What is the approach to fluid resuscitation in septic (Systemic Inflammatory Response Syndrome) shock?

From the Guidelines

Fluid resuscitation in septic shock should begin immediately with crystalloid solutions, preferably balanced crystalloids like lactated Ringer's or Plasma-Lyte at 30 mL/kg within the first 3 hours. For an average 70 kg adult, this means approximately 2-2.5 liters initially. After this initial bolus, additional fluid should be given based on frequent reassessment of hemodynamic status using dynamic parameters such as passive leg raise tests, pulse pressure variation, or ultrasound assessment of inferior vena cava collapsibility. Ongoing fluid needs may require an additional 500-1000 mL every 30 minutes until hemodynamic goals are met, typically targeting a mean arterial pressure (MAP) ≥65 mmHg. If patients remain hypotensive despite adequate fluid resuscitation (typically 2-3 liters in adults), vasopressors should be initiated, with norepinephrine as the first-line agent (starting at 0.05-0.1 mcg/kg/min, titrated to effect) 1. Excessive fluid administration can lead to pulmonary edema, prolonged mechanical ventilation, and increased mortality, so a conservative approach after the initial resuscitation is warranted. Early fluid resuscitation works by restoring intravascular volume, improving cardiac output, enhancing tissue perfusion, and reducing the inflammatory cascade triggered by hypoperfusion, which ultimately helps prevent progression to multi-organ failure.

Some key points to consider in fluid resuscitation include:

• The use of crystalloids as the initial fluid of choice in the resuscitation of severe sepsis and septic shock 1
• The avoidance of hydroxyethyl starches for fluid resuscitation of severe sepsis and septic shock 1
• The potential use of albumin in addition to crystalloids for initial resuscitation and subsequent intravascular volume replacement in patients with sepsis and septic shock, when patients require substantial amounts of crystalloids 1
• The importance of frequent reassessment of hemodynamic status to guide further fluid administration 1

It is also important to note that the Surviving Sepsis Campaign guidelines recommend a fluid challenge technique be applied where fluid administration is continued as long as hemodynamic factors continue to improve 1. Additionally, the guidelines suggest using dynamic over static variables to predict fluid responsiveness, where available 1.

Overall, the approach to fluid resuscitation in septic shock should prioritize the use of crystalloids, careful monitoring of hemodynamic status, and a conservative approach to fluid administration to minimize the risk of complications.

From the FDA Drug Label

2.2 Hypotension associated with Septic Shock ... To provide hemodynamic support in septic shock associated hypotension in adult patients, the suggested dosing infusion rate of intravenously administered epinephrine is 0.05 mcg/kg/min to 2 mcg/kg/min, and is titrated to achieve a desired mean arterial pressure (MAP). The approach to fluid resuscitation in septic shock is not directly addressed in the provided text, but the administration of epinephrine in hypotension associated with septic shock is mentioned.

• Key points:
  • Administer whole blood or plasma separately if indicated.
  • Avoid using a catheter tie-in technique.
  • Avoid the veins of the leg in elderly patients or in those suffering from occlusive vascular diseases. However, the question of fluid resuscitation approach is not answered, as the label only discusses epinephrine administration. 2

From the Research

Approach to Fluid Resuscitation

The approach to fluid resuscitation in septic shock involves several key considerations, including:

• The type of fluid to be used: Crystalloid solutions are generally recommended as the initial fluid of choice for resuscitation of septic shock patients 3, 4.
• The volume of fluid to be administered: The Surviving Sepsis Campaign guidelines recommend rapid administration of at least 30mL/kg of crystalloid fluid 5, but some studies suggest that a more restrictive approach to fluid resuscitation may be beneficial 6, 7.
• The use of vasopressors and inotropes: These may be necessary to achieve hemodynamic goals, particularly in patients who require large amounts of fluid to restore hemodynamic stability 3.
• The monitoring of patient response: This should include parameters such as central venous pressure, mean arterial pressure, mixed or central venous oxygen saturation, and arterial lactate levels 3.

Types of Fluids

The following types of fluids have been studied for use in septic shock resuscitation:

• Crystalloids: These are the preferred initial fluid of choice, with balanced crystalloids potentially offering theoretical advantages over classic solutions 3, 4.
• Colloids: Semi-synthetic colloids, such as hydroxyethyl starches, are generally not recommended due to the increased risk of acute renal failure and mortality 3, 4.
• Albumin: The role of albumin in septic shock resuscitation is uncertain, but it may be considered as an alternative to crystalloids in certain situations 3, 4.

Volume of Fluid Administration

The optimal volume of fluid to be administered in septic shock resuscitation is a topic of ongoing debate:

• Some studies suggest that a medium initial fluid volume dose (20-30mL/kg) may be associated with reduced 28-day mortality 6.
• Others argue that a more restrictive approach to fluid resuscitation may be beneficial, with excessive fluid administration potentially worsening shock 7.
• The Surviving Sepsis Campaign guidelines recommend rapid administration of at least 30mL/kg of crystalloid fluid, but the evidence for this recommendation is limited 5.