Peripheral intravenous catheters (PIVCs) are widely used invasive devices in hospital settings and are associated with a broad range of complications, among which infiltration is one of the most common and clinically significant. Infiltration, defined as the leakage of intravenous fluids or medications into surrounding tissues, may result in local tissue damage, pain, infection, delayed treatment, and increased healthcare costs. Despite its high prevalence and impact on patient safety, early recognition and appropriate management of infiltration remain challenging, particularly among nursing students.

Conventional educational approaches that rely predominantly on theoretical instruction may be insufficient to develop the clinical reasoning and decision-making skills required for timely identification and management of such complications. Therefore, there is a growing emphasis on the use of innovative, learner-centered educational strategies that promote active participation and experiential learning.

Simulation-based education, including in situ simulation and standardized patient methodologies, has been shown to provide realistic, safe, and effective learning environments that enhance both technical and non-technical skills. In situ simulation enables training within real clinical settings using existing resources and team structures, while standardized patients facilitate the development of communication, clinical assessment, and decision-making competencies.

This randomized controlled trial aims to evaluate the effectiveness of standardized patient and in situ simulation-based training, compared with traditional teaching methods, in improving nursing students' ability to recognize PIVC-related infiltration and enhance their clinical decision-making skills. Secondary outcomes include learning satisfaction and self-confidence.

By integrating evidence-based simulation approaches into nursing education, this study seeks to strengthen clinical competence and contribute to improved patient safety outcomes.

Peripheral intravenous catheters (PIVCs) are among the most commonly used invasive devices for delivering intravenous therapy in hospital settings. PIVC insertion is one of the most frequently performed invasive procedures under the responsibility of nurses and is associated with a wide range of complications. These complications include phlebitis, infiltration, extravasation, pain, local infection, ecchymosis, hematoma, thrombophlebitis, embolism, and pulmonary edema.

Among these, infiltration is one of the most prevalent complications and is characterized by the leakage of intravenous fluids or medications into surrounding tissues. This condition may result in local tissue damage, pain, infection, delayed treatment, and increased healthcare costs. The incidence of infiltration has been reported to range between 13% and 20%, representing a substantial burden on both patient outcomes and healthcare systems. Furthermore, PIVC-related complications are considered to be more extensive than currently reported, with estimates suggesting that up to 70-90% of patients with PIVCs may experience complications that can prolong hospital stays by up to 22 days. These complications negatively affect patient comfort, contribute to unnecessary diagnostic and therapeutic interventions, delay treatment processes, increase healthcare costs, elevate patient stress levels, and intensify the workload of healthcare professionals.

In this context, early recognition of infiltration and the development of clinical decision-making skills among nursing students are critical for ensuring patient safety. Traditional educational approaches that primarily focus on theoretical knowledge are increasingly being recognized as insufficient for preparing students to manage complex clinical situations. Consequently, there is a growing need for realistic, interactive, and learner-centered educational strategies that support early identification of complications and appropriate clinical decision-making.

Simulation-based education has emerged as an effective approach for improving patient safety-related outcomes. One cost-effective and contextually relevant form of simulation is in situ simulation, which is conducted in real clinical environments such as hospital units or other healthcare settings. In situ simulation is a team-based training method that utilizes existing equipment and involves actual healthcare team members, thereby enhancing realism and system-level awareness. Beyond improving individual technical and non-technical skills, such as communication and teamwork, in situ simulation also enables the identification of latent system vulnerabilities that may contribute to medical errors.

Simulation-based learning provides a safe environment that minimizes patient harm while facilitating the development of clinical competencies. In addition, standardized patients-trained individuals who accurately simulate real patient scenarios-are widely used for educational, assessment, and research purpos. This method has been shown to enhance students' communication skills, practical competencies, professional attitudes (including empathy), and clinical decision-making abilities, ultimately contributing to improved patient outcomes.

This study is grounded in the recognition that infiltration, although common, is often detected late in clinical practice and cannot be effectively addressed through theoretical instruction alone. Given its direct impact on patient safety, the inability of nursing students to adequately recognize and manage this complication highlights the need for a strategic transformation in educational approaches.

Accordingly, this study aims to evaluate the effectiveness of innovative, learner-centered educational models-specifically standardized patient and in situ simulation-compared to traditional teaching methods, in enhancing nursing students' ability to recognize infiltration and improve their clinical decision-making skills. By doing so, the study seeks to contribute to the advancement of nursing education and support the development of competent, safety-oriented future nurses.

Research Hypotheses H1: Nursing students who receive training through standardized patient or in situ simulation methods will demonstrate higher levels of knowledge in recognizing infiltration compared to those receiving traditional education.

H2: Nursing students who receive training through standardized patient or in situ simulation methods will achieve higher clinical decision-making scores compared to those receiving traditional education.

H3: Nursing students who receive training through standardized patient or in situ simulation methods will report higher levels of learning satisfaction and self-confidence compared to those receiving traditional education.

Inclusion Criteria:

• First-year undergraduate nursing students at the Faculty of Nursing
• Students enrolling in the "Fundamentals of Nursing" course for the first time
• Students who gave informed consent and agreed to participate in the study voluntarily.

Exclusion Criteria:

• Students reviewing the "Fundamentals of Nursing" course
• Students who refused to participate in the study