What is the appropriate management of hypovolemic shock?

Management of Hypovolemic Shock

Immediately initiate aggressive fluid resuscitation with isotonic crystalloids (normal saline or lactated Ringer's solution) using 20 mL/kg boluses over 5-10 minutes, repeating up to 60 mL/kg in the first hour for children or 30 mL/kg within 3 hours for adults, while simultaneously controlling any obvious bleeding source. 1

Immediate Recognition and Assessment

Clinical signs of hypovolemic shock include:

• Tachycardia (heart rate >100 bpm in adults) with or without hypotension 2
• Cold extremities with prolonged capillary refill (>2 seconds) 2
• Decreased urine output (<1 mL/kg/hour in children, <0.5 mL/kg/hour in adults) 1
• Altered mental status or confusion 2
• Narrow pulse pressure indicating compensated shock 2

Critical pitfall: Normal blood pressure does NOT exclude significant hemorrhage—young patients can lose 30-40% of blood volume before systolic pressure drops due to compensatory mechanisms. 2 A heart rate >100 bpm with normal blood pressure indicates Class II hemorrhagic shock (20-40% blood loss). 2

Use the shock index (heart rate/systolic blood pressure) to assess severity and transfusion requirements. 2 Measure blood lactate levels to estimate tissue hypoperfusion, with base deficit as an alternative. 2

Immediate Interventions

Establish large-bore intravenous access (preferably two lines) or intraosseous access if IV cannot be rapidly obtained. 1, 2

For patients with obvious bleeding or hemorrhagic shock in extremis, proceed immediately to bleeding control procedures—do not delay for diagnostic confirmation. 2

Perform FAST (Focused Assessment with Sonography for Trauma) within 2-3 minutes to detect occult intra-abdominal hemorrhage. 2 If FAST is positive with hemodynamic instability, proceed directly to operative exploration without CT imaging. 2

Fluid Resuscitation Protocol

First-line fluid choice: Isotonic crystalloids (0.9% saline or balanced crystalloids like lactated Ringer's solution). 1, 2 The Dutch Pediatric Society found excess mortality in albumin-treated trauma patients compared to crystalloid-treated groups, with no evidence that synthetic colloids are superior. 1

Dosing algorithm:

• Children: 20 mL/kg boluses over 5-10 minutes, reassess immediately after each bolus 1
• Repeat up to 60 mL/kg in the first hour if perfusion does not normalize 1
• Maximum total volume up to 200 mL/kg if no signs of fluid overload 1
• Adults: 500-1000 mL boluses over 15-30 minutes 1
• Up to 30 mL/kg within 3 hours 1

Titrate fluid boluses to achieve these endpoints:

• Capillary refill ≤2 seconds 1
• Normal heart rate for age 1
• Warm extremities with strong peripheral pulses equal to central pulses 1
• Normal mental status 1
• Urine output >1 mL/kg/hour (children) or >0.5 mL/kg/hour (adults) 1
• Mean arterial pressure (MAP) ≥65 mmHg in adults 1

STOP fluid administration immediately if any signs of fluid overload develop:

• Hepatomegaly 1
• Pulmonary rales/crackles 1
• Gallop rhythm on cardiac auscultation 1
• Increased work of breathing 1
• Decreased oxygen saturation 1
• Increased jugular venous pressure (adults) 1

Permissive Hypotension in Hemorrhagic Shock

In ongoing hemorrhage, target systolic blood pressure 80-100 mmHg (permissive hypotension) until definitive bleeding control is achieved to avoid disrupting early clot formation. 2 This principle applies specifically to uncontrolled hemorrhage, not to other causes of hypovolemic shock. 3

Vasopressor Support

Initiate norepinephrine if shock persists after 40-60 mL/kg in children or 30 mL/kg in adults, targeting MAP of 65 mmHg. 1, 2 Norepinephrine is the first-line vasopressor choice. 1, 2

Critical pitfall: Early vasopressor use before adequate fluid resuscitation (≥2000 mL crystalloid in adults) can be harmful in hemorrhagic shock and should be avoided. 2 Vasopressors may be transiently required to sustain life while fluid expansion is in progress, but use cautiously. 2

Special Populations and Considerations

Traumatic brain injury:

• Maintain adequate systolic blood pressure for age 1
• Use isotonic saline exclusively—avoid hypotonic solutions 1
• Avoid hyperventilation in severely hypovolemic patients as it decreases cardiac output 2

Burn patients:

• Give 20 mL/kg within the first hour for adults with ≥15% TBSA or children with ≥10% TBSA burns 1
• Use balanced crystalloids (Ringer's Lactate) as first-line treatment 1

Hypovolemic hyponatremia:

• Fluid restriction is contraindicated—it worsens tissue perfusion and can precipitate cardiovascular collapse 1
• Use 0.9% saline for resuscitation (does not exacerbate hyponatremia) 1
• Do not correct sodium by more than 8 mmol/L in 24 hours to avoid osmotic demyelination 1

Blood Product Administration

Maintain hemoglobin at minimum 10 g/dL in patients with ongoing hemorrhage. 2 In massive transfusion, use a ratio of red blood cells:plasma:pooled platelets of 4:4:1. 4

Administer tranexamic acid early in hemorrhagic shock to stabilize coagulation. 4

Ongoing Monitoring

Continuously monitor:

• Vital signs (heart rate, blood pressure, respiratory rate) 2
• Capillary refill and peripheral perfusion 2
• Mental status 2
• Urine output 1
• Serial hemoglobin/hematocrit to detect ongoing bleeding 2

Use dynamic measures of fluid responsiveness (pulse pressure variation, stroke volume variation) rather than static measures like CVP alone when available. 1

Failure to improve hemodynamics after 2000 mL (or ≈40 mL/kg) of crystalloid suggests ongoing hemorrhage and should trigger rapid escalation to surgical or endovascular control. 2

Critical Pitfalls to Avoid

• Do not use hypotonic fluids for shock resuscitation in any age group 1
• Do not rely solely on blood pressure to guide therapy—assess comprehensive perfusion parameters 1
• Do not continue aggressive fluid without reassessment for overload after each bolus 1
• Do not delay vasopressor initiation in fluid-refractory shock beyond 40-60 mL/kg in children or 30 mL/kg in adults 1
• Do not use etomidate for intubation in pediatric patients with septic shock due to associated higher mortality 1
• Absence of external injuries does not exclude life-threatening internal bleeding—blunt abdominal trauma frequently causes solid-organ injury without obvious external signs 2