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14.1 Sepsis-3 Definitions & Surviving Sepsis Campaign 2026 Guidelines

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ABIM Critical Care Medicine Study Guide Exam

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1 Chapter 1: Exam Orientation: Format, Blueprint & Study Strategy

1.1 ABIM Critical Care Medicine Exam: Format, Blueprint & Study Strategy

2 Chapter 2: Acute Respiratory Failure & ARDS

2.1 ARDS Definition, Pathophysiology & Phenotypes 2.2 Lung-Protective Mechanical Ventilation 2.3 Refractory ARDS: Prone Positioning, Neuromuscular Blockade & VV-ECMO

3 Chapter 3: Obstructive Airways, Pulmonary Vascular & Pleural Emergencies

3.1 Severe Asthma & COPD Exacerbations in the ICU 3.2 Massive & Submassive Pulmonary Embolism 3.3 Pulmonary Hypertension & Right Ventricular Failure in the ICU 3.4 Massive Hemoptysis, Complex Pleural Effusions & Thoracic Drainage

4 Chapter 4: Airway, Parenchymal & Nonthrombotic Pulmonary Emergencies

4.1 Airway Management, Upper-Airway Obstruction & Artificial-Airway Complications 4.2 Diffuse Alveolar Hemorrhage, Interstitial Lung Disease, Pulmonary Vasculitis & Noncardiogenic Edema 4.3 Severe Community-Acquired & Viral Pneumonia 4.4 Nonthrombotic Embolism (Air, Fat, Amniotic Fluid, Tumor, Septic) & Acute Chest Syndrome

5 Chapter 5: Mechanical Ventilation Modes, Dyssynchrony & Liberation

5.1 Mechanical Ventilator Modes & Advanced Breath Delivery 5.2 Patient-Ventilator Dyssynchrony & Waveform Analysis 5.3 Ventilator Liberation, Spontaneous Breathing Trials & Post-Extubation Support

6 Chapter 6: Shock Syndromes & Hemodynamic Principles

6.1 Shock Classification, Cellular Pathophysiology & Biomarkers 6.2 Hemodynamic Monitoring: Arterial Lines, CVP & Pulmonary Artery Catheter 6.3 Dynamic Assessment of Fluid Responsiveness & Resuscitation Targets

7 Chapter 7: Vasoactive Therapies & Mechanical Circulatory Support

7.1 Vasopressors & Inotropes: Pharmacology & Clinical Titration 7.2 Temporary Mechanical Circulatory Support: IABP, Impella & TandemHeart 7.3 Venoarterial ECMO (VA-ECMO) & Differential Hypoxemia 7.4 Post-Cardiac Arrest Care, Targeted Temperature Management & Neuroprognostication

8 Chapter 8: Acute Kidney Injury & Renal Replacement Therapy

8.1 KDIGO AKI Classification, Etiologies & Diagnostic Evaluation 8.2 Continuous Renal Replacement Therapy (CRRT) vs Intermittent Hemodialysis 8.3 Indications & Timing for RRT in Critical Illness: AKIKI & STARRT-AKI

9 Chapter 9: Electrolyte, Acid-Base & Endocrine Emergencies

9.1 Severe Dysnatremias: Hyponatremia, Hypernatremia & Osmotic Demyelination 9.2 Potassium, Calcium, Magnesium & Phosphate Disorders 9.3 Complex & Mixed Acid-Base Disorders: Boston vs Copenhagen vs Stewart 9.4 Endocrine Crises: DKA, HHS, Thyroid Storm, Myxedema Coma & Adrenal Crisis

10 Chapter 10: Glycemic Control, Hyperammonemia, Pituitary & Adrenal Disorders

10.1 ICU Glycemic Control & Severe Hypoglycemia 10.2 Non-Hepatic Hyperammonemia & Metabolic Encephalopathy 10.3 Pituitary Emergencies, Adrenal Excess & Critical Illness-Related Corticosteroid Insufficiency

11 Chapter 11: Acute Coronary Syndromes & Cardiac Arrhythmias

11.1 Acute Coronary Syndromes & Mechanical Complications of Myocardial Infarction 11.2 Critical Tachyarrhythmias: Atrial Fibrillation with RVR, VT & VF 11.3 Critical Bradyarrhythmias, Conduction Blocks & Temporary Cardiac Pacing

12 Chapter 12: Acute Heart Failure, Valvular & Pericardial Emergencies

12.1 Acute Decompensated Heart Failure & Cardiogenic Pulmonary Edema 12.2 Acute Valvular Regurgitation & Prosthetic Valve Emergencies 12.3 Pericardial Tamponade & Acute Aortic Syndromes

