Cerebral Oxygen Saturation, Mean Systemic Filling Pressure and Haemodynamic Effects of PEP and CPAP in Lower Body Negative Pressure
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 20
- 试验地点
- 2
- 主要终点
- StO2 (tissue oxygen saturation).
研究概览
简要总结
The study aims to describe hemodynamic effects of lower body negative pressure (LBNP).
- If and how changes in cerebral oxygen saturation (StO2) measured by near infrared spectroscopy (NIRS) relate to changes in blood flow in the carotid arteries during progressive LBNP.
- If and how mean systemic filling pressure (MSFP) can be measured by brief occlusion of blood flow to an arm and if this relates to LBNP-level.
- If and how pulse pressure variations and photoplethysmographic amplitude variations during positive expiratory pressure (PEP) and continuous positive airway pressure (CPAP) relate to LBNP-level.
详细描述
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). 2. 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.
研究设计
- 研究类型
- Interventional
- 分配方式
- Na
- 干预模型
- Single Group
- 主要目的
- Diagnostic
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Healthy volunteer (informed consent)
排除标准
- •Disease/physical condition limiting normal physical activity or requiring medication (except allergies/contraceptives)
- •History of syncope (except with obvious vasovagal etiology)
- •Cardiac arrhythmia
- •Pregnancy
- •Skin infections in the elbow crease
结局指标
主要结局
StO2 (tissue oxygen saturation).
时间窗: Approximatrly 30 min: From start LBNP (lower body negative pressure) exposure to 5 min after end LBNP.
Association between cerebral StO2 and flow in a. carotis interna.
次要结局
- MSFP, mean systemic filling pressure (arm venous pressure during vascular occlusion).(Approximatrly 30 min: From start LBNP (lower body negative pressure) exposure to 5 min after end LBNP.)
- Dynamic variables and PEP (positive expiratory pressure)/CPAP (continuous positive airway pressure)(Approximatrly 30 min: From start LBNP (lower body negative pressure) exposure to 5 min after end LBNP.)
研究者
Svein Aslak Landsverk
MD, PhD
Oslo University Hospital