Cerebral OxygenationNCT07514026
The Effect Of Low-Flow And Hıgh-Flow Anesthesıa On Intracranıal Pressure
An observational study of Cerebral Oxygenation and Low Flow Anesthesia, run by Bursa City Hospital at 1 site in Turkey (Türkiye).
Trial summary
This prospective randomized study was conducted to evaluate the effects of low-flow and high-flow anesthesia on intracranial dynamics and cerebral oxygenation in patients undergoing laparoscopic hysterectomy in the Trendelenburg position. Read more about this study
- Who is it for?
- Ages 18 to 75 years, women only
- Conditions the study is for
- Cerebral Oxygenation, Low Flow Anesthesia, Optic Nerve Sheath Diameter Measurement
- How many people
- 64 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Jan 2024to 1 Jun 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 75 years
- Women only
- No healthy volunteers
- Adult, Older adult
Study population: According to the study, 64 female patients aged between 18 and 75 who were to undergo laparoscopic hysterectomy were included, all of whom were classified as Class I or II according to the American Society of Anesthesiologists (ASA) physical status.
Who may be able to join
- Female patients aged 18-75 years
- Scheduled for elective laparoscopic hysterectomy
- American Society of Anesthesiologists (ASA) physical status I-II
- Ability to provide written informed consent
Who cannot join
- Septicemia
- Risk of malignant hyperthermia
- Uncontrolled diabetes mellitus
- Chronic alcohol use
- Prolonged fasting
- Body mass index (BMI) > 40 kg/m²
Show all 16Show fewer
- Intracranial space-occupying lesions (e.g., tumors, metastases, abscesses, hematomas, aneurysms)
- History of head trauma or cerebrovascular stroke within the preceding six months
- Known heart failure
- Diagnosis of glaucoma
- Prior carotid surgery or carotid artery stenosis
- ASA physical status ≥ III
- Requirement for massive blood transfusion
- Conversion from volume-controlled to pressure-controlled mechanical ventilation during surgery
- Intraoperative conversion to open surgery
- Patient refusal to participate
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Comparative Effects of High-Flow and Low-Flow Anesthesia on Optic Nerve Sheath Diameter and Cerebral Oxygenation During Laparoscopic Hysterectomy
This prospective randomized study was conducted to evaluate the effects of low-flow and high-flow anesthesia on intracranial dynamics and cerebral oxygenation in patients undergoing laparoscopic hysterectomy in the Trendelenburg position. Intracranial pressure was assessed noninvasively using optic nerve sheath diameter (ONSD), and cerebral oxygenation was monitored using near-infrared spectroscopy (NIRS). Changes in these parameters were assessed under standardized pneumoperitoneum and positioning conditions, and comparisons between anesthesia flow groups were performed according to the predefined study protocol.
Read the detailed description
Laparoscopic surgical procedures commonly involve the establishment of pneumoperitoneum (PP) and the application of the Trendelenburg position (TP) to optimize surgical exposure. These interventions are known to increase intra-abdominal pressure and may influence venous return, intrathoracic pressure, and cerebral hemodynamics. The combined use of pneumoperitoneum and Trendelenburg positioning is considered to have the potential to increase intracranial pressure (ICP). Therefore, the intraoperative assessment of intracranial dynamics is of clinical importance.
Optic nerve sheath diameter (ONSD) measurement is a noninvasive, reproducible, and bedside-applicable method used to assess changes in intracranial pressure. ONSD is considered to correlate with ICP alterations. Cerebral oxygenation can be evaluated using near-infrared spectroscopy (NIRS), a noninvasive technique that enables continuous monitoring of cerebral tissue oxygenation.
Low-flow anesthesia is based on the reduction of fresh gas flow rates and offers several advantages, including decreased anesthetic gas consumption, preservation of heat and humidity in the respiratory tract, and reduced environmental impact. However, data regarding the effects of low-flow anesthesia on cerebral physiology and intracranial dynamics remain limited. In surgical settings where pneumoperitoneum and Trendelenburg positioning are applied, evaluating the impact of different fresh gas flow rates on intracranial pressure and cerebral oxygenation is particularly important.
