Capillary Refill Time Response to a Rapid Fluid Challenge in Septic Shock Patients (AUSTRALIS)

December 30, 2020 updated by: Glenn Hernández, Pontificia Universidad Catolica de Chile

Capillary Refill Time Response to a Rapid Fluid Challenge in Septic Shock Patients: Pathophysiological Determinants, and Relation to Changes in Systemic, Regional and Microcirculatory Blood Flow

In septic shock patients, the hemodynamic coherence between systemic, regional and microcirculatory blood flow can be tracked by "capillary refill time (CRT) response to an increase in stroke volume induced by a rapid fluid challenge". A parallel improvement in regional blood flow, microcirculation and hypoperfusion-related parameters should be expected in CRT-responders as reflection of preserved hemodynamic coherence. CRT non-response is associated with a more severe systemic inflammatory state, endothelial and microvascular dysfunction, and a higher adrenergic tone.

The objective of this study is to determine if CRT response after a rapid fluid challenge signals a state of hemodynamic coherence as demonstrated by a parallel improvement in regional and microcirculatory blood flow in CRT-responders, and to explore the pathophysiological mechanisms associated to CRT non-response.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

INTRODUCTION Septic shock is associated with a high mortality risk of up to 30-60%. Multiple pathogenic factors can lead to progressive tissue hypoperfusion in the context of severe systemic inflammation. However, despite extensive research on the best monitoring and resuscitation strategy many uncertainties persist. Over-resuscitation, particularly when inducing fluid overload, might contribute to a worse outcome. Fluid overload more likely occurs when fluids are administered to fluid unresponsive patients, but also when inappropriate resuscitation goals are pursued. The systematic use of bedside techniques to determine fluid responsiveness (FR) can help to avoid fluid overload. Moreover, further deleterious fluid administration can be prevented by adding the evaluation of hemodynamic coherence in parallel or sequentially to FR. Further research on this topic is imperative considering not only the extremely high morbidity and mortality of septic shock, but also the increasing economic burden over the health system in both developed and low/medium income countries.

CAPILLARY REFILL TIME (CRT) AS A TARGET FOR FLUID RESUSCITATION IN SEPTIC SHOCK The skin territory lacks auto-regulatory flow control, and therefore, sympathetic activation impairs skin perfusion during circulatory dysfunction, a phenomenon that can be evaluated by peripheral perfusion assessment. Abnormal peripheral perfusion after initial or advanced resuscitation is associated with increased morbidity and mortality. A cold clammy skin, mottling or prolonged CRT have been suggested as triggers for fluid resuscitation in patients with septic shock. Moreover, the excellent prognosis associated with CRT recovery, its rapid-response time to fluid loading, its relative simplicity, its availability in resource-limited settings, and its capacity to change in parallel with perfusion of physiologically relevant territories such as the hepatosplanchnic region, constitute strong reasons to consider CRT as a target for fluid resuscitation in septic shock patients.

THE CONCEPT OF A FLUID CHALLENGE Since absolute or relative hypovolemia is almost universally present in early septic shock, resuscitation starts with fluid loading in pre-ICU settings. Fluid loading is the rapid administration of fluids without necessarily monitoring the response in real-time, when confronting severe life-threatening hypotension and hypoperfusion. In this setting, usually 20-30 ml/kg crystalloids are loaded.

If circulatory dysfunction is not resolved with this initial management, patients are transferred to the ICU, where advanced fluid resuscitation is started with the fundamental objective to increase systemic blood flow. The initial step is assessment of FR. Fluid-responsive patients will increase stroke volume >10 to 15% after receiving a fluid bolus (usually 250 to 500 ml of crystalloids) since they are in the ascending part of the Starling curve. On the contrary, being fluid-unresponsive implies to be in the flat part of the curve where fluids will only lead to congestion without increasing stroke volume.

The standard practice is to perform a fluid challenge in fluid-responsive patient who are still hypoperfused. A fluid challenge consists of a fluid bolus, large and rapid enough, to increase venous return and cardiac output (CO) in fluid responsive patients, and eventually improve tissue perfusion, depending on the status of hemodynamic coherence (see below). Fluid is given as a fluid challenge so that response can be assessed looking at the target, and the need for ongoing fluid therapy ascertained.