13 Chapter 13: Myocardial Disease, Hypertensive & Cardiac Device Emergencies

13.1 Fulminant Myocarditis, Stress & Peripartum Cardiomyopathy, and Hypertrophic Cardiomyopathy 13.2 Hypertensive Emergencies & Ruptured Abdominal Aortic Aneurysm 13.3 Implanted Cardiac Devices, LVAD Emergencies & Electrical Storm

14 Chapter 14: Sepsis & Systemic Infectious Diseases

14.1 Sepsis-3 Definitions & Surviving Sepsis Campaign 2026 Guidelines 14.2 Refractory Septic Shock & Adjunctive Therapies 14.3 Multidrug-Resistant Pathogens & Antimicrobial Stewardship in the ICU

15 Chapter 15: ICU-Acquired & Severe Focal Infections

15.1 Hospital-Acquired & Ventilator-Associated Pneumonia 15.2 Central Line-Associated Bloodstream Infections & Catheter-Associated UTIs 15.3 Intra-Abdominal Sepsis, Necrotizing Soft Tissue Infections & CNS Infections

16 Chapter 16: Focal, Special-Host & Systemic Infections

16.1 CNS Infections Beyond Bacterial Meningitis: Encephalitis, Brain Abscess & Epidural Abscess 16.2 Infections in the Immunocompromised Host, Tropical & Bioterror Infections 16.3 Infective Endocarditis, Device Infections & Other Focal Cardiovascular Infections 16.4 Antimicrobial Pharmacokinetics, Allergy, Toxicity & Infection Prevention 16.5 Gastrointestinal & Hepatobiliary Infections: Fulminant C. difficile, Typhlitis, CMV Colitis & Abscesses

17 Chapter 17: Neurocritical Care & Coma

17.1 Coma, Altered Mental Status & Acute Delirium in the ICU 17.2 Status Epilepticus & Non-Convulsive Status Epilepticus 17.3 Acute Ischemic Stroke & Intracranial Hemorrhage

18 Chapter 18: Cerebrovascular Syndromes, Encephalopathy & Withdrawal States

18.1 Cerebral Venous Sinus Thrombosis, PRES & Reversible Cerebral Vasoconstriction Syndrome 18.2 Alcohol & Sedative Withdrawal, Wernicke Encephalopathy & Drug-Induced Encephalopathy

19 Chapter 19: Intracranial Hypertension & Neuromuscular Weakness

19.1 Intracranial Pressure Monitoring, Cerebral Perfusion & Tiered ICP Management 19.2 Acute Neuromuscular Respiratory Failure, ICU-Acquired Weakness & Brain Death Determination

20 Chapter 20: Traumatic Brain Injury, Spinal Cord Injury & Toxin-Mediated Paralysis

20.1 Traumatic Brain Injury Management & Paroxysmal Sympathetic Hyperactivity 20.2 Acute Spinal Cord Injury, Neurogenic Shock & Autonomic Dysreflexia 20.3 Toxin-Mediated Paralysis & Neuromuscular Crises: Botulism, Tetanus, Tick Paralysis & Myasthenic Crisis

21 Chapter 21: Gastrointestinal, Hepatic & Abdominal Emergencies

21.1 Acute Upper & Lower Gastrointestinal Bleeding in the ICU 21.2 Acute Liver Failure & Severe Acute Pancreatitis 21.3 Abdominal Compartment Syndrome & Acute Mesenteric Ischemia

22 Chapter 22: Luminal GI Emergencies & Complications of Cirrhosis

22.1 Esophageal, Gastric & Bowel Emergencies: Perforation, Obstruction, Ogilvie Syndrome & Colonic Ischemia 22.2 Complications of Cirrhosis: Alcohol-Associated Hepatitis, Hepatorenal Syndrome & Pulmonary Vascular Syndromes

23 Chapter 23: Trauma, Burns & Perioperative Critical Care

23.1 Polytrauma Resuscitation, Damage Control & Massive Transfusion 23.2 Severe Burn Injury, Inhalation Injury & Environmental Emergencies 23.3 Perioperative Critical Care for High-Risk Surgical Patients