This prospective, randomized study was conducted in patients scheduled for elective laparoscopic hysterectomy at Bursa City Hospital. Patients aged between 18 and 75 years with an American Society of Anesthesiologists (ASA) physical status of I-II were included. Patients meeting predefined exclusion criteria were not enrolled in the study. Written informed consent was obtained from all participants prior to inclusion.
Patients were randomized into two groups using the closed-envelope method to receive either low-flow or high-flow anesthesia. Standard monitoring, including electrocardiography, noninvasive blood pressure, peripheral oxygen saturation, and NIRS monitoring, was applied to all patients. General anesthesia induction and maintenance were performed according to standardized protocols. Mechanical ventilation was provided in volume-controlled mode, and ventilator parameters were maintained within standard ranges.
Pneumoperitoneum was established using carbon dioxide (CO₂) insufflation at a predefined pressure range and was maintained throughout the surgical procedure. Following the establishment of pneumoperitoneum, patients were placed in the Trendelenburg position at a predefined angle, which was maintained during the operation.
Optic nerve sheath diameter measurements were performed using ultrasonography with minimal pressure applied to the globe. Measurements were obtained at predefined time points. Cerebral oxygenation was continuously monitored using NIRS throughout the intraoperative period. In addition, hemodynamic and respiratory parameters, including heart rate, arterial blood pressure, end-tidal carbon dioxide (EtCO₂), and ventilatory variables, were recorded.
Within the scope of this study, the effects of low-flow and high-flow anesthesia on intracranial dynamics and cerebral oxygenation were planned to be comparatively evaluated, and the study was conducted in accordance with the predefined protocol.
- Keywords
- optic nerve sheath diameter (ONSD, low-flow anesthesia, near-infrared spectroscopy(NIRS), intracranial pressure
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| LOW-FLOW ANESTHESİA | USE OF ANESTHESIA AT A FLOW RATE OF 1 LT/MIN DURING GENERAL ANESTHESIA | |
| HIGH-FLOW ANESTESIA | USE OF ANESTHESIA AT A FLOW RATE OF 3 L/MIN DURING GENERAL ANESTHESIA |
What is being measured
The primary outcome is the main question the study is designed to answer.
Optic Nerve Sheath Diameter
To determine the differences between the two groups of trendelenburg and pneumoperitoneum, which increase intracranial pressure.
Measured: 1-4 hour
Secondary outcomes (1)
Cerebral Oxygenation
To determine the effects of low-flow and high-flow anesthesia on cerebral oxygenation in conditions that increase intracranial pressure.
Measured: 1-4 hour
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Apr 2026
- Study start1 Jan 2024
- Primary completion1 Dec 2024
- Study completion1 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for Cerebral OxygenationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 64 participants (actual)
Sponsor and investigators
- Lead sponsor
- Bursa City Hospital
- Sponsor type
- Other government
- Responsible party
- Principal investigator, Yasin Karabacak, Bursa City Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07514026
- Sponsor's protocol ID
- 2023-17/2
- Status last verified
- Nov 2023
- First submitted
- 25 Mar 2026
- Last updated
- 7 Apr 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Protecting patient privacy and ensuring the security of patient personal information is paramount. However, in our study, some data can be shared without compromising patient safety.
Publications
Ishiyama T, Kotoda M, Asano N, Ikemoto K, Shintani N, Matsuoka T, Matsukawa T. Effects of hyperventilation on cerebral oxygen saturation estimated using near-infrared spectroscopy: A randomised comparison between propofol and sevoflurane anaesthesia. Eur J Anaesthesiol. 2016 Dec;33(12):929-935. doi: 10.1097/EJA.0000000000000507.
