Critical Care

Shock

Shock requires simultaneous resuscitation and etiologic diagnosis. Recognize tissue hypoperfusion before sustained hypotension, establish monitoring and access, use focused bedside testing to identify the hemodynamic phenotype, and rapidly deliver source- or mechanism-directed treatment while reassessing perfusion and treatment response.

Clinical question: How should clinicians stabilize and phenotype undifferentiated circulatory shock while initiating cause-specific treatment?

Updated August 21, 20266 minute readCritical Care Medicine

What matters in practice

Treat shock as a time-critical syndrome of inadequate tissue perfusion; resuscitation must proceed while the cause is investigated. PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH
Mental status, urine output, and skin perfusion provide rapid bedside evidence of systemic hypoperfusion; prolonged capillary refill, reduced peripheral temperature, and shock index of at least 0.7-0.8 support concern for shock. PubMedPubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion
Focused point-of-care ultrasound can help distinguish shock phenotype and assess fluid responsiveness, but should complement rather than delay definitive treatment. PubMedPubMedCirculatory shock in adults in emergency department
Balanced crystalloids are the preferred initial resuscitation fluid in undifferentiated circulatory shock; subsequent fluid should be individualized to perfusion response and congestion risk. PubMedPubMedCirculatory shock in adults in emergency department
Norepinephrine is the preferred vasopressor in septic shock and profound cardiogenic shock. PubMedPubMedCirculatory shock in adults in emergency department
For cardiogenic shock, assign SCAI shock severity early and reassess serially; deterioration during the first 24 hours identifies a particularly high-risk trajectory. jacc+2jaccSerial Shock Severity Assessment Within 72 Hours After ...jaccCriteria for Defining Stages of Cardiogenic Shock Severity jacc2025 Concise Clinical Guidance: An ACC Expert ...

First Minutes

Recognize shock from hypoperfusion, not blood pressure alone

Begin stabilization and diagnostic phenotyping in parallel.

Shock is a life-threatening state requiring urgent intervention, often in a critical care setting. A structured <C>ABCDE approach prioritizes immediate threats while empirical treatment begins. BMJBMJShock - Symptoms, diagnosis and treatment | BMJ Best Practice 临床实践 Hypotension may be absent early; concerning findings include altered mentation, tachycardia, tachypnea, cool or mottled extremities, oliguria, metabolic acidosis, and hyperlactatemia. PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH

Use repeated bedside assessment of the brain, kidneys, and skin to judge perfusion. Reduced peripheral perfusion or temperature, prolonged capillary refill, and a shock index (heart rate divided by systolic blood pressure) of at least 0.7-0.8 are validated clinical indicators of shock. PubMedPubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion Trend these findings with arterial pressure, lactate, urine output, and evolving organ dysfunction rather than accepting transient blood-pressure correction as adequate resuscitation. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion

Activate appropriate critical care, emergency, procedural, surgical, trauma, cardiology, or interventional support early when a rapidly reversible cause is plausible.
Obtain continuous cardiac monitoring and a 12-lead ECG; ECG findings may identify acute coronary syndrome or arrhythmia and may provide clues to pericardial effusion or pulmonary embolism. PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH
Establish reliable vascular access and obtain blood for targeted testing without delaying resuscitation or definitive source control. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMed2023 Update on Sepsis and Septic Shock in Adult Patients

Bedside findings that support systemic hypoperfusion and warrant immediate reassessment or escalation. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion
Clinical window	Concerning finding	Clinical implication
Brain	Obtundation or abnormal mental status PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH	Supports inadequate cerebral perfusion or evolving organ dysfunction; reassess immediately. PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH
Kidney	Oliguria PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH	Supports impaired renal perfusion; trend with hemodynamics and fluid balance. PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH
Skin	Cool or mottled extremities, prolonged capillary refill, reduced peripheral temperature PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion	Rapid marker of impaired peripheral perfusion and a useful serial resuscitation endpoint. PubMedPubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion
Integrated vital signs	Shock index at least 0.7-0.8 PubMedPubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion	Raises concern for shock even before overt hypotension. PubMedPubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion

Diagnostic Strategy

Identify the mechanism driving hypoperfusion

Categorize the dominant physiology while maintaining a differential for mixed shock.

