Heparin is a widely used anticoagulant for thrombosis prevention, and low molecular weight heparin (LMWH) has become the preferred option due to its higher bioavailability, strong antithrombotic effect, and lower risk of complications. However, subcutaneous LMWH injections-commonly administered in the abdomen, arm, or thigh-often cause local side effects such as pain, ecchymosis, and hematoma. The incidence of ecchymosis after injection ranges between 26-89%, and various factors such as injection site, needle size, injection duration, and techniques can influence these outcomes. Cold application is frequently used to reduce injection-related pain and bruising by inducing vasoconstriction, decreasing nerve conduction, and increasing pain tolerance.

In orthopedic surgery patients, limited injection sites due to dressings, casts, or splints may increase the risk of repeated bruising and pain. Although cold compresses have been studied in reducing injection-related complications, no research has evaluated the effect of cold spray prior to LMWH administration in this patient group. Therefore, standardized studies are needed to determine whether cold spray is an effective, practical alternative for reducing pain and ecchymosis following LMWH prophylaxis after orthopedic surgery.

Heparin is an anticoagulant used in the surgical prevention of thrombosis and can prevent and treat venous thrombosis by rapidly achieving its anticoagulant effects. Low molecular weight heparin (LMWH), a relatively new anticoagulant developed in the 1970s, has the advantages of high bioavailability, potent antithrombotic effect, a low risk of heparin-induced thrombocytopenia, and fewer bleeding side effects. Therefore, LMWH is increasingly used in clinical practice. Venous thromboembolism is a common complication during and after hospitalization in medical and surgical patients, including orthopedic patients. Without any prophylaxis, the incidence of fatal pulmonary embolism in hospitalized patients is 0.1-0.8% after elective general surgery, 2-3% after elective hip replacement, and 4-7% after hip fracture surgery. Therefore, patients receive heparin for several days or weeks from hospital admission until discharge.

Nurses, in their therapeutic role, administering medications is one of the most fundamental nursing functions requiring knowledge and skill.The basis of medication administration is to ensure patient safety, enhance the beneficial effects of the medication, prevent complications, and increase individual satisfaction and comfort.

The primary route of administration for low molecular weight heparin (LMWH) is subcutaneous injection into the abdominal area, midline of the triceps muscle, or lateral thigh. This method is preferred due to its easy accessibility and slow absorption of the medication. However, local side effects such as pain, ecchymosis (26.6%-88.9%), hematoma (40%-88%), and, in rare cases, tissue sclerosis can occur. Post-injection ecchymosis often occurs between 48 and 72 hours. Factors affecting the pain and bruising caused by subcutaneous injection of LMWH may include injection time; different injection sites; LMWH dose; needle size; slow delivery of heparin to tissues; use of the aspiration airlock technique; and cold application. Cold application has been frequently used to prevent injection-related pain and ecchymosis. In cold applications, when the skin temperature drops to 15 °C, vasoconstriction develops in superficial vessels, and vasodilation develops as the temperature drops even lower. Cold application reduces muscle spasm by slowing down the conduction properties of peripheral nerves and increases pain tolerance. Additionally, vasoconstriction resulting from cold application can reduce blood flow to the tissue, reducing bruising and hematoma formation.

After orthopedic surgery, patients are applied a dressing, bandage, cast, or splint, and post-traumatic bruising or ecchymosis can occur in many areas of the skin. Therefore, injection sites are limited, making rotation between these areas difficult. Using the same area can lead to the formation of new ecchymosis and increased pain sensitivity in the area. There are no studies in the literature on the effects of cold spray applied before SC LMWH application after orthopedic surgery. A more standardized and practical study is needed to evaluate the effects of cold spray on pain and ecchymosis, which can be achieved with cold compresses instead of cold compresses.

Inclusion Criteria:

Patients who are:

• 18 years of age or older
• Receiving 1 x 0.4 ml anticoagulant therapy
• Are on the first day of LMWH therapy
• Have no infection, scar tissue, lipodystrophy, or incision at the injection site
• Have not received any other parenteral therapy at the injection site
• Are not allergic to cold or heparin
• Volunteer to participate in the study

Exclusion Criteria:

• Patients were excluded from the study if they were: • Pregnant, • Had any acute or chronic coagulation disorder or hematological disease,

  • Had a subcutaneous injection into the same area 24 hours prior,
  • Wanted to withdraw from the study.

The study employed a single-blind design. To prevent bias in the analysis of the research data, blinding was also applied to the outcomes assessor and statistician. The care provider and researcher in the study were composed of different individuals. When coding the research data, the study groups were coded as A and B, preventing the statistician from knowing which letter represented which group.