AnisocoriaNCT06964997
Anisocoria in the Intensive Care Unit (AICU Study)
An observational study of Anisocoria, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.
Trial summary
This retrospective single-center cohort study aims to determine the prevalence of acute "new onset" pupillary abnormalities in adult intensive care unit patients, assess their clinical impact, identify the contexts leading to treatment changes, and evaluate their prognostic implications. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Anisocoria
- How many people
- 920 participants
- Where
- 1 siteSwitzerland
- Study dates
- 1 Mar 2025to Dec 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients (i.e., patients ≥18 years of age) with a reported incident of pupillary abnormality (either anisocoria or non-normal pupillary reactivity) in the intensive care unit at the University Hospital Basel between 2013-2024.
Who may be able to join
- Adult patients (i.e., patients ≥18 years of age)
- Reported incident of pupillary abnormality (either anisocoria or non-normal pupillary reactivity) in the intensive care unit at the University Hospital Basel between 2013-2024.
Who cannot join
- Patients younger than 18 years
- Patients with documented refusal of data use.
Trial locations and contacts
1 site in 1 country.
Switzerland1 site
University Hospital Basel, Clinic for Intensive Care Medicine
Basel, Canton of Basel-City, 4031
About this study
Official title: Anisocoria in the ICU (AICU Study): Diagnostic Implications and Clinical Outcomes
This retrospective single-center cohort study aims to determine the prevalence of acute "new onset" pupillary abnormalities in adult intensive care unit patients, assess their clinical impact, identify the contexts leading to treatment changes, and evaluate their prognostic implications.
Read the detailed description
Assessment of the pupil symmetry and reactivity to light are important parts of the neurological evaluation of critically ill patients in intensive care units (ICUs). Anisocoria, a condition where the pupils are unequal in size, can be found in up to 60% of patients with acute neurologic injuries. It may indicate serious underlying issues like traumatic brain injury, cerebrovascular accidents, brain tumors or viral encephalitis. However, anisocoria or impaired pupillary reactivity can also be caused from less severe conditions, such as drug effects (e.g., ipratropium bromide),Horner's syndrome after central venous cannulation, or intoxications with substances like anticholinergics, opioids, and cannabinoids. Despite these well-known causes, there is limited data on the prevalence and clinical consequences of anisocoria in ICU patients.
New onset of pupillary abnormalities often requires immediate neurological evaluation and neuroimaging (computed tomography (CT) or magnetic resonance imaging (MRI)), but many of these scans may not reveal clinically relevant findings and could expose patients to unnecessary risks. This is particularly concerning as benign causes of pupillary abnormalities are common, while more serious conditions can sometimes be overlooked. Current studies do not fully address when CT or MRI scans are necessary, or when they provide no significant clinical benefit.
This retrospective single-center cohort study has four primary objectives:
- to determine the prevalence of acute "new onset" pupillary abnormalities (anisocoria and/or impaired light-reactive pupillary response) in adult ICU patients.
- to assess the clinical impact of these abnormalities, particularly in terms of the frequency of diagnostic tests like CT or MRI scans, and ophthalmologic and neurologic consultations.
- to identify when pathological findings lead to treatment modifications
- to evaluate the prognostic implications of these pupillary abnormalities on patient outcomes.
The results of this study may improve the understanding of acute pupillary abnormalities in ICU patients, helping to optimize diagnostic strategies, reduce unnecessary neuroimaging, and enhance patient safety and outcome prediction.
- Conditions
- Anisocoria
- Keywords
- Pupillary abnormality, Intensive care unit
- Medical subject headings
- Anisocoria
What is being measured
The primary outcome is the main question the study is designed to answer.
Acute prehospital management data
Data from acute prehospital management, as documented in emergency medical services (EMS) treatment protocols, is collected. The collected data elements are aggregated to describe the overall EMS response.
Measured: 2013-2024
Duration of intensive care unit stay
The length of intensive care unit (ICU) stay is recorded.
Measured: 2013-2024
Duration of hospital stay
The length of the total hospital stay is recorded.
Measured: 2013-2024
Discharge destination
The destination at discharge is recorded.
Measured: 2013-2024
Date of incident
The date when acute "new onset" pupillary abnormalities were first documented in patient records is recorded.
Measured: 2013-2024
Characteristics of incident
Details on the pupillary abnormality as described in nurses' and physicians' progress notes (e.g. wording) to characterize the condition.
Measured: 2013-2024
Type of incident
The type of pupillary abnormality (anisocoria, areactivity, or altered reaction to light) is recorded.
Measured: 2013-2024
Additional features of the incident
Assessment of additional features related to incident of pupillary abnormality (shift type, time of day (daytime or nighttime), and environment). These features are aggregated to characterize the context in which the assault occurred.
