Functional Near-infrared Spectroscopy in Unconscious Patients (fNIRS)

Prognostic Value of Functional Near-infrared Spectroscopy in Unconscious Neurocritical Care Patients- a Prospective Pilot Study

The study design is a single-center prospective pilot study. Hypothesis: Results of cerebral fNIRS examination in unconscious patients with severe hemorrhagic or ischemic stroke in the ICU are congruent with the results of SSEP and AEP. Hence, making it a potential prognostic tool for unconscious ICU patients.

In a specific subgroup of unconscious patients after cardiac arrest and cardiopulmonary resuscitation the fNIRS measurement is congruent with the results of electroencephalography (EEG).

The primary purpose of this study is to evaluate the agreement of the results of fNIRS examination to those of evoked potentials and EEG in unconscious ICU patients with severe hemorrhagic, or ischemic strokes or hypoxic brain injury after cardiac arrest and cardiopulmonary resuscitation.

fNIRS will be compared to evoked potentials in an experimental group consisting of unconscious neuro-intensive care patients and in a control group consisting of healthy, conscious subjects.

To compare fNIRS with evoked potentials there are two test phases:

1. The cerebral response to a somatosensory stimulus (peripheral nerve stimulation) is measured by fNIRS and SSEP
2. The cerebral response to an auditory stimulus is measured by fNIRS and AEP

To avoid biases the following has to be considered:

• The timing of the measurements plays an important role. A time difference between compared measurements can influence the outcome significantly due to deterioration or recovery of the neuronal network during the time gap. Therefore, fNIRS and evoked potentials will be measured simultaneously.
• If the compared measurement methods are conducted by the same researcher the possibility of bias is high. Hence, two different researcher will conduct each one measurement without knowing the results of each other during the measurement.

Study Overview

• Status: Recruiting
• Conditions: Nervous System Diseases; Healthy Subjects
• Intervention / Treatment: Other: single-center prospective pilot study

Detailed Description

Severe ischemic and hemorrhagic stroke, as well cardiac arrest even after successful cardiopulmonary reanimation are great causes of morbidity and mortality in Europe and worldwide. Although prevention and therapy strategies, have been successfully improved during the past decades, the global stroke burden - measured in disability adjusted life years (DALY) - is still great.

Specifically, the improvements of intensive care treatments and neurosurgical procedures have lowered mortality rates, but simultaneously have increased survivors with severe disorder of consciousness (DoC) or persistent disabilities. As a result, an early prognosis in unconscious patients suffering from severe stroke in the intensive care unit (ICU) becomes more important for the clinician. An early reliable prognosis enables the clinician to empower the surrogates of an unconscious patient to make choices consistent with his preferences. It improves also overall patient management in the NICU and helps to identify an appropriate rehabilitation care. Since clinical assessment of comatose Patients is limited, other examinations are needed to enhance the reliability of a prognosis.

Evoked potentials, especially somatosensory and auditory evoked potentials (SSEP and AEP) are well established prognostic tools in unconscious ICU patients.

The advantage of evoked potentials over clinical assessments such as the Glasgow coma score (GCS) or laboratory values are that they are not influenced by intensive care interventions, and have a higher interrater reliability. They are also resistant to metabolic changes or sedation.

Electroencephalography (EEG) is another established prognostic tool in comatose patients. However, both, evoked potential and EEG are highly vulnerable to artefacts and expensive due to high workforce requirements.

Functional near-infrared spectroscopy (fNIRS) is a promising strictly non-invasive, bedside examination. It is based on the finding that infrared light is absorbed by oxygenated and deoxygenated haemoglobin. Brain activation can be measured with fNIRS due to an increase of oxygenated haemoglobin and decrease of deoxygenated haemoglobin. Different studies show that brain activation as a response to peripheral somatosensory and auditory stimulation as it is conducted in SSEP and AEP can be detected by fNIRS. Recent studies investigated also the use of fNIRS in unconscious patients. However, it is unknown whether and how the brain activation measured by fNIRS due to sensory stimulation correlates to the measurements of evoked potentials in unconscious patients and if it has any prognostic value in unconscious patients.

Therefore, the investigator aims to compare fNIRS with SSEP and AEP in unconscious neuro-intensive care patients suffering from severe hemorrhagic or ischemic stroke and in a control group with healthy conscious subjects. Hence, making it a potential prognostic tool for unconscious ICU patients.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Emanuela Keller, Prof. Dr.; Phone Number: +41 44 255 56 71; Email: emanuela.keller@usz.ch

Study Locations

• Switzerland
  • Canton of Zurich
    • Zurich, Canton of Zurich, Switzerland, CH-8091
      • Recruiting
      • University Hospital Zurich
      • Contact: Emanuela Keller, Prof MD; Phone Number: +41 44 255 56 71; Email: Emanuela.Keller@usz.ch

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria - experimental group:

