed in three groups, based on the anesthetic technique selected by the attending anesthesiologist.

Data collection will include demographic and baseline clinical variables, as well as anesthetic depth parameters (eMAC, MAC, Bispectral Index \[BIS\]) and hemodynamic variables (heart rate, mean arterial pressure, SpO₂). Measurements will be recorded at predefined time points: prior to induction (T0), 5 minutes after induction (T1), at the beginning of surgery (T2), at the midpoint of surgery (T3), and at the end of surgery (T4).

The primary outcome measure is the correlation between eMAC and MAC values obtained during anesthesia. Secondary outcome measures include the correlation between eMAC and BIS values, comparisons of eMAC, MAC, and BIS among different anesthetic techniques, and evaluation of hemodynamic stability in relation to anesthetic depth.

Statistical analysis will be performed using appropriate parametric or non-parametric tests, depending on the distribution of variables. Correlation analyses will be conducted using Pearson or Spearman methods, and the impact of demographic factors on eMAC will be explored using multivariate regression. A p-value \<0.05 will be considered statistically significant.

The anticipated enrollment is 90 patients. The study is planned to start in September 2025 and is expected to be completed by November 2025. Findings may provide novel insights into the clinical validity of eMAC as a tool for assessing anesthetic depth, and its relationship with established parameters such as MAC and BIS.

Study Timeline

• Study First Submitted: 2025-08-31
• Status Verified: 2025-09
• Study First Submitted QC: 2025-09-22
• Last Update Submitted: 2025-09-22
• Study First Posted: 2025-09-29
• Last Update Posted: 2025-09-29
• Study Start: 2025-11-01
• Primary Completion: 2025-12-01
• Study Completion: 2026-12-01

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 90

Inclusion Criteria

• Adults aged 18-65 years
• Scheduled for elective surgery under general anesthesia
• American Society of Anesthesiologists (ASA) Physical Status I-III
• Feasibility of Bispectral Index (BIS) monitoring
• Provision of written informed consent

Exclusion Criteria

• History of neurological disease (e.g., epilepsy, dementia, severe brain injury)
• Known allergy to anesthetic agents
• Severe cardiovascular or respiratory failure

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Inhalational Anesthesia Group	Sevoflurane + Remifentanil	Patients receiving general anesthesia maintained with inhalational agents (e.g., sevoflurane) according to standard clinical practice.
Total Intravenous Anesthesia (TIVA) Group	Propofol + Remifentanil	Patients receiving general anesthesia maintained exclusively with intravenous agents (propofol, remifentanil) according to standard clinical practice.
Combined Intravenous-Inhalational Anesthesia (CIVIA) Group	Sevoflurane + Propofol + Remifentanil	Patients receiving general anesthesia with a combination of intravenous and inhalational agents according to standard clinical practice.

Primary Outcome Measures

Name	Time	Method
Correlation between Equivalent Minimum Alveolar Concentration (eMAC) and Minimum Alveolar Concentration (MAC)	From induction of anesthesia until the end of surgery (measured at five perioperative time points: prior to induction, 5 minutes after induction, at surgical incision, at the midpoint of surgery, and at the end of surgery)	To determine the relationship between eMAC values and conventional MAC values obtained from the anesthesia workstation.

Secondary Outcome Measures

Name	Time	Method
Correlation between eMAC and Bispectral Index (BIS)	From induction of anesthesia until the end of surgery (measured at five perioperative time points: prior to induction, 5 minutes after induction, at surgical incision, at the midpoint of surgery, and at the end of surgery)	To assess the relationship between eMAC values and BIS as indicators of anesthetic depth.
Comparison of eMAC, MAC, and Bispectral Index (BIS) Values Measured by Anesthesia Workstation and BIS Monitor Across Different Anesthetic Techniques	From induction of anesthesia until the end of surgery (measured at five perioperative time points: prior to induction, 5 minutes after induction, at surgical incision, at the midpoint of surgery, and at the end of surgery)	To compare anesthetic depth parameters obtained from the anesthesia workstation (eMAC and MAC values) and BIS monitor (BIS values) among patients managed with inhalational anesthesia, total intravenous anesthesia (TIVA), or combined intravenous-inhalational anesthesia (CIVIA).
Heart Rate During Anesthesia	From induction of anesthesia until the end of surgery (measured at five perioperative time points: prior to induction, 5 minutes after induction, at surgical incision, at the midpoint of surgery, and at the end of surgery)	To evaluate heart rate (beats per minute) in relation to anesthetic depth parameters across study groups.
Mean Arterial Pressure During Anesthesia	From induction of anesthesia until the end of surgery (measured at five perioperative time points: prior to induction, 5 minutes after induction, at surgical incision, at the midpoint of surgery, and at the end of surgery)	To evaluate mean arterial pressure (mmHg) in relation to anesthetic depth parameters across study groups.
Peripheral Oxygen Saturation (SpO₂) During Anesthesia	From induction of anesthesia until the end of surgery (measured at five perioperative time points: prior to induction, 5 minutes after induction, at surgical incision, at the midpoint of surgery, and at the end of surgery)	To evaluate peripheral oxygen saturation (percentage, %) in relation to anesthetic depth parameters across study groups.

Trial Locations

Locations (1)

Sakarya University Training and Research Hospital, Department of Anesthesiology and Reanimation; Sakarya, Adapazari, Turkey (Türkiye)