Shock Overview

• Shock = Inadequate perfusion.*

Prolonged shock may lead to cellular injury, organ dysfunction, and potentially death if not corrected in a timely fashion. Causes are multifactorial. Management should be directed toward the underlying pathophysiology.

General Categories

1. Hypovolemic (hemorrhagic and non-hemorrhagic)
2. Distributive (sepsis, neurogenic, anaphylactic, adrenal, pharmacologic)
3. Cardiogenic (nonobstructive and obstructive)
4. Mixed (combination of two or more)

• Goal of resuscitation:* Regain adequate perfusion and maintain adequate oxygen delivery.

• Goal:* Restore circulating volume and minimize further intravascular losses.

Hemorrhagic Shock

Sources: trauma, GI, gynecologic, vascular, spontaneous solid organ rupture.

• Replacement of volume should be primarily with blood and blood products
• Timely control of bleeding source is paramount — surgery or IR
• For accessible traumatic bleeding: point pressure or tourniquets can buy time

Hemorrhagic Shock Classification

• Resuscitation:* Target 1:1:1 ratio — PRBCs : FFP : Platelets (massive transfusion protocol).

Hypovolemic Non-Hemorrhagic Shock

Causes: severe dehydration, vomiting/diarrhea, unregulated diuresis (DI, DKA, severe hyperglycemia), Addisonian crisis.

• Replace with balanced crystalloid solutions
• Monitor electrolytes closely

Result of vasodilation of vascular smooth muscle. Peripheral "pooling" → loss of perfusion to vital organs.

• Therapy:* Balanced resuscitation.

1. First: Crystalloid/colloid for normovolemia restoration
2. Second: Pressors to re-establish vasomotor tone

Common Types

• Sepsis (mixed; prominent distributive component)
• SIRS
• Neurogenic (SCI above T6)
• Anaphylactic
• Adrenal insufficiency
• Pharmacologic

Do not use vasopressor dosing protocols without attending guidance and current local institutional review.

There is no single "gold standard" measurement of resuscitation.

Signs of Adequate Volume Status

• UOP > 0.5 mL/kg/hr and normal creatinine (without concern for DI or hyperosmolar diuresis)
• Minimally or non-compressible transhepatic IVC throughout respiratory cycle on ultrasound
• Adequate right heart filling on ECHO
• MAP > 65 mmHg off all pressors
• CVP − PEEP > 5 mmHg
• Corrected lactate over 2 successive measurements within first 6 hours
• Correction of metabolic acidosis (normalizing base deficit)

If Not Correcting in 6 Hours — Consider:

• Ongoing blood loss
• Systemic inflammatory response
• Missed injuries

Weaning Pressors

Wean in concert with volume replacement. Patient is not "fully resuscitated" until pressors are off, OR until other endpoints suggest adequate volume status.

• Exception:* Neurologic injury — low-dose pressors may be necessary to maintain goal MAP.

• Vasopressors
• Hemorrhagic Shock
• Spinal Cord Injury

• MAP Calculator
• Shock Index

• Adapted from SurgCritCare. org shock content. Verify against current institutional resuscitation protocols and attending guidance.*