What is the chemical mediator involved in the inflammatory response of a scald burn?

Chemical Mediator in a Spilled Hot Water Burn

Prostaglandins are the primary chemical mediator in a spilled hot water burn (scald burn), playing a crucial role in the inflammatory response and pain sensation following thermal injury. 1

Pathophysiology of Thermal Burns and Inflammatory Response

When hot water contacts the skin, it causes immediate tissue damage that triggers a cascade of inflammatory events. The pathophysiological response involves:

1. Initial Tissue Damage:

   • Direct heat effect damages cell membranes and microvasculature
   • Activation of inflammatory pathways
   • Release of multiple inflammatory mediators

2. Mediator Release Sequence:

   • Histamine is released in the earliest stage, causing initial vasodilation and increased permeability 2
   • Damage to cell membranes activates enzymes that catalyze the hydrolysis of arachidonic acid 2
   • This leads to rapid formation of prostaglandins, which are the predominant mediators in the burn response 1, 2

3. Prostaglandin Effects:

   • Enhance vasodilation
   • Potentiate plasma exudation
   • Sensitize nociceptors, leading to pain
   • Modulate the adrenergic nervous system response to thermal injury 2

Evidence Supporting Prostaglandins as Primary Mediators

The European Respiratory Journal guidelines specifically identify prostaglandins as key mediators in thermal injury 1. In their table of mediators involved in inflammatory responses, prostaglandins are listed as primary mediators released during thermal challenges 1.

Additionally, research has demonstrated that:

• Prostaglandins act as vasodilators that potentiate the plasma exudation produced by other permeability-increasing mediators 3
• Non-steroidal anti-inflammatory drugs (NSAIDs) effectively reduce burn-related inflammation by inhibiting prostaglandin synthesis 3
• Prostaglandins are derived from arachidonic acid through the cyclooxygenase pathway following thermal injury 2

Role of Other Mediators

While prostaglandins are the primary mediators, other substances also contribute to the burn response:

• Bradykinins: Act through B2 receptors but have a more limited role compared to prostaglandins 1
• Histamine: Involved in the earliest stage of vasodilation but not the sustained response 2, 4
• Thromboxanes: Play a role in platelet aggregation but are not the primary mediator in thermal burns 1
• Serotonin: Has some vasoactive properties but is not the predominant mediator in burn injury 4

Clinical Implications

Understanding that prostaglandins are the primary mediator in scald burns explains why:

• NSAIDs are effective in managing burn pain and inflammation
• Cooling the burn immediately helps limit prostaglandin production
• The inflammatory response continues even after the initial injury

Therefore, the answer to the question "What is the chemical mediator in a spilled hot water burn?" is D. Prostaglandins.