• Clinical science

Sepsis

Abstract

Sepsis is an acute life-threatening condition characterized by organ dysfunction due to a dysregulated immune response to infection. The previously widely used term “systemic inflammatory response syndrome” (SIRS) is now considered outdated because its criteria were too simplified. Initial infection is generally bacterial and commonly of respiratory, genitourinary, gastrointestinal, dermatological, or soft tissue origin. Risk factors include immunocompromise, chronic comorbidities (e.g., diabetes mellitus), young or old age, and lengthy or invasive medical care. Patients may present with fever, tachycardia, confusion, and signs of the primary infection. Organ dysfunction is determined using a sequential organ failure assessment (SOFA) score that considers multiple parameters, but may be quickly evaluated and assumed if two of the following findings are present: hyperpnea, hypotension, and altered mental status. Diagnostic workup focuses on determining the responsible pathogen via cultures and identifying the source of infection (e.g., via imaging, ECG, lumbar puncture). Laboratory findings are largely nonspecific. Prompt, aggressive treatment is vital to survival and consists of resuscitation, empiric antibiotic therapy, and control of the infectious source.

Etiology

References:[1][2][3][4][5][6][7]

Classification

2015 criteria and SOFA classification (The third international consensus definitions for sepsis and septic shock, Sepsis-3)

  • Sepsis: acute and life-threatening organ dysfunction due to abnormal host response to infection
    • Organ dysfunction: an acute change in total SOFA score ≥ 2 points
    • Infection: may be confirmed (via culture) or suspected
  • Septic shock consists of the following parameters:
    • Sepsis +
    • Significant circulatory, metabolic, and cellular abnormalities +
    • Requiring vasopressor therapy to maintain a mean blood pressure of ≥ 65 mmHg and presence of increased lactate levels > 2 mmol/L (18 mg/dL) in the absence of hypovolemia
  • The term “severe sepsis” is no longer used
  • Quick SOFA criteria (qSOFA): to predict mortality in adult patients with suspected infection outside of the ICU (e.g., ward, emergency unit, or prior to hospitalization)
    • Positive if ≥ 2 of the following are present:
      • Mental status change
      • Respiratory rate: ≥ 22 breaths per minute
      • Systolic BP: ≤ 100 mmHg
    • If positive then the patient should be assessed for organ dysfunction via the SOFA score.
SOFA Score


References:[3][8][9][10][11][12]

Pathophysiology

An adequate immune response requires a balance between proinflammatory (anti-infectious) and anti-inflammatory signals!

Clinical features

Origin Example of infection Characteristic features
CNS Meningitis
  • Meningism, altered mental status, photophobia
Respiratory Pneumonia
Cardiac Endocarditis
Abdominal Any cause of acute abdomen (e.g., appendicitis)
  • Abdominal pain, peritonism, possible distension, vomiting
Pelvic Pelvic inflammatory disease
Urinary Pyelonephritis, Urosepsis
  • Dysuria, frequency, flank pain
Bone Osteomyelitis
  • Local pain (possibly exacerbated with movement), tenderness, warmth, erythema
Soft tissue Abscess
  • Local warmth, erythema, tenderness with firm or fluctuant swelling (possibly indurated or draining pus)
  • Possible foreign body at the site of inflammation

References:[1][2][13]

Diagnostics

References:[14][1][2][3][11][15]

Treatment

In addition to immediate resuscitation and empiric therapy, the infectious focus must be identified and treated!
References:[14][1][2][16][17]

Complications

  • Critical illness polyneuropathy
    • Definition: axonal injury, particularly to the motor neurons, as a sequela of sepsis and multiple organ dysfunction
    • Clinical features
    • Diagnosis
      • Typical clinical features and sepsis AND
      • Electrophysiological evidence of motor and sensory neuropathy
        • Nerve conduction studies: normal velocity, reduced amplitude
        • Electromyography (EMG): spontaneous activity (e.g., fibrillations)
    • Treatment: no specific treatment available, usually gradual spontaneous resolution (weeks to months)

Critical illness polyneuropathy is a common cause of prolonged weaning from mechanical ventilation in a patient with sepsis!
References:[18]

We list the most important complications. The selection is not exhaustive.