Not provided
| ID | Type | Description | Link |
|---|---|---|---|
| 2024/16/925 | Other Identifier | T.C. Sağlık Bilimleri Üniversitesi Kartal Dr. Lütfi Kırdar Eğitim ve Araştırma Hastanesi |
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
Not provided
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.
This prospective, single-center, interventional study was designed to evaluate and compare the effects of minimal-flow and low-flow anesthesia on sevoflurane consumption, anesthetic depth, and respiratory parameters during retrograde intrarenal surgery (RIRS). After obtaining ethics committee approval (Decision No: 2024/16/925, Date: 17.09.2024), a total of 62 adult patients undergoing elective RIRS under general anesthesia were enrolled and divided into two groups based on the fresh gas flow rate used during the maintenance phase of anesthesia.
In Group 1 (Minimal-flow group), the fresh gas flow was reduced to 0.5 L/min after the initial 10 minutes of anesthesia. In Group 2 (Low-flow group), a 1.0 L/min flow rate was maintained. Both groups received the same induction and maintenance protocols with sevoflurane, and depth of anesthesia was monitored via BIS (Bispectral Index). Key variables measured included the total amount of sevoflurane consumed (mL), the time to reach 1 MAC, the vaporizer shut-off time, intraoperative BIS and MAC values, EtCO₂, and respiratory rate. Safety outcomes such as hemodynamic stability and desaturation were also recorded.
The primary outcome was total sevoflurane consumption. Secondary outcomes included anesthetic depth consistency (BIS/MAC), respiratory parameters, and time-based metrics. Statistical analysis revealed that minimal-flow anesthesia significantly reduced sevoflurane usage without compromising patient safety or anesthetic depth.
The results support the clinical use of minimal-flow anesthesia as a safe, cost-effective, and environmentally favorable alternative to low-flow techniques in selected urological procedures.
Not provided
Not provided
Not provided
Not provided
| Label | Type | Description | Intervention Names |
|---|---|---|---|
| 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. |
|
| 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). |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| 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. |
| Measure | Description | Time Frame |
|---|---|---|
| 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) |
Not provided
| Measure | Description | Time Frame |
|---|---|---|
| Time to Reach 1 MAC (minutes) | Time in minutes from anesthesia induction to reaching 1 Minimum Alveolar Concentration (MAC) of sevoflurane, as recorded by the anesthesia machine. | Intraoperative (within first 10 minutes of anesthesia) |
| Vaporizer Shut-off Time (minutes) |
Inclusion Criteria:
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
Exclusion Criteria:
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
Not provided
Not provided
Not provided
Not provided
Not provided
| Name | Affiliation | Role |
|---|---|---|
| UMIT YILDIZ, M.D. | Department of Anesthesiology and Reanimation, Kartal Dr. Lütfi Kırdar City Hospital, University of Health Sciences, Istanbul, Turkey | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Kartal Dr. Lütfi Kırdar City Hospital, University of Health Sciences | Istanbul | 34865 | Turkey (Türkiye) |
Our study is:
Single-center
Non-commercial
Conducted as part of a medical specialty thesis
There is no stated plan to share anonymized individual-level data beyond what is reported in our thesis or publication
Not provided
Not provided
Not provided
Not provided
Not provided
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.
Not provided
Not provided
Not provided
Not provided
|
| 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. |
|
Time in minutes from the start of surgery to the moment the sevoflurane vaporizer was turned off. |
| Intraoperative |
| End-Tidal CO₂ (EtCO₂) Levels (mmHg) | Mean and peak end-tidal CO₂ levels measured intraoperatively at 10-minute intervals. | Throughout surgery |
| BIS Values During Maintenance (BIS Index Units) | Bispectral Index values recorded at 10-minute intervals during the maintenance phase of anesthesia to assess anesthetic depth. | Throughout surgery |
| MAC Values During Maintenance (MAC Units) | MAC values recorded during anesthesia maintenance to assess depth and consistency of volatile agent effect. | Throughout surgery |
| Respiratory Rate (breaths per minute) | Intraoperative respiratory rates monitored and recorded to assess ventilatory response under different flow settings. | Throughout surgery |
| Oxygen Saturation (SpO₂, %) | Minimum oxygen saturation values recorded intraoperatively to evaluate respiratory safety. | Throughout surgery |
| ID | Term |
|---|---|
| D052878 | Urolithiasis |
| D015270 | Mycobacterium avium-intracellulare Infection |
| ID | Term |
|---|---|
| D014570 | Urologic Diseases |
| D052776 | Female Urogenital Diseases |
| D005261 | Female Urogenital Diseases and Pregnancy Complications |
| D000091642 | Urogenital Diseases |
| D052801 | Male Urogenital Diseases |
| D009165 | Mycobacterium Infections, Nontuberculous |
| D009164 | Mycobacterium Infections |
| D000193 | Actinomycetales Infections |
| D016908 | Gram-Positive Bacterial Infections |
| D001424 | Bacterial Infections |
| D001423 | Bacterial Infections and Mycoses |
| D007239 | Infections |
Not provided
Not provided