The immediate diagnostic objective is to identify whether hypoperfusion is primarily due to volume loss, vasodilation or maldistribution, pump failure, obstructed circulation, or a mixed process. Etiology determines the definitive intervention; therefore, a focused history, medication review, physical examination, ECG, laboratory testing, and imaging should proceed concurrently with supportive care. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedCirculatory shock in adults in emergency department

Point-of-care ultrasound is useful in undifferentiated shock to assess cardiac function, congestion, pericardial fluid, volume status, and fluid responsiveness. PubMedPubMedCirculatory shock in adults in emergency department Its value is greatest when findings are integrated with the examination and serial perfusion response; a single static measure should not substitute for reassessment after fluids, vasoactive therapy, or a corrective procedure. PubMed+1PubMedCirculatory shock in adults in emergency department PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion

Hypovolemic or hemorrhagic phenotype: seek external or concealed bleeding, gastrointestinal loss, trauma, or other fluid loss; prioritize hemorrhage control and blood-product support when bleeding is present. PubMedPubMedHypovolemia and Hypovolemic Shock - StatPearls - NCBI - NIH
Distributive phenotype: evaluate for infection and other inflammatory, toxicologic, endocrine, or neurogenic causes; obtain appropriate cultures before antimicrobials when feasible, but do not delay prompt treatment for suspected sepsis. PubMedPubMed2023 Update on Sepsis and Septic Shock in Adult Patients
Cardiogenic phenotype: evaluate acute coronary syndrome, arrhythmia, acute valvular disease, mechanical complications, myocarditis, and acute or decompensated heart failure. jacc+1jacc2025 Concise Clinical Guidance: An ACC Expert ...PubMedShock - StatPearls - NCBI Bookshelf - NIH
Obstructive phenotype: rapidly evaluate for pericardial disease, pulmonary embolism, and tension physiology; definitive mechanical relief or reperfusion may be time-sensitive. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedManagement of cardiogenic shock: a narrative review - PMC

Septic shock

Septic shock is defined by a vasopressor requirement to maintain mean arterial pressure of at least 65 mm Hg and serum lactate of at least 2 mmol/L. PubMedPubMed2023 Update on Sepsis and Septic Shock in Adult Patients Obtain appropriate culture specimens before antibiotics when possible, then administer empiric antimicrobial therapy promptly; the cited emergency medicine review identifies an ideal goal of administration within 1 hour. PubMedPubMed2023 Update on Sepsis and Septic Shock in Adult Patients

Reassess antimicrobial selection as microbiology, source, host factors, and clinical trajectory become available; short courses and de-escalation may be appropriate when supported by the clinical syndrome. PubMedPubMed2023 Update on Sepsis and Septic Shock in Adult Patients
No single biomarker adequately determines infection presence, pathogen type, and severity; do not use an isolated biomarker result as a substitute for clinical assessment and microbiologic evaluation. NatureNatureClinical validation of an AI-based blood testing device for ...

Cardiogenic shock

Initial suspicion and diagnosis of cardiogenic shock do not require invasive hemodynamic monitoring, but arterial access, pulmonary artery catheterization, or other invasive assessment can clarify ventricular involvement and congestion and may inform treatment decisions. jaccjacc2025 Concise Clinical Guidance: An ACC Expert ... Once suspected, classify severity using the SCAI shock stage and reassess as physiology and treatment intensity change. jacc+1jaccCriteria for Defining Stages of Cardiogenic Shock Severity jacc2025 Concise Clinical Guidance: An ACC Expert ...

Clinical and biochemical tissue hypoperfusion define cardiogenic shock; traditional hemodynamic criteria include cardiac index no greater than 2.2 L/min/m² and pulmonary capillary wedge pressure greater than 15 mm Hg. PubMedPubMedCardiogenic Shock - StatPearls - NCBI Bookshelf - NIH
Serial reassessment is essential: more than half of patients initially classified as SCAI stage B or C worsened by 24 hours in a contemporary cohort, and patients presenting in or progressing to stage E had the poorest prognosis. jaccjaccSerial Shock Severity Assessment Within 72 Hours After ...

Resuscitation

Use response-guided fluids and early vasopressor support

Support perfusion while avoiding reflexive, unmeasured fluid loading.

