Clinical trial NCT03341676: Spectroscopic and Diffusion Weighted Analysis of the Effects of Dexamethasone on High Altitude Cerebral Oedema (HACE)
Official title: Spectroscopic and Diffusion Weighted Analysis of the Effects of Dexamethasone on High Altitude Cerebral Oedema (HACE)
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE1
Conditions: High Altitude Cerebral Edema
Lead sponsor: University Hospitals Coventry and Warwickshire NHS Trust
Sponsor class: OTHER
First posted: 2017-11-14
Enrollment: 10
Sex: ALL
Minimum age (years): 20
Maximum age (years): 50
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Intervention model description: Double-blind, randomised controlled trial
Primary purpose: TREATMENT

Brief summary: When the brain detects a drop in oxygen levels in the blood (hypoxia) there is a compensatory increase in blood flow. Acute mountain sickness (AMS) is a cluster of symptoms which commonly occur in those ascending to high altitude and experiencing hypoxia due to increased blood flow and then swelling in the brain. Symptoms include headache, nausea, insomnia and fatigue. The exact mechanisms by which AMS develops remains poorly understood. Dexamethasone has been shown to reduce the risk of developing significant brain swelling in other settings. Therefore we hypothesise that administering low dose Dexamethasone could protect against hypoxia induced cerebral and spinal oedema.

Detailed description: The exact mechanisms by which AMS develops remains poorly understood. Interestingly, brain and spinal cord swelling due to low oxygen levels can also occur in the period following surgery to treat thoracic and abdominal aortic aneurysms, dangerous swellings of the major blood vessel in the body. Therefore, if we find a therapeutic benefit of receiving a dose of Dexamethasone in a controlled, reversible setting of hypoxia, it is possible that this could be useful in the treatment of post-operative hypoxia as well.

Work with MRI imaging has demonstrated reduced measures of water movement in patients suffering from cerebral or spinal ischaemia, due to swelling. Specific water channels in brain cells (astrocytes) are involved in the movement of water, and Dexamethasone has been shown to reduce expression of these channels in animal models. Dexamethasone already plays a role in lowering pressure in the brain in the setting of brain tumours. Although high doses are typically used in this setting, there is evidence that lower doses may be equally effective, especially in patients with less severe swelling.

Subjects will be consented and randomised in the weeks before the actual study.

Before entering the tent, the following data will be collected:

* Lake Louise Acute Mountain Sickness self-assessment questionnaire
* Pulse oximetry
* Non-invasive cardiac monitoring (ECG)
* End tidal CO2
* Venous blood collection (Full blood count, renal function, S100 and GFAP)
* Finger-prick blood collection (Purines)
* Magnetic Resonance Angiography

Non-invasive monitoring will continue every 2 hours at the start of the study and around the time of administration of the study drug. They will continue at less frequent intervals throughout the study period. This includes ECG trace and an AMS self-assessment questionnaire.

Venous sampling will be performed on 5 occasions throughout the study. Finger prick sampling will be done at the same time points

Each subject will have 5 MRI scans during the course of the study.

Subjects will be begin hypoxication 1 hour after entering the tent. They will be returned to normal oxygen levels after 24 hours.

Eligibility criteria: Inclusion Criteria:

* Provision of informed consent
* Healthy men and women aged 20-50 years
* Ability to fully understand the requirements of the protocol
* Negative pregnancy
* BMI \<30 kg/m2

Exclusion Criteria:

* Recent experience of high altitude: Any subject who has visited high altitudes (defined as 8,000 - 12,000 feet above sea level) within 4 weeks of starting the study.
* Abnormal blood pressure: AHA guidelines state blood pressures ≥140/90 mmHg require medical management. Patients with a blood pressure above these parameters will be excluded.
* Any evidence of systemic infection e.g. respiratory tract infection.
* Any evidence of renal disease (i.e. eGFR \<60, as this precludes intravenous contrast required for MRI scan)
* History of Tuberculosis
* History of heart disease
* Conditions including but not limited to: Glaucoma (including family history), ocular herpes simplex (risk of corneal perforation), severe affective disorders (particularly if history of steroid-induced psychosis), epilepsy, peptic ulcer, hypothyroidism, history of steroid myopathy, ulcerative colitis, diverticulitis, recent intestinal anastomoses, thromboembolic disorders or myasthenia gravis.
* Breastfeeding
* Current smoker
* Contraindications for MRI
* Known sensitivity to the study drug and / or it's excipients: History of hypersensitivity to steroids (any preparation).
* Taking pharmaceutical preparations or over the counter medications known to interact with intravenous Dexamethasone.
* Current participation in other interventional research

Primary outcomes:
measure: Differences in oedematous changes in the brain and spinal cord
timeFrame: 0 hour and 8, 11, 22 and 26 hours post hypoxic insult
Secondary outcomes:
measure: Primary blood brain barrier breakdown in hypoxic cytotoxic oedema
timeFrame: 0 hour and 8, 11, 22 and 26 hours post hypoxic insult
measure: Assessing the usefulness of biomarkers of hypoxic cerebral changes.
timeFrame: 0 hour and 8, 11, 22 and 26 hours post hypoxic insult
measure: Spinal cord model
timeFrame: 0 hour and 8, 11, 22 and 26 hours post hypoxic insult
Other outcomes:
Locations:
city: Coventry
country: United Kingdom
facility: University Hospitals Coventry and Warwickshire NHS Trust
state: West Midlands
Study officials:
affiliation: University Hospital Coventry and Warwickshire NHS Trust
name: Christopher Imray, PhD MBBS
role: PRINCIPAL_INVESTIGATOR
References:
citation: Fisher O, Benson RA, Wayte S, Kimani PK, Hutchinson C, Imray CHE. Multimodal analysis of the effects of dexamethasone on high-altitude cerebral oedema: protocol for a pilot study. Trials. 2019 Oct 24;20(1):604. doi: 10.1186/s13063-019-3681-0.