24 Chapter 24: Thoracic Trauma, Environmental Injury & Obstetric Critical Care

24.1 Thoracic Trauma: Flail Chest, Pulmonary Contusion, Great Vessel & Tracheobronchial Injury 24.2 Environmental Injury: Drowning, Diving, Altitude, Heat, Cold, Electrical & Radiation 24.3 Obstetric & Genitourinary Emergencies and the Physiology of Pregnancy

25 Chapter 25: Transplantation, Donor Management & Post-Cardiac Surgery Care

25.1 Solid Organ Transplant Recipients & Deceased Donor Management 25.2 Post-Cardiac Surgery Critical Care: Bleeding, Tamponade, Low Output & Vasoplegia

26 Chapter 26: Hematologic Emergencies, Toxicology, Critical Ultrasound & ICU Liberation

26.1 Hematologic Emergencies in the ICU: HIT, DIC, TMA & Anticoagulant Reversal 26.2 Critical Care Toxicology, Toxidromes & Specific Antidotes 26.3 Critical Care Point-of-Care Ultrasound (POCUS) 26.4 ICU Liberation, Analgosedation, Goals of Care & Critical Care Ethics

27 Chapter 27: Transfusion Medicine, Hematologic & Oncologic Disorders

27.1 Transfusion Medicine: Products, Thresholds, Reactions & Apheresis 27.2 Red and White Cell Disorders, Hemoglobinopathies, Factor Deficiencies & Hypercoagulable States 27.3 Oncologic Emergencies, Hematopoietic Cell Transplant Complications & Cellular Therapy Toxicity

28 Chapter 28: Clinical Pharmacology, Adverse Drug Reactions & Specific Poisonings

28.1 Pharmacokinetic Principles, Dose Adjustment & Drug Interactions in Critical Illness 28.2 Adverse Drug Reactions: Anaphylaxis, Severe Cutaneous Reactions & Hyperthermic Syndromes 28.3 Specific Poisonings: Sodium-Channel Blockers, Lithium, Valproate, Theophylline, Iron, Sulfonylureas & Methemoglobinemia

29 Chapter 29: Ethics, Research Methods, Administration & Abdominal Ultrasound

29.1 Advance Care Planning, Nonbeneficial Treatment, Informed Consent & Confidentiality 29.2 Critical Care Research Methods, Statistics, IRB Oversight & Quality Improvement 29.3 Abdominal, Vascular & Procedural Point-of-Care Ultrasound

14.1 Sepsis-3 Definitions & Surviving Sepsis Campaign 2026 Guidelines

Key Takeaways Explain This Topic AI

The Sepsis-3 consensus defines sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized clinically as an acute increase in total Sequential Organ Failure Assessment (SOFA) score >= 2 points.

Septic shock represents a subset of sepsis with profound circulatory and cellular/metabolic abnormalities, defined by persistent hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) >= 65 mmHg AND a serum lactate > 2.0 mmol/L despite adequate volume resuscitation.

The 2026 Surviving Sepsis Campaign recommends NEWS, NEWS2, MEWS, or SIRS over qSOFA as a single sepsis screening tool (strong recommendation), because qSOFA is specific but insensitive.

SSC 2026 recommends antimicrobials within 1 hour for septic shock and for probable or definite sepsis (possible sepsis without shock: within 3 hours if concern persists), suggests >= 30 mL/kg crystalloid in the first 3 hours, and recommends an initial MAP target of 65 mmHg (60-65 mmHg suggested at age >= 65).

Balanced crystalloids are suggested over 0.9% saline (conditional recommendation): SMART showed a modest MAKE30 reduction while BaSICS and PLUS were neutral; CLASSIC and CLOVERS found liberal and restrictive fluid strategies equivalent after initial resuscitation.

Last updated: October 2026

Sepsis is one of the leading causes of critical illness, intensive care unit admission, and in-hospital mortality worldwide. Over the past three decades, the conceptual understanding and clinical operationalization of sepsis have evolved fundamentally—transitioning from an inflammation-centric framework to an emphasis on life-threatening, pathogen-triggered multiorgan failure.

