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Symptoms and abnormal findings

Septic shock

Septic shock is a subset of sepsis in which profound circulatory, cellular, and metabolic abnormalities lead to persistent hypotension requiring vasopressors despite adequate fluid resuscitation, along with a serum lactate greater than 2 mmol/L. It occurs most often in elderly, immunocompromised, or critically ill patients with an underlying infection. The single most testable fact: diagnosis requires vasopressor need to maintain mean arterial pressure (MAP) ≥65 mmHg plus lactate >2 mmol/L after adequate fluids, per Sepsis-3 criteria.

Practice questionsHigh-yield facts
ICD-10R57.2
Typical patientElderly or immunocompromised patient with infection and hypotension
Key findingVasopressor-dependent hypotension with lactate above 2 mmol/L
First-line treatmentIV fluids, early broad-spectrum antibiotics, norepinephrine
6 min readFor medical studentsUpdated 2026-10-14

Definition and epidemiology

Septic shock is defined by the Sepsis-3 consensus (2016) as sepsis with persisting hypotension requiring vasopressors to maintain MAP ≥65 mmHg and a serum lactate >2 mmol/L despite adequate volume resuscitation. It represents the most severe end of the sepsis spectrum and carries high mortality.

Sepsis itself is life-threatening organ dysfunction caused by a dysregulated host response to infection, identified clinically by a Sequential Organ Failure Assessment (SOFA) score increase of ≥2 points. Septic shock is a clinical subset of sepsis, not a separate disease process.

Epidemiology

  • Sepsis affects millions of hospitalized patients worldwide each year; a substantial minority progress to septic shock.
  • Mortality from septic shock is approximately 30-40%, among the highest of any acute medical condition.
  • Risk increases with age, with the highest incidence in patients over 65 years.
  • Common sources include pneumonia, urinary tract infection, intra-abdominal infection, and bloodstream infection (bacteremia).
High-yield for exams
  • Septic shock = sepsis + vasopressor-dependent hypotension (MAP <65) + lactate >2 mmol/L despite adequate fluids
  • Norepinephrine is the first-line vasopressor in septic shock
  • Lipopolysaccharide (endotoxin) from gram-negative bacteria is a classic trigger via Toll-like receptor activation
  • Early (warm) septic shock presents with warm, flushed skin from vasodilation; late (cold) shock has cool, mottled skin
  • qSOFA (RR ≥22, altered mentation, SBP ≤100) is a quick bedside screening tool, not a diagnostic criterion
  • Antibiotics should be given within 1 hour of recognized septic shock
  • Hydrocortisone is reserved for shock refractory to fluids and vasopressors
  • Pneumonia is the most common source of sepsis leading to septic shock

Etiology and risk factors

Any infection can progress to septic shock, but gram-negative and gram-positive bacterial infections are most common; fungal sepsis (especially Candida) is increasingly seen in critically ill and immunosuppressed patients.

Common sources

  • Pulmonary: pneumonia (most common overall source)
  • Genitourinary: pyelonephritis, urosepsis
  • Intra-abdominal: perforation, cholangitis, peritonitis
  • Skin and soft tissue: cellulitis, necrotizing fasciitis
  • Catheter-related bloodstream infections

Risk factors

  • Extremes of age (very young or elderly)
  • Immunosuppression (chemotherapy, HIV, chronic steroid use, asplenia)
  • Diabetes mellitus
  • Indwelling catheters or recent surgery/instrumentation
  • Chronic illness: liver disease, kidney disease, malignancy
  • ICU admission and mechanical ventilation

Pathophysiology

Septic shock results from a dysregulated systemic inflammatory response to pathogens or their toxins (e.g., lipopolysaccharide from gram-negative bacteria). Pattern recognition receptors (Toll-like receptors) on immune cells trigger massive release of pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6).

Key mechanisms

  • Widespread vasodilation from nitric oxide release causes distributive shock with low systemic vascular resistance.
  • Increased vascular permeability leads to capillary leak, relative hypovolemia, and tissue edema.
  • Endothelial dysfunction and activation of the coagulation cascade can trigger disseminated intravascular coagulation (DIC).
  • Myocardial depression (septic cardiomyopathy) reduces cardiac output despite initial compensatory tachycardia.
  • Mitochondrial dysfunction impairs oxygen utilization at the cellular level, raising lactate even when oxygen delivery seems adequate (cytopathic hypoxia).
  • The net effect is impaired tissue perfusion and multi-organ dysfunction despite often preserved or increased cardiac output in the early (warm) phase.

Clinical features

Presentation varies by source of infection but shares common features of shock and systemic infection.

