Central venous access and its complications
Why examiners ask this
Every anesthesiologist places central lines, so the examiner tests whether I do it the way the ASA practice guideline describes and whether I know what to do when it goes wrong. The favorite question is the dilated carotid. It stresses application of knowledge (site choice, confirmation) and judgment (when not to pull the catheter).
The 60-second answer
I place a central line when I need vasopressors, reliable large-bore or multi-lumen access, central pressures, or a route for air aspiration. I choose the right internal jugular, larger and straighter to the vena cava, with real-time ultrasound because it raises success and lowers complications.1 I use full barrier precautions and chlorhexidine skin preparation, put the patient head down to fill the vein and prevent air entry, and I confirm venous placement before I dilate: by seeing the wire in the vein on ultrasound, or by manometry or a venous pressure waveform from the needle or a small catheter.1 I confirm the tip lies in the superior vena cava near its junction with the right atrium, and exclude pneumothorax, with a chest radiograph or ultrasound,1 and I watch for pneumothorax, arterial injury, air embolism, arrhythmia and, later, infection and thrombosis.
Decision points and the "why"
- Site — internal jugular for the best ultrasound view and compressibility; subclavian has the lowest infection rate but more bleeding and pneumothorax risk, and the puncture site under the clavicle cannot be compressed, so I avoid it in coagulopathy;2 femoral avoids the chest, at the cost of higher infection,3 and drugs given through it during CPR may not circulate above the diaphragm.3
- Ultrasound — the ASA guideline recommends it for the internal jugular; it shows the artery, a thrombosed vein and the overlap that makes a through-and-through puncture likely.
- Confirm before dilating — color of blood and pulsatility are unreliable in a hypotensive or hypoxemic patient; I need wire-in-vein on ultrasound, manometry or a transduced venous waveform, because dilating an artery is the harm I am trying to prevent.
- Trendelenburg and occluded hubs — negative intrathoracic pressure in a spontaneously breathing patient entrains air through an open needle; I keep every port closed and remove lines with the patient flat or head down, with an occlusive dressing.
- Wire depth and ectopy — I advance the wire only 10–15 cm from the right internal jugular and watch the ECG; ectopy means the wire is in the heart and I withdraw it until it stops.1 A pre-existing left bundle branch block matters, because a wire in the right ventricle can cause complete heart block.1
- Tip position — above the pericardial reflection, roughly at the level of the carina on the radiograph, because a tip in the atrium can erode the wall and cause tamponade.
- Infection bundle — hand hygiene, maximal barrier, chlorhexidine allowed to dry, a chlorhexidine dressing, avoid femoral when possible, and removal as soon as the line is no longer needed.1
The complication they will inject
After the line is in, the transduced waveform is arterial and the blood is pulsatile: a 7 French dilator and catheter are in the carotid. I do not pull it. I tell the surgeon and call vascular surgery, leave the catheter in place,1 and keep the patient anticoagulation-free while we plan. Removal with compression risks hematoma, airway compression, stroke and pseudoaneurysm; the vascular team removes it with open or endovascular repair. I check neurologic status, document, and disclose to the patient. The variant inject is a sudden fall in end-tidal CO2 and hypotension when a hub is left open: venous air embolism, which I treat with 100% oxygen, closing the hub, left-side-down head-down positioning and aspiration through the catheter. Prevention is inserting and removing lines with the site below the heart.1
Pitfalls that cost points
- Relying on blood color or lack of pulsation to confirm venous placement.
- Pulling a large-bore catheter out of an artery and holding pressure.
- Not looking at the ECG while passing the wire.
- Forgetting pneumothorax when an intraoperative patient becomes hypotensive after a subclavian attempt.
- Leaving a femoral line in for convenience after the case.
Rapid-why
Q: Why does needle-in-artery matter less than dilator-in-artery? A: A thin needle hole seals with compression; a 7–9 French dilator tear does not and needs surgical repair.
Q: Why do you ask about a left-sided line? A: The left internal jugular crosses the brachiocephalic vein at an angle, has a higher perforation risk, and the thoracic duct sits on the left.
Q: How does ultrasound help confirm the tip? A: Agitated saline flushed through the catheter appears in the right atrium within about 2 seconds on a subcostal view.
Q: Why can a CVP be normal in a hypovolemic patient? A: CVP is a pressure, not a volume, and venoconstriction and positive pressure raise it; trends and dynamic indices are more useful.
Numbers to know
| Item | Value |
|---|---|
| Insertion depth, right IJ | ~15–16 cm |
| Insertion depth, left IJ | ~18–20 cm |
| Insertion depth, right subclavian | ~15 cm (left 16–17 cm)2 |
| Pneumothorax, all central lines | ~1%, highest with subclavian3 |
| Tip position | Cavoatrial junction, at or just above the carina on the radiograph |
Links
- Pulmonary artery catheter: indications, waveforms, complications, Pneumothorax and tension pneumothorax, Venous air embolism and the sitting position, Cardiac tamponade, including post-cardiac surgery, Sepsis and septic shock
- Atlas: Vascular access: IJ, femoral, radial, cubital fossa
- ASA Practice Guidelines for Central Venous Access (2020)
Sources
- 1.How To Do Internal Jugular Vein Cannulation, Ultrasound-Guided · Merck Manual Professional Edition, 2026 · merckmanuals.com
- 2.How To Do Infraclavicular Subclavian Vein Cannulation · Merck Manual Professional Edition, 2026 · merckmanuals.com
- 3.Vascular Access · Merck Manual Professional Edition, 2025 · merckmanuals.comASA 2020 central venous access practice guideline was not reachable from the fetcher; claims here are checked against these procedural references.
Facts on this page were checked against these sources on Oct 14, 2026. Guidelines change; confirm doses against current institutional protocols.