There was an updated meta-analysis recently published looking at the utility of CVP measurement to predict fluid responsiveness. You can probably guess the answer. If the CVP is low then give them some fluid and they get better... right? Not so fast.
These authors from Virginia and Kentucky performed a typical
but good quality systematic review. They were looking for clinical trials that
reported the correlation coefficient or area under the curve (AUC), between CVP
and change in cardiac performance following an intervention that altered
cardiac preload. 43 studies were
eventually selected for data abstraction. The vast majority were small studies conducted in an ICU or
operating room and none were done in an
emergency department. Most patients got a small bolus of colloid. Cardiac
output was measured using various means.
Results? 57% of patients were fluid responders. The summary AUC was 0.56. This is as good as flipping a
coin. The summary correlation coefficient was a terrible 0.18. (1.0 would
be considered perfect and 0 is no correlation.)
The authors conclude that there is no data to support the
widespread practice of using CVP to guide fluid therapy and it should be abandoned.
This looks to be quite
definitive. The Achilles heel of a meta-analysis is negative reporting
bias. One should be quite cautions of “positive” meta-analysis, but one that tells you something doesn’t
work is believable.
I would most
certainly not place a central line for the sole purpose of CVP measurement.
Many would argue that they only real reason for placing one would be for
administration of noradrenalin (norepinephrine).
With the widespread uptake of point-of-care ultrasound I
can’t imagine relying on a CVP measurement to guide therapy. One only needs to
non-invasively take a quick look at the IVC (and probably the lungs and heart
while you are there) to get an idea of fluid status. Sure, this is far from
perfect. But it probably works well at the extremes (when it’s important) and
will certainly avoid the morbidity of central line placement.
Covering:
Marik PE, Cavallazzi R. Does
the Central Venous Pressure Predict Fluid Responsiveness? An Updated
Mea-Analysis and a Plea for Some Common Sense. Crit Care Med
2013;41:1774-1778.
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