Equivalent MAC in General Anesthesia

NCT ID: NCT07197567

Last Updated: 2026-01-28

Basic Information

• Recruitment Status: COMPLETED
• Total Enrollment: 60 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2025-11-01
• Study Completion Date: 2026-01-15

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 60 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.

Conditions

General Anesthesia; Intraoperative Monitoring; Anesthetic Depth

Study Design

• Observational Model Type: COHORT
• Study Time Perspective: PROSPECTIVE

Study Groups

Inhalational Anesthesia Group

Patients receiving general anesthesia maintained with inhalational agents (e.g., sevoflurane) according to standard clinical practice.

Sevoflurane + Remifentanil

Intervention Type: DRUG

Combination of an inhalational anesthetic (sevoflurane) and an intravenous opioid analgesic (remifentanil), both routinely used in clinical practice for maintenance of general anesthesia. These agents are administered according to standard of care, not as experimental interventions.

Combined Intravenous-Inhalational Anesthesia (CIVIA) Group

Patients receiving general anesthesia with a combination of intravenous and inhalational agents according to standard clinical practice.

Sevoflurane + Propofol + Remifentanil

Intervention Type: DRUG

Combination of an inhalational anesthetic (sevoflurane), an intravenous anesthetic (propofol), and an intravenous opioid analgesic (remifentanil). These agents are routinely used together in clinical practice for combined intravenous-inhalational anesthesia (CIVIA). All drugs are administered according to standard of care, not as experimental interventions.

Interventions

Sevoflurane + Remifentanil

Combination of an inhalational anesthetic (sevoflurane) and an intravenous opioid analgesic (remifentanil), both routinely used in clinical practice for maintenance of general anesthesia. These agents are administered according to standard of care, not as experimental interventions.

Intervention Type: DRUG

Sevoflurane + Propofol + Remifentanil

Combination of an inhalational anesthetic (sevoflurane), an intravenous anesthetic (propofol), and an intravenous opioid analgesic (remifentanil). These agents are routinely used together in clinical practice for combined intravenous-inhalational anesthesia (CIVIA). All drugs are administered according to standard of care, not as experimental interventions.

Intervention Type: DRUG

Eligibility Criteria

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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 65 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Sakarya University

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Ayca Tas Tuna, Professor, M.D.

Role: PRINCIPAL_INVESTIGATOR

Sakarya University Faculty of Medicine

Locations

Sakarya University Training and Research Hospital, Department of Anesthesiology and Reanimation

Sakarya, Adapazari, Turkey (Türkiye)

Countries

Turkey (Türkiye)

References

Zhang H, Zhang J, Li X, He S, Deng Z, Wang L, Wang Y, Wang X, Wan C, Huang F, Zhu Z, Dong H. Feasibility Study of an Indicator of Equivalent Potency of Multiple Anesthetics Normalized by Minimum Alveolar Concentration Derived From Response Surface Models. Anesth Analg. 2025 Apr 17. doi: 10.1213/ANE.0000000000007514. Online ahead of print.

Reference Type: BACKGROUND

PMID: 40244902 (View on PubMed)

Other Identifiers

SEAH-EMAC-2025

Identifier Type: -

Identifier Source: org_study_id