  • Evolution of Diagnostic Frameworks: From SIRS to Sepsis-3
  • The Historical Paradigm (Sepsis-1 and Sepsis-2)

In 1991, the American College of Chest Physicians and the Society of Critical Care Medicine (ACCP/SCCM) established the Sepsis-1 consensus , defining sepsis as infection accompanied by the Systemic Inflammatory Response Syndrome (SIRS) . SIRS required at least two of four systemic criteria:

  • Body temperature > 38.0 ∘ C > 38.0^\circ\text{C} > 38. 0 ∘ C or < 36.0 ∘ C < 36.0^\circ\text{C} < 36. 0 ∘ C
  • Heart rate > 90 beats/min > 90\text{ beats/min} > 90 beats/min

Respiratory rate > 20 breaths/min > 20\text{ breaths/min} > 20 breaths/min or PaCO 2 < 32 mmHg \text{PaCO}_2 < 32\text{ mmHg} PaCO 2 ​ < 32 mmHg

White blood cell count > 12 , 000 / μ L > 12,000/\mu\text{L} > 12 , 000/ μ L , < 4 , 000 / μ L < 4,000/\mu\text{L} < 4 , 000/ μ L , or > 10 % > 10\% > 10% immature band forms

Under Sepsis-1 and its 2001 iteration (Sepsis-2), the clinical continuum was stratified into:

  • Sepsis : SIRS criteria plus suspected or proven infection
  • Severe Sepsis : Sepsis complicated by acute organ dysfunction, hypoperfusion, or hypotension
  • Septic Shock : Sepsis-induced hypotension refractory to fluid resuscitation requiring vasoactive therapy
  • Limitations of SIRS and the Genesis of Sepsis-3

Epidemiological analyses revealed critical flaws in this architecture. SIRS criteria exhibited extremely high sensitivity but dismal specificity: over 90% of all patients admitted to an intensive care unit meet SIRS criteria, and up to one-third of non-infected hospitalized patients exhibit SIRS physiology following major surgery, trauma, pancreatitis, or athletic exertion. Furthermore, large international cohort studies demonstrated that 12% to 15% of patients with severe, infection-induced organ failure failed to meet two SIRS criteria. The term "severe sepsis" proved redundant because any infection generating host organ failure is inherently life-threatening.

The Sepsis-3 Consensus Definitions

In 2016, the European Society of Intensive Care Medicine (ESICM) and the Society of Critical Care Medicine (SCCM) published the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) :

Sepsis: Life-threatening organ dysfunction caused by a dysregulated host response to infection.

Septic Shock: A subset of sepsis in which particularly profound circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than with sepsis alone.

Key changes introduced by Sepsis-3 include:

Elimination of the term "severe sepsis" : The concept of non-severe organ failure was discarded.

Focus on organ dysfunction : Sepsis is fundamentally distinguished from an uncomplicated infection by the presence of acute multiorgan failure.

Operationalization via the SOFA Score : Organ dysfunction is objectively defined as an acute change in total Sequential Organ Failure Assessment (SOFA) score of ≥ 2 \ge 2 ≥ 2 points consequent to the infection.

The Sequential Organ Failure Assessment (SOFA) Score

The SOFA score quantifies dysfunction across six physiological organ systems on a graded scale from 0 (normal function) to 4 (profound organ failure). In patients without preexisting chronic organ impairment, the baseline SOFA score is assumed to be zero. An acute increase in SOFA score ≥ 2 \ge 2 ≥ 2 points reflects an attributable in-hospital mortality rate greater than 10%.

Organ System Metric Score 0 Score 1 Score 2 Score 3 Score 4

Respiration PaO 2 / FiO 2 (mmHg) \text{PaO}_2/\text{FiO}_2\text{ (mmHg)} PaO 2 ​ / FiO 2 ​ (mmHg) ≥ 400 \ge 400 ≥ 400 < 400 < 400 < 400 < 300 < 300 < 300 < 200 with ventilatory support < 200\text{ with ventilatory support} < 200 with ventilatory support < 100 with ventilatory support < 100\text{ with ventilatory support} < 100 with ventilatory support

Coagulation Platelets ( × 10 3 / μ L ) (\times 10^3/\mu\text{L}) ( × 1 0 3 / μ L ) ≥ 150 \ge 150 ≥ 150 < 150 < 150 < 150 < 100 < 100 < 100 < 50 < 50 < 50 < 20 < 20 < 20

Liver Bilirubin ( mg/dL ) (\text{mg/dL}) ( mg/dL ) < 1.2 < 1.2 < 1.2 1.2 − 1.9 1.2-1.9 1.2 − 1.9 2.0 − 5.9 2.0-5.9 2.0 − 5.9 6.0 − 11.9 6.0-11.9 6.0 − 11.9 ≥ 12.0 \ge 12.0 ≥ 12.0