Measured: 2013-2024
Patient characteristics
Information on the patient (e.g., principal diagnosis, comorbidities, medication) is documented.
Measured: 2013-2024
Consequences of the Incident
Evaluation of medical assessments and interventions following the incident, including Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scans, ophthalmologic or neurologic consultations.
Measured: 2013-2024
Comprehensive assessment of the neurological status based on validated clinical assessment
Neurological status during ICU stay is assessed using available data in the patient register from validated neurological assessments. These may include the Richmond Agitation-Sedation Scale (RASS), Sedation-Agitation Scale (SAS), Glasgow Coma Scale (GCS), Intensive Care Delirium Screening Checklist (ICDSC), or Status Epilepticus Severity Score (STESS). The specific tool used, as well as the scale of the score and meaning behind the score, depends on routine clinical practice and available documentation in the register. If multiple scores are available for a patient, they will be aggregated to provide a comprehensive assessment of neurological status. This outcome will be reported as a descriptive summary, synthesizing findings across tools, rather than as a single quantitative score.
Measured: 2013-2024
Comprehensive assessment of critical illness severity based on standardized scoring systems
Disease severity during ICU stay is assessed using standardized scoring systems, including the Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology Score II (SAPS II), and Sequential Organ Failure Assessment (SOFA), depending on data availability in the patient register. The specific scoring system applied, as well as the scale and interpretation of the score, varies based on routine clinical practice and available documentation. Where multiple severity scores are available, they will be synthesized to provide a descriptive summary of overall illness severity rather than a single quantitative score.
Measured: 2013-2024
Charlson Comorbidity Index
The Charlson Comorbidity Index (CCI) is calculated based on pre-existing comorbidities and additional diagnoses. The CCI predicts the ten-year mortality for a patient who may have a range of comorbid conditions. It assigns weighted scores (from 0 to maximal 6) to 17 comorbid conditions (e.g., heart disease, diabetes, cancer), resulting in a total score ranging from 0 to 33, if the patient had the most severe form of each of the 17 conditions.
Measured: 2013-2024
Laboratory parameters
Routine laboratory value for e.g. C-Reactive Protein (CRP), albumin, Lactate Dehydrogenase (LDH), Creatine Kinase (CK), procalcitonin, white blood cell levels, creatinine, liver enzymes, blood gas analyses, metabolic data, and toxicologic screenings, is collected. The specific parameters recorded may vary depending on the laboratory assessments documented in the patient register. All values will be reported using their respective units of measurement.These parameters are aggregated to support an overall clinical interpretation rather than a single numerical value. This approach reflects standard clinical practice, where multiple lab values are considered together to assess a patient's condition.
Measured: 2013-2024
Glasgow Outcome Score
The Glasgow Outcome Score (GOS) is calculated based on the assessment of key clinical outcomes such as inhospital mortality, survival, survival with neurofunctional alteration, return to premorbid neurological function, and hospital readmission to determine the patient outcome.
The GOS ranges from 1 (death) to 5 (good recovery).
Measured: 2013-2024
Therapeutic intervention
The therapeutic intervention is document, including information on duration, dosage and number of treatment medication, number of neuroleptic, sedative and analgesic drugs, use of ipratropium bromide, invasive procedures, such as intubation, mechanical, ventilation, vasopressors, installation of central lines, i.v. thrombolysis, endovascular thrombectomy, surgical hemicraniectomy, insertion of ventricular drains, intracranial pressure monitoring, i.v. administration of mannitol or saline, nutrition, etc.
Measured: 2013-2024
Vital signs
Vital signs are analyzed based on the data available in the patient register. These may include blood pressure, heart rate, respiratory rate, oxygen saturation, body temperature, level of consciousness, intracranial pressure, and drainage rate of cerebrospinal fluid. The specific parameters recorded depend on the clinical documentation available. All values will be reported using their respective units of measurement. These values are aggregated to support an overall clinical assessment rather than a single numerical score. This reflects standard practice, where multiple vital signs are interpreted together to evaluate a patient's condition.
Measured: 2013-2024
Fluid balance data
Fluid balance data, including the administration of fluids such as blood products, crystalloids, and enteral/parenteral nutrition, are documented. These components are aggregated to represent overall fluid input for each patient.
Measured: 2013-2024
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 May 2025
- Study start1 Mar 2025
- Primary completionDec 2026 (estimated)
- Study completionDec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AnisocoriaStudies of the same condition, open and under way.
- More trials run by University Hospital, Basel, SwitzerlandThe sponsor's other registered studies.
