Investigating CBF and ICP Using DCS (ICP-CBF)

Investigating the Relationship Between Intracranial Pressure and Cerebral Blood Flow Using Near-infrared Diffuse Correlation Spectroscopy

We aim to acquire data using DCS on patients who are undergoing invasive ICP and ABP monitoring on ITU as part of their normal treatment.

Data will then be correlated to derive various parameters including CBF and BFI.

All interventions are entirely non-invasive.

Study Overview

• Status: Completed
• Conditions: Traumatic Brain Injury; Intracranial Hypertension
• Intervention / Treatment: Device: DCS

Detailed Description

Cerebral Autoregulation (CA) is the complex process whereby the body maintains constant blood flow to the brain (cerebral blood flow, CBF) over a wide range of mean arterial pressures (MAP) in order to provide constant oxygenation and nutrition supply to cerebral tissue. By balancing blood and cerebrospinal fluid (CSF) pressures, CA dynamically stabilises cerebral perfusion pressure (CPP) and hence blood flow. Disordered CA may result in reduced oxygen and nutrient delivery to the brain tissue leading to hypoxic and ischaemic damage resulting in significant morbidity and mortality.

High intracranial pressure (ICP) is frequently associated with failing CA. Hence ICP is routinely monitored in patients suffering from traumatic brain injury (TBI) and other conditions which may result in CA failure. Raised ICP contributes to the majority of mortalities following severe TBI. All currently available ICP monitoring systems require insertion of an electrical or pneumatic transducer into the cranial cavity, usually sited within the brain parenchyma but occasionally into the subdural space (between the brain and the skull) or into the ventricles. This is currently only performed by neurosurgeons and carries a small but significant risk of haemorrhage or infection.

Non-invasive ICP and hence CA monitoring would eliminate the risk of complications, could be used by all healthcare professionals, would extend the use to outside a hospital settings and may extend the range of conditions to benefit from ICP monitoring.

This project pilots an approach to expand our understanding of the basic physiological interplay between intracranial pressure, arterial blood pressure, and cerebral blood flow in adult in-patients.

A recently-developed form of near-infrared (NIR) optical sensing known as Diffuse Correlation Spectroscopy (DCS) offers an opportunity to investigate cerebral blood flow at the bed-side continuously. DCS measures blood flow in the microvasculature of the brain by determining a blood flow index (BFi).

A similar technology based on near-infrared spectroscopy (NIRS), was recently successfully applied by the Chief Investigator in the same population in the same manner as in the current proposal (IRAS ID: 219476, approved by the East of England - Cambridge Central Research Ethics Committee (18/EE/0276) on 14/02/19). We therefore have extensive experience working with optical instruments in these patient groups.

In this proposal we will use a custom DCS research instrument. This research instrument is designed to measure microvascular cerebral blood flow for neuroscience and neurological research applications. While this device is a bespoke instrument, built with this study in mind, it is based on established research technologies and has been tested successfully in more than 20 healthy volunteers and in a range of quality-control experiments to date. It uses a forehead-mounted optical probe that contains near-infrared light sources that can illuminate the brain tissue non-invasively and continuously. The light's path within brain tissue is modulated by the flow of blood in the cerebral microvasculature and it is ultimately absorbed or backscattered. The backscattered light is collected at a different point within the probe.

The interplay between mean arterial blood (MAP) (measured by means of an intra-arterial catheter (part of normal medical care for patients on ITU) or a non-invasive finger-cuff) and ICP affects the morphology of the pulsatile flow in the cerebral microvascular, so the analysis of these signals in unison will help us better understand the relationship between ICP (which is measured clinically), MAP (which is measured clinically) and cerebral blood flow (which is not). This in turn could help support new research into head injury management, notably ICP-targeted treatment regimes. Ultimately this could lead to significant improvements in secondary injury-related mortality, length of hospital stay and reduced post-trauma disability. In addition the non-invasive nature of the monitor could extend the range of medical conditions that may benefit from ICP and CA monitoring including stroke, brain tumour surveillance, hydrocephalus, pre-hospital care of trauma patients, routine anaesthetic and ICU monitoring systems and screening of patients with headache in primary care.

In addition, if successfully developed, this technology is likely to be extremely relevant to low and middle income countries where access to neurosurgeons (and hence ICP monitoring) is extremely limited.

• Study Type: Observational
• Enrollment (Actual): 17

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom
    • Royal London Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The largest demographic of patients undergoing ICP monitoring is trauma, therefore the study population is patients who have suffered TBI and are undergoing ICP monitoring on ITU.

Description

Inclusion Criteria:

• Invasive monitoring of ICP and ABP as part of normal treatment

Exclusion Criteria:

• Not meeting inclusion criteria.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Participants; Participants are patients who are undergoing invasive ICP and ABP measurement as part of their normal medical treatment.	Device: DCS; DCS monitoring of brain

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
DCS signal acquisition	Successful acquisition of DCS signals from brain tissue	12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation of DCS signals with routine physiological data measurements	Correlation of DCS signals with routine physiological data measurements	10 months
ML approach to derive secondary parameters	Machine learning approach to derive additional parameters non-invasively	10 months

Collaborators and Investigators

• Sponsor: Queen Mary University of London
• Collaborators: Barts & The London NHS Trust

Study record dates

Study Major Dates

• Study Start (Actual): January 5, 2023
• Primary Completion (Actual): August 20, 2023
• Study Completion (Actual): August 20, 2023

Study Registration Dates

• First Submitted: September 8, 2023
• First Submitted That Met QC Criteria: September 8, 2023
• First Posted (Actual): September 15, 2023

Study Record Updates

• Last Update Posted (Actual): February 20, 2024
• Last Update Submitted That Met QC Criteria: February 16, 2024
• Last Verified: February 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Wounds and Injuries; Craniocerebral Trauma; Trauma, Nervous System; Brain Injuries; Brain Injuries, Traumatic; Intracranial Hypertension
• Other Study ID Numbers: 317751

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data will be shared with organizations / individuals upon reasonable request.
• IPD Sharing Time Frame: Once data have been acquired
• IPD Sharing Access Criteria: Upon reasonable request to be determined by the CI.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No