What is the stepwise approach to fluid resuscitation in shock?

Stepwise Approach to Fluid Resuscitation in Shock

Begin immediate fluid resuscitation with isotonic crystalloids, specifically balanced crystalloids (lactated Ringer's or Plasma-Lyte) over normal saline, administering at least 30 mL/kg within the first 3 hours, followed by frequent reassessment using dynamic hemodynamic measures to guide additional fluid boluses, and initiate norepinephrine if hypotension persists despite adequate fluid administration. 1, 2

Step 1: Immediate Initial Fluid Bolus

• Administer at least 30 mL/kg of crystalloid solution within the first 3 hours of recognizing shock, as this is a strong recommendation from the Surviving Sepsis Campaign guidelines 1, 2
• Use balanced crystalloids (lactated Ringer's or Plasma-Lyte) as first-line therapy rather than normal saline to reduce the risk of hyperchloremic metabolic acidosis 2, 3
• In pediatric patients, give boluses of up to 20 mL/kg over 5-10 minutes, which can be repeated as needed 1
• The initial bolus should be given rapidly to restore intravascular volume and tissue perfusion 1

Rationale for Crystalloid Choice

Balanced crystalloids are associated with lower in-hospital mortality compared to normal saline alone (17.7% vs 20.2% mortality) 3. Normal saline causes hyperchloremic metabolic acidosis and increases the risk of acute kidney injury progression 2, 4.

Step 2: Continuous Reassessment During Fluid Administration

• Continue fluid administration as long as hemodynamic parameters continue to improve 1, 2
• Assess response using both dynamic and static variables:
  • Dynamic measures (preferred): pulse pressure variation, stroke volume variation 1
  • Static variables: arterial pressure, heart rate, mental status, urine output (≥0.5 mL/kg/hr), capillary refill, peripheral pulses 1, 5
• After the initial 30 mL/kg bolus, administer smaller fluid challenges of 250-500 mL and reassess after each bolus, particularly in patients with kidney disease or cardiac dysfunction 4

Critical Monitoring Points

• In pediatric patients, monitor specifically for hepatomegaly or pulmonary rales as signs of fluid overload 1
• In adults, assess for pulmonary crackles, increased jugular venous pressure, and worsening respiratory function 5
• Blood pressure alone is unreliable in children, as hypotension is a late finding; focus on perfusion markers 1

Step 3: Stopping Criteria for Fluid Administration

Stop fluid administration when any of the following occur:

• No improvement in tissue perfusion markers despite continued fluid 2, 4
• Signs of fluid overload develop (pulmonary edema, hepatomegaly, rales) 1, 5
• Hemodynamic parameters stabilize without further improvement 2, 4
• In pediatric patients, if hepatomegaly or rales develop, immediately cease fluids and initiate inotropic support rather than continuing resuscitation 1

Step 4: Vasopressor Initiation

• Initiate norepinephrine as the first-choice vasopressor if hypotension persists despite adequate fluid resuscitation 1, 2, 5, 6
• Target a mean arterial pressure (MAP) of ≥65 mmHg 1, 2
• In previously hypertensive patients, raise blood pressure no higher than 40 mmHg below the preexisting systolic pressure 6
• Norepinephrine should be administered through a large central vein when possible, though peripheral administration can be initiated while establishing central access 6
• In pediatric patients with fluid-refractory shock, begin peripheral inotropic support until central venous access can be obtained, as delays in inotrope therapy are associated with increased mortality 1

Vasopressor Dosing

• Start norepinephrine at 2-3 mL/minute (8-12 mcg/minute) and titrate to effect 6
• Average maintenance dose ranges from 0.5-1 mL/minute (2-4 mcg/minute of base) 6
• Consider adding epinephrine when an additional agent is needed to maintain adequate blood pressure 5

Step 5: Special Considerations and Adjustments

For Patients with Chronic Kidney Disease

• Use the same initial 30 mL/kg crystalloid bolus, but monitor more closely for fluid overload due to impaired renal excretion 4
• Consider earlier initiation of vasopressors to maintain perfusion while limiting excessive fluid administration 4
• Albumin may be considered when substantial crystalloid volumes are required to reduce total volume needed 4

For Pediatric Patients

• Initial fluid resuscitation may require 40-60 mL/kg or more in the absence of hepatomegaly or rales 1
• In children with severe hemolytic anemia (severe malaria or sickle cell crises) who are not hypotensive, blood transfusion is superior to crystalloid or albumin bolusing 1
• Pediatric patients may present with different hemodynamic states (low cardiac output/high SVR, high cardiac output/low SVR, or low cardiac output/low SVR) and require tailored inotrope/vasopressor therapy 1

Albumin Consideration

• Albumin may be added when substantial amounts of crystalloids are required, though this is a weak recommendation 4
• In pediatric patients, isotonic crystalloids or albumin can both be used for initial resuscitation 1

Common Pitfalls to Avoid

• Do not delay resuscitation due to concerns about fluid overload—delayed resuscitation increases mortality 2
• Do not rely solely on central venous pressure (CVP) to guide fluid therapy, as it has poor predictive ability for fluid responsiveness 2, 4
• Do not use hydroxyethyl starches, as they increase mortality and worsen acute kidney injury 2, 4
• Do not use low-dose dopamine for renal protection—it is ineffective 2
• Do not use normal saline exclusively when balanced crystalloids are available, as saline increases the risk of hyperchloremic acidosis and acute kidney injury 2, 4, 3
• In pediatric patients, do not continue fluid administration if hepatomegaly or rales develop—switch immediately to inotropic support 1
• Blood volume depletion should always be corrected as fully as possible before relying primarily on vasopressors, though vasopressors can be administered concurrently in emergency situations 6