This prospective observational study aims to evaluate the association between preoperative frailty and the procedural difficulty of ultrasound-guided internal jugular vein catheterization in adult patients undergoing elective cardiac surgery.

Frailty will be assessed using the Clinical Frailty Scale and handgrip strength measurements. Preprocedural ultrasound evaluation will include internal jugular vein anatomical characteristics such as anteroposterior and transverse vein diameters, cross-sectional area (CSA), common carotid artery diameter, skin-to-vein distance, overlap status, and sternocleidomastoid muscle thickness Catheterization difficulty will be assessed using the Gaber Procedural Difficulty Index.

The study seeks to determine whether frailty and ultrasound-derived anatomical parameters can predict difficult internal jugular venous catheterization and improve preprocedural risk assessment without altering routine clinical care.

Central venous catheterization via the internal jugular vein is routinely performed in adult cardiac surgery patients for perioperative hemodynamic monitoring and administration of vasoactive medications. Although ultrasound guidance has improved the success and safety of internal jugular vein catheterization, procedural difficulty still varies considerably among patients and may be influenced by patient-related factors beyond vascular anatomy.

Frailty is increasingly recognized as a marker of reduced physiological reserve and adverse perioperative outcomes. However, its relationship with the technical difficulty of ultrasound-guided internal jugular vein catheterization has not been well established. In addition to frailty, reduced muscle strength may reflect diminished physiological reserve and may be associated with anatomical characteristics influencing catheterization difficulty.

This prospective observational study aims to evaluate the association between preoperative frailty and the procedural difficulty of ultrasound-guided internal jugular vein catheterization in adult patients undergoing elective cardiac surgery. The study will also investigate the contribution of handgrip strength and preprocedural ultrasonographic characteristics of the internal jugular vein to catheterization difficulty.

Preoperative frailty will be assessed using the 9-point Clinical Frailty Scale (CFS), ranging from 1 (Very Fit) to 9 (Terminally Ill), with higher scores indicating greater frailty. Handgrip strength will be measured preoperatively using a calibrated hand dynamometer. Three measurements will be obtained from the dominant hand, and the mean value (kg) will be used for analysis. Low muscle strength will be defined according to the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) criteria as <27 kg for men and <16 kg for women.

Before catheterization, ultrasound evaluation of the internal jugular vein will include anteroposterior and transverse vein diameters, cross-sectional area (CSA), common carotid artery diameter, skin-to-vein distance, overlap status, and sternocleidomastoid muscle thickness. According to the study protocol, CSA will be categorized as <50 mm², 50-100 mm², and >100 mm².

Catheterization difficulty will be assessed using the Gaber Procedural Difficulty Score. The score is based on four procedural domains: number of puncture attempts (1-3 points), cannulation time (1-3 points), procedure-related complications (1-3 points), and procedural success (1-2 points). Higher total scores indicate greater procedural difficulty. Difficult catheterization will be defined as a Gaber Procedural Difficulty Score >4.

The primary aim of this study is to evaluate the relationship between preoperative frailty status and handgrip strength, and the difficulty of ultrasound-guided internal jugular vein catheterization in patients undergoing elective cardiac surgery. Catheterization difficulty will be assessed using the Gaber Procedural Difficulty Index, and difficult catheterization will be defined as a Gaber score >4.

Secondary Objectives:

1. To evaluate the relationship between preoperative frailty status and handgrip strength, and the ultrasonographic anatomical characteristics of the internal jugular vein.
2. To investigate the independent predictive role of ultrasonographically measured anatomical parameters of the internal jugular vein in the development of difficult catheterization.

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.

Adult patients (≥18 years) scheduled for elective cardiac surgery at Ankara Bilkent City Hospital who require ultrasound-guided internal jugular vein catheterization as part of routine perioperative care. Participants will undergo preoperative frailty assessment, handgrip strength measurement, and ultrasound evaluation of the internal jugular vein before catheterization.

This is a single-center academic observational study. Individual participant data (IPD) will not be shared publicly. Only de-identified aggregate study results will be reported in scientific publications.