Post-Aggression Syndrome – Causes, Symptoms and Treatment

What Is Post-Aggression Syndrome?

Post-aggression syndrome (PAS) refers to the complex, systemic response of the human body to severe physical stress such as major trauma, extensive surgical procedures, serious infections (sepsis), or burns. The term derives from the Latin word aggressio (attack), reflecting the assault on the body by these triggering events. The response represents a phylogenetically ancient survival strategy of the organism, but in its exaggerated form it can lead to serious complications.

Causes and Triggering Factors

Post-aggression syndrome is triggered by a variety of severe physical insults. The most common triggers include:

• Severe trauma: Polytrauma, traumatic brain injury, fractures
• Surgical procedures: Major abdominal or thoracic surgeries
• Severe infections: Sepsis, peritonitis, pneumonia
• Burns: Extensive thermal injuries
• Shock states: Hemorrhagic, septic, or cardiogenic shock
• Pancreatitis: Severe acute inflammation of the pancreas

The common denominator of all these triggers is a massive activation of the neuroendocrine, immune, and coagulation systems.

Pathophysiology and Phases

Post-aggression syndrome follows characteristic phases reflected in metabolic and organ function changes:

Ebb Phase (Shock Phase)

In the first hours after the triggering event, the so-called ebb phase occurs. The body responds with a decrease in cardiac output, reduced energy expenditure, and centralization of circulation. Body temperature falls and metabolism is suppressed to protect vital organs.

Flow Phase (Hypermetabolic Phase)

Following the initial shock phase, the flow phase begins, characterized by markedly elevated metabolism (hypermetabolism). During this phase:

• Basal metabolic rate and oxygen consumption increase significantly
• Catabolism dominates: muscle protein is broken down for energy, resulting in a negative nitrogen balance
• Blood glucose levels rise (stress diabetes)
• Fever and systemic inflammatory response occur (SIRS – Systemic Inflammatory Response Syndrome)
• Stress hormones are released, including cortisol, adrenaline, noradrenaline, and glucagon
• Pro-inflammatory cytokines such as TNF-alpha, interleukin-1, and interleukin-6 are elevated

Anabolic Recovery Phase

If the triggering event is successfully treated and no complications arise, the anabolic recovery phase follows, characterized by gradual normalization of metabolism, rebuilding of muscle tissue, and restoration of organ function.

Clinical Symptoms

Post-aggression syndrome manifests through a broad spectrum of clinical signs:

• Fever or hypothermia
• Tachycardia (rapid heart rate)
• Tachypnea (rapid breathing)
• Elevated or reduced white blood cell count
• Muscle wasting (sarcopenia) and weight loss
• Hyperglycemia (elevated blood sugar)
• Fluid and electrolyte imbalances
• Coagulation disorders, potentially progressing to disseminated intravascular coagulation (DIC)

In severe cases, post-aggression syndrome can lead to multi-organ failure (MOF), in which multiple vital organs such as the lungs, kidneys, liver, and heart are simultaneously impaired.

Diagnosis

Diagnosis of post-aggression syndrome is based on clinical findings and laboratory parameters. Typical diagnostic measures include:

• Laboratory tests: Full blood count, inflammatory markers (CRP, procalcitonin, IL-6), blood glucose, lactate, albumin, blood urea nitrogen (as a marker of protein catabolism)
• Vital sign monitoring: Heart rate, respiratory rate, body temperature, blood pressure
• Organ function parameters: Creatinine (kidneys), transaminases (liver), troponin (heart), blood gas analysis (lungs)
• SOFA Score (Sequential Organ Failure Assessment): A clinical scoring system used to quantify organ dysfunction

Treatment and Intensive Care Management

Treatment of post-aggression syndrome is multidisciplinary and aims to address the underlying cause, stabilize organ functions, and limit catabolism:

Causal Therapy

The primary goal is to treat the triggering event, such as surgical debridement of an infection source, antibiotic therapy for sepsis, or surgical repair of injuries.

Intensive Care Supportive Therapy

• Hemodynamic stabilization: Fluid therapy and vasopressors in shock
• Ventilation therapy: Lung-protective mechanical ventilation in respiratory failure
• Renal replacement therapy: Dialysis in acute kidney injury
• Blood glucose control: Insulin therapy to maintain normoglycemia

Nutritional Therapy

Tailored nutritional therapy is essential to limit catabolism and support recovery. Guidelines from organizations such as ESPEN recommend:

• Early enteral nutrition (via the gastrointestinal tract) within 24 to 48 hours of the event
• Adequate protein and caloric intake adjusted to hypermetabolic demands
• Supplementation with specific nutrients such as glutamine, omega-3 fatty acids, and antioxidants
• Parenteral nutrition (intravenous) only when enteral feeding is contraindicated

Early Mobilization and Physiotherapy

To counteract muscle wasting, early mobilization and physiotherapeutic care of patients are strongly recommended.

Prognosis

The prognosis of post-aggression syndrome depends heavily on the severity of the triggering event, the age and pre-existing conditions of the patient, and the quality of intensive care management. Modern critical care, early nutritional therapy, and consistent organ function monitoring have significantly reduced mortality in recent decades. Nevertheless, multi-organ failure as the most severe complication remains associated with high mortality rates.

References

1. Weissman C. - The metabolic response to stress: an overview and update. Anesthesiology. 1990;73(2):308-327. PubMed PMID: 2200312.
2. Singer P. et al. - ESPEN guideline on clinical nutrition in the intensive care unit. Clinical Nutrition. 2019;38(1):48-79. doi:10.1016/j.clnu.2018.08.037.
3. Marino P.L. - The ICU Book. 4th edition. Lippincott Williams and Wilkins, Philadelphia 2014.