Rodent Model for High Altitude and Ebullism Exposure Studies

Area of Science:

• Aerospace Medicine and Physiology
• Environmental Extremes Research
• Pathophysiology of Extreme Altitudes

Background:

• Ebullism, a critical risk in aerospace, involves physiological responses to pressures below 47 mmHg.
• Research on ebullism has stagnated since the mid-20th century due to perceived lethality and facility limitations.
• Lack of standardized models hinders understanding and mitigation of ebullism effects.

Purpose of the Study:

• To develop and validate a rodent model for studying ebullism at extreme altitudes.
• To characterize the pathophysiological effects of rapid depressurization beyond the Armstrong Line.
• To establish distinct classifications for ebullism based on pressure and time exposures.

Main Methods:

• Exposure of a rodent model (N=20) to rapid depressurization down to 0.3 mmHg for up to 2 minutes.
• Implementation of a three-tiered pressure approach to simulate varying exposure degrees.
• Post-exposure autopsies to document pathological changes.

Main Results:

• A novel three-tiered pressure system was established for controlled ebullism exposure.
• Significant thermal impacts were observed when exceeding the water triple point (approx. 120 kft).
• Distinct pathophysiological regimes were identified beyond the Armstrong Line.

Conclusions:

• Ebullism exposures were successfully classified into Type A (Complex) and Type B (Simple).
• Type A ebullism involves barotrauma, hypoxia, ebullism, and decompression sickness.
• Type B ebullism is characterized solely by ebullism, relevant to suit or cabin depressurization events.