Central Line Question

[MDMBSNRN]

I feel like this is a really stupid question, but I'm going to ask it anyway (because you never learn if you never ask, and I really want to understand this). While floating in ICU, I was recently assisting with a patient who had metastatic cancer (started as breast cancer and metastasized to the brain and lungs). The patient suffered a perforated duodenal ulcer, and underwent surgery for this. Following surgery, the patient developed severe ARDS, and landed in ICU for several weeks. During her ICU stay, the patient had a central line and arterial line placed (she became severely hypotensive, and was placed on a Levophed drip). While transducing CVP and arterial waveforms and numbers, I noticed that the CVP numbers didn't match up with the rest of the clinical picture. Since I float, and ICU isn't my home unit, I'm not guaranteed to come back there. I kept up with the progress notes, and noted that the surgeon had written a note the next day stating "since the central line is not placed in the superior vena cava, we will no longer use it to obtain information regarding the CVP."

I thought that the SVC was the termination point for central lines, and that this was basically a given. I could see that centrals might work in other locations, but I always thought that SVC placement was standard practice. Is it common to place a central in another location, and continue to use it? The line was never moved, and the patient was receiving Levophed, TPN, and Lipids through it. The surgeon never specified where exactly the line was, and I didn't have a chance to interact with either him or the ICU staff again while the patient was still in ICU. Just wondered if someone could shed some light on this issue. Thanks.

[Corey Narry, MSN, RN, NP]

Central Venous Catheters (CVC) placed in the internal jugular and subclavian veins must terminate within the vicinity or right at the caval-atrial junction (our policy is plus or minus 2 cm per the chest x-ray read). This is a widely acceptable location to measure CVP.

Some clinicians feel that lines placed in the femoral vein though considered CVC are not accurate for measuring CVP but some studies do show some correlation with numbers taken from catheters with tips right at the caval-atrial junction in certain conditions.

Multi-lumen Access Catheters and Introducer Catheters (i.e., MAC, Cordis) are shorter in length and typically terminate farther from the caval-atrial junction so these are also sometimes not considered accurate for CVP measurement depending on who you ask.

Can Central Venous Pressure Be Measured with a Femoral Line? - NEJM Journal Watch

Critical Care | Full text | Central venous pressure in a femoral access: a true evaluation?

Is the central venous pressure reading equally reliable if the central line is inserted via the femoral vein

[MDMBSNRN]

Thank you for the great information! This was a right subclavian tripe lumen central venous catheter. I thought it was incredibly odd that the line wasn't in the right position for CVP measurement, yet no action was taken, and was still being used for vasoactives and parenteral feedings.

[Corey Narry, MSN, RN, NP]

That is odd. I'd be interested to see where the tip terminates on the chest film. I place lines at work as an NP and I've seen line tips do odd things (i.e., SC line coiling up to the IJ, IJ lines taking an angle to the SC, IJ lines coiling back up within the IJ). Sometimes there are preexisting thrombus that block the natural course of the catheter and in those situations, the provider should place a new line in another site and remove the malpositioned catheter.

[OhioCCRN, MSN, NP]

@juan what are your thoughts on transducing tunneled catheters for a cvp? Is it accurate

[Corey Narry, MSN, RN, NP]

It all depends on where the tip of that catheter is. The rule is if the tip terminates close to the caval-atrial junction, then the CVP would be "accurate". That is, as long as the transducer is positioned and zeroed in relation to the level of the R atrium is followed. I typed accurate in quotation marks because there are multiple studies that show that CVP really is a wild card - it is an inconsistent number that varies widely and should not be the only number used to assess intravascular volume.

[MDMBSNRN]

Juan,

I have also read that CVP measurement is not a highly reliable indicator of intravascular volume. Would it be safer to say that a PA line, and the numbers obtained from it, are better indicators of volume status, as well as the functional ability of the patient's heart? My current hospital does not utilize PA lines, but in the trauma center I spent some time in, we occasionally placed them before sending the patient to ICU or an outside hospital. Because of this, my exposure to them is limited at best.

[Corey Narry, MSN, RN, NP]

PA catheters used to be common in ICU's but they have lost favor because through the years studies have shown no mortality benefit nor improved length of stay with patients who had one placed. Having said that, clinicians still agree that the numbers obtained from a Swan-Ganz catheter are helpful in assessing the overall picture of fluid volume status and R sided heart function.

In most places, they are used in circumstances when the clinical picture is confusing in terms of what direction to take in treating patients. Some patient populations benefit from their use - patients in cardiac surgery, lung transplant surgery, and cardiogenic shock states. I think they still have a place in critical care but certainly not how they were initially used which was placing them randomly and leaving them in indefinitely.

More recently, ultrasound technology has gained an increase in utilization in critical care. More and more ICU's are purchasing portable ultrasound equipment with a cardiac probe and you'll see them as part of the ICU providers' armamentarium of equipments. Intensivists are learning to use ultrasound to perform cardiac evaluations to assess heart function (similar to a formal echocardiogram).

Fluid volume status can also be assessed by looking at the size and compressibility of the inferior vena cava by ultrasound. There are also limitations to this approach one of which is operator skillset but one should also consider the effect of positive pressure ventilation on IVC appearance which unfortunately many patients in the ICU are mechanically ventilated.

For further reading about Swan-Ganz and the studies done on them, see: JAMA Network | JAMA | Impact of the Pulmonary Artery Catheter in Critically Ill Patients: Â*Meta-analysis of Randomized Clinical Trials

[gypsyd8]

Excellent info Juan, very informative. What about SVV and PPV? I've heard their are noninvasive ways to assess these.