PubMed 27802250Mermer A, Kozanhan B. Comparison of the effects of low-flow and normal-flow anesthesia on intracranial pressure, cerebral oxygenation and bispectral index in laparoscopic cholecystectomy operation. Eur Rev Med Pharmacol Sci. 2023 Sep;27(18):8514-8522. doi: 10.26355/eurrev_202309_33776.
PubMed 37782167Hanel F, Blobner M, Bogdanski R, Werner C. Effects of carbon dioxide pneumoperitoneum on cerebral hemodynamics in pigs. J Neurosurg Anesthesiol. 2001 Jul;13(3):222-6. doi: 10.1097/00008506-200107000-00007.
PubMed 11426096
Study at a glance
From the registry record, last updated by the sponsor on 7 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparative Effects of High-Flow and Low-Flow Anesthesia on Optic Nerve Sheath Diameter and Cerebral Oxygenation During Laparoscopic Hysterectomy
- ClinicalTrials.gov ID
- NCT07514026
- Acronym / sponsor ID
- 2023-17/2
- Keywords
- optic nerve sheath diameter (ONSD, low-flow anesthesia, near-infrared spectroscopy(NIRS), intracranial pressure
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 64 participants (actual)
- Lead sponsor
- Bursa City HospitalOther government
- Study start
- 1 Jan 2024 (actual)
- Primary completion
- 1 Dec 2024 (actual)
- Study completion
- 1 Jun 2025 (actual)
- First posted
- 7 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This prospective randomized study was conducted to evaluate the effects of low-flow and high-flow anesthesia on intracranial dynamics and cerebral oxygenation in patients undergoing laparoscopic hysterectomy in the Trendelenburg position. Intracranial pressure was assessed noninvasively using optic nerve sheath diameter (ONSD), and cerebral oxygenation was monitored using near-infrared spectroscopy (NIRS). Changes in these parameters were assessed under standardized pneumoperitoneum and positioning conditions, and comparisons between anesthesia flow groups were performed according to the predefined study protocol.
Detailed description
Laparoscopic surgical procedures commonly involve the establishment of pneumoperitoneum (PP) and the application of the Trendelenburg position (TP) to optimize surgical exposure. These interventions are known to increase intra-abdominal pressure and may influence venous return, intrathoracic pressure, and cerebral hemodynamics. The combined use of pneumoperitoneum and Trendelenburg positioning is considered to have the potential to increase intracranial pressure (ICP). Therefore, the intraoperative assessment of intracranial dynamics is of clinical importance.
Optic nerve sheath diameter (ONSD) measurement is a noninvasive, reproducible, and bedside-applicable method used to assess changes in intracranial pressure. ONSD is considered to correlate with ICP alterations. Cerebral oxygenation can be evaluated using near-infrared spectroscopy (NIRS), a noninvasive technique that enables continuous monitoring of cerebral tissue oxygenation.
Low-flow anesthesia is based on the reduction of fresh gas flow rates and offers several advantages, including decreased anesthetic gas consumption, preservation of heat and humidity in the respiratory tract, and reduced environmental impact. However, data regarding the effects of low-flow anesthesia on cerebral physiology and intracranial dynamics remain limited. In surgical settings where pneumoperitoneum and Trendelenburg positioning are applied, evaluating the impact of different fresh gas flow rates on intracranial pressure and cerebral oxygenation is particularly important.
This prospective, randomized study was conducted in patients scheduled for elective laparoscopic hysterectomy at Bursa City Hospital. Patients aged between 18 and 75 years with an American Society of Anesthesiologists (ASA) physical status of I-II were included. Patients meeting predefined exclusion criteria were not enrolled in the study. Written informed consent was obtained from all participants prior to inclusion.
Patients were randomized into two groups using the closed-envelope method to receive either low-flow or high-flow anesthesia. Standard monitoring, including electrocardiography, noninvasive blood pressure, peripheral oxygen saturation, and NIRS monitoring, was applied to all patients. General anesthesia induction and maintenance were performed according to standardized protocols. Mechanical ventilation was provided in volume-controlled mode, and ventilator parameters were maintained within standard ranges.
