Severe limb trauma often requires the use of a tourniquet to stop life-threatening bleeding. While tourniquets are essential for saving lives, prolonged interruption of blood flow may lead to tissue ischemia, nerve injury, and inflammatory responses that could contribute to the development of chronic pain.

The TOURNI-PAIN Study is a prospective observational study designed to investigate whether the duration of tourniquet use during the treatment of severe limb injuries is associated with an increased risk of persistent pain after recovery. The study will enroll adult patients with major upper or lower limb trauma who required tourniquet application in the prehospital or hospital setting.

Researchers will collect information about the duration and characteristics of tourniquet use, details of the injury, surgical treatment, and recovery. Participants will be followed for up to 6 months after injury to assess pain levels, possible neuropathic pain, functional recovery, and quality of life.

The goal of this research is to better understand whether longer tourniquet exposure increases the risk of long-term pain. The findings may help improve trauma care practices by balancing the life-saving benefits of hemorrhage control with strategies that minimize long-term complications and improve recovery for patients with severe limb injuries.

Severe extremity trauma is frequently associated with life-threatening hemorrhage. Tourniquet application has become a critical intervention in both military and civilian trauma systems to rapidly control bleeding and prevent exsanguination. The widespread adoption of prehospital tourniquet use has significantly improved survival in patients with major limb injuries. However, prolonged interruption of blood flow may lead to ischemia-reperfusion injury, which can affect muscles, nerves, and microvascular structures.

Experimental and clinical evidence suggests that prolonged ischemia can trigger inflammatory cascades, oxidative stress, and neural sensitization pathways that may contribute to persistent pain after trauma. Potential mechanisms include peripheral nerve ischemia, muscle necrosis, microvascular dysfunction, compartment syndrome, and systemic inflammatory activation. These processes may increase the risk of chronic pain syndromes, including neuropathic pain and, in amputees, phantom limb pain.

Despite the widespread use of tourniquets, the relationship between tourniquet duration and long-term pain outcomes after severe limb trauma has not been prospectively evaluated in large clinical cohorts. Understanding this association is important for optimizing trauma care strategies that balance the life-saving benefits of hemorrhage control with potential long-term functional and pain-related consequences.

The TOURNI-PAIN Study is a prospective observational cohort study designed to evaluate whether cumulative tourniquet exposure is associated with the development of persistent clinically significant pain after severe limb trauma. Adult patients with major upper or lower extremity injuries who required tourniquet application in the prehospital or hospital setting will be enrolled. Clinical data will be collected from medical records and structured patient assessments.

Key exposure variables will include cumulative tourniquet duration, location of application (prehospital vs. hospital), repeated applications, and total ischemia time. Additional injury-related and clinical variables such as injury severity, mechanism of injury, nerve injury, compartment syndrome, surgical procedures, transfusion requirements, and critical care parameters will also be recorded.

Participants will be followed for up to six months after injury. Pain outcomes will be evaluated using standardized measures including the Numeric Rating Scale (NRS) for pain intensity, the DN4 questionnaire for neuropathic pain, and the Brief Pain Inventory for pain interference. Additional outcomes will include opioid consumption, functional recovery, and health-related quality of life.

The primary objective is to determine whether prolonged tourniquet exposure is independently associated with persistent clinically significant pain at 3 or 6 months after injury. Secondary analyses will explore dose-response relationships between ischemia duration and pain outcomes, as well as interactions between tourniquet exposure and clinical factors such as amputation, compartment syndrome, and nerve injury.

The results of this study may help inform trauma care guidelines by providing evidence on the potential long-term consequences of prolonged tourniquet use and by identifying modifiable risk factors for chronic pain after severe limb trauma.

Inclusion Criteria:

• Age ≥18 years
• Severe upper or lower limb trauma
• Documented tourniquet use (prehospital or in-hospital)
• Available documentation of tourniquet duration
• Informed consent

Exclusion Criteria:

• Pre-existing chronic limb pain
• Known severe peripheral neuropathy
• Cognitive inability to complete follow-up
• Expected survival <48 hours

The study population will include adult patients (≥18 years) with severe upper or lower limb trauma who required tourniquet application for hemorrhage control in the prehospital or hospital setting. Participants will be recruited from trauma centers treating combat-related and civilian traumatic injuries. Eligible patients must have documented tourniquet use and available information on tourniquet duration. The cohort will include patients undergoing limb salvage as well as those requiring primary or secondary amputation. Participants will be followed prospectively to assess the relationship between tourniquet exposure and the development of persistent pain and functional outcomes.

Individual participant data (IPD) will not be publicly shared due to ethical, legal, and security considerations related to sensitive clinical data from trauma patients, including those with combat-related injuries. Data may contain potentially identifiable health information and details associated with military trauma. De-identified aggregated data may be shared upon reasonable request and subject to approval by the study investigators and institutional ethics committees, in accordance with institutional policies and applicable data protection regulations.