Uncontrolled hemorrhagic shock outcome model in rats

Area of Science:

• Trauma and Emergency Medicine
• Surgical Research
• Animal Models in Research

Background:

• Uncontrolled hemorrhagic shock (UHS) in animal models often lacks clinical realism, hindering the evaluation of resuscitation strategies.
• Previous models showed high variability in blood loss, shock severity, and mortality, limiting their utility for outcome studies.

Purpose of the Study:

• To develop and validate a clinically relevant, long-term animal model of uncontrolled hemorrhagic shock in rats.
• To establish a reproducible model for assessing the efficacy of different pre-hospital treatment modalities for UHS.

Main Methods:

• A three-phase study involving simulated pre-hospital (Phase I) and hospital (Phase II) treatment, followed by a 72-hour survival observation (Phase III).
• Phase I included controlled hemorrhage and tail amputation for UHS over 90 minutes.
• Phase II involved 60 minutes of hemostasis and aggressive fluid resuscitation (FR) with lactated Ringer's and blood to achieve a hematocrit of 30%.

Main Results:

• UHS induced solely by tail amputation resulted in unpredictable hemostasis and high mortality variability.
• The refined model, incorporating initial controlled hemorrhage followed by tail amputation, achieved consistent blood loss and outcomes.
• In a group receiving no FR, all rats died within 12 hours; in a group with FR, 90% mortality was observed by 72 hours.

Conclusions:

• The developed volume-initiated UHS model provides a consistent and reproducible platform for studying long-term outcomes.
• This model is suitable for comparative studies of pre-hospital interventions in uncontrolled hemorrhagic shock.
• Further research is needed to optimize resuscitation strategies within this validated animal model.