Cerebral Blood Flow During Propofol Anaesthesia
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 30
- 试验地点
- 1
- 主要终点
- Changes in Internal Carotid Artery Blood Flow by Treatment of Anaesthesia-induced Hypotension
研究概览
简要总结
General anaesthesia often reduces blood pressure whereby blood flow to the brain and other vital organs may become insufficient. Thus, medicine is often administered during anaesthesia to maintain blood pressure. However, it is unclear at what level blood pressure should be aimed at during anaesthesia.
Several factors may affect blood flow to the brain during anaesthesia. During surgery on the internal organs, a hormone may be released that dilates blood vessels and causes a so-called mesenteric traction syndrome characterised by a decrease in blood pressure and flushing. This reaction lasts for approximately thirty minutes and is observed in about half of the patients who undergo surgery on the stomach and intestines. It is unknown whether a mesenteric traction syndrome affects blood flow to the brain. Ventilation is also of importance for blood flow to the brain. Thus, blood flow to the brain is reduced by hyperventilation and increases if breathing is slower. It is unclear whether the relation between blood flow to the brain and ventilation is affected during anaesthesia.
This study will evaluate how blood flow to the brain is affected by anaesthesia and standard treatment of a possible reduction in blood pressure. Further, the study will assess whether blood flow to the brain is affected by development of a mesenteric traction syndrome. Lastly, the project will evaluate blood flow to the brain during short-term changes in the patient's ventilation by adjustments on the ventilator.
Thirty patients planned for major abdominal surgery will be included in the project. The study will take place from the patient's arrival at the operation room and until two hours after the start of surgery. Placement of catheters and anaesthesia are according to standard care. Blood flow to the brain will be evaluated using ultrasound. Oxygenation of the brain, skin and muscle will be evaluated by probes that emit light. Depth of anaesthesia is assessed by recording the electrical activity of the brain. Blood pressure is measured by a catheter placed in an artery at the wrist and blood samples will be drawn from the catheter.
详细描述
Background General anaesthesia reduces blood pressure, but cerebral autoregulation is considered to maintain its blood flow if mean arterial pressure (MAP) is between 60-150 mmHg. Thus, vasoactive medication is administered to treat anaesthesia-induced hypotension if MAP decreases to below approximately 60 mmHg. In young healthy adults, propofol anaesthesia, with limited reduction in blood pressure, decreases cerebral blood flow by approximately 50% by a decrease in neuronal activity. However, it is unknown whether the anaesthesia-induced reduction in cerebral blood flow is affected by a marked decrease in MAP and whether propofol anaesthesia affects the lower level of cerebral autoregulation.
If central blood volume is maintained, cerebral oxygenation may be unaffected by a decrease in MAP to ~40 mmHg whereas a reduction in central blood volume and cardiac output (CO) during orthostasis or bleeding, reduces cerebral oxygenation when MAP is lower than approximately 80 mmHg. Thus, CO may affect cerebral blood flow and the ability to increase CO is likely of importance for maintaining a sufficient cerebral blood flow.
During anaesthesia, cerebral blood flow and MAP may be affected by various factors including release of vasoactive substances. Manipulation of the abdominal organs may induce a so-called mesenteric traction syndrome (MTS) encompassing a triad of flushing, hypotension, and tachycardia in about half of the patients who undergo major abdominal surgery. MTS typically develops 15-20 min after the start of surgery and the haemodynamic manifestations, that appear to be mediated by prostaglandin I2, last for approximately 30 min. The effect of MTS on cerebral blood flow is unknown. Prostaglandin I2 dilates cerebral arteries in vitro but does not affect cerebral blood flow when administered to healthy subjects. In a previous study we found that MTS increases near-infrared spectroscopy determined frontal lobe oxygenation possibly due to an increase in extracranial circulation while there was no effect on middle cerebral artery mean flow velocity as an index of changes in cerebral blood flow.
Propofol anaesthesia appears not to affect the CO2 reactivity of the middle cerebral artery as determined by transcranial Doppler ultrasonography, but the CO2 reactivity of the internal carotid artery during propofol anaesthesia is unknown.
