THE CHIEF
COMPLAINT

Resuscitation

Shock

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  • Adult undifferentiated shock. Recognize hypoperfusion, identify the cause, and resuscitate simultaneously. Pediatric assessment and treatment require a separate pathway.

The Algorithm...

01 True Shock?

  • Assess mental status, BP / pulse, skin perfusion, respiratory effort, and urine output; obtain lactate when shock is suspected.
  • Normal BP does not exclude shock. Interpret the examination, trends, and laboratory findings together. See Recognition.

02 Initial Resuscitation

  • ABCs, IV / IO access, monitoring, and oxygen / ventilation as needed.
  • Immediate threats: Control hemorrhage, relieve tension pneumothorax / tamponade, treat an unstable rhythm, and recognize anaphylaxis.
  • Select fluids, blood, and vasoactive support according to the likely physiology—not a fixed treatment ladder. See Resuscitation.

03 What Type Of Shock?

  • Hypovolemic: Hemorrhage or nonhemorrhagic volume loss.
  • Distributive: Vasodilation / maldistributed flow; consider sepsis, anaphylaxis, and other causes.
  • Cardiogenic: Pump, rhythm, or mechanical cardiac failure.
  • Obstructive: Impaired filling or outflow; tension pneumothorax, tamponade, or high-risk PE.
  • History / examination + POCUS + ECG direct further testing. More than one mechanism may be present. See Cause.

04 Cause-Specific Treatment

  • Volume loss: Crystalloid for nonhemorrhagic depletion; blood and hemorrhage control for significant bleeding.
  • Septic shock: Antibiotics / source control, appropriate fluid, and norepinephrine when needed.
  • Anaphylaxis: IM epinephrine; refractory compromise requires escalation.
  • Cardiogenic / obstructive shock: Support perfusion while arranging definitive treatment. See Treatment.

05 Reassess / Destination

  • Reassess perfusion, respiratory status, fluid response / tolerance, and vasoactive requirements after interventions.
  • OR / Cath Lab / IR: Definitive treatment when indicated.
  • ICU: Persistent shock, advanced respiratory support, or vasoactive infusions.
  • See Reassessment / Disposition.

True Shock? — Recognize Hypoperfusion

Clinical Assessment

  • Shock is acute circulatory failure with inadequate tissue perfusion / oxygen utilization—not simply a low BP.
  • Mental status: New confusion, agitation, lethargy, or reduced responsiveness.
  • Skin: Delayed capillary refill, cool extremities, pallor, or mottling. Warm skin does not exclude distributive shock.
  • Circulation: BP / MAP trend, pulse quality, heart rate, and rhythm.
  • Respiration: Tachypnea, increased effort, or fatigue; these may reflect acidosis, hypoxemia, or a primary cardiopulmonary cause.
  • Urine output: Falling output supports impaired perfusion; oliguria is commonly <0.5 mL/kg/hour.
  • Do not wait for sustained hypotension before treating hypoperfusion. ESICM — Foundational Shock Consensus.

Shock Index

  • Heart rate ÷ systolic BP: A value around 0.9 or higher increases concern, particularly with suspected blood loss.
  • Interpret with the examination and trend. Rate-limiting medication, pacing, or dysrhythmia may make the ratio misleading; a reassuring value does not exclude shock. Shock Index Review.

Lactate / Acid–Base Status

  • Obtain lactate when shock is suspected; trend an elevated result alongside clinical response.
  • Elevated lactate may reflect hypoperfusion, adrenergic stimulation, seizures, impaired clearance, or medications / toxins. A normal result does not exclude early or regional hypoperfusion.
  • Blood gas / base deficit may help assess severe illness, especially hemorrhage or a mixed acid–base disorder.
  • Use mmol/L for lactate thresholds. Neither lactate >4 nor a particular base deficit is required to recognize shock. ESICM — Perfusion Markers.

Initial Resuscitation

ABCs / Access / Monitoring

  • Assess airway protection, ventilation, circulation, and consciousness. Pulseless collapse requires the cardiac-arrest pathway.
  • Establish reliable vascular access; large-bore IVs for rapid volume / blood delivery, with IO access when urgent access cannot otherwise be obtained.
  • Cardiac monitoring, frequent BP, pulse oximetry, temperature, and bedside glucose. Correct hypoxemia and inadequate ventilation.
  • Obtain an early ECG and blood samples while resuscitation proceeds. Track urine output; consider a catheter when accurate measurement will guide ongoing care.
  • Call for appropriate resuscitation, procedural, and critical-care support early. RCUK — ABCDE.

