Makindo Medical Notes

Ultrasound 2D guidance is strongly recommended for central venous line insertion in both elective and emergency situations. It aids in identifying local vascular anatomy, significantly reducing the failure rate, complications, and the number of attempts needed for successful access.

Precautions

• Only trained and competent staff (or supervised trainees) should perform this procedure to minimize risks and complications.

Indications

• Monitoring central venous pressure (CVP).
• Obtaining central venous blood gas measurements to guide fluid resuscitation.
• When peripheral venous access is not possible or fails.
• Administration of drugs such as inotropes, antiarrhythmics, chemotherapy, or total parenteral nutrition (TPN).
• For procedures such as haemodialysis, plasmapheresis, or temporary cardiac pacing.

Contraindications

• Agitated or uncooperative patients where maintaining a sterile field is difficult.
• Uncorrected bleeding disorders (e.g., anticoagulation therapy, post-thrombolysis) without appropriate reversal.
• Local infection or skin burns at the intended puncture site.
• Pneumothorax or haemothorax on the contralateral side or in patients with only one functioning lung.
• Some of these are relative contraindications, and senior advice should be sought if the procedure is urgent.

Choosing a Vascular Access Site

• Selection depends on the indication, the risk of complications, and the operator's experience. Central veins are deep, and access is typically gained without direct vision, increasing the risk of complications if performed by inexperienced staff.
• Successful catheterization via the internal jugular or subclavian vein requires a thorough understanding of neck anatomy and the use of ultrasound for guidance.
• Internal Jugular Vein: Located at the apex of the triangle formed by the heads of the sternocleidomastoid muscle and the clavicle. It is preferred for its compressibility, but there is a risk of arterial puncture and pneumothorax.
• Subclavian Vein: Crosses under the clavicle just medial to the midclavicular point. It is not compressible, which increases the risk of bleeding complications and pneumothorax.
• Femoral Vein: Located medially to the femoral artery. The "NAVY" acronym (Nerve, Artery, Vein, Y-fronts) helps identify its anatomy. While the femoral vein is more compressible, it carries a higher risk of infection, particularly in long-term use, and ultrasound is less helpful in this area.

Internal Jugular Vein Considerations

• This vein is compressible, making it advantageous in bleeding scenarios. However, arterial puncture is possible, and there is a risk of pneumothorax or haemothorax.
• The patient is positioned head down (Trendelenburg) to distend the vein, but this position may exacerbate cardiac or respiratory failure.

Subclavian Vein Considerations

• The subclavian vein is not compressible if bleeding occurs, making it a higher-risk option. The risk of pneumothorax or haemothorax is also present.
• Positioning the patient head down can improve access but may negatively affect cardiac or respiratory function in certain patients.

Femoral Vein Considerations

• Highly compressible, which is useful in managing bleeding, but this site carries a greater infection risk compared to internal jugular or subclavian approaches.
• Ultrasound is less effective for this vein, but positioning the patient head up can help alleviate cardiac and respiratory distress during the procedure.

Equipment Required

• Central venous catheters (CV catheters) typically 20 cm long for subclavian or internal jugular access.

Procedure Technique

• Explain the procedure to the patient and obtain informed consent.
• Position the patient in the Trendelenburg position (head down, feet up) for internal jugular or subclavian access to enhance venous return. For femoral access, place the patient supine.
• Use full sterile technique, including sterile gown, gloves, mask, cap, and sterile ultrasound probe cover. Prepare the area with an appropriate disinfectant and apply sterile drapes.
• Infiltrate the puncture site with 1-2% lidocaine/lignocaine for local anesthesia. The artery is usually medial to the vein, smaller, and pulsatile; unlike the vein, it is non-compressible.
• Insert the needle under ultrasound guidance while applying negative pressure to the syringe. When venous blood is aspirated, proceed with the Seldinger technique: insert the guidewire through the needle, then withdraw the needle, leaving only the guidewire in place.
• Advance the catheter over the guidewire and remove the guidewire. A post-procedure chest X-ray is necessary to confirm catheter position and to rule out pneumothorax.

Complications

• Malposition of the catheter.
• Air embolism.
• Bleeding or hematoma formation.
• Catheter embolism or breakage.
• Arterial puncture and thrombosis.
• Pneumothorax or haemothorax.
• Cardiac tamponade.
• Sepsis or infection at the catheter site.
• Cardiac arrhythmias during catheter insertion.

Central Venous Pressure (CVP) Monitoring

• CVP is measured in cm H₂O above a point level with the right atrium. Normal CVP is between 0-8 cm H₂O, measured with the patient lying flat.
• A fluid challenge of 250 ml of colloid over 15 minutes is used to assess hypovolaemia. If the CVP increases by less than 5 cm H₂O or is not sustained for more than 10 minutes, this suggests hypovolaemia.
• Serial CVP measurements are more useful than single readings. Consider anatomical variants such as tricuspid regurgitation, which can alter baseline CVP readings.