Residency · Residency · General Surgery

Sepsis and Septic Shock in the Surgical Patient

Introduction

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. It remains the leading cause of death in non-cardiac ICU patients and a major source of morbidity and mortality in surgical practice. The general surgeon plays a critical role in sepsis management, both in identifying and controlling the surgical source of infection and in leading multidisciplinary critical care. Understanding the evolving definitions, pathophysiology, and evidence-based management of sepsis is essential for surgical trainees.

Definitions (Sepsis-3, 2016)

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as an increase in the Sequential Organ Failure Assessment (SOFA) score of 2 or more points from baseline. Septic shock is a subset of sepsis with circulatory and cellular/metabolic dysfunction associated with higher mortality, defined as sepsis with persistent hypotension requiring vasopressors to maintain MAP at or above 65 mmHg and serum lactate above 2 mmol/L despite adequate volume resuscitation. The qSOFA (quick SOFA) is a bedside screening tool for patients outside the ICU that uses 2 of 3 criteria: respiratory rate of 22 or greater, altered mentation (GCS below 15), and systolic blood pressure of 100 mmHg or less. It identifies patients at risk of poor outcomes but is not part of the sepsis definition. SIRS criteria (temperature above 38 or below 36 degrees Celsius, heart rate above 90, respiratory rate above 20 or PaCO2 below 32, and WBC above 12,000 or below 4,000 or more than 10% bands) are no longer used to define sepsis but remain clinically useful as screening indicators.

Pathophysiology

Immune Dysregulation

Pattern recognition receptors (Toll-like receptors, NOD-like receptors) on innate immune cells detect pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) and damage-associated molecular patterns (DAMPs). The resulting cytokine storm involves early pro-inflammatory release of TNF-alpha, IL-1, IL-6, and IL-8, which drives fever, vasodilation, capillary leak, and coagulation activation. A compensatory anti-inflammatory response (CARS) occurs simultaneously or subsequently, with IL-10 and TGF-beta release, T-cell apoptosis, and immune paralysis that predisposes to secondary infections. Endothelial dysfunction leads to loss of barrier function, glycocalyx degradation, and activation of the coagulation cascade, resulting in microvascular thrombosis and tissue hypoperfusion.

Hemodynamic Derangements

Distributive shock results from pathologic vasodilation driven by nitric oxide, prostacyclin, and inflammatory mediators that reduce systemic vascular resistance. Myocardial depression (septic cardiomyopathy) occurs in up to 60% of septic shock patients and is characterized by biventricular dilation and decreased ejection fraction, though it is typically reversible in survivors. Microcirculatory dysfunction involves heterogeneous capillary flow with shunting, leading to regional tissue hypoxia despite adequate macrocirculatory parameters.

<image>Pathophysiology diagram showing the cascade from bacterial infection through PAMP/DAMP recognition by toll-like receptors, pro-inflammatory cytokine release, endothelial dysfunction, and the resulting organ dysfunction in sepsis including cardiovascular, pulmonary, renal, and hepatic manifestations</image>

Common Surgical Sources of Sepsis

The most common surgical sources of sepsis include intra-abdominal infections (perforated appendicitis, diverticulitis, or peptic ulcer; anastomotic leak; biliary sepsis from cholangitis or cholecystitis; necrotizing pancreatitis; and mesenteric ischemia), soft tissue infections (necrotizing fasciitis, Fournier gangrene, wound infections, and infected prosthetic material), thoracic sources (empyema and mediastinitis from esophageal perforation or sternotomy), vascular infections (infected grafts, mycotic aneurysms, and suppurative thrombophlebitis), and line-related infections (central line-associated bloodstream infections). The principle of source control -- drainage, debridement, diversion, or definitive repair -- is the most important surgical contribution to sepsis management and should be achieved within 6-12 hours of recognition.

Early Recognition and Screening

The Hour-1 Bundle from the 2021 Surviving Sepsis Campaign calls for resuscitation to begin immediately upon recognition without delay for ICU transfer. The bundle includes measuring a lactate level (and remeasuring if the initial lactate exceeds 2 mmol/L), obtaining blood cultures before antibiotics (at least 2 sets, aerobic and anaerobic), administering broad-spectrum antibiotics within 1 hour of recognition, beginning rapid IV fluid resuscitation with 30 mL/kg of crystalloid for hypotension or lactate of 4 mmol/L or greater, and applying vasopressors if hypotension persists during or after fluid resuscitation to maintain MAP at or above 65 mmHg. Lactate serves as a surrogate marker of tissue hypoperfusion, and serial measurement guides resuscitation adequacy. Lactate clearance exceeding 10% in 2-4 hours is associated with improved outcomes.

Antimicrobial Therapy

Empiric broad-spectrum antibiotics must be administered within 1 hour of sepsis recognition, as each hour of delay increases mortality by approximately 4-8%. Coverage considerations include gram-positive organisms (vancomycin if MRSA risk is present), gram-negative organisms (piperacillin-tazobactam, cefepime, or carbapenems), anaerobes (metronidazole if not covered by the primary agent), and fungal pathogens (echinocandins if risk factors are present). Source-directed narrowing should be performed based on culture results and clinical response within 48-72 hours. Duration is typically 7-10 days for most infections, with shorter courses of 5-7 days potentially appropriate for adequately source-controlled intra-abdominal infections. Procalcitonin trending can guide antibiotic de-escalation. Pharmacokinetics in sepsis are altered by increased volume of distribution, augmented renal clearance in early sepsis, and decreased clearance in organ dysfunction, which may warrant extended or continuous infusions of beta-lactams.

