Time Course Evolution of Cardiac Output
Condition: Acute Circulatory Failure
MeSH terms: Shock
Study type: Observational

Summary: 
      Fluid expansion is the first therapeutic option in patients presenting acute circulatory
      failure but the duration of its hemodynamic effects (persistency and time of maximal increase
      in cardiac output) is unknown.

      This study is seeking to describe in critically ill patients, the time course evolution of
      cardiac output over a 2-hours period after a fluid expansion.

      The objectives are:

        1. to identify patterns of fluid responsiveness

        2. to determine the time when the maximal increase in cardiac output occurs during and a
           after fluid expansion

        3. to compare patients' characteristics between patterns

      Patients with acute circulatory failure will be recruited as soon as a fluid expansion will
      be decided by the physician in charge and the effects of fluid expansion on hemodynamic
      indices (cardiac output, arterial pressure) will be continuously recorded through a
      transpulmonary thermodilution device over a 2-hours period.

      No changes in ventilatory settings nor vasopressors or sedatives will be allowed during the
      study.

      Patients will be categorized into patterns according to the changes in cardiac output after
      fluid expansion and their characteristics will be compared.
    

Detailed description: 
      The study will be conducted in four medico-surgical ICUs in France between April 2016 and
      April 2018.

      Since fluid challenge and invasive monitoring by thermodilution device is standard of care
      for septic shock management, the institutional review board waived patient consent. All
      patients and/or their next of kind will receive written information.

      Eligible patients will have to present an acute circulatory failure for whom the physician in
      charge will decide to start a fluid expansion.

      Hemodynamic variables will be obtained through transpulmonary thermodilution and pulse
      contour analysis (PICCO2 device, Pulsion Germany).

      Fluid expansion will consist in the infusion of 500 ml of saline through a central venous
      catheter in a standardized 10-minutes period. The duration of infusion will be controlled by
      an airbag pressurized at 300 mmHg.

      Fluid responsiveness will be defined by an increase in cardiac output over 15-per-cent from
      baseline (before fluid expansion).

      Study design:

      At time of decision to make the fluid expansion, a calibration of the PICCO2 device will be
      performed and a first set of hemodynamic measurements will be collected (cardiac output,
      cardiac function index, extravascular lung water, permeability vascular pulmonary index,
      global end diastolic volume, arterial pressure, heart rate).

      Then, fluid expansion will be administrated in less than 10 minutes. From the start of fluid
      expansion to the end of the two-hours period ot time, pulse contour cardiac output and
      arterial pressure will be continuously recorded.

      During the whole two hours period, no change in vasopressor dosage nor mechanical ventilation
      settings will be allowed.

      In case of hemodynamic instability, defined by a mean arterial pressure under 65mmHg, a new
      fluid expansion could be realized. In this last case, the protocol will start again from the
      beginning.
    

Intervention name(s): Saline Solution for Injection
Intervention type(s): Drug
Intervention description(s): The fluid expansion will consist in a less than 10 min infusion of 500 milliliters of saline through a central venous catheter (jugular). The duration of infusion will be controlled by an airbag pressurized at 300 mmHg.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Critically ill patients admitted in the intensive care unit receiving mechanical
        ventilation and presenting an acute circulatory failure.
      
Keywords: shock; fluid expansion; fluid responsiveness