AnesthesiaNCT06684704
Intraocular Pressure, Optic Nerve Sheath Diameter and Optic Perfusion Pressure of Minimal Low and High-Flow Anesthesia
A study testing minimal and high flow anesthesia in people with Anesthesia and Intraocular Pressure, run by Elazıg Fethi Sekin Sehir Hastanesi at 1 site in Turkey (Türkiye).
Trial summary
The aim of this clinical trial is to determine the effect of minimal low-flow versus high-flow anesthesia on intraocular pressure (IOP) by non-contact tonometry, optic nerve sheath diameter (ONSD) by USG and optic perfusion pressure (OPP) in percutaneous nephrolithotomy operations. Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Anesthesia, Intraocular Pressure, Nephrolithiasis
- What is being tested?
- minimal and high flow anesthesia
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 15 Sep 2024to 20 Aug 2025
- Phase
- Interventional
- 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 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Patients aged 18-60 years
- ASA (American Society of Anesthesiologists) risk classification I-II-III
- Unilateral percutaneous nephrolithotomy (PCNL) operation
Who cannot join
- Patients with drug and alcohol addiction,
- long-term smoking history (at least 1 pack/1 year),
- BMI>35,
- chronic lung disease,
- cerebrovascular disease,
- severe systemic diseases such as kidney, liver or advanced heart failure .
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Elazığ Fethi Sekin City Hospital
Elâzığ, Seçiniz, 23100
About this study
Official title: Comparison of Intraocular Pressure (Icare Non-contact Tonometry), Optic Nerve Sheath Diameter and Optic Perfusion Pressure of Minimal Low and High-Flow Anesthesia in Percutaneous Nephrolithotomy (Randomized, Prospective, Clinical Study)
The aim of this clinical trial is to determine the effect of minimal low-flow versus high-flow anesthesia on intraocular pressure (IOP) by non-contact tonometry, optic nerve sheath diameter (ONSD) by USG and optic perfusion pressure (OPP) in percutaneous nephrolithotomy operations. He will also learn about the effect on hemodynamic responses and arterial oxygenation. The main questions it aims to answer are:
What are the effects of low-flow anesthesia combined with prone position on intraocular pressure (IOP), optic nerve sheath diameter (ONSD) and optic perfusion pressure (OPP)? Which anesthesia flow type has optimal eye-protective results? The investigators will compare minimal low-flow and high-flow anesthesia.
Read more
Participants:
The study will include patients between the ages of 18-60 years with ASA (American Society of Anesthesiologists) risk classification I-II-III, who are scheduled for unilateral percutaneous nephrolithotomy (PCNL) operation in the Urology Clinic under elective conditions and who have given informed consent.
Read the detailed description
Today, rapidly depleting resources and deteriorating ecosystems bring the concept of sustainability to the forefront in all areas. Anesthesia applications have also become an important evaluation subject in terms of sustainability. One of the important components of sustainable anesthesia is low-flow anesthesia. Low-flow anesthesia technique is a technique based on the re-breathing of at least half of the gas exhaled in semi-closed systems by returning at least half of the exhaled gas to the patient in the next inspiration (1). This reduces anesthetic gas consumption, reduces the carbon footprint and prevents environmental pollution. In addition, low-flow anesthesia protects mucociliary clearance mechanisms by preventing airway moisture loss and supports the physiological balance of the respiratory system (2). With the widespread use of low-flow anesthesia, research on the systemic effects of this method compared to high-flow anesthesia has also increased. Prone position may lead to undesirable effects such as increased intracranial pressure, increased intraocular pressure, increased cerebral blood flow and atelectasis. Although the effects of this position on intracranial and intraocular pressure are well known, studies on the effect of low-flow anesthesia on these parameters are limited. Therefore, how the use of low-flow anesthesia in combination with the prone position changes these effects should be evaluated in larger-scale studies (3).