Very few studies have addressed the best way to perform a fluid challenge. A recent study demonstrated that a minimum of 4 ml/kg fluid bolus maximizes the impact on stroke volume. On the other hand, the rate of administration is also important. The FENICE study found that the most common practice in Europe is to administer 500 ml of crystalloids in 30 minutes as a fluid challenge (standard method). However, a more rapid fluid challenge in 5 to 10 minutes might exert more beneficial effects on tissue perfusion by inducing a vasodilatory reflex in addition to the increase in stroke volume. T

THE CONCEPT AND CLINICAL RELEVANCE OF HEMODYNAMIC COHERENCE IN SEPTIC SHOCK Hemodynamic coherence is the condition in which resuscitation of systemic macrohemodynamic variables results in concurrent improvement in regional and microcirculatory flow, and correction of tissue hypoperfusion. Loss of coherence in septic shock is associated with increasing organ dysfunction and a worse prognosis.

The relationship between macrocirculation and regional/microcirculatory blood flow is conditioned by the predominant pathogenic mechanism at different stages of septic shock. At an early stage, hypovolemia and vascular tone depression predominate, leading to low CO and hypotension. An increase in systemic blood flow induced by fluids and/or vasopressors improves regional and microcirculatory flow at this stage. This suggests that macro- and microcirculation are coupled, and should lead to sustained efforts to increase systemic blood flow until hypoperfusion-related variables are corrected.

At a more advanced stage, excessive adrenergic tone (or high-dose vasopressors), and microvascular/endothelial inflammation predominate, leading to abnormal regional flow distribution, and microcirculatory dysfunction that might not respond to systemic blood flow optimization. Microvascular dysfunction occurs because of endothelial dysfunction, leukocyte-endothelium interactions, coagulation and inflammatory disorders, hemorheologic abnormalities, functional shunting, and as an iatrogenic effect of fluid overload/tissue edema.

Hemodynamic coherence is lost in this advanced stage, and efforts to further increase cardiac CO) with fluids or inodilators might lead to fluid overload and the toxicity of vasoactive agents without improving tissue perfusion.

TRACKING THE STATUS OF HEMODYNAMIC COHERENCE IN SEPTIC SHOCK PATIENTS:

A major risk of ICU-based fluid resuscitation is to induce fluid overload. Administering fluids to patients with septic shock after they lost hemodynamic coherence might deteriorate tissue oxygenation, even if they are still fluid-responsive in cardiac function terms. This is a very important consideration. Assessment of hemodynamic coherence is a step forward over the fluid responsiveness concept. This latter looks at the cardiac function curve, but the former instead at the holistic relationship between different components of the cardiovascular system.

The problem is that no single static parameter can predict the status of hemodynamic coherence, and therefore, fluids are abused and probably contribute to progression to refractory shock and death. This is a fundamental contradiction in septic shock resuscitation and highlights the difference between the concepts of FR and hemodynamic coherence. As an example, patients with capillary leak maintain FR along the process because fluids are rapidly lost to the interstitium, and the severe endothelial/microcirculatory dysfunction precludes reperfusion. So, these patients are both fluid-responsive and uncoupled. Moreover, clinicians in despair keep pushing more fluids to try to correct hypoperfusion, which only worsens microcirculatory abnormalities and further impairs perfusion.

Only a novel dynamic test could reveal if the macrocirculation is still coupled or not to regional/microcirculatory blood flow and prevent mismanagement and fluid overload as stated above. The hypothesis of AUSTRALIS is that CRT response to a single rapid fluid challenge can be used as a novel "hemodynamic coherence test." CRT is a sort of bridge between the two worlds (macro-and microcirculation), since it directly represents systemic blood flow (due to the lack of autoregulation), and microcirculation. Normalization of CRT represents an improvement in regional and microcirculatory skin perfusion secondary to an increase in systemic blood flow and/or a reactive decrease in adrenergic tone, thus reflecting hemodynamic coherence. On the contrary, CRT non-response after a rapid fluid challenge is abnormal and a signal of loss of coherence.

PATHOPHYSIOLOGICAL DETERMINANTS OF CRT NON-RESPONSE There are many possible explanations on why CRT might not respond to a stroke volume increase induced by a fluid challenge. Some of these possible mechanisms will be addressed in the proposed study. Adrenergic tone and systemic inflammation, and endothelial/coagulation dysfunction will be addressed by a series of biomarkers selected to provide a broad overview of systemic inflammatory/anti-inflammatory response, and of the transition between endothelial/coagulation activation to established dysfunction, plus direct visualization of microcirculatory status under the tongue, and assessment of microvascular reactivity.

