Choose the site for insertion: the jugular and femoral veins carry less bleeding risk and low risk of pneumothorax; the subclavian vein is a cleaner site and is technically more difficult – we have not covered the technique here. The femoral vein is probably the easiest site. Put on your gloves and gown. Clean and drape the site.
Tilt the head end of the bed down by 10°–15°.
Draw up 10 ml of lidocaine; raise a bleb on the skin with a 27-gauge needle.
Infiltrate local anesthetic all around the site, working down toward the vein. Pull back on the plunger before injecting each time to ensure that you don't inject into the vein.
Have the assistant open the central line pack and take all of the items out. Ensure that the wire moves freely on its reel – you will need to advance the wire one-handed.
Flush each port of the central line with saline or heparin saline, and close off each line except the distal (usually brown) line; the wire threads through this line.
Attach a syringe to the large needle provided, and then proceed as follows:
– right femoral line: find the arterial pulse and enter the skin 1 cm medial to this, at a 45° angle to the vertical and heading parallel to the artery. Advance slowly, aspirating all the time, until you enter the vein (Fig. 14)
– right jugular line: palpate the carotid artery with your left hand, covering the artery with your fingers. Insert the needle 0.5–1 cm laterally to the artery, aiming at a 45°angle to the vertical. In men, aim for the right nipple; in women, aim for the iliac crest. Advance slowly, aspirating all the time, until you enter the vein (Fig. 15). If you fail to aspirate blood after entering 3–4 cm, withdraw, re-enter at the same point, but aim slightly more medially
When the needle is in the vein, ensure that you can reliably aspirate blood. Remove the syringe, keeping the needle very still, and immediately put your thumb over the end of the needle.
Insert the wire into the end of the needle, and advance the wire until at least 30 cm are inserted. The wire should advance very easily – do not force it.
Keeping one hand on the wire at all times, remove the needle, keeping the wire in place. Make a nick in the skin where the wire enters the skin. Insert the dilator over the wire and push into the skin as far as it will go. Remove the dilator.
Fig. 14 Femoral artery sampling.
Fig. 15 Placing a central line. Insert the needle lateral to the carotid artery, aiming for the right nipple in men or the anterior superior iliac spine in women. (Adapted from Sprigings, D., Chambers, J., and Jeffrey, A. Acute Medicine, 2nd edition. 1995, Blackwell Science)
Insert the central line over the wire. Keep one hand on the wire at all times. When the central line is 2 cm away from the skin, slowly withdraw the wire back through the central line until the wire tip appears from the line port. Hold the wire here while you insert the line. Leave a few centimeters of the line outside the skin. Withdraw the wire and immediately clip off the remaining port.
Attach the line to the skin with sutures. Tie loosely so as not to pinch the skin; this causes necrosis and detachment of the line. Clean the skin around the line once more, dry, and cover with occlusive dressings.
Ensure that you can aspirate blood from each lumen of the line, then flush each lumen with saline or heparin saline.
Order a chest x-ray to check for line position and pneumothorax if a jugular or subclavian line has been inserted. Femoral lines do not require an x-ray.
Cannot cannulate the vein: try another site. If you have access to a portable ultrasound device, try using it.
Arterial puncture: this is not always obvious, especially in shocked, hypoxic patients, when the blood can be dark and flow sluggishly. If you do hit an artery, remove the needle and press firmly for 5 minutes with a gauze pad.
Vein cannulated but wire fails to advance: sometimes veins are small, tortuous, or occluded (e.g., by thrombus from previous cannulation attempts). Do not force the wire; try another site.
Line in wrong place: occasionally, lines double back on themselves or subclavian lines go up into the jugular. If this occurs, either remove the line and start again or, if you have access to fluoroscopic guidance, try to reinsert the wire, remove the line, and reposition the wire.
Beware of using too much local anesthetic on multiple line insertions; the maximum dose should not really exceed 3–5 mg/kg(e.g., 10–15 ml of 2% lidocaine for a 70-kg patient).
Central lines do not cure patients. They take longer to put in than you think and often require the patient to lie flat with drapes on the head for some time. Make sure that you are treating the patient's condition as well as inserting a central line.