Effects of Targets of Blood Pressure on Cerebral Hemodynamics in Septic Shock

Study Overview
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Brief Summary
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The sudy objective is to evaluate the cerebral haemodynamic status in different ranges of systemic arterial pressure in patients with septic shock by noninvasive tools, transcranial doppler and intracranial compliance by mechanical sensor (B4C). Patients participating in the study will be submitted to different levels of arterial pressure, titrated with vasopressor and them their cerebral hemodynamic variables will be evaluated,

Detailed Description
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Sepsis is the most prevalent cause of admissions to the intensive care unit (ICU) and many of these patients develop septic shock (SC) (need for vasoactive drug, after adequate fluid administration, plus hyperlactatemia). The SC involvement is systemic, so the investigators started to monitor organ dysfunctions and their perfusion windows, including neurological disorders, when is affected, in addition to indicating severity, are also a predictor of worse prognosis. The principle of cerebral autoregulation (CA) is the basic defense mechanism against pressure oscillations in the most diverse contexts. The SC is a state of vasodilation and consequent drop in mean arterial pressure (MAP), that under normal physiological conditions would be compensated by CA. But it is not known exactly how CA performance at this profile of patients. The investigators will assess cerebral hemodynamics in SC patients at different MAP targets, in order to identify whether this regulatory variable would be able to generate better parameters of cerebral hemodynamics. Some smaller studies have shown that liver and heart dysfunction correlate with worsening autoregulation. Another clinical trial showed an inverse relationship between CA and the Sequential Organ Failure Assessment, in addition to the loss of CA in patients with circulatory shock in general. Post-mortem data found generalized ischemic lesions in the brain of septic patients, which translates into a state of reduction at vascular flow. This patient profile has more blood-brain barrier dysfunction, but further studies are needed to correlate CA and CS. The study will be carried out in the ICU of Hospital São Rafael (HSR), located in the city of Salvador-Ba, Brazil. For the evaluation of cerebral hemodynamics Transcranial Doppler and a Mechanical sensor (B4C) will be used. Data collection on admission will include the following: demographic characteristics, comorbidities, source of infection, Sequential Organ Failure Assessment (SOFA) at ICU admission, temperature, Glasgow Coma scale (GCE) or Richmond Agitation Sedation Scale (RASS), mechanical ventilation, arterial blood gasses before and after the protocol. All patients will be monitored with an arterial line, cardioscopy, pulse oximetry and capnography (if unavailable at the time of collection, this will be described). Before starting the monitoring, the proper functioning of the arterial circuit will be confirmed and a blood gas analysis will be collected, as well as at the end. The investigators will collet data with the patient's baseline pressure for 5 minutes (T0), then through the titration of vasopressors, for another 5 minutes each mean arterial pressure target at 65mmHg (T1), 75 mmHg (T2) and 85 mmHg (T3). After collection, the baseline mean arterial pressure will be restored

Official Title
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Effects of Systemic Blood Pressure Targets on Cerebral Hemodynamics in Septic Shock: a Prospective Study

Conditions
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Septic Shock, Cerebral Autoregulation

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: < 48 hours in the intensive care unit Septic shock (sepsis 3.0) Exclusion Criteria: No window for DTC Hepatic or uremic encephalopathy Pregnancy Acute or prior structural neurological insult Exogenous intoxication Dementia Chronic Obstructive Pulmonary Disease Instability for acute arrhythmia Extracorporeal support by modifying the pulse wave form (intra aortic balloon pump and Extracorporeal membrane oxygenation Extreme severity, with imminent risk of death

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| ALL PATIENTS<br>All patients are monitored with the transcranial Doppler helmet and the 2Hz probe in one of the middle cerebral hemispheres and the Brain 4 care on the other side. Necessary monitoring: arterial line, electrocardiographic monitor, pulse oximetry, temperature. ETCO2 monitoring whenever possible. Step 1: Test arterial line circuit, ensure proper temperature, arterial blood gases Step 2: Record data with the patient's baseline pressure (data from the monitor, transcranial doppler and brain4care), for 5 min Step 3: Vasopressor titrant for 3 MAP targets (65, 75 and 85 mmHg) , record data with the patient's baseline pressure (data from the monitor, transcranial doppler and brain4care), each target record for 3 minutes Step 4: Arterial blood gases, gradually restore PAM to baseline value | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The primary objective is to evaluate the effects of cerebral haemodynamic in patients with septic shock in different targets of MAP, through ARI (by Transcranial Doppler), and intracranial compliance by mechanical sensor (B4C) | This outcome will be analyzed by transcranial Doppler (ARI, PI) and B4C (intracranial compliance) index). Data will be obtained at the time of collection (mean arterial pressure targets) and subsequently analyzed | Data will be obtained at the time of collection (mean arterial pressure targets) and subsequently analyzed | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assess factors that influence cerebral autoregulation (by ARI) and intracranial compliance (B4C) | To verify clinical factors that influence cerebral autoregulation (CA) and intracranial compliance of septic patients | Data will be obtained at the time of collection (mean arterial pressure targets) and subsequently analyzed | 
| Evaluate the correlation between CA by TDC and B4C index. | Report the similarity between the two indices | Data will be obtained at the time of collection (mean arterial pressure targets) and subsequently analyzed | 
| Correlate mechanical ventilation time with perfusion pressure value | Observation that there is a correlation between the duration of mechanical ventilation and the patient's baseline perfusion pressure | Mechanical ventilation time up to 28 days | 
| Explore the correlation between incidence of brain dysfunction | Brain dysfunction will be considered as: Glasgow Coma Scale score < 15 or when disorientation, altered thinking or agitation was reported by the attending physician, independently of the use of sedatives/analgesics and in the absence of previous neurological diseases (i.e., dementia, cerebrovascular disease, brain tumors, previous traumatic brain injury) with DTC and B4C index. | Until 28º day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Septic Shock, Cerebral autoregulation, Cerebral hemodynamics