CLINICAL RELEVANCE OF THE PRESENT STUDY If the hypothesis is confirmed, CRT-response to a rapid fluid challenge could be used as a hemodynamic coherence test, and help to avoid futile and dangerous further fluid administration in uncoupled patients, and eventually reduce additional iatrogenic-related excess mortality. Fluid resuscitation could then be focused in fluid responsive patients in whom hemodynamic coherence is still preserved while other perfusion parameters are still not normalized.

Furthermore, establishing the status of hemodynamic coherence with this simple test in pre-ICU or resource-limited settings, could eventually aid in taking triage decisions. CRT non-responders who concentrate septic shock mortality might be rapidly transferred to hospitals with ICU facilities for advanced monitoring and treatment, including reinforcement of source control and eventually rescue therapies.

At the end, this study will help to position CRT, a costless, universally available, and simple test, not only as key target for septic shock resuscitation, but also as a dynamic test of the circulatory function that might help clinicians to interpret the stage of evolution, and help to take timely and critical decisions on fluid resuscitation beyond the concept of fluid responsiveness.

For research purposes, CRT response is defined by "CRT-normalization", and not by "CRT improvement but without normalization" which will be categorized as CRT non-response. This is because hemodynamic tests require to be dichotomous to be applied on a decision branch. In addition, normalization is the only alternative to get certainty that reperfusion has been completed. In any case, partial response will be also included in post-hoc analyses, and the results of the test are not of a binding nature for attending intensivists.

OBJECTIVES AND HYPOTHESIS OR RESEARCH QUESTIONS HYPOTHESIS: In septic shock patients, the hemodynamic coherence between systemic, regional and microcirculatory blood flow can be tracked by "CRT response to an increase in stroke volume induced by a rapid fluid challenge". A parallel improvement in regional blood flow, microcirculation and hypoperfusion-related parameters should be expected in CRT-responders as reflection of preserved hemodynamic coherence. CRT non-response is associated with a more severe systemic inflammatory state, endothelial and microvascular dysfunction, and a higher adrenergic tone.

GENERAL OBJECTIVE: To determine if CRT response after a rapid fluid challenge signals a state of hemodynamic coherence as demonstrated by a parallel improvement in regional and microcirculatory blood flow in CRT-responders, and to explore the pathophysiological mechanisms associated to CRT non-response.

SPECIFIC OBJECTIVES

  1. To determine if CRT normalization after an increase in stroke volume (>10%) induced by a rapid fluid challenge is associated with a parallel improvement in regional, microcirculatory blood flow and perfusion variables.
  2. To determine if the rate of fluid challenge (rapid vs. standard) influences CRT response rate.
  3. To determine if CRT non-response is associated with a more severe systemic inflammatory state, endothelial and microvascular dysfunction, and a higher adrenergic tone.

Study Type

Interventional

Enrollment (Anticipated)

42

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Metropolitana
      • Santiago, Metropolitana, Chile, 7500000
        • Pontificia Universidad Catolica de Chile
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  1. Septic shock according to the Sepsis-3 Consensus Conference [1], basically septic patients with hypotension requiring norepinephrine (NE) to maintain a MAP of 65 mmHg, and serum lactate levels > 2 mmol/l after initial fluid resuscitation.
  2. Less than 24h after fulfilling criteria for septic shock
  3. Abnormal CRT (>3 secs)
  4. Mechanical ventilation
  5. Sinus rhythm with positive predictors of fluid responsiveness [4]
  6. Continuous CO monitor, arterial line and central venous catheters in place
  7. Required fluid challenge as decided by the attending physician.

Exclusion Criteria:

  1. Pregnancy
  2. Emergency surgery or dialytic procedure scheduled within the next two hours
  3. Do-not-resuscitate status
  4. Active bleeding
  5. Severe acute respiratory distress syndrome
  6. Right ventricular failure

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Group A (rapid fluid challenge)
Patients will receive a rapid fluid challenge (4ml/kg of crystalloids in 5 minutes using a syringe of 60 mL and a timer in the multiparameter monitor).
Fluid challenge according to the assigned group
Active Comparator: Group B (standard fluid challenge)
Patients will receive a standard fluid challenge (500 ml of crystalloids in 30 minutes).
Fluid challenge according to the assigned group