General

  • Fever or hypothermia (hypothermia is a poor prognostic sign)
  • Tachycardia and tachypnea
  • Altered mental status, confusion, or lethargy
  • Hypotension unresponsive to fluids

Signs of hypoperfusion

  • Warm shock (early): flushed, warm extremities from vasodilation
  • Cold shock (late): mottled, cool, clammy skin from compensatory vasoconstriction
  • Oliguria from renal hypoperfusion
  • Delayed capillary refill

Source-specific clues

SourceClue
PneumoniaCough, hypoxia, consolidation on exam
UTI/pyelonephritisFlank pain, dysuria, costovertebral tenderness
Intra-abdominalAbdominal pain, rigidity, rebound tenderness
MeningitisNeck stiffness, photophobia, petechial rash

Diagnosis

Diagnosis is clinical and relies on identifying infection plus evidence of shock physiology; no single confirmatory test exists.

Sepsis-3 criteria

  • Suspected or confirmed infection
  • SOFA score increase ≥2 points (organ dysfunction)
  • Septic shock adds: vasopressor requirement to keep MAP ≥65 mmHg AND lactate >2 mmol/L despite adequate fluid resuscitation

Bedside screening

  • qSOFA (quick SOFA): respiratory rate ≥22/min, altered mentation, systolic BP ≤100 mmHg — used to flag high-risk patients outside the ICU, not for formal diagnosis.

Workup

  • Lactate level (trend to assess response to therapy)
  • Blood cultures (two sets, before antibiotics if feasible without delaying treatment)
  • Cultures from suspected source (urine, sputum, wound, CSF)
  • CBC, comprehensive metabolic panel, liver function tests, coagulation studies (PT/INR, fibrinogen if DIC suspected)
  • Arterial blood gas
  • Imaging directed at suspected source (chest X-ray, CT abdomen/pelvis, ultrasound)
  • Procalcitonin may support but is not required for diagnosis

Differential diagnosis

Other causes of shock must be considered, especially when a clear infectious source is not identified.

  • Cardiogenic shock: elevated jugular venous pressure, pulmonary edema, poor cardiac output
  • Hypovolemic shock: history of hemorrhage or fluid losses, flat neck veins
  • Anaphylactic shock: recent allergen exposure, urticaria, angioedema
  • Adrenal crisis: history of steroid use or adrenal insufficiency, hyponatremia with hyperkalemia
  • Obstructive shock (tension pneumothorax, cardiac tamponade, massive pulmonary embolism): distinct exam findings (absent breath sounds, muffled heart sounds, JVD)
  • Toxic shock syndrome: associated with tampon use or wound infection, diffuse rash, desquamation

Management

Management follows international guidelines, most notably the Surviving Sepsis Campaign, and emphasizes early recognition and rapid intervention within the first hours (the 'hour-1 bundle').

Initial resuscitation

  • Obtain lactate; remeasure if initial lactate is elevated to assess trend
  • Obtain blood cultures before antibiotics if this does not significantly delay therapy
  • Administer broad-spectrum antibiotics within 1 hour of recognition, then narrow based on culture results and source control
  • Begin rapid IV crystalloid fluid resuscitation (typically 30 mL/kg within the first 3 hours) for hypotension or lactate ≥4 mmol/L
  • Apply vasopressors if hypotension persists during or after fluid resuscitation to maintain MAP ≥65 mmHg

Vasopressor and adjunct therapy

  • Norepinephrine is the first-line vasopressor
  • Vasopressin or epinephrine may be added if MAP goals are not met with norepinephrine alone
  • Hydrocortisone (corticosteroids) is considered for patients with ongoing vasopressor requirement despite adequate fluids and vasopressors (refractory shock)
  • Dobutamine may be added if myocardial dysfunction with persistent hypoperfusion is suspected

Source control

  • Identify and control the infectious source as soon as feasible: drainage of abscess, removal of infected catheter/device, debridement of necrotic tissue, or surgery for perforation

Supportive care

  • Mechanical ventilation for respiratory failure using lung-protective strategies
  • Renal replacement therapy if indicated by acute kidney injury
  • Glycemic control, stress ulcer prophylaxis, and venous thromboembolism prophylaxis per standard ICU care
  • Guidelines broadly agree on these principles, though specific fluid volumes and the role of dynamic hemodynamic monitoring (e.g., passive leg raise, pulse pressure variation) to guide further fluid therapy vary by institution and evidence base.

Complications and prognosis

Septic shock carries substantial morbidity and mortality even with timely treatment.

Complications

  • Multi-organ dysfunction syndrome (MODS): acute kidney injury, acute respiratory distress syndrome (ARDS), hepatic dysfunction
  • Disseminated intravascular coagulation (DIC)
  • Critical illness myopathy and neuropathy
  • Secondary nosocomial infections
  • Post-sepsis syndrome: long-term cognitive impairment, physical weakness, and psychological effects (anxiety, depression, PTSD) in survivors

Prognosis

  • Mortality is approximately 30-40% and rises further with delayed recognition or treatment
  • Prognosis worsens with higher lactate levels, higher number of failed organ systems, advanced age, and comorbidities
  • Early antibiotic administration and fluid resuscitation are strongly associated with improved survival
  • Survivors frequently experience prolonged functional decline and increased risk of rehospitalization
Mnemonic

SEPSIS bundle mnemonic 'LACTATES': Lactate measurement, Antibiotics early, Cultures before antibiotics, Treat the source, Administer fluids (30 mL/kg), Titrate vasopressors (norepinephrine first), Evaluate response, Steroids if refractory.

