Characterization of a Rabbit Model of Traumatic Hemorrhagic Shock Under High-Altitude Cold Conditions.

Area of Science:

• Physiology
• Trauma Medicine
• Environmental Medicine

Background:

• Traumatic hemorrhagic shock (THS) is often complicated by high-altitude hypoxia and cold.
• Existing models lack time-resolved quantification of these interacting stressors.
• Understanding these combined effects is crucial for developing effective treatments.

Purpose of the Study:

• To establish a time-resolved model of THS under high-altitude hypoxia and cold conditions.
• To quantify the interactive effects of hypoxia and cold on physiological parameters during THS.
• To investigate the impact on coagulation, metabolism, and organ injury.

Main Methods:

• A composite-trauma THS model was developed in New Zealand rabbits at ~5,000 m altitude and 8°C.
• Animals were subjected to hemorrhagic shock (HS) with combinations of cold (COL) and hypoxia (HYP).
• Vital signs, blood gases, coagulation markers, electrolytes, cytokines, and histology were measured over 120 minutes.

Main Results:

• The HS+HYP+COL group exhibited supra-additive injury, with significantly elevated lactate and acidosis (pH ~6.52).
• Progressive electrolyte disturbances (Na⁺↓, Cl⁻↑, K⁺↑, iCa²⁺↓) and hypocoagulability with secondary fibrinolysis were observed.
• Early hepatorenal injury and surges in pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) and IL-10 occurred.

Conclusions:

• High-altitude hypoxia and cold significantly amplify the detrimental effects of hemorrhagic shock.
• The combined stressors induce a complex imbalance in inflammation, coagulation, and metabolism.
• This model supports multi-axis therapeutic strategies including rewarming, oxygenation, and targeted fluid/immune modulation.