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Normalization of capillary refill time (CRT)
Time Frame: At baseline, and immediately after the single fluid challenge; then at 30 minutes, and 1, 2, 6 and 24h.
CRT-response is defined as normalization of the variable after the fluid challenge (normal value CRT ≤3.0 secs).
At baseline, and immediately after the single fluid challenge; then at 30 minutes, and 1, 2, 6 and 24h.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Procalcitonin
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Inflammation biomarker assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
IL-6
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Inflammation biomarker assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
IL-10
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Inflammation biomarker assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
TNF-alpha
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Inflammation biomarker assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
Syndecan-1
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Marker of endothelial dysfunction, assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
s- ICAM-1
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Marker of endothelial dysfunction, assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
E-selectin
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Marker of endothelial dysfunction, assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
von Willebrand factor
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Marker of endothelial dysfunction, assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
Platelet count
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Marker of coagulation abnormalities, assessed in serum samples (normal >150.000)
Baseline, and at 6 and 24h after the single fluid challenge
P-selectin
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Marker of coagulation abnormalities, assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge
D-Dimer
Time Frame: Baseline, and at 6 and 24h after the single fluid challenge
Marker of coagulation abnormalities, assessed in serum samples (upper normal limits according to assay)
Baseline, and at 6 and 24h after the single fluid challenge

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Vascular occlusion test assessed by NIRS
Time Frame: Baseline, at 30 min, and at 1, 6 and 24h after the single fluid challenge
Marker of Microvascular reactivity, assessed by dedicated software
Baseline, at 30 min, and at 1, 6 and 24h after the single fluid challenge
Vascular occlusion test assessed by Laser-Doppler
Time Frame: Baseline, at 30 min, and at 1, 6 and 24h after the single fluid challenge
Marker of Microvascular reactivity, assessed by dedicated software
Baseline, at 30 min, and at 1, 6 and 24h after the single fluid challenge
Test of thermal challenge with Laser-Doppler, assessed by dedicated software
Time Frame: Baseline, at 30 min, and at 1, 6 and 24h after the single fluid challenge
Marker of Microvascular reactivity
Baseline, at 30 min, and at 1, 6 and 24h after the single fluid challenge
Epinephrine serial serum levels
Time Frame: Baseline, immediately after, and at 5, at 30 min, and at 1 hour after a single fluid challenge
Marker of Adrenergic tone, assessed in serum samples (upper normal limits according to assay)
Baseline, immediately after, and at 5, at 30 min, and at 1 hour after a single fluid challenge
Kidney: renal resistive index
Time Frame: Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of regional blood flow, assessed by point-of-care ulltrasound
Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Liver: Indocyanine green plasma disappearance rate
Time Frame: Baseline, at 30 min, and at 1h after a single fluid challenge
Marker of regional blood flow, assessed with LiMON technique (normal 18-25%)
Baseline, at 30 min, and at 1h after a single fluid challenge
Muscle tissue oxygenation
Time Frame: Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of regional blood flow, assessed with NIRS (normal>70%)
Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Skin blood flow
Time Frame: Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of regional blood flow, assessed with Laser-Doppler
Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Sublingual microcirculatory flow and density
Time Frame: Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of microcirculatory status, assessed with intravital videomicroscopy (PPV<80%, MFI>2.5)
Baseline, and at 5, 30 min, and at 1, 6 and 24h after a single fluid challenge
Lactate
Time Frame: Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of perfusion (normal value <2 mmol/l
Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge
ScvO2
Time Frame: Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of perfusion (normal value >70%)
Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge
pCO2 gradient
Time Frame: Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of perfusion (normal value <6)
Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge
Central venous-arterial pCO2 to arterial-venous O2 content difference ratio
Time Frame: Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge
Marker of perfusion (normal value <1.4)
Baseline, and at 30 min, and at 1, 6 and 24h after a single fluid challenge

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Anticipated)

February 1, 2021

Primary Completion (Anticipated)

June 1, 2023

Study Completion (Anticipated)

September 1, 2023

Study Registration Dates

First Submitted

December 21, 2020

First Submitted That Met QC Criteria

December 30, 2020

First Posted (Actual)

January 5, 2021

Study Record Updates

Last Update Posted (Actual)

January 5, 2021

Last Update Submitted That Met QC Criteria

December 30, 2020

Last Verified

December 1, 2020

More Information

Terms related to this study

Other Study ID Numbers

  • 190527001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

Yes

IPD Plan Description

Will be available on a website 6 months after completing recruitment

IPD Sharing Time Frame

6 months after completing recruitment

IPD Sharing Access Criteria

Formal request from investigators

IPD Sharing Supporting Information Type

  • Study Protocol
  • Statistical Analysis Plan (SAP)
  • Informed Consent Form (ICF)
  • Clinical Study Report (CSR)
  • Analytic Code

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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