Cardiovascular Mean Arterial Pressure or Vasopressor Requirement MAP ≥ 70 mmHg \text{MAP} \ge 70\text{ mmHg} MAP ≥ 70 mmHg MAP < 70 mmHg \text{MAP} < 70\text{ mmHg} MAP < 70 mmHg Dopamine ≤ 5 \le 5 ≤ 5 or Dobutamine (any dose) Dopamine > 5 > 5 > 5 , Norepinephrine ≤ 0.1 \le 0.1 ≤ 0.1 , or Epinephrine ≤ 0.1 \le 0.1 ≤ 0.1 Dopamine > 15 > 15 > 15 , Norepinephrine > 0.1 > 0.1 > 0.1 , or Epinephrine > 0.1 > 0.1 > 0.1

Central Nervous System Glasgow Coma Scale (GCS) 15 13-14 10-12 6-9 < 6 < 6 < 6

Renal Creatinine ( mg/dL ) (\text{mg/dL}) ( mg/dL ) or Urine Output < 1.2 < 1.2 < 1.2 1.2 − 1.9 1.2-1.9 1.2 − 1.9 2.0 − 3.4 2.0-3.4 2.0 − 3.4 3.5 − 4.9 3.5-4.9 3.5 − 4.9 or < 500 mL/day < 500\text{ mL/day} < 500 mL/day ≥ 5.0 \ge 5.0 ≥ 5.0 or < 200 mL/day < 200\text{ mL/day} < 200 mL/day

Note: Catecholamine dosages are expressed in mcg/kg/min \text{mcg/kg/min} mcg/kg/min .

Screening Tools: qSOFA vs. NEWS vs. SIRS

To facilitate bedside screening outside the intensive care unit where complex laboratory values are not immediately available, Sepsis-3 proposed the quick SOFA (qSOFA) score, incorporating three bedside physical examination variables (1 point each):

  • Respiratory rate ≥ 22 breaths/min \ge 22\text{ breaths/min} ≥ 22 breaths/min
  • Altered mentation (Glasgow Coma Scale score < 15 < 15 < 15 )
  • Systolic blood pressure ≤ 100 mmHg \le 100\text{ mmHg} ≤ 100 mmHg
  • The Surviving Sepsis Campaign Verdict on qSOFA

While a qSOFA score ≥ 2 \ge 2 ≥ 2 is moderately specific for predicting in-hospital deterioration and death, subsequent prospective multicenter evaluations demonstrated that qSOFA has dangerously low sensitivity for the early detection of sepsis (frequently below 40% to 50%). Relying on qSOFA as a primary screening triage tool leads to delayed antimicrobial administration and delayed resuscitation.

Warning

The Surviving Sepsis Campaign issued a strong recommendation in 2021 against using qSOFA as a single screening tool , and the 2026 guideline restates it positively: for acutely ill hospital patients, use NEWS, NEWS2, MEWS, or SIRS rather than qSOFA as a single screening tool (strong recommendation). It also recommends hospital-wide sepsis performance-improvement programs and suggests a "code sepsis" huddle protocol.

  • Screening Tool Sensitivity for Sepsis Specificity for In-Hospital Mortality SSC Position
  • qSOFA Poor (~35% to 55%) High (~85% to 92%) Recommended AGAINST as single screening tool
  • SIRS High (~85% to 95%) Very Low (~20% to 35%) Acceptable screening tool despite poor specificity
  • NEWS / MEWS Very High (~80% to 90%) Moderate (~65% to 75%) Preferred early warning screening system
  • The Clinical Triad of Septic Shock

Under Sepsis-3, septic shock is defined by a rigorous clinical triad reflecting both cardiovascular collapse and profound cellular/metabolic dysregulation:

Documented or suspected systemic infection

Persistent hypotension requiring vasopressors to maintain a mean arterial pressure (MAP) ≥ 65 mmHg \ge 65\text{ mmHg} ≥ 65 mmHg despite adequate intravascular volume resuscitation

Serum lactate level > 2.0 mmol/L > 2.0\text{ mmol/L} > 2.0 mmol/L ( 18 mg/dL 18\text{ mg/dL} 18 mg/dL ) despite adequate volume resuscitation ┌────────────────────────────────────────┐

  • │ Documented or Suspected Infection │
  • └───────────────────┬────────────────────┘
  • │
  • ▼
  • ┌────────────────────────────────────────┐
  • │ Acute SOFA Increase >= 2 Points │ ──► SEPSIS
  • │ (In-Hospital Mortality > 10%) │
  • └───────────────────┬────────────────────┘
  • │
  • ▼
  • ┌────────────────────────────────────────────────────────────┐
  • │ Resuscitation Completed With IVF │
  • └─────────────────────────────┬──────────────────────────────┘
  • │

Persistent Derangements Present?

