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Procedural Skills (SLO6)
Question 101 of 141
Whilst on your ITU rotation, you are asked to perform central venous cannulation on a patient with sepsis. Which of the following is an advantage of using the subclavian vein site compared to the internal jugular vein site?
Answer:
Subclavian vein advantages:- Easier to maintain dressings
- More comfortable for patient
- Better landmarks in obese patients
- Accessible when airway control is being established
- Lower rates of infection, comfortable, leaves SVC available for other lines, good flow rates for dialysis
Central Venous Cannulation
Procedural Skills (SLO6)
Last Updated: 13th April 2023
Indications
- Inadequate peripheral venous access
- Unable to obtain or complex infusion regimen
- Peripherally incompatible infusions
- Long-term intermittent or continuous administration of medications such as vasopressors, chemotherapy and parenteral nutrition are typically administered by central venous catheters because they can cause phlebitis when given peripherally)
- Haemodynamic monitoring
- Central venous access permits measurement of central venous pressure, venous oxyhaemoglobin saturation (ScvO2), and cardiac parameters.
- Extracorporeal therapies
- Large-bore venous access is required to support high-volume flow required for many extracorporeal therapies, including renal replacement therapy (e.. haemodialysis) and plasmapheresis.
Contraindications (relative)
- Coagulopathy and/or thrombocytopaenia
- Site-specific considerations
- Cannulation is generally avoided at sites with anatomic distortion or other indwelling intravascular hardware, such as a pacemaker or haemodialysis catheter. Vascular injury proximal to the insertion site represents another relative contraindication.
Site of insertion
The most appropriate site for central venous cannulation is selected with the use of ultrasound in addition to the expertise and skill of the operator, patient anatomy (e.g. known venous occlusion, presence of lymphoedema), risks associated with placement (e.g. coagulopathy, pulmonary disease), and access needs (e.g. patient needs and duration of catheter use). Specific veins (jugular, subclavian, femoral) and access approaches have inherent advantages and disadvantages.
| Site | Advantages | Disadvantages |
|---|---|---|
| Internal jugular vein |
|
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| Subclavian vein |
|
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| Femoral vein |
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Clinical anatomy
- Internal jugular vein
- The primary surface landmarks for internal jugular cannulation relate to the borders of the sternocleidomastoid muscle, which are accentuated by muscle flexion (asking the patient to raise the head off the bed), or turning the head away from the access vein. Palpation of the two origins of the sternocleidomastoid muscle (ie. sternal and clavicular heads) defines a triangular gap just above the medial clavicle. The medial sternal head is more easily palpated than the broad, flat clavicular head. The vein normally courses deep to the muscle and emerges along the medial border of the clavicular head.
- Subclavian vein
- The clavicle is the primary surface landmark for subclavian cannulation. Moving laterally from the suprasternal notch, the bulky sternal head takes an elongated S-shape (a double curve in the horizontal plane); the medial two-thirds are convex anteriorly, and the lateral third is concave anteriorly. The anterior convexity at the junction of the medial and middle thirds is known as the "bend" or "break" in the clavicle and serves as an important palpable landmark. The subclavian vein is the direct continuation of the axillary vein beginning at the lateral border of the first rib. The vein arches cephalad behind the medial clavicle and then slopes caudally to join the internal jugular vein to form the brachiocephalic (innominate) vein posterior to the sternoclavicular joint. The vein is accompanied by the subclavian artery located superior and posterior to the vein and separated from the vein by the anterior scalene muscle.
- Femoral vein
- The femoral vein is located by palpating the femoral artery pulsation; the femoral vein lies directly medial to the femoral artery within the femoral sheath. The femoral artery can be palpated in the femoral triangle (bounded superiorly by the inguinal ligament, laterally by the sartorius muscle and medially by the medial border of the adductor longus muscle) as it passes over the femoral head, just inferior to the inguinal ligament, midway between the anterior superior iliac spine and the pubic symphysis (at the mid-inguinal point). The surface anatomy of the femoral vein is identified by palpating the point of maximal pulsation of the femoral artery immediately below the level of the inguinal ligament and marking a point approximately 0.5 cm medial to this pulsation.
