Low-flow Anesthesia
Conditions
Brief summary
The aim of this study is to observe the effects of minimal and metabolically required basal anesthetic gas flow rates delivered by the anesthesia workstation under general anesthesia on body temperature, blood pressure, and heart rate during surgery. It also aims to evaluate the impact of reducing excessive delivery of anesthetic gases, air, and oxygen beyond the patient's physiological needs during general anesthesia on minimizing the harmful effects of anesthetic gases on the environment, climate, and global warming, as well as on contributing positively to hospital costs.
Detailed description
This prospective randomized study will be conducted in adult female patients undergoing elective gynecological surgery under general anesthesia. Following standard intravenous induction and endotracheal intubation, anesthesia will be maintained with sevoflurane using an advanced anesthesia workstation capable of delivering minimal and metabolic fresh gas flow rates. After achieving the target anesthetic depth guided by minimum alveolar concentration (MAC) and MAC Brain monitoring, patients will be randomized to receive either minimal-flow (0.5 L/min) or metabolic-flow (0.3 L/min) fresh gas anesthesia. Randomization will be performed using an internet-based randomization tool. Standard intraoperative monitoring will be applied in all patients, including electrocardiography, non-invasive blood pressure monitoring, pulse oximetry, capnography, anesthetic gas analysis, and esophageal temperature monitoring. Hemodynamic and respiratory parameters will be recorded at predefined time intervals throughout surgery. Sevoflurane consumption will be automatically calculated by the anesthesia workstation. At the end of surgery, fresh gas flow will be increased to eliminate residual anesthetic gases, and patients will be extubated according to standard clinical criteria. Postoperative monitoring will continue in the post-anesthesia care unit. The total study duration for each participant includes the intraoperative period and approximately 30 minutes of postoperative monitoring.
Interventions
PROCEDURELow Flow Anesthesia
Adjustment of fresh gas flow rates during general anesthesia using a modern anesthesia workstation (Getinge Flow-C). Patients will be randomized to receive anesthesia with either minimal flow (0.5 L/min) or metabolic flow (0.3 L/min). All other anesthetic agents and monitoring parameters will remain standardized according to institutional protocols.
Sponsors
Baskent University
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
FEMALE
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Female patients aged 18-65 years * Undergoing elective gynecologic surgery under general anesthesia (including hysterectomy and/or oophorectomy)
Exclusion criteria
* Pregnant patients * Patients with advanced cardiac disease * Patients with advanced renal disease * Patients with advanced hepatic disease * Patients with advanced respiratory disease * Severe obesity * Heavy smokers * Excessive alcohol consumption * Known allergic sensitivity to halogenated anesthetic gases * Use of medications that may interact with volatile anesthetics * History of or susceptibility to malignant hyperthermia or neuromuscular disorders
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Core body temperature (°C) | From induction of anesthesia until the end of surgery (approximately 1-2 hours) | Mean intraoperative core body temperature (Degrees Celsius (°C)): Measured intraoperatively using an esophageal temperature probe. |
| Mean intraoperative heart rate (bpm) | From induction of anesthesia until the end of surgery (approximately 1-2 hours) | Mean intraoperative heart rate (Beats per minute (bpm)): Measured intraoperatively via electrocardiographic monitoring. |
| Mean intraoperative mean arterial pressure (mmHg) | From induction of anesthesia until the end of surgery (approximately 1-2 hours) | Mean intraoperative mean arterial pressure (Millimeters of mercury (mmHg)): Measured intraoperatively using non-invasive blood pressure monitoring. |
| Anesthetic gas consumption (mL) | From induction of anesthesia until the end of surgery (approximately 1-2 hours) | Total sevoflurane consumption (Milliliters (mL)): As recorded by the anesthesia workstation. |
| Richmond Agitation-Sedation Scale (RASS) (-5 to 4) | At the end of surgery / immediate postoperative period | Richmond Agitation-Sedation Scale (RASS) (-5 to 4): The RASS is a 10-point scale ranging from -5 to +4. Negative scores (-1 to -5) indicate increasing levels of sedation, with -5 indicating an unarousable patient. Positive scores (+1 to +4) indicate increasing levels of agitation, with +4 indicating combative behavior. Scores closer to 0 reflect better recovery quality. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Anesthetic gas cost (USD or local currency) | Intraoperative period - calculated at the end of surgery (1-2 hours). | Total intraoperative anesthetic gas cost (USD or local currency): Calculated based on total sevoflurane consumption recorded by the anesthesia workstation. |
Countries
Turkey (Türkiye)
Contacts
PRINCIPAL_INVESTIGATORAsude Ayhan, MD
Baskent University Ankara Hospital, Department of Anesthesiology and Reanimation
Outcome results
None listed