  • │
  • ┌──────────────────┴──────────────────┐
  • ▼ ▼
  • Need for Vasopressors Serum Lactate > 2.0 mmol/L
  • to Maintain MAP >= 65 mmHg (Cellular/Metabolic Stress)
  • │ │
  • └──────────────────┬──────────────────┘
  • │
  • ▼
  • ┌────────────────────────────────────────┐
  • │ SEPTIC SHOCK │
  • │ (Hospital Mortality Exceeds 40%) │
  • └────────────────────────────────────────┘

Note

Patients requiring vasopressors to maintain MAP ≥ 65 mmHg \text{MAP} \ge 65\text{ mmHg} MAP ≥ 65 mmHg but whose lactate remains ≤ 2.0 mmol/L \le 2.0\text{ mmol/L} ≤ 2.0 mmol/L , or patients with hyperlactatemia whose blood pressure normalizes with fluid alone, do not meet the full Sepsis-3 consensus definition for septic shock. The combination of vasopressor dependency and hyperlactatemia identifies a distinct subgroup whose in-hospital mortality exceeds 40%.

From the Hour-1 Bundle to the 2026 Surviving Sepsis Campaign Guideline

The Hour-1 Bundle (Surviving Sepsis Campaign, 2018) condenses the first resuscitation steps into an immediate checklist. The 2026 SSC adult guideline (Prescott et al., Crit Care Med and Intensive Care Med 2026; 129 statements, 46 of them new) keeps that framework but individualizes many targets. Learn both, because questions still describe the bundle while the graded recommendations come from the guideline.

Bundle Element Timing 2026 SSC Statement (strength)

1. Measure lactate At recognition Suggest measuring lactate (conditional); in sepsis with elevated lactate or shock, suggest serial lactate to guide resuscitation, individualizing fluids after the first bolus instead of chasing a normal value (conditional)

2. Blood cultures Before antimicrobials Recommend collecting blood cultures as soon as possible, ideally before antimicrobials (strong)

3. Antimicrobials Immediately Septic shock and probable or definite sepsis without shock : recommend antimicrobials immediately, ideally within 1 hour (strong). Possible sepsis without shock : suggest a time-limited rapid investigation and antimicrobials within 3 hours if concern persists (conditional). Low likelihood of infection, no shock : suggest deferring antimicrobials with close monitoring

4. Crystalloid First 3 hours For sepsis-induced hypoperfusion or septic shock, suggest at least 30 mL/kg of IV crystalloid in the first 3 hours

5. Vasopressors During or after fluids Suggest initial crystalloid then vasopressors if hypotension persists; suggest starting vasopressors peripherally rather than waiting for central access (conditional)

Blood Pressure Targets

Initial MAP target 65 mmHg over higher targets (strong recommendation).

Age 65 years or older: suggest an initial MAP range of 60-65 mmHg (conditional recommendation), based on the 65 trial (Lamontagne et al., JAMA 2020), in which permissive hypotension reduced vasopressor exposure without increasing 90-day mortality (41.0% vs. 43.8%).

In practice, an arterial catheter is placed for escalating vasopressor doses, frequent blood gas sampling, or unreliable cuff readings.

Other Early-Phase Statements Worth Knowing

Procalcitonin: suggest clinical evaluation alone, not procalcitonin, to decide whether to start antimicrobials; suggest procalcitonin plus clinical evaluation to decide when to stop them.

Source control: suggest early source control, ideally within 6 hours of diagnosis.

Empiric spectrum: cover a specific MDR pathogen only when the patient is at high risk for it; suggest against routine empiric antifungal therapy; give empiric anaerobic coverage only with specific risk factors (intra-abdominal, deep pelvic, necrotizing soft-tissue, head and neck, or CNS abscess sources).

Beta-lactam administration: recommend prolonged infusion for maintenance dosing after a loading dose (strong recommendation).

ICU admission: suggest admission within 6 hours for patients who need ICU care.

  • Intravenous Fluid Resuscitation: Crystalloid Selection
  • The 30 mL/kg 30\text{ mL/kg} 30 mL/kg Starting Volume

The 30 mL/kg figure is a conditional (weak) suggestion , not a mandate. After the initial volume, further fluid should be guided by repeated assessment of perfusion and fluid responsiveness. The 2026 guideline suggests either a liberal or a restrictive strategy after the first 30 mL/kg when hypoperfusion persists, because the major trials found no difference:

CLASSIC (NEJM 2022): In 1,554 ICU patients with septic shock, restricting IV fluid did not change 90-day mortality (42.3% vs. 42.1%).

