Acute Inflammation

This is the immediate, short-lived response occurring within minutes to hours of injury. It is characterized by:

1. Vascular Changes:

   • Transient Vasoconstriction: Brief constriction of arterioles at the site of injury to minimize blood loss.

   • Vasodilation: Dilation of arterioles and venules, leading to increased blood flow (causing redness and heat).

   • Increased Vascular Permeability: Endothelial cells contract, creating gaps that allow plasma proteins (including antibodies and complement) and leukocytes to leak out of blood vessels into the interstitial space (causing swelling/edema).

2. Cellular Events:

   • Leukocyte Recruitment (Chemotaxis): Chemical mediators (chemokines) attract white blood cells, primarily neutrophils, to the site of injury.

   • Margination, Rolling, Adhesion: Leukocytes slow down, roll along the endothelium, and adhere to the vessel wall.

   • Transmigration (Diapedesis): Leukocytes squeeze through the gaps between endothelial cells to enter the interstitial tissue.

   • Phagocytosis: Neutrophils and later macrophages engulf and destroy pathogens, foreign particles, and cellular debris.

Chronic Inflammation

If the acute inflammatory response fails to eliminate the injurious agent, or if the stimulus persists, inflammation can become chronic. This is a prolonged response (weeks to months) characterized by:

• Simultaneous processes of active inflammation, tissue destruction, and attempted repair.

• Infiltration by mononuclear cells (macrophages, lymphocytes, plasma cells).

• Proliferation of fibroblasts and blood vessels.

• Fibrosis (scarring).

• Formation of granulomas in some cases (e.g., foreign body reaction to surgical materials).

Key Mediators of Inflammation

A variety of chemical mediators orchestrate the inflammatory response. These can be cell-derived (e.g., from mast cells, macrophages) or plasma-derived (e.g., complement proteins). Key mediators include:

• Histamine: Released by mast cells and basophils; causes vasodilation and increased vascular permeability.

• Prostaglandins and Leukotrienes: Derived from arachidonic acid; involved in vasodilation, increased permeability, pain (prostaglandins), and chemotaxis. Targeted by NSAIDs (Non-Steroidal Anti-Inflammatory Drugs).

• Cytokines: Proteins produced by immune cells (e.g., TNF-alpha, IL-1, IL-6); regulate and coordinate the inflammatory response, influence leukocyte behavior, and can induce systemic effects like fever.

• Chemokines: A type of cytokine that acts as chemoattractants for leukocytes.

• Complement System: Plasma protein cascade that, when activated, produces mediators that enhance vascular permeability, cause chemotaxis, opsonize pathogens, and directly lyse cells.

Relevance to Surgical Nursing

Understanding inflammation is paramount in surgical nursing for several reasons:

• Post-operative Assessment: Distinguishing expected post-operative inflammation (part of the healing process) from signs of surgical site infection.

• Wound Healing: Inflammation is the first phase of wound healing. Impaired or excessive inflammation can delay healing.

• Pain Management: Pain is a cardinal sign of inflammation, and managing post-operative pain often involves targeting inflammatory pathways.

• Monitoring for Complications: Elevated inflammatory markers (CRP, ESR) can indicate systemic inflammation or infection. Persistent or escalating inflammation post-operatively warrants investigation.

• Immunosuppression: Patients on immunosuppressive therapy may have an attenuated inflammatory response, making them more susceptible to infections and potentially masking the usual signs of inflammation.

• Foreign Body Response: Surgical implants or sutures can trigger a chronic inflammatory response.

Investigations Related to Inflammation

Several investigations help assess the presence and severity of inflammation in surgical patients:

• Clinical Assessment: Observation for redness, swelling, heat, pain, and loss of function at the surgical site.

• Vital Signs: Monitoring temperature (fever), pulse, and blood pressure, which can be affected by systemic inflammation.

• Hematological Tests:

  • CBC with Differential: Leukocytosis (especially neutrophilia) is common in acute inflammation/infection.

• Inflammatory Markers:

  • C-Reactive Protein (CRP): An acute-phase protein whose levels rise rapidly in response to inflammation.

  • Erythrocyte Sedimentation Rate (ESR): Measures the rate at which red blood cells settle, which is increased by inflammatory proteins.

• Microbiological Cultures: To identify if inflammation is due to an infection.