Central venous catheter - use

1. Central venous catheter - use Type of catheter • Single double or triple lumen. • Sheaths for insertion of pulmonary artery catheter or pacing wire • Tunnelled catheter for long term use. • Triple lumen catheters allow multiple infusions given separately + continuous pressure monitoring. Minimizes risk of accidental bolus • 12Fr double lumen catheters used for venovenous dialysis/filtration. • Common routes are internal Jugular, subclavian and femoral. • Long catheters can be inserted via medical brachial or axillary veins though are generally not recommended due to the risk of thrombosis.

2. Uses • Invasive haemodynamic monitoring. • Infusion of drugs liable to cause peripheral phlebitis or tissue necrosis if tissue extravasation occurs (e.g. TPN, dopamine, amiodarone). • Rapid volume infusion, n.b. the rate of flow is inversely proportional to the length of the cannula. • Access, e.g. for pacing wire insertion. • Emergency access when peripheral circulation is ‘shout down’. • Renal replacement therapy, plasmapheresis, exchange transfusion.

3. Contraindications / cautions • Coagulopathy • Undrained pneumothorax on contralateral side • Agitated, restless patient. Complications • Arterial puncture • Haemorrhage • Arrhythmias. • Infection (Usually skin, occasionally sepsis or endocarditis). • Pneumothorax. • Air embolism, venous thrombosis, haemothorax, chylothorax (all rare).

4. Central venous pressure measurement • Use of an electronic pressure transducer is preferable to manometry which incorporates a three way tap, a fluid reservoir bag and a fluid filled vertical column, the height of which corresponds to CVP. • The pressure transducer should be placed and ‘zeroed’ at the level of the left atrium (approximately mid-axillary line) rather than the sternum which is more affected by patient position (supine/semi-erect/prone). • Venous pulsation and some respiratory swing should be seen in the trace but not a RV pressure waveform (i.e. catheter inserted too far).

5. Troubleshooting • Excessive bleeding at the insertion site is usually controlled by direct compression. • If not controlled, correct any coagulopathy, If post-thrombolysis, consider tranexamic acid. • The incidence of local infection (usually Staph. Epidermidis or Staph. Aureus) rises > 5 days. • Routine change of catheter at 5 days is not necessary though change over a wire may be sufficient if patient develops and unexplained pyrexia or neutrophilia. • However, removal + change of site is needed if site is cellulitic or blood cultures taken through the catheter are psoitive.

6. Central venous catheter - insertion Landmarks Various landmarks have been described. For example : • Internal jugular : Halfway between mastoid process and sternal notch, lateral to carotid pulsation and medial to medial border of sternocleidomastoid. Aim toward ipsilateral nipple, advancing under body of sternocleidomastoid until vein entered. • Subclavian : 3cm below junction of lateral third and medial two thirds of clavicle. Turn head to contralateral side. Aim for point between jaw and contralateral shoulder tip. Advance needle subcutaneously to hit clavicle. Scrape needle around clavicle and advance further until vein entered. • Formal : Locate femoral artery in groin. Insert needle 3 cm medially and angled rostrally. Advance until vein entered.

7. Insertion technique The Seldinger technique (described below is safer than the “catheter-over-needle” technique and should generally be used in ICU patients. • Use aseptic technique troughout. Clean area with antiseptic and surround with sterile drapes. Anaesthetise local area with 1% lignocaine. Flush lumen(s) of catheter with saline. • Use metal needle to locate central vein. • Pass wire (with ‘J’ or floppy end leading) through needle into vein. Only minimal resistance at most should be felt. If not remove wire and confirm needle tip is till locate within vein lumen. Monitor for arrhythmias. If these occure, wire is probably at tricuspid valve. Usually responds to pulling wire back a few cm.

8. Remove needle leaving wire extruding from skin puncture site. • Depending on size/type of catheter to be inserted, a rigid dilator (+ preceded by a scalpel incision to enlarge puncture site) may be passed over the wire to form a track through the subcutaneous tissues to the vein. Remove dilator. • Thread catheter over wire. Ensure end of wire extrudes from catheter to prevent accidental loss of wire in vein. Insert catheter into vein to depth of 15-20cm. Remove wire. • Check for flashback of blood down each lumen and respiratory swing, then flush with saline. • Suture catheter to skin. Clean and dry area. Cover with sterile transparent semi-permeable dressing. • A chest X ray is usually performed to very correct position of tip (junction of superior vena cava & right atrium ) and to exclude a pneumothorax. Unless in an emergency situation, a satisfactory position should generally be confirmed before use of the catheter.