CLOVERS (NEJM 2023): In 1,563 patients with sepsis-induced hypotension after 1 to 3 L of fluid, an early-vasopressor restrictive strategy and a liberal fluid strategy had similar 90-day mortality before discharge (14.0% vs. 14.9%).

Once the acute resuscitation phase is over, the guideline suggests active fluid removal .

Balanced Crystalloids vs. 0.9% Normal Saline

Normal saline (0.9% sodium chloride) contains 154 mEq/L 154\text{ mEq/L} 154 mEq/L of sodium and 154 mEq/L 154\text{ mEq/L} 154 mEq/L of chloride, yielding a strong ion difference (SID) of zero. Large volumes produce hyperchloremic metabolic acidosis , and experimental data link chloride loading with renal vasoconstriction.

Balanced crystalloids, including Lactated Ringer's and Plasma-Lyte A , contain lower chloride concentrations ( 98 − 109 mEq/L 98-109\text{ mEq/L} 98 − 109 mEq/L ) balanced with metabolizable bicarbonate precursors (lactate, acetate, or gluconate).

  • Solution Metric 0.9% Normal Saline Lactated Ringer's Plasma-Lyte A
  • Sodium ( mEq/L ) (\text{mEq/L}) ( mEq/L ) 154 130 140
  • Chloride ( mEq/L ) (\text{mEq/L}) ( mEq/L ) 154 109 98
  • Potassium ( mEq/L ) (\text{mEq/L}) ( mEq/L ) 0 4.0 5.0

Buffer System None Lactate ( 28 mEq/L 28\text{ mEq/L} 28 mEq/L ) Acetate ( 27 mEq/L 27\text{ mEq/L} 27 mEq/L ), Gluconate ( 23 mEq/L 23\text{ mEq/L} 23 mEq/L )

  • Effective Strong Ion Difference 0 about +28 about +50
  • Osmolarity ( mOsm/L ) (\text{mOsm/L}) ( mOsm/L ) 308 273 295

Physiological Impact Hyperchloremic acidosis with large volumes Minimal acid-base disturbance Minimal acid-base disturbance

Trial Evidence: SMART, BaSICS, and PLUS

SMART (NEJM 2018): In a pragmatic, cluster-crossover trial of 15,802 critically ill adults, balanced crystalloids modestly reduced MAKE30 (death, new renal replacement therapy, or persistent kidney dysfunction within 30 days) compared with saline ( 14.3% vs. 15.4% , p = 0.04 p = 0.04 p = 0.04 ).

BaSICS (JAMA 2021): In 11,052 ICU patients, a balanced solution did not change 90-day mortality compared with saline.

PLUS (NEJM 2022): In 5,037 ICU patients, Plasma-Lyte did not change 90-day mortality (21.8% vs. 22.0%).

A 2022 meta-analysis of these trials estimated a small, statistically uncertain mortality reduction with balanced solutions (odds ratio about 0.96, 95% CI 0.91-1.01).

SSC 2026 Statement: Recommend crystalloids as first-line resuscitation fluid (strong); suggest balanced crystalloids over 0.9% saline (conditional); suggest crystalloids alone over crystalloids with supplemental albumin; recommend against starches (strong) and suggest against gelatins.

Perfusion Targets: Lactate and Capillary Refill Time

ANDROMEDA-SHOCK (JAMA 2019): CRT-targeted resuscitation vs. lactate-targeted resuscitation produced a nonsignificant reduction in 28-day mortality (34.9% vs. 43.4%, p = 0.06 p = 0.06 p = 0.06 ) with less organ dysfunction at 72 hours.

ANDROMEDA-SHOCK-2 (JAMA 2025): A personalized, CRT-guided resuscitation protocol was superior to usual care for a hierarchical composite outcome, mainly by shortening organ support.

The 2026 SSC suggests using capillary refill time as an adjunct to other perfusion measures and dynamic measures (passive leg raise, stroke volume or pulse pressure variation) over physical examination or static measures alone (both conditional).

Assessing Fluid Responsiveness: Dynamic vs. Static Measures

Once the initial 30 mL/kg 30\text{ mL/kg} 30 mL/kg bolus has completed, continued empirical fluid loading causes fluid overload, increases extravascular lung water, worsens tissue edema, exacerbates renal capsular congestion, and increases mortality. Clinicians must distinguish volume depletion from fluid responsiveness :

Fluid Responsiveness: An increase in stroke volume or cardiac output of at least 10 % 10\% 10% to 15 % 15\% 15% in response to an intravenous fluid challenge of 500 mL crystalloid or an equivalent autotransfusion maneuver.