Pneumoperitoneum was established using carbon dioxide (CO₂) insufflation at a predefined pressure range and was maintained throughout the surgical procedure. Following the establishment of pneumoperitoneum, patients were placed in the Trendelenburg position at a predefined angle, which was maintained during the operation.
Optic nerve sheath diameter measurements were performed using ultrasonography with minimal pressure applied to the globe. Measurements were obtained at predefined time points. Cerebral oxygenation was continuously monitored using NIRS throughout the intraoperative period. In addition, hemodynamic and respiratory parameters, including heart rate, arterial blood pressure, end-tidal carbon dioxide (EtCO₂), and ventilatory variables, were recorded.
Within the scope of this study, the effects of low-flow and high-flow anesthesia on intracranial dynamics and cerebral oxygenation were planned to be comparatively evaluated, and the study was conducted in accordance with the predefined protocol.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| LOW-FLOW ANESTHESİA | – | –USE OF ANESTHESIA AT A FLOW RATE OF 1 LT/MIN DURING GENERAL ANESTHESIA |
| HIGH-FLOW ANESTESIA | – | –USE OF ANESTHESIA AT A FLOW RATE OF 3 L/MIN DURING GENERAL ANESTHESIA |
Who may qualify
- Ages
- 18 to 75 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- According to the study, 64 female patients aged between 18 and 75 who were to undergo laparoscopic hysterectomy were included, all of whom were classified as Class I or II according to the American Society of Anesthesiologists (ASA) physical status.
Key inclusion criteria (4 listed)
- Female patients aged 18-75 years
- Scheduled for elective laparoscopic hysterectomy
- American Society of Anesthesiologists (ASA) physical status I-II
- Ability to provide written informed consent
Key exclusion criteria (16 listed)
- Septicemia
- Risk of malignant hyperthermia
- Uncontrolled diabetes mellitus
- Chronic alcohol use
- Prolonged fasting
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Optic Nerve Sheath Diameter
Time frame: 1-4 hour
To determine the differences between the two groups of trendelenburg and pneumoperitoneum, which increase intracranial pressure.
1 secondary outcome
Cerebral Oxygenation
Time frame: 1-4 hour
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Apr 2026.
- Results publication: PubMed 27802250Ishiyama T, Kotoda M, Asano N, Ikemoto K, Shintani N, Matsuoka T, Matsukawa T. Effects of hyperventilation on cerebral oxygen saturation estimated using near-infrared spectroscopy: A randomised comparison between propofol and sevoflurane anaesthesia. Eur J Anaesthesiol. 2016 Dec;33(12):929-935. doi: 10.1097/EJA.0000000000000507.
- Results publication: PubMed 37782167Mermer A, Kozanhan B. Comparison of the effects of low-flow and normal-flow anesthesia on intracranial pressure, cerebral oxygenation and bispectral index in laparoscopic cholecystectomy operation. Eur Rev Med Pharmacol Sci. 2023 Sep;27(18):8514-8522. doi: 10.26355/eurrev_202309_33776.
- Results publication: PubMed 11426096Hanel F, Blobner M, Bogdanski R, Werner C. Effects of carbon dioxide pneumoperitoneum on cerebral hemodynamics in pigs. J Neurosurg Anesthesiol. 2001 Jul;13(3):222-6. doi: 10.1097/00008506-200107000-00007.
- Individual participant dataSharing planned: Undecided. Protecting patient privacy and ensuring the security of patient personal information is paramount. However, in our study, some data can be shared without compromising patient safety.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Cerebral Oxygenation and Low Flow Anesthesia, run by Bursa City Hospital at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 16 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 7 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Optic Nerve Sheath Diameter (time frame: 1-4 hour). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07514026, which also lists 3 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Apr 2026.