- 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
- Retrospective
- Enrolment
- 920 participants (actual)
Sponsor and investigators
- Lead sponsor
- University Hospital, Basel, Switzerland
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Raoul Sutter, Prof. Dr. med., Principal investigator, University Hospital Basel, Clinic for Intensive Care Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06964997
- Sponsor's protocol ID
- 2024-02347; am25Sutter3
- Status last verified
- Jun 2026
- First submitted
- 25 Mar 2025
- Last updated
- 17 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 17 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Anisocoria in the ICU (AICU Study): Diagnostic Implications and Clinical Outcomes
- ClinicalTrials.gov ID
- NCT06964997
- Acronym / sponsor ID
- 2024-02347; am25Sutter3
- Conditions
- Anisocoria
- Keywords
- Pupillary abnormality, Intensive care unit
- Study type
- Observational
- Recruitment status
- Active, not recruiting
- Enrolment
- 920 participants (actual)
- Lead sponsor
- University Hospital, Basel, SwitzerlandUniversity, hospital or other
- Study start
- 1 Mar 2025 (actual)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Dec 2026 (estimated)
- First posted
- 11 May 2025 (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 retrospective single-center cohort study aims to determine the prevalence of acute "new onset" pupillary abnormalities in adult intensive care unit patients, assess their clinical impact, identify the contexts leading to treatment changes, and evaluate their prognostic implications.
Detailed description
Assessment of the pupil symmetry and reactivity to light are important parts of the neurological evaluation of critically ill patients in intensive care units (ICUs). Anisocoria, a condition where the pupils are unequal in size, can be found in up to 60% of patients with acute neurologic injuries. It may indicate serious underlying issues like traumatic brain injury, cerebrovascular accidents, brain tumors or viral encephalitis. However, anisocoria or impaired pupillary reactivity can also be caused from less severe conditions, such as drug effects (e.g., ipratropium bromide),Horner's syndrome after central venous cannulation, or intoxications with substances like anticholinergics, opioids, and cannabinoids. Despite these well-known causes, there is limited data on the prevalence and clinical consequences of anisocoria in ICU patients.
New onset of pupillary abnormalities often requires immediate neurological evaluation and neuroimaging (computed tomography (CT) or magnetic resonance imaging (MRI)), but many of these scans may not reveal clinically relevant findings and could expose patients to unnecessary risks. This is particularly concerning as benign causes of pupillary abnormalities are common, while more serious conditions can sometimes be overlooked. Current studies do not fully address when CT or MRI scans are necessary, or when they provide no significant clinical benefit.
This retrospective single-center cohort study has four primary objectives:
- to determine the prevalence of acute "new onset" pupillary abnormalities (anisocoria and/or impaired light-reactive pupillary response) in adult ICU patients.
- to assess the clinical impact of these abnormalities, particularly in terms of the frequency of diagnostic tests like CT or MRI scans, and ophthalmologic and neurologic consultations.
- to identify when pathological findings lead to treatment modifications
- to evaluate the prognostic implications of these pupillary abnormalities on patient outcomes.
The results of this study may improve the understanding of acute pupillary abnormalities in ICU patients, helping to optimize diagnostic strategies, reduce unnecessary neuroimaging, and enhance patient safety and outcome prediction.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients (i.e., patients ≥18 years of age) with a reported incident of pupillary abnormality (either anisocoria or non-normal pupillary reactivity) in the intensive care unit at the University Hospital Basel between 2013-2024.
Key inclusion criteria (2 listed)
- Adult patients (i.e., patients ≥18 years of age)
- Reported incident of pupillary abnormality (either anisocoria or non-normal pupillary reactivity) in the intensive care unit at the University Hospital Basel between 2013-2024.
Key exclusion criteria (2 listed)
- Patients younger than 18 years
- Patients with documented refusal of data use.
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
Acute prehospital management data
Time frame: 2013-2024
Data from acute prehospital management, as documented in emergency medical services (EMS) treatment protocols, is collected. The collected data elements are aggregated to describe the overall EMS response.
Duration of intensive care unit stay
Time frame: 2013-2024
The length of intensive care unit (ICU) stay is recorded.
Duration of hospital stay
Time frame: 2013-2024
The length of the total hospital stay is recorded.
Discharge destination
Time frame: 2013-2024
The destination at discharge is recorded.
Date of incident
Time frame: 2013-2024
The date when acute "new onset" pupillary abnormalities were first documented in patient records is recorded.
Characteristics of incident
Time frame: 2013-2024
Details on the pupillary abnormality as described in nurses' and physicians' progress notes (e.g. wording) to characterize the condition.
Type of incident
Time frame: 2013-2024
The type of pupillary abnormality (anisocoria, areactivity, or altered reaction to light) is recorded.
Additional features of the incident
Time frame: 2013-2024
Assessment of additional features related to incident of pupillary abnormality (shift type, time of day (daytime or nighttime), and environment). These features are aggregated to characterize the context in which the assault occurred.
