What is the recommended initial resuscitation protocol for a patient in hypovolemic shock?

Hypovolemic Shock Resuscitation

Begin immediate fluid resuscitation with at least 30 mL/kg of isotonic crystalloid administered rapidly within the first 1–3 hours, using large-bore peripheral IVs, while simultaneously controlling the source of bleeding. 1, 2

Initial Assessment and Vascular Access

• Establish two large-bore peripheral IV lines (14- or 16-gauge) immediately; do not delay resuscitation to obtain central venous access. 1
• Rapidly assess the mechanism of injury to determine whether surgical hemorrhage control will be required (penetrating trauma, high-energy blunt mechanisms). 3
• Obtain baseline serum lactate immediately; values >2 mmol/L indicate tissue hypoperfusion and mandate aggressive resuscitation. 1
• Perform FAST examination in trauma patients; hemodynamically unstable patients with intra-abdominal free fluid require urgent operative intervention. 1

Fluid Resuscitation Strategy

Initial Crystalloid Bolus

• Administer 30 mL/kg of isotonic crystalloid (normal saline or balanced solution) within the first 1–3 hours as the cornerstone of initial resuscitation. 3, 1, 2
• Deliver crystalloid in 500–1,000 mL aliquots over 15–30 minutes, reassessing hemodynamic response after each bolus. 1
• Continue fluid administration as long as hemodynamic parameters improve (heart rate decreases, blood pressure increases, urine output increases, mental status improves). 2

Permissive Hypotension (Uncontrolled Hemorrhage)

• In trauma patients with ongoing bleeding, target a systolic blood pressure of 80–100 mmHg (MAP ≈65 mmHg) until definitive hemorrhage control is achieved. This "permissive hypotension" strategy reduces clot disruption and dilution of coagulation factors. 1, 4, 5
• Exception—Traumatic brain injury: maintain MAP ≥80 mmHg to preserve cerebral perfusion. 1
• Exception—Elderly or chronically hypertensive patients: target systolic pressure no more than 40 mmHg below baseline. 1

Controlled Hemorrhage

• When the bleeding source has been controlled, target normalization of hemodynamic parameters (normal blood pressure, heart rate, capillary refill <2 seconds, warm extremities, urine output ≥0.5 mL/kg/h, normal mental status). 3, 5

Hemorrhage Control

• Prioritize immediate surgical or interventional hemorrhage control over advanced airway management in exsanguinating patients; delaying intubation to focus on circulation improves survival by avoiding postintubation hypotension. 6
• For pelvic ring disruption with shock, apply a pelvic binder immediately; if instability persists, proceed to angiographic embolization or surgical packing. 1
• Evaluate for and reverse pneumothorax or pericardial tamponade in patients with refractory shock. 3

Monitoring and Reassessment

• Reassess hemodynamic status continuously after each fluid bolus by evaluating heart rate, blood pressure, capillary refill, skin temperature, urine output, and mental status. 2
• Use dynamic measures of fluid responsiveness (passive leg raise, pulse-pressure variation, stroke-volume variation) rather than static measures like CVP alone to guide ongoing fluid administration. 3, 2
• Repeat lactate measurement 2–6 hours after initial resuscitation; a decreasing trend signals adequate resuscitation, while persistent elevation indicates ongoing hypoperfusion. 3, 1
• Stop crystalloid infusion immediately if signs of fluid overload appear (pulmonary edema, hepatomegaly, rales, worsening oxygenation). 3, 1

Transition to Blood Products

• After the initial 30 mL/kg crystalloid bolus, transition to blood-product–based resuscitation when ongoing transfusion needs are anticipated. 1, 4
• Avoid excessive crystalloid beyond the initial bolus; volumes >2,000 mL are associated with >40% risk of coagulopathy, and >4,000 mL with >70% risk. 1
• Target hemoglobin 10 g/dL during active resuscitation of low central venous oxygen saturation shock (<70%); after stabilization, a lower target of 7 g/dL is acceptable. 3

Vasopressor Use (Rare in Hypovolemic Shock)

• Do not use vasopressors as first-line therapy in hypovolemic shock; early vasopressor administration before adequate volume replacement is associated with increased mortality. 1
• Vasopressors should only be considered after ≥30 mL/kg crystalloid has been given, bleeding is being controlled, and MAP remains <65 mmHg despite adequate fluid resuscitation. 1
• If vasopressors are required, norepinephrine is the first-choice agent. 3

Common Pitfalls to Avoid

• Do not delay fluid resuscitation to obtain central venous access; large-bore peripheral lines are sufficient and faster. 1
• Do not target normal blood pressure (120/80 mmHg) before bleeding is controlled in trauma patients; permissive hypotension is safer. 1, 4, 5
• Do not rely solely on CVP to guide fluid therapy; it has poor predictive ability for fluid responsiveness. 3, 2
• Do not continue aggressive crystalloid beyond the initial 30 mL/kg without reassessing fluid responsiveness; excess fluid leads to dilutional coagulopathy, abdominal compartment syndrome, and increased mortality. 1, 4
• Do not ignore the possibility of traumatic brain injury; if present, maintain MAP ≥80 mmHg rather than permissive hypotension. 1
• Do not use hydroxyethyl starches for resuscitation; they increase acute kidney injury and mortality. 2