- Conditions
- Anesthesia, Intraocular Pressure, Nephrolithiasis
- Being tested
- minimal and high flow anesthesia
- Keywords
- Minimal Low-Flow Anesthesia, Percutaneous Nephrolithotomy, Optic Nerve Sheath Diameter, non-contact tonometry
- Medical subject headings
- Nephrolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
minimal and high flow anesthesiaOther
Low-flow anesthesia technique is a technique based on the re-breathing of at least half of the gas exhaled in semi-closed systems by returning at least half of the exhaled gas to the patient in the next inspiration.
| Study group | Role | What they receive |
|---|---|---|
| Minimal Low-Flo Anesthesia | Other | Group M minimal flow (n=30, fresh gas flow 0.5 L/min) Receives: Other: minimal and high flow anesthesia |
| High-Flow Anesthesia | Other | Group Y high flow (n=30, fresh gas flow 4 L/min). Receives: Other: minimal and high flow anesthesia |
What is being measured
The primary outcome is the main question the study is designed to answer.
Optic nerve sheath diameter (ONSD) measurements
ONSD measurement bedside ultrasonography (POCUS) will be performed in accordance with the standardized ONSD POCUS Quality Criteria Checklist (ONSD POCUS QCC)
Measured: Measurements will be performed serially after induction of anesthesia (T0), 1 min after intubation (T1), 30 min after supine position (T2), supine from prone position (T3) and 5 min after extubation (T4).
Secondary outcomes (1)
Intraocular pressure (IOP)
Intraocular pressure (IOP) is calculated by spraying air into the center of the cornea with a noncontact tonometer and measuring the reflected air again by slightly flattening the cornea.
Measured: Measurements will be performed serially after induction of anesthesia (T0), 1 min after intubation (T1), 30 min after supine position (T2), supine from prone position (T3) and 5 min after extubation (T4).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Nov 2024
- Study start15 Sep 2024
- Primary completion15 Jun 2025
- Study completion20 Aug 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for AnesthesiaStudies 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Screening
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 60 participants (actual)
Sponsor and investigators
- Lead sponsor
- Elazıg Fethi Sekin Sehir Hastanesi
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06684704
- Sponsor's protocol ID
- FSCH-SB-2024/09-46
- Status last verified
- Jul 2025
- First submitted
- 9 Nov 2024
- Last updated
- 5 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Jang YE, Nam S, Ji SH, Kim EH, Lee JH, Jung JH, Kim HS, Kim JT. Effect of end-tidal carbon dioxide level on the optic nerve sheath diameter measured by transorbital ultrasonography in anesthetized pediatric patients: A randomized trial. Paediatr Anaesth. 2022 Jun;32(6):754-763. doi: 10.1111/pan.14437. Epub 2022 Mar 20.
PubMed 35279906Mermer 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 37782167
Study at a glance
From the registry record, last updated by the sponsor on 5 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparison of Intraocular Pressure (Icare Non-contact Tonometry), Optic Nerve Sheath Diameter and Optic Perfusion Pressure of Minimal Low and High-Flow Anesthesia in Percutaneous Nephrolithotomy (Randomized, Prospective, Clinical Study)
- ClinicalTrials.gov ID
- NCT06684704
- Acronym / sponsor ID
- FSCH-SB-2024/09-46
- Conditions
- Anesthesia, Intraocular Pressure, Nephrolithiasis
- Keywords
- Minimal Low-Flow Anesthesia, Percutaneous Nephrolithotomy, Optic Nerve Sheath Diameter, non-contact tonometry
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 60 participants (actual)
- Lead sponsor
- Elazıg Fethi Sekin Sehir HastanesiUniversity, hospital or other
- Study start
- 15 Sep 2024 (actual)
- Primary completion
- 15 Jun 2025 (actual)
- Study completion
- 20 Aug 2025 (actual)
- First posted
- 12 Nov 2024 (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.
The aim of this clinical trial is to determine the effect of minimal low-flow versus high-flow anesthesia on intraocular pressure (IOP) by non-contact tonometry, optic nerve sheath diameter (ONSD) by USG and optic perfusion pressure (OPP) in percutaneous nephrolithotomy operations. He will also learn about the effect on hemodynamic responses and arterial oxygenation. The main questions it aims to answer are:
What are the effects of low-flow anesthesia combined with prone position on intraocular pressure (IOP), optic nerve sheath diameter (ONSD) and optic perfusion pressure (OPP)? Which anesthesia flow type has optimal eye-protective results? The investigators will compare minimal low-flow and high-flow anesthesia.