Patient characteristics
Time frame: 2013-2024
Information on the patient (e.g., principal diagnosis, comorbidities, medication) is documented.
Consequences of the Incident
Time frame: 2013-2024
Evaluation of medical assessments and interventions following the incident, including Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scans, ophthalmologic or neurologic consultations.
Comprehensive assessment of the neurological status based on validated clinical assessment
Time frame: 2013-2024
Neurological status during ICU stay is assessed using available data in the patient register from validated neurological assessments. These may include the Richmond Agitation-Sedation Scale (RASS), Sedation-Agitation Scale (SAS), Glasgow Coma Scale (GCS), Intensive Care Delirium Screening Checklist (ICDSC), or Status Epilepticus Severity Score (STESS). The specific tool used, as well as the scale of the score and meaning behind the score, depends on routine clinical practice and available documentation in the register. If multiple scores are available for a patient, they will be aggregated to provide a comprehensive assessment of neurological status. This outcome will be reported as a descriptive summary, synthesizing findings across tools, rather than as a single quantitative score.
Comprehensive assessment of critical illness severity based on standardized scoring systems
Time frame: 2013-2024
Disease severity during ICU stay is assessed using standardized scoring systems, including the Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology Score II (SAPS II), and Sequential Organ Failure Assessment (SOFA), depending on data availability in the patient register. The specific scoring system applied, as well as the scale and interpretation of the score, varies based on routine clinical practice and available documentation. Where multiple severity scores are available, they will be synthesized to provide a descriptive summary of overall illness severity rather than a single quantitative score.
Charlson Comorbidity Index
Time frame: 2013-2024
The Charlson Comorbidity Index (CCI) is calculated based on pre-existing comorbidities and additional diagnoses. The CCI predicts the ten-year mortality for a patient who may have a range of comorbid conditions. It assigns weighted scores (from 0 to maximal 6) to 17 comorbid conditions (e.g., heart disease, diabetes, cancer), resulting in a total score ranging from 0 to 33, if the patient had the most severe form of each of the 17 conditions.
Laboratory parameters
Time frame: 2013-2024
Routine laboratory value for e.g. C-Reactive Protein (CRP), albumin, Lactate Dehydrogenase (LDH), Creatine Kinase (CK), procalcitonin, white blood cell levels, creatinine, liver enzymes, blood gas analyses, metabolic data, and toxicologic screenings, is collected. The specific parameters recorded may vary depending on the laboratory assessments documented in the patient register. All values will be reported using their respective units of measurement.These parameters are aggregated to support an overall clinical interpretation rather than a single numerical value. This approach reflects standard clinical practice, where multiple lab values are considered together to assess a patient's condition.
Glasgow Outcome Score
Time frame: 2013-2024
The Glasgow Outcome Score (GOS) is calculated based on the assessment of key clinical outcomes such as inhospital mortality, survival, survival with neurofunctional alteration, return to premorbid neurological function, and hospital readmission to determine the patient outcome. The GOS ranges from 1 (death) to 5 (good recovery).
Therapeutic intervention
Time frame: 2013-2024
The therapeutic intervention is document, including information on duration, dosage and number of treatment medication, number of neuroleptic, sedative and analgesic drugs, use of ipratropium bromide, invasive procedures, such as intubation, mechanical, ventilation, vasopressors, installation of central lines, i.v. thrombolysis, endovascular thrombectomy, surgical hemicraniectomy, insertion of ventricular drains, intracranial pressure monitoring, i.v. administration of mannitol or saline, nutrition, etc.
Vital signs
Time frame: 2013-2024
Vital signs are analyzed based on the data available in the patient register. These may include blood pressure, heart rate, respiratory rate, oxygen saturation, body temperature, level of consciousness, intracranial pressure, and drainage rate of cerebrospinal fluid. The specific parameters recorded depend on the clinical documentation available. All values will be reported using their respective units of measurement. These values are aggregated to support an overall clinical assessment rather than a single numerical score. This reflects standard practice, where multiple vital signs are interpreted together to evaluate a patient's condition.
Fluid balance data
Time frame: 2013-2024
Fluid balance data, including the administration of fluids such as blood products, crystalloids, and enteral/parenteral nutrition, are documented. These components are aggregated to represent overall fluid input for each patient.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Jun 2026.
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.
Raoul Sutter, Prof. Dr. med. principal investigator
University Hospital Basel, Clinic for Intensive Care Medicine
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 Anisocoria, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.
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 2 inclusion and 2 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: under way, not looking for participants, as of the sponsor's last update on 17 Jun 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 Switzerland. 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?
This study is still under way. Results are not available in the source record yet.
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?
Acute prehospital management data (time frame: 2013-2024). The study lists 18 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 17 Jun 2026.