Objective The purpose of this study is to evaluate how internal carotid artery blood flow is affected by propofol anaesthesia and related hypotension, and by administration of phenylephrine as standard care to treat anaesthesia-induced hypotension. Further, the study will assess whether internal carotid artery blood flow is affected by development of MTS and whether propofol anaesthesia affects the CO2 reactivity of the internal carotid artery.
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Prospective
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Patients planned for major abdominal surgery that require placement of an arterial line and central venous catheter, including oesophageal- or ventricular resection
- •Age ≥ 18 years.
排除标准
- •No informed consent
- •Robotic assisted procedures
- •Treatment with anti-inflammatory medication, including NSAID and corticosteroids
- •Atherosclerosis of the internal carotid artery that obstructs ≥ 30% of the vessel lumen
- •Neurologic disease considered to affect cerebral blood flow, including dementia, epilepsy, and apoplexy
结局指标
主要结局
Changes in Internal Carotid Artery Blood Flow by Treatment of Anaesthesia-induced Hypotension
时间窗: Two measurements; one measurement during anaesthesia-induced hypotension (mean arterial pressure < 65 mmHg) before administration of phenylephrine and one measurement 3-5 min after administration of phenylephrine.
Unilateral internal carotid artery blood flow \[ml/min\] assessed by duplex ultrasound.
次要结局
- Changes in Forehead Skin Blood Flow by Development of Mesenteric Traction Syndrome (MTS).(Six measurements during anaesthesia; 5 min before and after incision and 0, 20, 40, and 70 min after flushing and 20, 40, 60, and 90 min after the start of surgery in those patients who do not develop mesenteric traction syndrome.)
- Association by Multiple Regression Between Changes in Internal Carotid Artery Blood Flow, Mean Arterial Pressure and Cardiac Output by Treatment of Anaesthesia-induced Hypotension.(Two measurements; one measurement during anaesthesia-induced hypotension (mean arterial pressure < 65 mmHg) before administration of phenylephrine and one measurement 3-5 min after administration of phenylephrine.)
- Changes in Frontal Lobe Oxygenation by Development of Mesenteric Traction Syndrome (MTS).(Six measurements during anaesthesia; 5 min before and after incision and 0, 20, 40, and 70 min after flushing and 20, 40, 60, and 90 min after the start of surgery in those patients who do not develop mesenteric traction syndrome.)
- Changes in Mean Arterial Pressure From Baseline Before Induction of Anaesthesia.(Continuous measurements from before induction of anaesthesia and until 2 hours after start of surgery.)
- Changes in Cardiac Output From Baseline Before Induction of Anaesthesia.(Continuous measurements from before induction of anaesthesia and until 2 hours after start of surgery.)
- Changes in Stroke Volume From Baseline Before Induction of Anaesthesia.(Continuous measurements from before induction of anaesthesia and until 2 hours after start of surgery.)
- Changes in Internal Carotid Artery Blood Flow by Induction of Anaesthesia.(Two measurements; one measurement 5-10 min before induction of anaesthesia and one measurement 5-20 min after induction of anaesthesia.)
- Changes in Forehead Skin Oxygenation by Development of Mesenteric Traction Syndrome (MTS).(Six measurements during anaesthesia; 5 min before and after incision and 0, 20, 40, and 70 min after flushing and 20, 40, 60, and 90 min after the start of surgery in those patients who do not develop mesenteric traction syndrome.)
- Changes in Internal Carotid Artery Blood Flow by Development of Mesenteric Traction Syndrome (MTS).(Six measurements during anaesthesia; 5 min before and after incision and 0, 20, 40, and 70 min after flushing and 20, 40, 60, and 90 min after the start of surgery in those patients who do not develop mesenteric traction syndrome.)
- Changes in Heart Rate From Baseline Before Induction of Anaesthesia.(Continuous measurements from before induction of anaesthesia and until 2 hours after start of surgery.)
- Changes in the CO2 Reactivity of the Internal Carotid Artery From Before to After Induction of Anaesthesia.(Four measurements; before induction of anaesthesia during normoventilation and during hyperventilation to reduce PaCO2 by 1.5 kPa and during anaesthesia at a PaCO2 at the value before induction of anaesthesia and 1.5 kPa below that value.)
研究者
Niels Damkjær Olesen
MD
Rigshospitalet, Denmark