Evaluation of Sevoflurane Consumption During Initial Phase of Minimal-Flow Anesthesia in Retrograde Intrarenal Surgery

NCT07248917 | Completed

• 2 other identifiers: KLKSH-ANES-SEVOMIN-RIRS-0012024/16/925
• Study Type: interventional
• Target: 62
• Locations: 1 country
• Sites: 1

Brief Summary

This study aimed to compare the effects of minimal-flow (0.5 L/min) and low-flow (1.0 L/min) sevoflurane anesthesia on agent consumption, anesthetic depth, and cardiorespiratory safety during retrograde intrarenal surgery (RIRS). A total of 62 adult patients undergoing elective RIRS were enrolled in this single-center interventional trial. Patients were divided into two groups based on the fresh gas flow rate used during the maintenance phase of anesthesia. The primary outcome was total sevoflurane consumption at the end of anesthesia. Secondary outcomes included time to reach 1 minimum alveolar concentration (MAC), vaporizer shut-off time, BIS values, MAC levels, and respiratory parameters. The study found that minimal-flow anesthesia was as effective and safe as low-flow anesthesia, with lower agent consumption and no adverse effects on hemodynamic or respiratory parameters. These findings support the use of minimal-flow anesthesia for improved cost-efficiency and environmental sustainability.

Conditions

Retrograde Intrarenal Surgery (RIRS); Urolithiasis; Minimal-flow Anesthesia; Sevoflurane; Anesthetic Consumption; Inhalational Anesthesia; Anesthesia Depth Monitoring

Keywords

minimal-flow anesthesia, low-flow anesthesia, sevoflurane, retrograde intrarenal surgery (RIRS), volatile consumption, environmental sustainability, MAC, BIS

Outcome Measures

Primary Outcomes (1)

• Total Sevoflurane Consumption (mL)

  Total volume of sevoflurane (in milliliters) used during the maintenance phase of general anesthesia, calculated automatically by the anesthesia machine and recorded at the end of surgery.

  End of surgery (approximately 60-90 minutes after anesthesia induction)

Other Outcomes (7)

• Time to Reach 1 MAC (minutes)

  Intraoperative (within first 10 minutes of anesthesia)

• Vaporizer Shut-off Time (minutes)

  Intraoperative

• End-Tidal CO₂ (EtCO₂) Levels (mmHg)

  Throughout surgery

Study Arms (2)

Minimal-flow Sevoflurane Group

EXPERIMENTAL

Participants in this group received general anesthesia using sevoflurane with a fresh gas flow rate reduced to 0.5 L/min after the initial 10 minutes of induction. Anesthesia depth was monitored using BIS, and agent consumption and respiratory parameters were recorded throughout the retrograde intrarenal surgery (RIRS) procedure.

Drug: Sevoflurane Anesthesia with Minimal-flow

Low-flow Sevoflurane Group

ACTIVE COMPARATOR

Participants in this group received general anesthesia using sevoflurane with a consistent 1.0 L/min fresh gas flow during the maintenance phase. BIS monitoring, agent consumption, and respiratory parameters were recorded throughout the retrograde intrarenal surgery (RIRS).

Drug: Sevoflurane Anesthesia with Low-flow

Interventions

Sevoflurane Anesthesia with Minimal-flow DRUG

Patients received general anesthesia with sevoflurane. After induction, the fresh gas flow rate was reduced to 0.5 L/min during the maintenance phase of anesthesia for retrograde intrarenal surgery (RIRS). Agent consumption and anesthetic depth (via BIS and MAC) were monitored.

Minimal-flow Sevoflurane Group

Sevoflurane Anesthesia with Low-flow DRUG

Patients received general anesthesia with sevoflurane. A fresh gas flow rate of 1.0 L/min was maintained during the maintenance phase of anesthesia for retrograde intrarenal surgery (RIRS). BIS, MAC, and respiratory parameters were recorded.

Low-flow Sevoflurane Group

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adults aged 18 to 65 years
• ASA (American Society of Anesthesiologists) Physical Status I or II
• Scheduled to undergo elective retrograde intrarenal surgery (RIRS) under general anesthesia
• Provided written informed consent
• Able to cooperate with preoperative evaluation procedures

You may not qualify if:

• ASA Physical Status III or higher
• History of respiratory disease (e.g., asthma, COPD, restrictive lung disease)
• Known hepatic or renal dysfunction
• Neurological or psychiatric disorders that may affect BIS monitoring or anesthetic response
• Known allergy or hypersensitivity to sevoflurane or other volatile anesthetics
• Pregnancy or breastfeeding
• Obesity (BMI \> 30 kg/m²)
• Anticipated difficult airway or history of intubation complications
• Participation in another clinical trial within the past 30 days

Sponsors & Collaborators

• Dr. Lutfi Kirdar Kartal Training and Research Hospital: lead

Study Sites (1)

Kartal Dr. Lütfi Kırdar City Hospital, University of Health Sciences

Istanbul, 34865, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Urolithiasis; Mycobacterium avium-intracellulare Infection

Condition Hierarchy (Ancestors)

Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Male Urogenital Diseases; Mycobacterium Infections, Nontuberculous; Mycobacterium Infections; Actinomycetales Infections; Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Infections

Study Officials

• UMIT YILDIZ, M.D.

  Department of Anesthesiology and Reanimation, Kartal Dr. Lütfi Kırdar City Hospital, University of Health Sciences, Istanbul, Turkey

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Medical Doctor in Anesthesiology and Reanimation

Model Details: This was a prospective, two-arm, parallel-group study in which patients undergoing retrograde intrarenal surgery (RIRS) were randomly assigned to receive either minimal-flow (0.5 L/min) or low-flow (1.0 L/min) sevoflurane anesthesia. Participants were allocated to one group only and followed independently throughout the procedure. No crossover between groups occurred. The study aimed to compare anesthetic consumption, depth of anesthesia, and cardiorespiratory safety between the two anesthetic flow techniques.

Study Record Dates

• First Submitted: November 18, 2025
• First Posted: November 25, 2025
• Study Start: October 1, 2024
• Primary Completion: June 1, 2025
• Study Completion: September 1, 2025
• Last Updated: November 25, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)