Central venous pressure during the post-anhepatic phase is not associated with early
postoperative outcomes following orthotopic liver transplantation
Cywinski JB, Mascha E, You J, Argalious M, Kapural L, Christiansen E, Parker BM.
Minerva Anestesiol. 2010 Oct;76(10):795-804.
Purpose/Hypothesis
The aim of this study was to evaluate the association between intraoperative central venous
pressure (CVP) during the post-anhepatic phase (PAH) of surgery and defined postoperative
outcomes after OLT.
Fluid management during OLT is a matter of current concern. Some studies have suggested that
low CVP strategy could be associated with reduced blood losses and improved outcome whereas
others have suggested that these strategies could have deleterious effects such as increasing
postoperative renal dysfunction or even mortality. However, this debate is still ongoing since no
definitive high quality data are available. In this article, the authors have focused their interest on
the relation between CVP during the PAH of the surgery and postoperative clinical outcomes.
Approach/Methods/ Analysis (Study Design)
This is a retrospective observational study based on the analysis of an electronic anesthesia
record keeping system between April 2005 and December 2006. Patients who underwent singleorgan whole liver transplant were included. Intraoperative management was left to the attending
physician, pulmonary artery catheter was used in all patients and there was no specific
hemodynamic goal directed strategy.
The median CVP during PAH (defined as the time between portal vein reperfusion and the end of
surgery) was used to stratify patients in two groups: PAH CVP below <10 mmHg or PAH CVP ≥
10 mmHg.
The primary endpoint was a combination of overall survival, graft survival and composite
graft/patient survival. Secondary outcomes were clinical: estimated blood losses, blood products
requirement, length of stay, infections, parameters for graft function. Numerous pre or
intraoperative variables, which are potential confounders such as body mass index, MELD score,
blood products requirement, case duration or donor risk index were used for adjustment in the
analysis.
Findings
144 patients (56 with “low CVP” (median CVP: 8) and 88 with “high CVP” (median CVP: 13))
were identified. After adjustment, none of the clinically relevant studied outcomes was
significantly different between the two groups. This is especially true for overall survival, graft
function, ICU or hospital length of stay. The only difference was a steeper improvement between
postoperative day 1 and day 3 of transaminases and bilirubin level in the low CVP group.
Shortcomings
The main shortcomings of this study are related to its retrospective design. Despite a meticulous
attention to reduce possible bias by adjustment on numerous variables, the retrospective design
does not allow to definitively eliminate possible interactions. Since there was no predetermined
goal-directed therapy aiming at decreasing CVP, the results of this work should not be interpreted
as the effect of such a strategy. The authors have chosen 10 mmHg as a cut-off level.
Unfortunately, CVP levels in the two groups were not so different. The median CVP in the “low
CVP” group was 8 which might be not low enough to demonstrate an effect, particularly as
previous studies have used < 5 for low CVP.
Finally, the study was focused on the post
anhepatic phase. To my knowledge this is the first study to focus on this specific phase which
may limit its comparability with other studies and its generalizability.
Conclusion/Lessons
Well-accepted fluid management relies on avoiding hypovolemia and overhydratation. When CVP
is used for hemodynamic monitoring, this concept usually results in maintaining CVP values
between 7- 8 mmHg to 13-15 mmHg. The current study could suggest that this “traditional” fluid
management does not affect the outcome of liver recipients. More widely, this study underlines
the current lack of definitive data regarding how fluids should be managed during OLT to optimize
patient outcome.
Catherine Paugam-Burtz