Pulse Oximeter-Derived Pleth Variability Index is a Reliable Indicator of Cardiac Preload in Patients Undergoing Liver Transplantation.

BACKGROUND: Accurate estimation of cardiac preload during liver transplantation is essential. The right ventricular end-diastolic volume index (RVEDVI) is recognized as a good preload indicator in patients undergoing liver transplantation. Recently, dynamic variation parameters including pleth variability index (PVI) have been used as predictors of fluid responsiveness. However, the correlation between PVI and preload status has not been well studied. We evaluated the relationship between PVI and RVEDVI during liver transplantation. METHODS: Eighteen patients undergoing liver transplantation were enrolled in this study. Data of hemodynamic parameters including PVI derived by Masimo Rainbow SET Pulse CO-Oximeter, central venous pressure (CVP), pulmonary arterial occlusion pressure (PAOP), and RVEDI were obtained at 10 defined time points throughout liver transplantation. The correlation between RVEDVI and CVP, PAOP, and PVI was analyzed using Spearman rank test. We also investigated the ability of PVI to accurately differentiate RVEDVI <123 or >142 mL/m(2) using receiver operating characteristic (ROC) analysis. RESULTS: There was fair to good correlation between PVI and RVEDVI (correlation coefficient = -0.492, P < .001). The correlation coefficient between CVP, PAOP, and RVEDVI was 0.345 and 0.463, respectively. A 13.5% cutoff value of PVI estimated the RVEDVI <123 mL/m(2) (area under the curve [AUC] = 0.762). A 12.5% cutoff value of PVI estimated the RVEDVI >142 mL/m(2) (AUC = 0.745). CONCLUSIONS: PVI presented as a reliable estimate of preload status and may be a useful predictor of fluid responsiveness in patients undergoing liver transplantation.

Accuracy and Trending of Continuous Noninvasive Hemoglobin Monitoring in Patients Undergoing Liver Transplantation.

BACKGROUND: Shift in large fluid volumes and massive blood loss during liver transplantation frequently leads to rapid changes in hemoglobin (Hb) concentration; thus, to ensure adequate tissue oxygenation, accurate and rapid determination of Hb concentration is essential in transplant recipients. The Radical-7 Pulse CO-Oximeter provides a noninvasive and continuous way to monitor Hb concentration (SpHb) in real time and is an ideal candidate for use during liver transplantation. In this study, we assessed the relationship between SpHb and total Hb (tHb) obtained from arterial blood samples during surgery. METHODS: Forty patients undergoing liver transplantation were enrolled in this study. tHb and time-matched SpHb were measured at 5 different phases throughout surgery. Paired SpHb and tHb levels were assessed using linear regression, Bland-Altman analysis, and the Critchley polar plot method. RESULTS: A total of 161 paired measurements with sufficient signal quality were analyzed. The correlation between SpHb and tHb was 0.59 (P < .001). Bland-Altman analysis revealed that a bias between SpHb and tHb was 2.28 g/dL, and limits of agreement (LoA) were from -0.78 to 5.34 g/dL. Trending analysis showed that 87% of data were located within the acceptable trending area, indicating that the trending ability was not satisfied. CONCLUSIONS: The Radical-7 Pulse CO-Oximeter was not sufficient to monitor Hb levels and trends during liver transplantation surgery in our cohort. In particular, in critical patients and in those with low Hb levels, invasive Hb measurement should be used for assessment.

Cardiac Output Assessed by the Fourth-Generation Arterial Waveform Analysis System Is Unreliable in Liver Transplant Recipients.

BACKGROUND: Liver transplant recipients often have violent hemodynamic fluctuation during surgery that may be related to perioperative and postoperative morbidity. Because there are some considerations for the risk of the pulmonary arterial catheter (PAC), the conventional invasive device for cardiac output (CO) measurement, a reliable and minimally invasive alternative is required. We validated the reliability of CO measurements with the use of a minimally invasive FloTrac system with the latest fourth-generation algorithm in liver transplant recipients. METHODS: Forty liver transplant recipients without atrial fibrillation, valvular pathology, or intracardiac shunt were recruited in this prospective, observational study. CO values measured by use of PAC with continuous thermodilution method (COTh) and FloTrac devices (COFT) were collected simultaneously throughout the operation for reliability validation. RESULTS: Four hundred pairs of CO data points were collected in total. The linear regression analysis showed a high correlation coefficient (73%, P < .001). However, the percent error between COTh and COFT was 42.2%, which is worse than the established interchangeability criterion of 30%. The concordance rates were calculated at 89% and 59% by 4-quadrant plot and polar plot analysis, respectively. Neither met the preset validation criteria (>92% for the 4-quadrant plot and >90% for polar plot analyses). CONCLUSIONS: Our study demonstrates that the CO measurements in liver transplant recipients by the latest FloTrac system and the PAC do not meet the recognized interchangeability criterion. Although the result showed improvement in linear regression analysis, it failed to display a qualified trending ability.

Ischemic reperfusion injury-induced oxidative stress and pro-inflammatory mediators in liver transplantation recipients.

OBJECTIVE: Liver ischemic reperfusion injury is harmful to transplant recipients, and is associated with postoperative morbidity and mortality. Our study was designed to investigate the oxidative stress and pro-inflammatory mediators in liver transplant recipients. METHODS: We prospectively analyzed 14 recipients who underwent liver transplantation by measuring their blood levels of malondialdehyde (MDA) and cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and IL-6, at nine time points perioperatively. We also evaluated the correlations between oxidative stress (MDA levels) and the characteristics of the recipient or the donated graft. RESULTS: These parameters significantly increased from 1 minute before reperfusion, and the values peaked within 3 to 30 minutes after reperfusion. On the time point at 5 minutes after reperfusion, the MDA levels which were the highest in the recipients correlated with the values of preoperative direct/and total bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), model for end-stage liver disease (MELD) score, international normalized ratio (INR), and surgical blood loss. CONCLUSION: The levels of MDA, TNF-α, IL-1ß, and IL-6 greatly increased with the ischemic reperfusion insult. Recipients with higher values of preoperative direct/and total bilirubin, AST, ALT, MELD score, INR, and surgical blood loss tended to have higher levels of MDA and may suffer more injury from this insult.

The ratio of plasma interleukin-18 is a sensitive biomarker for acute kidney injury after liver transplantation.

BACKGROUND: Acute kidney injury (AKI) is common after liver transplantation (OLT) and is associated with high morbidity and mortality. Previous studies have shown that interleukin-18 (IL-18) levels are associated with AKI. The purpose of this study was to determine whether plasma IL-18 levels were early predictors for AKI after liver transplantation. METHODS: Plasma samples were obtained from 26 patients who underwent OLT at induction of anesthesia (T1), 1 hour after the surgical incision (T2), the time of reperfusion (T3), as well as 1 (T4), 2 (T5), and 4 hours (T6) after reperfusion. Samples were also obtained at 24 hours after surgery (T7). The AKI criteria were taken according to the Acute Kidney Injury Network criteria. RESULTS: Twelve patients (46%) developed AKI after OLT. The area under the receiver operating curve of plasma IL-18 concentrations (T4/T1) to predict AKI occurrence was 0.842 at T5, 0.905 at T6, 0.726 at T7, and 0.726 at T5 to T7. CONCLUSION: Plasma IL-18 concentrations taken 1 hour after reperfusion were predictive of AKI. Therefore, changing IL-18 ratio may be an early predictor for AKI after OLT.