• Patients of either sex with severe hemorrhagic, ischemic stroke or hypoxic brain injury after cardiac arrest and cardiopulmonary resuscitation treated at the Institute of Intensive Care Medicine, University Hospital Zurich
• Unconsciousness (GCS < 9) or sedated to the severity of the disease (for the subgroup of patients included in the fNIRS-EEG measurement unconscious patients are defined as not responding to verbal stimuli. The motor response to pain should be one of the following: no response to pain / extensor response / flexor response / localize to pain)
• Age ≥ 18 years
• Signed informed consent obtained from legal representative
• Measurement logistically and technical possible within the first 7 days after admission

Inclusion Criteria - control group:

• Subjects of either sex
• Conscious (GCS = 15)
• Age ≥ 18 years
• Signed informed consent

Exclusion Criteria - experimental group:

• Patients age < 18 years
• Positive pregnancy test for any female of childbearing potential or breast feeding female
• Previous auditory complaints or any ear diseases
• No response detectable at Erb's point in SSEP (e.g. due to peripheral nerve lesions, edema etc.)
• Any history of previous cerebral or brainstem disease
• Concomitant instable critical illness (e.g. sepsis, multi-organ failure, hemodynamic or respiratory instability)
• Acute status epilepticus
• Clinical recovery (GCS ≥ 9) or death before enrolment of the study

Exclusion Criteria - control group:

• Subjects age < 18 years
• Positive pregnancy test for any female of childbearing potential or breast feeding female
• Previous auditory complaints or any ear diseases
• No response detectable at Erb's point in SSEP (e.g. due to peripheral nerve lesions, edema etc.)
• Any history of previous cerebral or brainstem disease

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Experimental (unconscious); fNIRS will be compared to evoked potentials in an experimental group (unconscious neuro-intensive care patients) and in a control group (healthy, conscious subjects)	Other: single-center prospective pilot study; fNIRS will be compared to evoked potentials in an experimental group consisting of unconscious neuro-intensive care patients and in a control group consisting of healthy, conscious subjects. To compare fNIRS with evoked potentials there are two test phases: The cerebral response to a somatosensory stimulus (peripheral nerve stimulation) is measured by fNIRS and SSEP; The cerebral response to an auditory stimulus is measured by fNIRS and AEP
Sham Comparator: Control group (healthy, conscious); fNIRS will be compared to evoked potentials in an experimental group (unconscious neuro-intensive care patients) and in a control group (healthy, conscious subjects)	Other: single-center prospective pilot study; fNIRS will be compared to evoked potentials in an experimental group consisting of unconscious neuro-intensive care patients and in a control group consisting of healthy, conscious subjects. To compare fNIRS with evoked potentials there are two test phases: The cerebral response to a somatosensory stimulus (peripheral nerve stimulation) is measured by fNIRS and SSEP; The cerebral response to an auditory stimulus is measured by fNIRS and AEP

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Results of fNIRS examination to those of evoked potentials (presence or absence of response) in unconscious ICU patients with severe hemorrhagic, ischemic strokes or hypoxic brain injury after cardiac arrest and cardiopulmonary resuscitation.	Correlation of presence of typical relative changes in NIRS pattern (increase of oxygenated hemoglobin and decrease of deoxygenated haemoglobin) to positive response to somatosensory and auditory stimulation measured by electroencephalography (change of cortical electrical acivity after stimulation). Both signals will be either present or absent.	7 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluation of the agreement of the results of the experimental group and the control group	Frequency of presence of typical relative changes in NIRS pattern (increase of oxygenated hemoglobin and decrease of deoxygenated haemoglobin) compared in healthy controls and patients.	1 day

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety endpoints (adverse events)	Incidence of adverse events (for evoked potentials: skin infection or bleeding at the puncture site of electrode needles; for fNIRS: local allergic reaction against plaster or burning of the skin)	7 days

Collaborators and Investigators

• Sponsor: Emanuela Keller
• Investigators: Principal Investigator: Emanuela Keller, Prof. Dr., University Hospital, Zürich

Study record dates

Study Major Dates

• Study Start (Actual): January 15, 2020
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: November 12, 2020
• First Submitted That Met QC Criteria: February 4, 2021
• First Posted (Actual): February 10, 2021

Study Record Updates

• Last Update Posted (Actual): April 27, 2026
• Last Update Submitted That Met QC Criteria: April 21, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: ischemic stroke; functional near-infrared spectroscopy; electroencephalography; evoked potentials; severe cerebral hemorrhage; unconscious neurocritical care patients
• Additional Relevant MeSH Terms: Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Pathologic Processes; Hemorrhage; Intracranial Hemorrhages; Stroke; Pathological Conditions, Signs and Symptoms; Ischemic Stroke; Nervous System Diseases; Cerebral Hemorrhage
• Other Study ID Numbers: 2019-02192

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No