Effect of Ventilation Mode in the Pupillary Light Reflex: A Crossover Study
NCT ID: NCT07082569
Last Updated: 2025-07-24
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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NOT_YET_RECRUITING
NA
36 participants
INTERVENTIONAL
2025-07-15
2026-09-30
Brief Summary
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The comparison involves volume control, pressure control, and pressure-regulated volume control in a randomized crossover design to assess whether ventilation mode has a measurable effect on pupil response.
Eligible participants will be intubated ICU patients receiving assist control ventilation who are not yet ready for spontaneous breathing trials. Serial pupillometry measurements will be conducted while participants are ventilated with each mode for at least 15 minutes. Sedation and lighting conditions will remain consistent throughout the protocol. Participants with acute or chronic neurologic conditions or ventilator dyssynchrony will be excluded.
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Detailed Description
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The pupillary light reflex (PLR), measured using automated infrared pupillometry, provides a quantitative, non-invasive assessment of brainstem and autonomic nervous system function. IThe investigators aim to determine whether the PLR, specifically, the mean and maximum constriction velocity, differs across three commonly used ventilation modes: Volume Control (VC), Pressure Control (PC), and Pressure-Regulated Volume Control (PRVC).
All included participants will be mechanically ventilated, sedated, and not yet candidates for spontaneous breathing trials. Exclusion criteria include any acute or chronic neurologic disorder or signs of ventilator dyssynchrony. Sedation regimens (e.g., propofol, remifentanil, dexmedetomidine) will be kept constant during the study, and ambient light will remain unchanged.
Each participant will undergo the three ventilation modes in a randomized order, with each mode applied for a minimum of 15 minutes to ensure washout before pupillometry measurements are performed. Physiological parameters such as respiratory rate, minute ventilation, FiO₂, heart rate, and mean arterial pressure will be recorded in parallel with pupil measurements. Blood gas analysis and full pupillometry data, including pupil size, constriction and dilation velocities, latency, and the Neurological Pupil Index (NPi), will also be collected.
The primary outcome is the difference in maximum pupillary constriction velocity between ventilation modes. Secondary outcomes include mean constriction velocity, NPi, and other pupillary metrics. Based on pilot data, a total of 36 participants are required to detect a significant difference in the primary outcome. Statistical analysis will include repeated measures ANOVA or the Friedman test, with post hoc Wilcoxon Signed-Rank testing as appropriate.
The findings of this study may provide support for the use of pupillometry as a tool to assess subtle CNS effects of mechanical ventilation and could support the theory of ventilation-brainstem interactions during mechanical ventilation.
Conditions
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Study Design
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RANDOMIZED
CROSSOVER
OTHER
SINGLE
Study Groups
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Sequence A: VC → PC → PRVC
Participants receive mechanical ventilation in the following sequence: Volume Control (VC), followed by Pressure Control (PC), then Pressure-Regulated Volume Control (PRVC). Pupillometry is performed after each mode following a 15-minute stabilization period.
Volume Control Ventilation
Standard mode of mechanical ventilation delivering a preset tidal volume. Commonly used in ICU patients requiring controlled ventilation.
Pressure Control Ventilation
Pressure-targeted ventilation mode that delivers breaths at a fixed pressure. Commonly used in critically ill patients.
Pressure-Regulated Volume Control (PRVC)
Hybrid ventilation mode that automatically adjusts inspiratory pressure to achieve a preset tidal volume.
Sequence B: VC → PRVC → PC
Participants receive mechanical ventilation in the following sequence: Volume Control (VC), followed by Pressure-Regulated Volume Control (PRVC), then Pressure Control (PC). Pupillometry is performed after each mode following a 15-minute stabilization period.
Volume Control Ventilation
Standard mode of mechanical ventilation delivering a preset tidal volume. Commonly used in ICU patients requiring controlled ventilation.
Pressure Control Ventilation
Pressure-targeted ventilation mode that delivers breaths at a fixed pressure. Commonly used in critically ill patients.
Pressure-Regulated Volume Control (PRVC)
Hybrid ventilation mode that automatically adjusts inspiratory pressure to achieve a preset tidal volume.
Sequence C: PC → VC → PRVC
Participants receive mechanical ventilation in the following sequence: Pressure Control (PC), followed by Volume Control (VC), then Pressure-Regulated Volume Control (PRVC). Pupillometry is performed after each mode following a 15-minute stabilization period.
Volume Control Ventilation
Standard mode of mechanical ventilation delivering a preset tidal volume. Commonly used in ICU patients requiring controlled ventilation.
Pressure Control Ventilation
Pressure-targeted ventilation mode that delivers breaths at a fixed pressure. Commonly used in critically ill patients.
Pressure-Regulated Volume Control (PRVC)
Hybrid ventilation mode that automatically adjusts inspiratory pressure to achieve a preset tidal volume.
Sequence D: PC → PRVC → VC
Participants receive mechanical ventilation in the following sequence: Pressure Control (PC), followed by Pressure-Regulated Volume Control (PRVC), then Volume Control (VC). Pupillometry is performed after each mode following a 15-minute stabilization period.