Failure of Static Indices

Static measures of intravascular volume—such as Central Venous Pressure (CVP) and Pulmonary Artery Wedge Pressure (PAWP) —do not predict fluid responsiveness. Multiple systematic reviews confirm that the area under the receiver operating characteristic curve (AUROC) for CVP is approximately 0.56 (equivalent to a coin flip). An isolated low CVP does not prove responsiveness, nor does an elevated CVP preclude it.

Dynamic Heart-Lung Interaction Indices

Dynamic tests utilize cyclic changes in intrathoracic pressure during positive-pressure ventilation to evaluate preload sensitivity on the Frank-Starling curve.

Dynamic Modality Technique & Physiology Threshold for Responsiveness Mandatory Prerequisites & Caveats

Passive Leg Raise (PLR) Patient shifted from semi-recumbent ( 45 ∘ 45^\circ 4 5 ∘ ) to supine with legs elevated 45 ∘ 45^\circ 4 5 ∘ for 60-90 seconds. Autotransfuses ∼ 300 mL \sim 300\text{ mL} ∼ 300 mL of blood from venous reservoirs into the right ventricle. ≥ 10 % \ge 10\% ≥ 10% increase in real-time cardiac output or stroke volume Gold standard. Valid in spontaneous breathing, arrhythmias, and low lung compliance. Requires continuous, real-time CO monitoring.

Pulse Pressure Variation (PPV) Calculates cyclic variation in arterial pulse pressure across respiratory cycle: PPV = 100 × ( PP max − PP min ) / PP mean \text{PPV} = 100 \times (\text{PP}_{\text{max}} - \text{PP}_{\text{min}}) / \text{PP}_{\text{mean}} PPV = 100 × ( PP max ​ − PP min ​ ) / PP mean ​ . PPV ≥ 12 % to 13 % \text{PPV} \ge 12\%\text{ to }13\% PPV ≥ 12% to 13% Strict prerequisites: Passive mechanical ventilation (no spontaneous efforts), sinus rhythm, V T ≥ 8 mL/kg V_T \ge 8\text{ mL/kg} V T ​ ≥ 8 mL/kg PBW, normal chest compliance.

Stroke Volume Variation (SVV) Calculates cyclic variation in stroke volume derived from arterial pulse contour analysis: SVV = 100 × ( SV max − SV min ) / SV mean \text{SVV} = 100 \times (\text{SV}_{\text{max}} - \text{SV}_{\text{min}}) / \text{SV}_{\text{mean}} SVV = 100 × ( SV max ​ − SV min ​ ) / SV mean ​ . SVV ≥ 12 % to 13 % \text{SVV} \ge 12\%\text{ to }13\% SVV ≥ 12% to 13% Strict prerequisites: Same as PPV. Completely invalid in atrial fibrillation or spontaneous patient-triggered breaths.

End-Expiratory Occlusion Test (EEOT) 15-second ventilator expiratory hold stops cyclic positive intrathoracic pressure, increasing venous return. ≥ 5 % \ge 5\% ≥ 5% increase in cardiac output or arterial pulse pressure Valid in ARDS ventilated with low tidal volume ( 6 mL/kg 6\text{ mL/kg} 6 mL/kg PBW). Requires direct stroke volume measurement.

IVC Respiratory Variation (POCUS) Collapsibility Index (spontaneous) or Distensibility Index (passively ventilated). Measures IVC diameter changes via subxiphoid ultrasound. Collapsibility > 50 % > 50\% > 50% (spontaneous); Distensibility > 18 % > 18\% > 18% (ventilated) High operator variability; distorted by elevated intra-abdominal pressure, severe RV failure, and tricuspid regurgitation.

Tip

In the intensive care unit, the majority of patients exhibit spontaneous respiratory efforts, low tidal volume ventilation ( 6 mL/kg 6\text{ mL/kg} 6 mL/kg ), or cardiac dysrhythmias, rendering PPV and SVV completely unreliable. Under these prevalent conditions, the Passive Leg Raise (PLR) test coupled with real-time cardiac output measurement (via echocardiographic velocity-time integral [VTI] or pulse contour analysis) is the most accurate, physiologically robust method for determining fluid responsiveness.