Practice questions

1. A 72-year-old man is brought to the emergency department with fever, confusion, and a 2-day history of dysuria. His blood pressure is 78/40 mmHg despite 30 mL/kg of IV crystalloid, heart rate is 118/min, and lactate is 4.2 mmol/L. Blood and urine cultures are obtained. Which of the following is the most appropriate next step in management?

Answer: B. This patient has septic shock given persistent hypotension and elevated lactate despite adequate fluid resuscitation. The first-line vasopressor is norepinephrine, titrated to maintain MAP ≥65 mmHg. Antibiotics should already have been started empirically without waiting for cultures, and corticosteroids are reserved for shock refractory to fluids and vasopressors.

2. A 55-year-old woman with septic shock from a perforated diverticulum is on norepinephrine at an escalating dose with persistent hypotension despite adequate fluid resuscitation and source control planning. Which of the following is the most appropriate next step?

Answer: B. In refractory septic shock with escalating norepinephrine requirements, guidelines support adding a second vasopressor such as vasopressin and/or initiating hydrocortisone to help stabilize blood pressure and potentially reduce vasopressor dose. Dopamine is not preferred due to higher arrhythmia risk, and diuretics are inappropriate in a hypotensive, hypoperfused patient.

3. A 68-year-old man with septic shock secondary to pneumonia is treated with fluids, antibiotics, and norepinephrine. Despite normalization of blood pressure, his lactate remains elevated at 5 mmol/L after several hours. Which mechanism best explains this finding?

Answer: B. Persistently elevated lactate despite restored blood pressure in sepsis is often due to mitochondrial dysfunction and impaired cellular oxygen utilization (cytopathic hypoxia), not simply inadequate oxygen delivery. This reflects ongoing cellular metabolic derangement from the systemic inflammatory response rather than a macrovascular perfusion problem alone.

Frequently asked questions

What causes septic shock?

Septic shock is caused by a severe, dysregulated immune response to infection, most commonly bacterial pneumonia, urinary tract infection, or intra-abdominal infection. The infection triggers massive cytokine release, widespread vasodilation, and capillary leak, leading to dangerously low blood pressure that does not improve with fluids alone. Fungal and, less commonly, viral infections can also trigger it, particularly in immunocompromised patients.

What are the first symptoms of septic shock?

Early symptoms typically include fever or chills, rapid heart rate, rapid breathing, and confusion or altered mental status, often alongside signs of the underlying infection like cough or abdominal pain. As it progresses, blood pressure drops and patients may develop warm, flushed skin initially, later becoming cool and mottled. Reduced urine output and worsening confusion signal progression toward organ failure.

How is septic shock diagnosed?

Septic shock is diagnosed clinically in a patient with confirmed or suspected infection who requires vasopressor medication to maintain a mean arterial pressure of at least 65 mmHg and has a blood lactate level above 2 mmol/L despite adequate fluid resuscitation. Supporting tests include blood cultures, complete blood count, metabolic panel, and imaging to find the infection source. There is no single lab test that confirms the diagnosis alone.

Is septic shock curable?

Septic shock can be survived and reversed with prompt treatment, but it is not instantly 'curable' in the way an infection alone might be, since it reflects a dangerous whole-body response that can cause lasting organ damage. With early antibiotics, fluids, and vasopressor support, many patients recover, though mortality remains around 30-40%. Survivors often face prolonged recovery and increased risk of long-term complications, sometimes called post-sepsis syndrome.

Septic shock vs cardiogenic shock — what is the difference?

Septic shock is a distributive shock caused by infection, characterized by low systemic vascular resistance, often warm extremities early on, and typically normal or high cardiac output initially. Cardiogenic shock results from pump failure of the heart itself, presenting with low cardiac output, cold extremities, and signs of fluid overload like pulmonary edema and elevated jugular venous pressure. Hemodynamic monitoring and echocardiography help distinguish the two when the clinical picture is unclear.

Key drugs

NorepinephrineVasopressinEpinephrineDobutamineHydrocortisonePiperacillin-tazobactamVancomycinMeropenem
SepsisSystemic inflammatory response syndromeDisseminated intravascular coagulationAcute respiratory distress syndromeCardiogenic shockToxic shock syndromeAdrenal insufficiencyMulti-organ dysfunction syndrome

Sources and further reading

StatPearls (NCBI Bookshelf)MedlinePlusWHO ICD-10: R57.2

Educational content for medical students, prepared by the WhiteCoat Pro editorial team with AI assistance; every page is reviewed by a second AI model for factual errors. It is not medical advice and does not replace the product label, local guidelines or a clinician.