ICU Map
cardiovascular / hemodynamic

Acute Hypotension & Undifferentiated Shock

Rapid bedside hemodynamic categorization: confirming MAP < 65 mmHg, assessing peripheral perfusion, POCUS cardiac/IVC profiling, and differentiating hypovolemic, distributive, cardiogenic, and obstructive etiologies.

Acute hypotension (Mean Arterial Pressure [MAP] < 65 mmHg or Systolic Blood Pressure [SBP] < 90 mmHg, or a drop > 40 mmHg from baseline) in the ICU signals inadequate tissue perfusion until proven otherwise. The immediate objective is not to normalize blood pressure mechanically, but to screen for immediately treatable life threats, categorize the physiological shock phenotype (distributive vs hypovolemic vs cardiogenic vs obstructive), and initiate phenotype-directed resuscitation.

Caution

Dangerous Diagnosis Not to Miss: Tension Pneumothorax, Cardiac Tamponade, Massive Pulmonary Embolism, Catastrophic Internal Hemorrhage (retroperitoneal/GI), and Acute STEMI / Cardiogenic Shock. Perform a rapid ultrasound screen (RUSH protocol) within minutes.

CLINICAL ALGORITHMMedically Verified (2026-09-15)

Undifferentiated shock: identify the physiology while resuscitation is already underway

Figure: Undifferentiated shock: identify the physiology while resuscitation is already underway. This action-focused visual summarizes the linked Clinical Problem; the full problem text, evidence references and local policy remain the source of truth.(Action pathway — use the full evidence-linked problem and local protocol for clinical decisions)
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CONFIRM & SCREEN FOR LIFE THREATS

  • Verify Arterial Line / Cuff: Check arterial line transducer level (phlebostatic axis), zero reference, and flush test (damped waveform gives false hypotension); verify with manual cuff.

  • Rapid Perfusion Screen: Assess the 3 clinical windows of perfusion: (1) Brain (altered mental status, agitation, coma); (2) Kidneys (oliguria < 0.5 mL/kg/hr); (3) Skin (cool clammy extremities, mottled knees, capillary refill time > 3 seconds).

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IMMEDIATE STABILIZATION

  • First-Line Vasopressor: Start Norepinephrine infusion (titrated to defend MAP ≥ 65 mmHg) via central venous or dedicated peripheral IV while diagnostic workup proceeds.

  • Passive Leg Raise (PLR) Test: Perform a 1-minute PLR test (legs elevated 45°, torso flat) to assess dynamic preload responsiveness before administering unguided fluid boluses.

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PHENOTYPE-BASED DIFFERENTIAL (RUSH PROTOCOL)

  • Distributive Shock (Warm shock, bounding pulses, wide pulse pressure, hyperdynamic LV, collapsible IVC): Septic shock (most common), anaphylaxis, neurogenic shock, acute adrenal crisis, post-cardiac arrest vasoplegia.

  • Hypovolemic Shock (Cool extremities, flat neck veins, hyperdynamic collapsing LV, flat IVC): Hemorrhagic shock (GI bleed, trauma, retroperitoneal hematoma), dehydration, burns, third-spacing.

  • Cardiogenic Shock (Cool extremities, elevated JVP, pulmonary crackles, dilated poorly contracting LV, plethoric IVC): Acute myocardial infarction, acute decompensated heart failure, severe myocarditis, acute valvular catastrophe.

  • Obstructive Shock (Elevated JVP, severe hypotension, distinct mechanical blockage):

    • Massive Pulmonary Embolism (dilated failing RV, septal D-sign, McConnell's sign).
    • Cardiac Tamponade (pericardial effusion with diastolic RA/RV collapse, pulsus paradoxus).
    • Tension Pneumothorax (unilateral absent breath sounds, tracheal deviation, hyperresonance).
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TARGETED INVESTIGATIONS

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INITIAL MANAGEMENT BY PHENOTYPE

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REASSESSMENT & ESCALATION

Caution

Common Diagnostic Trap: Reflexively administering repeated 1–2 liter crystalloid boluses for all hypotensive patients. If the patient has acute RV failure, cardiogenic shock, or severe capillary leak, excess fluid worsens ventricular interdependence, causes cardiorenal venous congestion (VExUS grade 3), and dramatically increases mortality.

Destination Topics

  • Shock: Hemodynamic classification, oxygen delivery equations, and perfusion endpoints.

  • Septic Shock: SSC 2026 antimicrobial-timing framework, individualized fluids, vasopressor algorithms, and source control.

  • Cardiogenic Shock: SCAI shock staging, inotropes, and mechanical circulatory support.

  • Obstructive Shock: Pulmonary embolism, tamponade, and tension pneumothorax.

  • Hemodynamic Monitoring: Arterial line damping, stroke volume variation, and PAC indices.

Evidence status

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Status, review dates and guideline versions appear here once editorial metadata is authored for this content.

Actionable Clinical Workflows (17)

Step-by-step ICU Processes
Initial Hemodynamic Resuscitation & Shock Bundling

From recognizing hypoperfusion and initial crystalloid bolus to dynamic fluid responsiveness assessment and vasopressor targets.

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Vasopressor & Inotrope Initiation & Titration

From first-line norepinephrine titration to multi-agent vasopressor escalation and inotrope selection.

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Refractory Shock Support Escalation

From multi-vasopressor failure to rescue non-adrenergic agents and mechanical circulatory support.

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Hypotension

From confirming true hypotension to recognizing shock and its likely category.

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Deep-Dive Topic Destinations (6)

Reference Knowledge
Shock: Foundational Critical Care Frameworkcardiovascular

Cellular dysoxia, DO2/VO2 physiology, the 4 shock phenotypes, dynamic fluid responsiveness (PLR/PPV) vs fluid tolerance (VExUS), and vasoactive pharmacology.

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Septic Shockcardiovascular

The subset of sepsis with profound circulatory and cellular/metabolic abnormality — clinically identified by a vasopressor requirement to maintain MAP ≥ 65 mmHg plus lactate > 2 mmol/L despite adequate fluid resuscitation.

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Cardiogenic Shockcardiovascular

Primary pump failure, SCAI staging (A–E), PAC hemodynamics (CPO, PAPi), inotrope selection, emergent revascularization, and mechanical circulatory support.

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Obstructive Shockcardiovascular

Extracardiac mechanical barriers to filling or ejection: Massive PE, Cardiac Tamponade, Tension Pneumothorax, and Auto-PEEP.

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Acute Right Ventricular Failurecardiovascular

RV anatomy and ischemia spiral, ventricular interdependence (D-sign), echocardiographic metrics (TAPSE, S', PAPi, VExUS), and the 4-pillar resuscitation strategy.

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Blood Product Transfusion in Critical Carehematology

Patient-specific RBC transfusion thresholds, current platelet/procedural thresholds, plasma/cryoprecipitate use, and the TRALI vs TACO diagnostic matrix.

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