Status
Conditions
Treatments
About
The study aims to describe hemodynamic effects of lower body negative pressure (LBNP).
Full description
20 healthy volunteers will be included. The study protocol consists of two parts.
LBNP is applied stepwise (20 mmHg increments). At each LBNP-level, after 2 min stabilization, blood flow in internal and external carotid arteries is measured. Thereafter, MSFP is measured. LBNP is applied to -80 mmHg, but terminated sooner if the subject experiences signs of decompensation.
Changes in cerebral StO2 will be related to relative changes in blood flow in the carotid arteries. After these measurements, blood flow to one arm will be occluded for 30 s. Venous pressure measured in an antecubital vein approximates MSFP. This will be related to volume status (LBNP-level and stroke volume reduction).
LBNP is applied stepwise (20 mmHg increments). At each LBNP-level, after 2 min stabilization, PEP and CPAP are applied at 0, 5 and 10 cmH20. LBNP is applied to -80 mmHg, but terminated sooner if the subject experiences signs of decompensation.
Flow in carotid arteries is measured by ultrasound/Doppler. Skin blood flow in the forehead measured by laser Doppler flowmetry and transcutaneous oxygen saturation.
If possible, blood flow velocity in a. cerebri media will be measured by transcranial Doppler.
Central venous pressure will be approximated by measuring pressure in the left subclavian vein ("half-way" catheter).
Cardiac stroke volume will be measured by suprasternal Doppler. Expiratory carbon dioxide (CO2) will be measured and recorded. Acral skin photoplethysmography performed using proprietary and custom-made photoplethysmographs.
Arterial blood pressure approximated by finger volume-clamp method.
The measurements above will be used for analyses of possible physiological mechanisms and post-hoc analyses.
Enrollment
Sex
Ages
Volunteers
Inclusion criteria
Exclusion criteria
Primary purpose
Allocation
Interventional model
Masking
20 participants in 1 patient group
Loading...
Data sourced from clinicaltrials.gov
Clinical trials
Research sites
Resources
Legal