What is the primary chemical mediator involved in a spilled hot water burn?

Chemical Mediators in Hot Water Burns

The primary chemical mediator involved in a spilled hot water burn is bradykinins (option B).

Pathophysiology of Thermal Burns

When hot water contacts the skin, it initiates a complex inflammatory cascade that involves several chemical mediators. According to current guidelines and evidence, the process unfolds as follows:

1. Initial tissue damage: Hot water causes immediate coagulative necrosis of skin cells, with the severity depending on temperature and exposure time 1

2. Inflammatory response: The damaged tissue releases inflammatory mediators that contribute to the clinical manifestations of burns:

   • Bradykinins are released first and play the primary role in increasing vascular permeability 2, 3
   • Prostaglandins act as vasodilators that potentiate the plasma exudation produced by bradykinins 3
   • Thromboxane and serotonin play secondary roles in the inflammatory cascade

3. Edema formation: Bradykinins cause increased vascular permeability, leading to the characteristic edema seen in burns 3

Evidence Supporting Bradykinins as Primary Mediator

The 2020 guidelines from Anaesthesia on management of severe thermal burns highlight the importance of understanding the inflammatory mediators in burns 2. The inflammatory cascade in burns is primarily initiated by bradykinins, which increase vascular permeability and lead to the characteristic edema formation 2, 3.

Research evidence shows that bradykinins are released immediately following thermal injury and are responsible for the initial vascular changes 3. While prostaglandins (option D) are also involved in the inflammatory response to burns, they primarily act as vasodilators that potentiate the effects of bradykinins rather than being the primary mediator 3.

Role of Other Chemical Mediators

• Serotonin (option A): While serotonin does play a role in pain perception following burns, it is not the primary chemical mediator responsible for the initial inflammatory response 2

• Thromboxane (option C): Thromboxane is involved in platelet aggregation and vasoconstriction during the inflammatory response but is not the primary mediator in thermal burns 2

• Prostaglandins (option D): Prostaglandins act as vasodilators that potentiate the plasma exudation produced by bradykinins but are not the primary mediator 3

Clinical Implications

Understanding that bradykinins are the primary mediator in hot water burns has important clinical implications:

• Initial cooling of burns helps limit the inflammatory cascade by reducing bradykinin release 2, 4
• The American Heart Association and American Red Cross guidelines recommend cooling burns with running water for at least 15 minutes to limit the inflammatory response 2
• Proper understanding of the chemical mediators helps guide appropriate treatment approaches, including pain management strategies 1

Conclusion

Based on the available evidence, bradykinins (option B) are the primary chemical mediator involved in the inflammatory response following a hot water burn. They increase vascular permeability, leading to edema formation, while other mediators like prostaglandins play supporting roles in the inflammatory cascade.