Airway / Respiratory Support

  • Intubation for failed oxygenation / ventilation, inability to protect the airway, or anticipated deterioration requiring airway control.
  • Preoxygenate and support perfusion during preparation. Induction and positive-pressure ventilation may precipitate cardiovascular deterioration.
  • Necessary airway control should not wait for complete resuscitation; shock alone is not an automatic indication for paralysis.
  • See RSI for preparation, medication selection, confirmation, and rescue. ACEP — Endotracheal Intubation.

Immediately Reversible Threats

  • Major hemorrhage: External control, early blood-based resuscitation, and definitive hemorrhage control.
  • Tension pneumothorax: Immediate decompression when clinically suspected in an unstable patient; imaging must not delay treatment.
  • Tamponade: Urgent drainage / operative assessment according to cause.
  • Unstable dysrhythmia: Rhythm-specific cardioversion, pacing, or pharmacologic treatment.
  • Anaphylaxis: IM epinephrine and airway / circulatory support.
  • High-risk PE / acute cardiac mechanical problem: Immediate specialist involvement and definitive-treatment planning. See Cause-Specific Treatment.

What Type Of Shock?

Four Mechanisms

  • Hypovolemic: Inadequate circulating volume.
  • Distributive: Loss of vascular tone and maldistributed flow.
  • Cardiogenic: Inadequate cardiac output from pump, rhythm, or mechanical failure.
  • Obstructive: Restricted cardiac filling or outflow.
  • These are working mechanisms, not exclusive diagnoses. Sepsis with myocardial dysfunction or trauma with several injuries may produce mixed shock. Classic filling-pressure / cardiac-output patterns are guides—not diagnostic requirements. ESICM — Mechanisms.

History / Examination — What Moves The Needle?

Hypovolemic

  • Hemorrhage: Trauma, GI / vaginal bleeding, abdominal or back pain, recent procedure, or anticoagulation.
  • Other losses: Vomiting / diarrhea, poor intake, burns, or substantial third spacing.
  • Assess wounds, abdomen / pelvis, mucous membranes, peripheral perfusion, and evidence of concealed bleeding.

Distributive

  • Sepsis: Possible source, fever / hypothermia, immunocompromise, recent infection or procedure.
  • Anaphylaxis: Abrupt illness after a likely trigger; wheeze, swelling, hives, or GI symptoms. Skin findings may be absent.
  • Other causes: Spinal injury, adrenal insufficiency / steroid interruption, medication or toxic exposure.
  • Warm extremities or a low diastolic BP may support vasodilation but do not establish the cause.

Cardiogenic

  • Chest discomfort, dyspnea, palpitations, known heart failure / coronary disease, or acute deterioration after MI.
  • Assess rhythm, JVP, crackles, edema, and a new murmur. Consider both LV and RV failure.

Obstructive

  • Tension pneumothorax: Sudden respiratory deterioration, asymmetric breath sounds, trauma / positive-pressure ventilation.
  • Tamponade: Relevant trauma, procedure, malignancy, or pericardial disease.
  • PE: Acute dyspnea / syncope, VTE risk, hypoxemia, or unilateral leg findings.
  • Integrate these clues with immediate bedside testing; absence of a classic finding does not exclude the diagnosis. RUSH — Clinical And Ultrasound Assessment.

POCUS / RUSH

  • Heart — Pump: LV / RV size and function, pericardial effusion, and major mechanical abnormalities.
  • Volume / Lungs — Tank: Venous filling, lung sliding, B-lines, pleural fluid, and abdominal free fluid when relevant.
  • Vessels — Pipes: Aorta and DVT assessment according to the suspected cause.
  • Pericardial fluid alone does not establish tamponade; RV enlargement alone does not establish acute PE. Interpret with physiology and history.
  • IVC size alone should not determine fluid treatment. Repeat focused imaging when the patient changes or treatment response is unexpected. RUSH 2012 · ESICM 2025.

ECG / Imaging / Laboratory Testing

  • ECG: Ischemia, tachy / bradyarrhythmia, conduction disease, and electrolyte / toxicologic clues.
  • CXR: Pulmonary edema, pneumonia, pneumothorax, or pleural blood / fluid when it will assist management.
  • Laboratory testing: Consider CBC, chemistry / renal function, glucose, lactate, blood gas, coagulation studies, and type and cross according to severity and differential.
  • Cause-directed tests: Troponin for cardiac concern; cultures / infection testing; pregnancy testing; selected toxicology studies. Cortisol / thyroid testing belongs to a supported endocrine differential.
  • CT / CTA: Consider when it answers a remaining urgent question and transport is safe. Bedside testing must not delay necessary operative or other definitive treatment. RCUK — Initial Investigations · European Trauma Guideline 2023.