Balanced crystalloids are favored for initial fluid resuscitation in circulatory shock. PubMedPubMedCirculatory shock in adults in emergency department Fluid administration should be followed by immediate reassessment of blood pressure, mental status, skin perfusion, urine output, lactate, pulmonary congestion, and dynamic evidence of fluid responsiveness. Point-of-care ultrasound may assist this assessment. PubMed+1PubMedCirculatory shock in adults in emergency department PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion

Escalate to norepinephrine when hypotension and hypoperfusion persist despite initial resuscitative measures or when additional fluid is unlikely to restore perfusion safely. Norepinephrine is identified as the preferred vasopressor in septic shock and profound cardiogenic shock. PubMedPubMedCirculatory shock in adults in emergency department The supplied sources do not provide a supported starting dose, titration range, or upper dose limit; use institutional critical-care protocols and patient-specific monitoring.

Avoid using central venous pressure alone as a marker of ongoing fluid requirement; post-resuscitation positive fluid balance has been associated with higher mortality in septic shock cohorts. NEJMNEJMNEJMra1208623_discussion_1
For suspected hemorrhage, do not treat crystalloid response as a substitute for bleeding control, transfusion support, and urgent operative or interventional management. PubMedPubMedHypovolemia and Hypovolemic Shock - StatPearls - NCBI - NIH
For suspected cardiogenic shock with congestion or ventricular failure, use fluids cautiously and reassess after each intervention; invasive hemodynamics may help define the congestive and ventricular profile. jacc+1jacc2025 Concise Clinical Guidance: An ACC Expert ...PubMedCirculatory shock in adults in emergency department
Monitor for deterioration after every major intervention; shock management requires repeated phenotyping because mixed physiology and treatment-related changes are common. PubMed+1PubMedCirculatory shock in adults in emergency department PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion

Etiology-directed priorities during initial stabilization. PubMed+3PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMed2023 Update on Sepsis and Septic Shock in Adult Patients PubMedCirculatory shock in adults in emergency department PubMedHypovolemia and Hypovolemic Shock - StatPearls - NCBI - NIH
Dominant phenotype	Immediate supportive approach	Definitive priority
Hypovolemic or hemorrhagic	Volume replacement and hemodynamic support while monitoring perfusion. PubMedPubMedHypovolemia and Hypovolemic Shock - StatPearls - NCBI - NIH	Identify and control bleeding or ongoing fluid loss; escalate to surgical or interventional treatment when needed. PubMedPubMedHypovolemia and Hypovolemic Shock - StatPearls - NCBI - NIH
Distributive or septic	Balanced crystalloid resuscitation, norepinephrine when vasopressor support is needed, and serial perfusion reassessment. PubMedPubMedCirculatory shock in adults in emergency department	Prompt empiric antimicrobial therapy and source-directed management after obtaining cultures when feasible. PubMedPubMed2023 Update on Sepsis and Septic Shock in Adult Patients
Cardiogenic	Support perfusion, avoid unmeasured fluid loading, and use norepinephrine in profound shock. PubMedPubMedCirculatory shock in adults in emergency department	Define myocardial, valvular, arrhythmic, or mechanical cause and pursue cause-specific cardiology or procedural treatment. jacc+1jacc2025 Concise Clinical Guidance: An ACC Expert ...PubMedManagement of cardiogenic shock: a narrative review - PMC
Obstructive	Temporize oxygenation and perfusion while rapidly confirming the obstruction. PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH	Urgent relief of the obstructive lesion or reperfusion when indicated. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedManagement of cardiogenic shock: a narrative review - PMC

Reassessment

Measure trajectory and escalate before refractory shock

The response over hours is more informative than a single initial measurement.

Monitor serial perfusion variables: mental status, skin temperature and capillary refill, urine output, lactate, arterial pressure, acid-base status, and evidence of pulmonary or systemic congestion. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion A falling lactate and improving peripheral perfusion support recovery, whereas worsening clinical perfusion, rising vasoactive requirements, or progressive organ dysfunction should trigger immediate reassessment of diagnosis, source control, hemorrhage control, cardiac function, and adequacy of procedural intervention. jacc+1jaccSerial Shock Severity Assessment Within 72 Hours After ...PubMedCirculatory shock in adults in emergency department

In cardiogenic shock, the first 24 hours are a particularly consequential treatment window. In a cohort of 3,268 patients, mortality was 44.6% among patients whose SCAI stage worsened within 24 hours, compared with 34.2% among those whose stage improved; survivors had lower lactate than nonsurvivors. jaccjaccSerial Shock Severity Assessment Within 72 Hours After ... Escalating shock severity should prompt early multidisciplinary discussion regarding invasive monitoring, revascularization or other corrective procedures, and temporary mechanical circulatory support where appropriate. jacc+1jacc2025 Concise Clinical Guidance: An ACC Expert ...PubMedManagement of cardiogenic shock: a narrative review - PMC