Volume Control Ventilation
Standard mode of mechanical ventilation delivering a preset tidal volume. Commonly used in ICU patients requiring controlled ventilation.
Pressure Control Ventilation
Pressure-targeted ventilation mode that delivers breaths at a fixed pressure. Commonly used in critically ill patients.
Pressure-Regulated Volume Control (PRVC)
Hybrid ventilation mode that automatically adjusts inspiratory pressure to achieve a preset tidal volume.
Sequence E: PRVC → VC → PC
Participants receive mechanical ventilation in the following sequence: Pressure-Regulated Volume Control (PRVC), followed by Volume Control (VC), then Pressure Control (PC). Pupillometry is performed after each mode following a 15-minute stabilization period.
Volume Control Ventilation
Standard mode of mechanical ventilation delivering a preset tidal volume. Commonly used in ICU patients requiring controlled ventilation.
Pressure Control Ventilation
Pressure-targeted ventilation mode that delivers breaths at a fixed pressure. Commonly used in critically ill patients.
Pressure-Regulated Volume Control (PRVC)
Hybrid ventilation mode that automatically adjusts inspiratory pressure to achieve a preset tidal volume.
Sequence F: PRVC → PC → VC
Participants receive mechanical ventilation in the following sequence: Pressure-Regulated Volume Control (PRVC), followed by Pressure Control (PC), then Volume Control (VC). Pupillometry is performed after each mode following a 15-minute stabilization period.
Volume Control Ventilation
Standard mode of mechanical ventilation delivering a preset tidal volume. Commonly used in ICU patients requiring controlled ventilation.
Pressure Control Ventilation
Pressure-targeted ventilation mode that delivers breaths at a fixed pressure. Commonly used in critically ill patients.
Pressure-Regulated Volume Control (PRVC)
Hybrid ventilation mode that automatically adjusts inspiratory pressure to achieve a preset tidal volume.
Interventions
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Volume Control Ventilation
Standard mode of mechanical ventilation delivering a preset tidal volume. Commonly used in ICU patients requiring controlled ventilation.
Pressure Control Ventilation
Pressure-targeted ventilation mode that delivers breaths at a fixed pressure. Commonly used in critically ill patients.
Pressure-Regulated Volume Control (PRVC)
Hybrid ventilation mode that automatically adjusts inspiratory pressure to achieve a preset tidal volume.
Eligibility Criteria
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Inclusion Criteria
* Receiving positive-pressure mechanical ventilation
* Under light or no sedation (e.g., RASS score between -2 and 0)
* Clinically assessed by the treating physician as not yet ready for weaning from mechanical ventilation
* Hemodynamically stable at the time of measurement
* Presence of an arterial catheter in place for blood gas analysis
Exclusion Criteria
* Dyssynchrony with the ventilator or need for high ventilatory support adjustments
* Facial injuries, edema, or conditions precluding accurate pupillometry
* Use of neuromuscular blocking agents within the prior 6 hours
* Severe metabolic or acid-base imbalances that may influence autonomic regulation
* Concurrent participation in another interventional study that could affect neurological or autonomic outcomes
18 Years
ALL
No
Sponsors
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Evangelismos Hospital
OTHER
Responsible Party
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Charikleia Vrettou
Principal Investigator
Principal Investigators
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Charikleia S Vrettou, MD, PhD
Role: PRINCIPAL_INVESTIGATOR
!st ICU dpt., Evangelismos General Hospital
Locations
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!st ICU dpt., Evangelismos Hospital
Athens, , Greece
Countries
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Central Contacts
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References
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Sibbald B, Roberts C. Understanding controlled trials. Crossover trials. BMJ. 1998 Jun 6;316(7146):1719. doi: 10.1136/bmj.316.7146.1719. No abstract available.
World Medical Association. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA. 2013 Nov 27;310(20):2191-4. doi: 10.1001/jama.2013.281053. No abstract available.
Muppidi S, Adams-Huet B, Tajzoy E, Scribner M, Blazek P, Spaeth EB, Frohman E, Davis S, Vernino S. Dynamic pupillometry as an autonomic testing tool. Clin Auton Res. 2013 Dec;23(6):297-303. doi: 10.1007/s10286-013-0209-7. Epub 2013 Jul 24.
Bassi TG, Rohrs EC, Fernandez KC, Ornowska M, Nicholas M, Gani M, Evans D, Reynolds SC. Transvenous Diaphragm Neurostimulation Mitigates Ventilation-associated Brain Injury. Am J Respir Crit Care Med. 2021 Dec 15;204(12):1391-1402. doi: 10.1164/rccm.202101-0076OC.
Cinnella G, Conti G, Lofaso F, Lorino H, Harf A, Lemaire F, Brochard L. Effects of assisted ventilation on the work of breathing: volume-controlled versus pressure-controlled ventilation. Am J Respir Crit Care Med. 1996 Mar;153(3):1025-33. doi: 10.1164/ajrccm.153.3.8630541.
Walter K. Mechanical Ventilation. JAMA. 2021 Oct 12;326(14):1452. doi: 10.1001/jama.2021.13084. No abstract available.
Other Identifiers
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PSVCPC
Identifier Type: -
Identifier Source: org_study_id
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