Participants:
The study will include patients between the ages of 18-60 years with ASA (American Society of Anesthesiologists) risk classification I-II-III, who are scheduled for unilateral percutaneous nephrolithotomy (PCNL) operation in the Urology Clinic under elective conditions and who have given informed consent.
Detailed description
Today, rapidly depleting resources and deteriorating ecosystems bring the concept of sustainability to the forefront in all areas. Anesthesia applications have also become an important evaluation subject in terms of sustainability. One of the important components of sustainable anesthesia is low-flow anesthesia. Low-flow anesthesia technique is a technique based on the re-breathing of at least half of the gas exhaled in semi-closed systems by returning at least half of the exhaled gas to the patient in the next inspiration (1). This reduces anesthetic gas consumption, reduces the carbon footprint and prevents environmental pollution. In addition, low-flow anesthesia protects mucociliary clearance mechanisms by preventing airway moisture loss and supports the physiological balance of the respiratory system (2). With the widespread use of low-flow anesthesia, research on the systemic effects of this method compared to high-flow anesthesia has also increased. Prone position may lead to undesirable effects such as increased intracranial pressure, increased intraocular pressure, increased cerebral blood flow and atelectasis. Although the effects of this position on intracranial and intraocular pressure are well known, studies on the effect of low-flow anesthesia on these parameters are limited. Therefore, how the use of low-flow anesthesia in combination with the prone position changes these effects should be evaluated in larger-scale studies (3).
Study design
- Primary purpose
- Screening
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Minimal Low-Flo Anesthesia | Other | Other: minimal and high flow anesthesiaGroup M minimal flow (n=30, fresh gas flow 0.5 L/min) |
| High-Flow Anesthesia | Other | Other: minimal and high flow anesthesiaGroup Y high flow (n=30, fresh gas flow 4 L/min). |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Patients aged 18-60 years
- ASA (American Society of Anesthesiologists) risk classification I-II-III
- Unilateral percutaneous nephrolithotomy (PCNL) operation
Key exclusion criteria (6 listed)
- Patients with drug and alcohol addiction,
- long-term smoking history (at least 1 pack/1 year),
- BMI>35,
- chronic lung disease,
- cerebrovascular disease,
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| minimal and high flow anesthesiaLow-flow anesthesia technique is a technique based on the re-breathing of at least half of the gas exhaled in semi-closed systems by returning at least half of the exhaled gas to the patient in the next inspiration. | Other | High-Flow Anesthesia, Minimal Low-Flo Anesthesia |
Primary outcome
Optic nerve sheath diameter (ONSD) measurements
Time frame: Measurements will be performed serially after induction of anesthesia (T0), 1 min after intubation (T1), 30 min after supine position (T2), supine from prone position (T3) and 5 min after extubation (T4).
ONSD measurement bedside ultrasonography (POCUS) will be performed in accordance with the standardized ONSD POCUS Quality Criteria Checklist (ONSD POCUS QCC)
1 secondary outcome
Intraocular pressure (IOP)
Time frame: Measurements will be performed serially after induction of anesthesia (T0), 1 min after intubation (T1), 30 min after supine position (T2), supine from prone position (T3) and 5 min after extubation (T4).
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 5 Sep 2025.
- Background: PubMed 35279906Jang YE, Nam S, Ji SH, Kim EH, Lee JH, Jung JH, Kim HS, Kim JT. Effect of end-tidal carbon dioxide level on the optic nerve sheath diameter measured by transorbital ultrasonography in anesthetized pediatric patients: A randomized trial. Paediatr Anaesth. 2022 Jun;32(6):754-763. doi: 10.1111/pan.14437. Epub 2022 Mar 20.
- Background: 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.
- Individual participant dataSharing planned: No
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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?
A study testing minimal and high flow anesthesia in people with Anesthesia and Intraocular Pressure, run by Elazıg Fethi Sekin Sehir Hastanesi 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 3 inclusion and 6 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 5 Sep 2025. 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 (ONSD) measurements (time frame: Measurements will be performed serially after induction of anesthesia (T0), 1 min after intubation (T1), 30 min after supine position (T2), supine from prone position (T3) and 5 min after extubation (T4).). 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 NCT06684704, which also lists 2 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 5 Sep 2025.