Document a working phenotype and its uncertainty; mixed shock is common and treatment should change as new evidence emerges. PubMedPubMedCirculatory shock in adults in emergency department
Reevaluate fluid responsiveness and congestion rather than continuing empiric fluids after initial resuscitation. PubMedPubMedCirculatory shock in adults in emergency department
In septic shock, reassess antimicrobials, source control, perfusion, and fluid balance repeatedly; persistent positive fluid accumulation after initial resuscitation is a concern. NEJM+1NEJMNEJMra1208623_discussion_1 PubMed2023 Update on Sepsis and Septic Shock in Adult Patients
In cardiogenic shock, communicate SCAI stage and trajectory during transfers and escalation decisions to standardize severity assessment. jacc+1jaccCriteria for Defining Stages of Cardiogenic Shock Severity jacc2025 Concise Clinical Guidance: An ACC Expert ...

Avoidable Errors

Prevent delays and misleading endpoints

Several common practices obscure ongoing hypoperfusion or delay definitive care.

Do not wait for persistent hypotension before treating suspected shock. Peripheral hypoperfusion, impaired mentation, oliguria, metabolic acidosis, hyperlactatemia, and an elevated shock index may precede or accompany hypotension. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion Conversely, restoration of an acceptable arterial pressure does not establish adequate tissue perfusion; continue to examine perfusion and organ-function trends. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion

Do not permit diagnostic uncertainty to delay treatment of rapidly reversible causes. Resuscitation should not be delayed while evaluating undifferentiated shock, and focused ultrasound, ECG, cultures, and targeted laboratory testing should be used to accelerate—not sequentially postpone—definitive treatment. PubMed+2PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMed2023 Update on Sepsis and Septic Shock in Adult Patients PubMedCirculatory shock in adults in emergency department

Do not use a single central venous pressure target as proof of fluid responsiveness or optimal fluid balance. NEJMNEJMNEJMra1208623_discussion_1
Do not rely on one biomarker to diagnose sepsis, define pathogen class, and determine severity. NatureNatureClinical validation of an AI-based blood testing device for ...
Do not treat a static cardiogenic shock designation as sufficient; serial SCAI-stage assessment identifies important early deterioration. jacc+1jaccSerial Shock Severity Assessment Within 72 Hours After ...jaccCriteria for Defining Stages of Cardiogenic Shock Severity
Do not continue fluid administration without reassessing for response and congestion, particularly in suspected cardiogenic shock. PubMedPubMedCirculatory shock in adults in emergency department

Common questions

What bedside findings are most useful for early recognition of shock?

Assess mentation, urine output, skin temperature and mottling, capillary refill, vital-sign trajectory, and shock index. A shock index of at least 0.7-0.8, prolonged capillary refill, or reduced peripheral temperature supports concern for shock. PubMed+1PubMedShock - StatPearls - NCBI Bookshelf - NIH PubMedThe MINUTES bundle for the initial 30 min management of undifferentiated circulatory shock: an expert opinion

Should hypotension be required before diagnosing shock?

No. Clinical evidence of tissue hypoperfusion, including altered mental status, oliguria, cool or mottled extremities, metabolic acidosis, and hyperlactatemia, may establish concern before sustained hypotension. PubMedPubMedShock - StatPearls - NCBI Bookshelf - NIH

When should point-of-care ultrasound be used in undifferentiated shock?

Use it early when available to help characterize cardiac function, congestion, pericardial fluid, and fluid responsiveness. Integrate findings with the examination and serial response to treatment rather than relying on a single ultrasound measure. PubMedPubMedCirculatory shock in adults in emergency department

Which vasopressor is preferred in septic and profound cardiogenic shock?

The cited review identifies norepinephrine as the preferred vasopressor in septic shock and profound cardiogenic shock. Specific dosing and titration are not provided in the supplied sources. PubMedPubMedCirculatory shock in adults in emergency department

How should cardiogenic shock severity be tracked?

Classify cardiogenic shock using SCAI stage after diagnosis and reassess serially, especially during the first 24 hours. Worsening stage is associated with high mortality and should prompt urgent reassessment and escalation. jacc+2jaccSerial Shock Severity Assessment Within 72 Hours After ...jaccCriteria for Defining Stages of Cardiogenic Shock Severity jacc2025 Concise Clinical Guidance: An ACC Expert ...