Frailty and Ultrasound-Guided Central Venous Catheterization Difficulty in Adult Cardiac Surgery Patients

Inclusion Criteria * Adults aged 18 years or older. * Scheduled for elective cardiac surgery. * Planned ultrasound-guided internal jugular vein catheterization as part of routine perioperative care. * Able to undergo preoperative frailty assessment using the Clinical Frailty Scale (CFS). * Able to perform handgrip strength measurement. * Able to undergo ultrasound assessment of the internal jugular vein. * Provided written informed consent. Exclusion Criteria Conditions Affecting Neck Anatomy 1. Previous neck surgery. 2. History of radiotherapy to the neck region. 3. Presence of a neck mass, infection, or any lesion that may distort neck anatomy. 4. Known internal jugular vein thrombosis. 5. Congenital vascular anomalies causing significant alteration of the internal jugular vein or carotid artery anatomy. Clinical Conditions Affecting Catheterization 1. Patients requiring emergency cardiac surgery. 2. Presence of an existing central venous catheter. 3. Severe coagulopathy (INR \> 2.0 or platelet count \< 50,000/mm³). 4. Hemodynamic instability or requirement for active cardiopulmonary resuscitation. Conditions Affecting Frailty and Handgrip Strength Assessment 1. Severe neurological disorders (e.g., advanced dementia or disabling sequelae of stroke). 2. Orthopedic or neuromuscular disorders affecting upper extremity function. 3. Inability to perform handgrip strength measurement due to severe arthritis or hand deformity. Conditions Affecting Study Participation 1. Cognitive impairment preventing reliable clinical assessment or informed participation. 2. Refusal to participate in the study. 3. Any other condition that, in the investigator's judgment, may compromise patient safety or interfere with study participation.