What are the recommendations for managing hypovolemic shock?

Management of Hypovolemic Shock

Begin immediate resuscitation with isotonic crystalloids (preferably isotonic saline or Ringer's lactate) at 20 ml/kg boluses in adults (500-1000 ml over 30 minutes) and 10-20 ml/kg boluses in children (over 5-10 minutes), titrating to clinical endpoints of perfusion rather than blood pressure alone. 1, 2, 3

Initial Assessment and Recognition

• Evaluate for signs of tissue hypoperfusion: prolonged capillary refill time (>2 seconds), cold extremities, altered mental status, and oliguria (<1 ml/kg/h) 2
• Measure serum lactate when available, as it serves as a marker of shock severity and adequacy of resuscitation 2
• Recognize that hypotension is a late finding, particularly in children who compensate through vasoconstriction and tachycardia until cardiovascular collapse is imminent 1

Fluid Resuscitation Protocol

First-Line Therapy: Crystalloids

• Administer isotonic crystalloids (isotonic saline or Ringer's lactate) as the first-choice fluid for initial resuscitation 1, 2, 3
• In adults: Give 500-1000 ml boluses over 30 minutes, with initial target of 30 ml/kg within the first 3 hours 1, 2, 3
• In children: Administer 10-20 ml/kg boluses over 5-10 minutes, with repeated doses based on clinical response 1, 2
• Pediatric patients may require 40-60 ml/kg or more in the initial phase, and up to 60 ml/kg total for hypovolemic shock 1, 3

Rationale for Crystalloid Preference

• Colloids offer no mortality benefit over crystalloids and carry risks of anaphylaxis, infection hazard, and significantly higher cost 1
• Meta-analyses demonstrate no advantage of albumin or synthetic colloids over crystalloids for resuscitation 1, 3
• When large fluid volumes are required (e.g., sepsis), synthetic colloids may be considered due to longer intravascular duration, but only after initial crystalloid resuscitation 1

Clinical Endpoints and Monitoring

Target Resuscitation Goals

• Capillary refill time <2 seconds 1, 2
• Normalization of heart rate and blood pressure (appropriate for age) 1, 2
• Warm extremities with normal peripheral pulses equal to central pulses 1, 2
• Improved mental status and level of consciousness 1, 2
• Urine output >1 ml/kg/h 1, 2
• Decreasing lactate levels 2

Continuous Reassessment

• Reassess clinical response after each fluid bolus before administering additional volume 2, 3
• Monitor for signs of fluid overload: hepatomegaly, pulmonary rales, increased jugular venous pressure 1, 2
• If hepatomegaly or rales develop, immediately cease fluid administration and initiate inotropic support rather than continuing resuscitation 1

Vasopressor Support

Indications and Timing

• Initiate vasopressor therapy if hypotension persists despite adequate fluid resuscitation 1, 2
• In children not responsive to fluid resuscitation, begin peripheral inotropic support while obtaining central venous access, as delays in inotrope use are associated with increased mortality 1
• Norepinephrine is the first-line vasopressor for distributive shock after adequate fluid resuscitation 2, 4

Norepinephrine Administration

• Dilute 4 mg/4 mL in 1000 mL of 5% dextrose solution (4 mcg/mL concentration) 4
• Initial dose: 2-3 mL/minute (8-12 mcg/minute), then titrate to maintain systolic blood pressure 80-100 mmHg 4
• Average maintenance dose: 0.5-1 mL/minute (2-4 mcg base/minute) 4
• Administer through large central vein when possible; peripheral administration acceptable temporarily while obtaining central access 1, 4
• Monitor blood pressure every 2 minutes until target achieved, then every 5 minutes 4

Special Considerations

Hemorrhagic Shock

• Rapid hemorrhage control is the priority alongside fluid resuscitation 2, 5
• Correct blood volume depletion as fully as possible before administering vasopressors 4
• In severe hemorrhagic shock, maintain hemoglobin target of 7-9 g/dL 5
• Apply permissive hypotension if no contraindications exist to limit ongoing bleeding 5
• Administer tranexamic acid and fibrinogen early for coagulation management 5

Pediatric-Specific Considerations

• In children with severe hemolytic anemia (malaria, sickle cell crisis) who are not hypotensive, blood transfusion is superior to crystalloid or albumin bolusing 1
• Blood pressure alone is unreliable for assessing adequacy of resuscitation in children; use perfusion endpoints 1
• Rapid fluid resuscitation exceeding 40 ml/kg in the first hour has been associated with improved survival in pediatric septic shock 3

Common Pitfalls and How to Avoid Them

Excessive Fluid Administration

• Avoid continuing fluid boluses without reassessing clinical response, as this leads to volume overload and pulmonary edema 2, 3
• Use dynamic measures (passive leg raise test) rather than static measurements like central venous pressure to predict fluid responsiveness 3
• In patients at risk for fluid intolerance (heart failure, elderly), perform frequent clinical evaluation for pulmonary edema 2

Delayed Intervention

• Do not delay vasopressor initiation while attempting to achieve complete volume repletion if hypotension persists 1, 4
• Obtain vascular access rapidly; in burn patients, use non-burned areas when possible 2
• Avoid leg veins in elderly patients or those with occlusive vascular disease due to increased risk of gangrene 4

Inadequate Source Control

• Always suspect occult blood volume depletion if large vasopressor doses are required 4
• Address the underlying cause of hypovolemia while implementing resuscitation 5, 6