Procedure
- Preparation:
- Informed consent
- Patient monitoring (including continuous cardiac rhythm and pulse oximetry; supplemental oxygen should be immediately available)
- Patient positioning (to optimise comfort and cardiopulmonary stability; Trendelenburg position facilitates venous filling for jugular and subclavian access and may reduce the risk of venous air embolism but may not be tolerated by critically ill and obese patients)
- Sterile technique
- Site preparation (including hair clipping)
- Skin antisepsis
- Analgesia and sedation
- Use of ultrasound:
- Precannulation vein assessment
- Before cannulation, routine bedside ultrasound by the provider placing the access can evaluate venous patency and aid in selecting the most appropriate site of access and is particularly useful in patients who have a history of prior instrumentation or deep vein thrombosis in the region of the proposed access site.
- Real-time dynamic guidance
- Real-time dynamic ultrasound (i.e. imaging during needle placement) reduces time to venous cannulation and the risk of complications.
- Detection of complications
- Ultrasound assists with early detection of arterial and venous guidewire malposition and identification of procedurally related pneumothorax.
- Precannulation vein assessment
- General technique (for non-tunneled central catheter):
- Obtain the equipment and devices needed for catheter placement.
- Prepare (consent, sedation) and position the patient. Confirm location and patency of the target vein with pre-procedure ultrasound, if available.
- Pause for a procedural time-out to verify the procedure, site, and technique.
- Using sterile technique, prepare the skin and drape the patient.
- Identify pertinent anatomic landmarks, even if ultrasound is used. Reconfirm the vein with ultrasound.
- Infiltrate the skin with local anaesthetic (e.g. 1% lidocaine)
- Cannulate the vein using dynamic ultrasound imaging via standard introducer needle, micropuncture needle or angiocatheter.
- Insert the guidewire into the vein through the access needle or angiocatheter. Confirm the intravenous guidewire via ultrasound.
- Maintain awareness of guidewire depth during insertion. In the absence of fluoroscopy, the guidewire should only be inserted just beyond the anticipated catheter depth, avoiding intracardiac advancement.
- Maintain telemetry monitoring to identify arrhythmias induced by the guidewire.
- Remove the needle or angiocatheter while controlling the guidewire.
- Make a single small stab incision in the skin at the puncture site adjacent to the guidewire.
- Advance the tissue dilator over the guidewire into the vein, taking care to control the guidewire, then remove the tissue dilator.
- Thread the catheter over the guidewire, taking care to control the guidewire.
- Remove the guidewire, taking care to control the catheter.
- Sequentially aspirate blood from each access hub and flush with saline to ensure a functioning catheter.
- Secure the catheter into place and dress the site using sterile technique.
- Confirm the position of the tip of the catheter with chest radiography (for jugular and subclavian approaches only).
- Catheter management:
- Management of central venous catheters is aimed at preventing catheter infection and thrombosis and handling mechanical complications.
- Proper catheter maintenance involves minimising the duration of temporary catheter access, performing routine catheter site inspections, periodically changing the catheter site dressing, using aseptic technique when handling catheters, and changing the catheter, when indicated.
- Catheter lumen thrombosis may be reduced using catheter lock solutions, and when thrombosis occurs, thrombolytic therapy may restore lumen patency.
Complications
- Immediate
- Bleeding
- Arterial puncture
- Arrhythmia
- Air embolism
- Thoracic duct injury
- Catheter malposition
- Pneumothorax or haemothorax
- Delayed
- Infection (local or systemic)
- Venous thrombosis, pulmonary emboli
- Venous stenosis
- Catheter malfunction
- Catheter migration
- Catheter embolisation
- Myocardial perforation
- Nerve injury
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