Cause-Specific Treatment

Fluid Responsiveness / Fluid Tolerance

  • Before further volume, assess the likely deficit, expected benefit, and risk of worsening congestion.
  • Responsiveness: Would additional preload increase stroke volume / cardiac output?
  • Tolerance: Can the patient accept additional fluid without worsening pulmonary edema or venous congestion?
  • Consider a passive leg raise with measured stroke-volume / cardiac-output response, or a monitored fluid challenge. A BP change alone is less informative.
  • Example challenge: 200–500 mL crystalloid over 5–10 minutes, with immediate reassessment; adjust volume and rate to the patient.
  • Reassess perfusion and lung / venous congestion. A transient response does not justify unlimited fluid; obvious hemorrhage requires blood and control rather than repeated crystalloid challenges. ESICM 2025 — Fluid Therapy.

Hypovolemic Shock

Nonhemorrhagic Volume Loss

  • Crystalloid replacement with reassessment; correct ongoing losses and electrolyte abnormalities.
  • Select fluid and volume for the cause and comorbidities. Avoid applying one weight-based bolus to every hypotensive patient.

Hemorrhagic Shock

  • Control bleeding and start blood-based resuscitation. Activate the massive-transfusion pathway when major ongoing blood loss is suspected.
  • Use whole blood or balanced components according to the institutional protocol; limit crystalloid that delays or dilutes effective resuscitation.
  • Whole blood is a reasonable option, not established as universally superior to balanced components. EAST's recommendation is conditional. EAST 2024 — Whole Blood.
  • Warm the patient / products; monitor ionized calcium, coagulation, and ongoing blood loss. Correct abnormalities during major transfusion.
  • Consider early TXA for qualifying traumatic hemorrhage; follow the trauma-specific timing / dosing pathway, not a generic shock indication.
  • An initially reassuring hemoglobin does not exclude acute major bleeding. Arrange surgery, IR, endoscopy, or obstetric intervention according to the source. European Trauma Guideline 2023.

Distributive Shock

Septic Shock

  • Obtain cultures without delaying treatment. Antibiotics immediately, ideally within one hour of recognition; select coverage for the source and resistance risk.
  • Identify infection requiring drainage, debridement, obstruction relief, or device removal; arrange urgent source control.
  • Balanced crystalloid is preferred in most septic resuscitation. Concurrent TBI changes fluid selection.
  • SSC 2026 suggests at least 30 mL/kg in the first three hours for sepsis-induced hypoperfusion / septic shock. This is conditional, low-certainty guidance: individualize and reassess frequently.
  • Persistent or profound hypotension warrants vasopressor support; unstable patients may require fluid and pressor treatment concurrently. See Vasoactive Support.
  • Infection-directed treatment belongs here; SIRS alone neither establishes shock nor identifies its cause. SSC 2026.

Anaphylaxis

  • IM epinephrine immediately, repeated for persistent compromise; airway support and crystalloid for shock.
  • Refractory respiratory / circulatory compromise requires a monitored IV epinephrine infusion and experienced resuscitation support.
  • Antihistamines do not treat shock. Isolated bradykinin-mediated angioedema requires a different treatment pathway. See Anaphylaxis / Angioedema. RCUK 2021.

Adrenal Crisis

  • Suspect with adrenal disease / steroid interruption, hypotension, volume depletion, or compatible electrolyte / glucose abnormalities.
  • Hydrocortisone 100 mg IV / IM immediately, then 200 mg over 24 hours; crystalloid and correction of hypoglycemia / electrolyte abnormalities.
  • Obtain diagnostic samples first when feasible, but do not delay treatment for cortisol results. Endocrine Society — Adrenal Crisis.

Neurogenic / Toxicologic / Other Endocrine Causes

  • Neurogenic: Spinal injury with impaired sympathetic tone; evaluate for concurrent hemorrhage and follow spinal-cord perfusion guidance.
  • Medication / toxin: Identify the exposure; arrange toxicology / poison-center input and cause-specific treatment.
  • Myxedema or other endocrine crisis: Consider when the history and examination support it. These may produce mixed circulatory failure rather than classic high-output vasodilation.

Cardiogenic Shock

  • Obtain ECG / echocardiographic assessment; identify ischemia, dysrhythmia, ventricular dysfunction, or an acute mechanical lesion.
  • ACS / mechanical disease: Urgent cardiology and definitive-treatment planning. Revascularization or repair may be more important than another vasoactive escalation.
  • Hypotensive shock: Norepinephrine is a reasonable initial vasopressor. Consider inotropic support for persistent low output with adequate pressure and volume assessment.
  • Fluids are selective; assess congestion and preload response. Generic afterload reduction is not treatment for an undifferentiated hypotensive patient.
  • Persistent hypoperfusion: Early shock-team / transfer discussion; selected invasive hemodynamics or temporary mechanical support. IABP is not an automatic next step. ACC 2025 — Cardiogenic Shock Guidance · ACC — Guidance Summary.

