What causes sepsis?

What Makes Someone Septic?

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, characterized by an increase in the Sequential Organ Failure Assessment (SOFA) score of 2 points or more. 1

Pathophysiology of Sepsis

Sepsis occurs when the body's normal response to infection becomes dysregulated, leading to widespread inflammation that damages the body's own tissues and organs. This abnormal immune response is the fundamental mechanism that distinguishes sepsis from a normal infection response 1.

The pathophysiological progression typically involves:

1. Initial infection: Can originate from various sources including:

   • Respiratory tract
   • Urinary tract
   • Gastrointestinal tract (intra-abdominal infections are the second leading cause of sepsis globally) 2
   • Skin/soft tissue
   • Bloodstream

2. Dysregulated host response: The immune system overreacts, causing:

   • Excessive inflammation
   • Microvascular dysfunction
   • Impaired tissue perfusion
   • Cellular metabolic abnormalities

3. Organ dysfunction: The dysregulated response leads to damage in multiple organ systems, which is the hallmark of sepsis

Clinical Identification of Sepsis

Sepsis can be identified using several clinical tools:

Quick SOFA (qSOFA)

A bedside screening tool that evaluates three parameters 1:

• Altered mental status
• Systolic blood pressure ≤100 mmHg
• Respiratory rate >22/min
• A score ≥2 indicates high risk of sepsis

SOFA Score

Evaluates six organ systems 1:

• Respiratory
• Cardiovascular
• Hepatic
• Coagulation
• Renal
• Neurological

An increase of ≥2 points indicates organ dysfunction associated with sepsis.

National Early Warning Score 2 (NEWS2)

Evaluates six physiological parameters with scores ranging from 0 (very low risk) to ≥7 (high risk) 1.

Septic Shock

Septic shock represents a more severe evolution of sepsis with:

• Circulatory, cellular, and metabolic abnormalities
• Need for vasopressors to maintain mean arterial pressure ≥65 mmHg
• Serum lactate level >2 mmol/L despite adequate fluid resuscitation
• Hospital mortality rates exceeding 40% 1

Common Manifestations of Organ Dysfunction in Sepsis

• Respiratory: Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) occur in 25-42% of sepsis patients 1
• Cardiovascular: Hypotension, tachycardia, reduced ejection fraction
• Renal: Acute kidney injury
• Neurological: Altered mental status, confusion, delirium
• Hematologic: Coagulopathy, thrombocytopenia
• Hepatic: Elevated liver enzymes, hyperbilirubinemia
• Metabolic: Lactic acidosis, hyperglycemia

Clinical Pitfalls to Avoid

1. Delayed recognition: Early identification is crucial for improved outcomes. Don't wait for all classic signs to appear before initiating treatment.

2. Overlooking non-specific presentations: Elderly patients and immunocompromised individuals may present atypically without fever or leukocytosis.

3. Focusing solely on the infection: While treating the underlying infection is essential, managing the dysregulated host response is equally important.

4. Inadequate source control: For intra-abdominal infections, controlling the source of infection is critical to prevent progression and mortality 2.

5. Misinterpreting screening tools: qSOFA has lower sensitivity (31-36%) but higher specificity (78-90%) compared to SIRS criteria 1. Consider using multiple assessment tools for better accuracy.

In summary, sepsis results from a dysregulated host response to infection leading to life-threatening organ dysfunction. Early recognition using established clinical criteria and prompt, appropriate management are essential to improve outcomes in this serious condition.