Evaluation of the pulse pressure variation index as a predictor of fluid responsiveness during orthotopic liver transplantation.

BACKGROUND: The pulse pressure variation (PPV) index has been shown to be a reliable predictor of fluid responsiveness (FR) in a variety of clinical settings. However, it has not been formally evaluated in the setting of orthotopic liver transplantation (OLT).
METHODS: Fifteen (n=15) patients undergoing OLT were enrolled in this study. All patients were monitored with a modified pulmonary artery catheter which measured the cardiac output on a semi-continuous basis. A fluid challenge (FC) with 350 ml of colloid was attempted during the following stages of surgery: hepatectomy (TH), anhepatic phase (TA), early post-reperfusion [(TE)--during the first 30 min], late post-reperfusion [(TL)--after hepatic artery anastomosis], and at the beginning of abdominal closure (TC). PPV and stroke volume index (SVI) were recorded at baseline and 5 min after the FC. Each individual FC which raised the SVI more than 10% from baseline was classified as responsive (R); otherwise, it was considered non-responsive (NR).
RESULTS: Forty-one FCs were performed, with 14 (34%) classified as responsive and 27 (66%) as non-responsive. The baseline PPV did not differ significantly between the R and NR groups, showing considerable overlap of its values throughout the procedure [R vs NR; TH: 20% (inter-quartile range 7-32) vs 7% (5-14); TA: 10% (7-14) vs 19% (12-21), and TE+TL: 7% (5-11) vs 9% (7-16)].
CONCLUSIONS: Under the conditions of this study, the PPV index was not shown to be a reliable predictor of FR during OLT. Further studies are warranted to elucidate the role of this and other dynamic indexes in this specific setting.