Obstructive Shock

  • Tension pneumothorax: Immediate decompression, then definitive chest drainage; do not wait for imaging in an unstable patient.
  • Tamponade: Urgent pericardial drainage / surgery according to cause. Traumatic tamponade generally requires operative management.
  • Fluids and pressors may temporarily support circulation, but the priority is relieving the obstruction. RUSH — Obstructive Shock.
  • High-risk PE: Urgent reperfusion assessment—systemic thrombolysis, catheter treatment, or surgery according to risk, contraindications, and resources. Involve the PE response team when available. AHA/ACC 2026 — Acute PE.

Vasoactive Support — Match The Physiology

  • Norepinephrine: First-line septic vasopressor; also reasonable for hypotensive cardiogenic shock.
  • Vasopressin: Adjunct for septic vasoplegia with escalating norepinephrine requirements.
  • Epinephrine: Refractory septic shock or selected cardiac dysfunction; disease-specific first-line treatment for anaphylaxis uses the IM route initially.
  • Dobutamine: Selected low-output states with adequate pressure / volume assessment—not a substitute for a needed vasopressor.
  • Peripheral initiation: A monitored peripheral infusion can avoid delay for central access. Follow a standardized concentration / pump protocol, assess the site, and arrange ongoing access as needed. SSC 2026 — Vasopressors · ACC — Vasoactive Guidance.

Reassessment / Disposition

Response To Treatment

  • Repeat mental status, capillary refill / skin perfusion, pulse, BP, oxygen requirement, and urine output.
  • Trend lactate when elevated; interpret persistent elevation in context rather than treating the number with additional fluid.
  • Reassess cardiac function, congestion, and fluid responsiveness when the response is inadequate or unexpected.
  • Rising pressor requirement or persistent hypoperfusion: Reassess the diagnosis, ongoing losses, mixed physiology, and adequacy of source control.
  • Consider arterial pressure monitoring for persistent shock / vasoactive support; selected patients need advanced hemodynamic assessment. ESICM 2025 — Monitoring.

Blood Pressure Targets

  • Septic shock: Initial MAP approximately 65 mm Hg; individualize for age, baseline pressure, and perfusion response. SSC 2026 — MAP.
  • Cardiogenic shock: An initial MAP around 65 mm Hg is reasonable, then adjust to perfusion and hemodynamics. ESICM 2025.
  • Uncontrolled traumatic hemorrhage: Selected patients may tolerate SBP 80–90 mm Hg until bleeding control; significant brain / spinal injury requires different targets. This is not a general target for medical shock. European Trauma Guideline 2023.

Definitive Treatment — OR / Cath Lab / IR

Monitored Admission

  • Sustained response to initial treatment without ongoing vasoactive or advanced respiratory support, but continued evaluation / treatment remains necessary.
  • Persistent uncertainty, recurrent hypotension, or organ dysfunction requires a setting capable of prompt escalation.

ICU Admission

  • Persistent / recurrent shock, vasoactive infusion, invasive ventilation, worsening organ dysfunction, or intensive monitoring requirements.
  • Communicate the suspected mechanism, interventions, response, fluid / blood totals, current support, and unresolved source-control needs.
  • Clarify goals of care and any treatment limits while continuing indicated resuscitation. SSC 2026.

Discharge

  • A transiently improved BP is insufficient. Consider discharge only when ongoing shock has been excluded, the cause and sustained recovery support a safe outpatient pathway, and follow-up is appropriate.
  • Persistent or unexplained hypoperfusion requires continued monitored care.

In The Pit

  • Crashing: ABC support; control bleeding, relieve obstruction, and treat unstable rhythms / anaphylaxis immediately.
  • Hypoperfusion: Normal BP does not exclude shock; reassess mentation, skin, urine output, and lactate in context.
  • Hemorrhage: Blood + source control—not repeated crystalloid alone.
  • Vasodilatory Shock: Appropriate fluid + early norepinephrine; suspected sepsis also needs antibiotics / source control.
  • Cardiogenic / Obstructive: POCUS + cause-specific treatment; fluids and pressors cannot replace correction of the underlying problem.
  • Reassessment: Additional fluid requires expected benefit and tolerance; persistent shock needs definitive intervention / critical care.

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