central line

**Definition and types** - A central venous catheter (CVC) ends in a central vein: the SVC at or near the cavoatrial junction, the right atrium, or the IVC. - Non-tunneled CVC: placed percutaneously for short-term ICU or acute use. Sites are the internal jugular (IJ), subclavian, and femoral veins. - Tunneled catheters (Hickman, Broviac, tunneled dialysis catheters): the tract is tunneled under the skin, and a Dacron cuff reduces infection. Used for long-term therapy. - Implanted port (Port-a-Cath): a subcutaneous reservoir, commonly used for chemotherapy. - PICC (peripherally inserted central catheter): inserted via the basilic, brachial, or cephalic vein, with the tip in the SVC. Used for intermediate-term therapy.

**Indications** - Vasopressors and inotropes (norepinephrine, dopamine) - Caustic or vesicant drugs, hyperosmolar solutions, TPN, and chemotherapy - Hemodialysis or plasmapheresis access - Poor peripheral access or long-term IV therapy - CVP monitoring, pulmonary artery catheter (Swan-Ganz) introduction, and transvenous pacing

**Site selection (high-yield)** - IJ: preferred for many ICU placements. It is compressible and gives ultrasound-guided access. It has a lower pneumothorax risk than the subclavian. - Subclavian: lowest infection risk and the most comfortable for patients. It has the highest pneumothorax risk and is non-compressible, so avoid it in coagulopathy. - Femoral: easiest in emergencies or during CPR. It has the highest risk of infection and DVT, so avoid it when possible.

**Technique** - Use real-time ultrasound guidance and the Seldinger technique: needle → guidewire → dilator → catheter over the wire. - Maximal sterile barrier precautions: cap, mask, sterile gown, gloves, and a large drape. Use chlorhexidine skin prep. - Always keep control of the guidewire to prevent it from being lost in the vessel. - Confirm placement: aspirate blood, check ultrasound or CXR, and look for pneumothorax. The tip should be at the lower SVC or cavoatrial junction. - Place the patient in Trendelenburg for IJ and subclavian insertion to increase venous pressure and reduce air embolism risk.

**Complications** - Mechanical: - Pneumothorax or hemothorax (subclavian > IJ) - Arterial puncture (carotid or femoral) and hematoma - Air embolism (sudden dyspnea, hypotension, "mill-wheel" murmur; treat with left lateral decubitus and Trendelenburg) - Arrhythmias if the wire or catheter enters the right atrium or ventricle - Cardiac tamponade or perforation - Thoracic duct injury (left-sided approaches) - Retained guidewire - Infectious (CLABSI, central line-associated bloodstream infection): - Common organisms are coagulase-negative staphylococci (S. epidermidis), S. aureus, Candida, and gram-negative rods. - Diagnose with paired blood cultures (peripheral and catheter) or differential time to positivity. - Treat with antibiotics and usually line removal, especially for S. aureus, Candida, or Pseudomonas. - Prevention: hand hygiene, chlorhexidine, maximal barrier precautions, avoiding the femoral site, daily review of line necessity, and prompt removal. - Thrombotic: catheter-related DVT (especially PICC and femoral lines) and SVC syndrome from chronic thrombosis or stenosis.

**Clinical pearls** - Check a CXR after IJ or subclavian placement to confirm tip position and exclude pneumothorax. This is not needed for ultrasound-confirmed femoral lines. - Fever in a patient with a central line: get cultures and suspect CLABSI. - Never infuse through a line until blood return is confirmed and placement is verified. - Normal CVP is about 2–8 mmHg. It reflects right atrial pressure and is used to estimate preload, though it is a poor predictor of fluid responsiveness. - Anatomy for boards: the IJ lies lateral to the carotid within the carotid sheath, and the apex of the lung lies behind the subclavian vein. Femoral NAVEL from lateral to medial: Nerve, Artery, Vein, Empty space, Lymphatics.