Hemodynamic Management

Fluid Resuscitation

Crystalloid, with balanced solutions (lactated Ringer's or Plasmalyte) preferred over normal saline, is the first-line fluid. Large volumes of normal saline cause hyperchloremic metabolic acidosis and may worsen renal injury. An initial bolus of 30 mL/kg is given within the first 3 hours, with further fluids guided by dynamic assessment of fluid responsiveness using passive leg raise, pulse pressure variation (greater than 13% suggests responsiveness in mechanically ventilated patients), stroke volume variation, or IVC ultrasonography. Albumin may be considered as a second-line fluid in patients requiring substantial crystalloid. Excessive fluid administration should be avoided, as positive fluid balance is independently associated with increased mortality, and restrictive strategies after initial resuscitation are recommended.

Vasopressor and Inotrope Therapy

Norepinephrine, an alpha-1 predominant agent with some beta-1 activity, is the first-line vasopressor and is titrated to maintain MAP at or above 65 mmHg. Vasopressin at 0.03-0.04 units per minute is added as a second agent to reduce norepinephrine requirements; it acts via V1 receptors and may be particularly beneficial in patients with tachyarrhythmias. Epinephrine is added as a third-line vasopressor or when inotropic support is needed for septic cardiomyopathy. Dobutamine is considered for persistent hypoperfusion despite adequate volume status and vasopressor support, as it increases cardiac output via beta-1 stimulation. Phenylephrine, a pure alpha-1 agonist, is reserved for situations where tachyarrhythmias limit norepinephrine use.

<image>Flowchart showing the stepwise hemodynamic management algorithm for septic shock starting with crystalloid resuscitation, assessment of fluid responsiveness, first-line norepinephrine, second-line vasopressin, and escalation pathways including epinephrine, dobutamine, and corticosteroids</image>

Source Control

Definitive source control should be achieved within 6-12 hours of identification when feasible. Percutaneous drainage is preferred for well-defined, accessible fluid collections such as intra-abdominal abscess, biliary obstruction via percutaneous transhepatic cholangiography, and empyema drainage. Operative intervention is required for generalized peritonitis, perforated viscus, necrotizing soft tissue infection, bowel ischemia, and failed percutaneous drainage. Damage control principles apply when patients are physiologically deranged, with abbreviated source control and planned return to the operating room. Infected intravascular devices, prosthetic material, and foreign bodies should be removed when they are the suspected source.

Adjunctive Therapies

Hydrocortisone at 200 mg per day IV (50 mg every 6 hours or as a continuous infusion) is recommended for septic shock refractory to fluids and vasopressors (requiring norepinephrine at or above 0.25 mcg/kg/min for more than 4 hours). The ADRENAL and APROCCHSS trials showed faster shock reversal, though the mortality benefit remains debatable. Stress ulcer prophylaxis with proton pump inhibitors or H2 receptor blockers is provided for at-risk patients (those with coagulopathy, mechanical ventilation exceeding 48 hours, or history of GI bleeding). VTE prophylaxis with low-molecular-weight heparin is preferred over unfractionated heparin unless renal insufficiency or high bleeding risk exists. Blood glucose is targeted at 140-180 mg/dL, and insulin-induced hypoglycemia (below 70 mg/dL) is avoided. Transfusion follows a restrictive strategy with a hemoglobin threshold of 7 g/dL unless active hemorrhage, myocardial ischemia, or acute blood loss is present.

Organ Support

Acute kidney injury occurs in 40-50% of sepsis patients and is managed by optimizing perfusion and avoiding nephrotoxins. Renal replacement therapy is indicated for refractory volume overload, severe acidosis, hyperkalemia, or uremic complications. ARDS is managed with lung-protective ventilation using tidal volumes of 6 mL/kg ideal body weight, plateau pressure below 30 cmH2O, a moderate PEEP strategy, and prone positioning when PaO2/FiO2 falls below 150. Hepatic dysfunction manifesting as coagulopathy and hyperbilirubinemia is managed supportively. Disseminated intravascular coagulation is addressed by treating the underlying sepsis, with supportive transfusion of platelets, FFP, and cryoprecipitate as needed for active bleeding.

<image>Illustration showing the multi-organ effects of sepsis with targeted organ support strategies, depicting the lungs (ARDS with ventilator settings), kidneys (AKI with RRT indications), heart (septic cardiomyopathy with inotrope support), liver, and brain (encephalopathy)</image>

Key Clinical Pearls

Source control is the surgeon's most important contribution to sepsis management; no amount of antibiotics or critical care substitutes for adequate drainage, debridement, or resection. Antibiotics must be administered within 1 hour of sepsis recognition, as each hour of delay measurably increases mortality. Balanced crystalloids should be used over normal saline, and fluid responsiveness should be assessed dynamically rather than relying on fixed volume targets. Norepinephrine is the first-line vasopressor and should be started early if hypotension persists despite initial fluid resuscitation. Serial lactate clearance is a reliable marker of resuscitation adequacy and guides ongoing therapy.

References

1. Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801-810.
2. Evans L, Rhodes A, Alhazzani W, et al. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021. Crit Care Med. 2021;49(11):e1063-e1143.
3. Annane D, Renault A, Brun-Buisson C, et al. Hydrocortisone plus fludrocortisone for adults with septic shock (APROCCHSS). N Engl J Med. 2018;378(9):809-818.
4. Sartelli M, Chichom-Mefire A, Labricciosa FM, et al. The management of intra-abdominal infections from a global perspective: 2017 WSES guidelines. World J Emerg Surg. 2017;12:29.

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