Evaluation of Plasma Disappearance Rate Indocyanine Green Clearance as a Predictor of Liver Graft Rejection in Donor Brain Death.

INTRODUCTION: There currently exist no quantitative methods to assess graft viability before the donor procurement procedure. In Europe, around 20% of liver grafts evaluated "in situ" by an experienced surgeon are discarded. The aim of this study is to evaluate the use of the plasma disappearance rate indocyanine green (PDR-ICG) clearance in predicting liver graft rejection to avoid this 20% of futile surgeries. OBJECTIVES: To evaluate PDR-ICG as a predictor of liver graft rejection in death brain donors compared with the gold standard evaluation by an experienced surgeon. MATERIAL AND METHODS: Prospective observational single center study. From March 2017 to July 2019, 29 donors were included in the study, 17 were men and 12 women with a median age of 68 years ± 16.9 years. Donors had an intensive care unit stay of 2 days ± 4 days. PDR-ICG was measured with PICCO2 monitor. Indocyanine green clearance dose was 0.25 mg/kg injected intravenously in the operating room just before donor procurement procedure is initiated. The surgeon was unaware of the PDR-ICG measure until the decision of graft acceptance was taken. Data regarding the donors and biopsy results were included in a prospective database. RESULTS: PDR-ICG measure could be obtained in 10 minutes in all of the cases included. The median PDR-ICG obtained was 18%/min (range, 2.4-31%/min). Graft rejection took place in 15 out of the 29 donors. PDR-ICG value was less than 10%/min in 6 of these rejected grafts and less than 15%/min in 10 donors. All donor grafts with PDR-ICG <15% were discarded. The graft had been discarded in 5 donors with a PDR-ICG >15%. CONCLUSIONS: In our study a plasma disappearance rate <10 would have identified the grafts that would be rejected, thus avoiding the displacement work and expense of the surgical team. These results should be confirmed in a multicentric study.

Donor Risk Index Has an Impact in Intraoperative Measure of Hepatic Artery Flow and in Clearance of Indocyanine Green: An Observational Cohort Study.

BACKGROUND: The increase in indications for liver transplantation has led to acceptance of donors with expanded criteria. The donor risk index (DRI) was validated with the aim of being a predictive model of graft survival based on donor characteristics. Intraoperative arterial hepatic flow and indocyanine green clearance (plasma clearance rate of indocyanine green [ICG-PDR]) are easily measurable variables in the intraoperative period that may be influenced by graft quality. Our aim was to analyze the influence of DRI on intraoperative liver hemodynamic alterations and on intraoperative dynamic liver function testing (ICG-PDR). METHODS: This investigation was an observational study of a single-center cohort (n = 228) with prospective data collection and retrospective data analysis. Measurement of intraoperative flow was made with a VeriQ flowmeter based on measurement of transit time (MFTT). The ICG-PDR was obtained from all patients with a LiMON monitor (Pulsion Medical Systems AG, Munich, Germany). DRI was calculated using a previously validated formula. Normally distributed variables were compared using Student's t test. Otherwise, the Mann-Whitney U test or Kruskal-Wallis test was applied, depending on whether there were 2 or more comparable groups. The qualitative variables and risk measurements were analyzed using the chi-square test. P < .05 was considered statistically significant. RESULTS: DRI score (mean ± SD) was 1.58 ± 0.31. The group with DRI >1.7 (poor quality) had an intraoperative arterial flow of 234.2 ± 121.35 mL/min compared with the group having DRI < 1.7 (high quality), with an intraoperative arterial flow of 287.24 ± 156.84 mL/min (P = .02). The group with DRI >1.70 had an ICG-PDR of 14.75 ± 6.52%/min at 60 minutes after reperfusion compared to the group with DRI <1.70, with an ICG-PDR of 16.68 ± 6.47%/min at 60 minutes after reperfusion (P = .09). CONCLUSION: Poor quality grafts have greater susceptibility to ischemia-reperfusion damage. Decreased intraoperative hepatic arterial flow may represent an increase in intrahepatic resistance early in the intraoperative period.

Are high-sensitivity troponins always reliable? Donor-recipient troponin transfusion in liver transplantation.

Blood troponins are used to diagnose perioperative myocardial injury and infarction. During liver transplantation, a passive donor-recipient troponin transfer with the graft may result in an increase of troponins in the transplant recipient questioning the diagnosis of myocardial injury. We present a case of liver transplantation with sudden elevation of recipient's serum troponin levels immediately after graft reperfusion and its subsequent normalization in which myocardial damage and other non-ischaemic potential causes were ruled out. Patient consent for publication was obtained prior to submission of the manuscript.

Cardiac output monitoring with pulmonary versus transpulmonary thermodilution during liver transplantation: interchangeable methods?

BACKGROUND: Liver transplantation (LT) implies hemodynamic instability, making invasive monitoring of cardiac output (CO) mandatory. Intermittent thermodilution with pulmonary artery catheter (PAC) remains the clinical gold standard to measure CO. The agreement between PAC and new monitoring methods in LT needs to be further investigated. Our aim is to clarify whether cardiac index (CI) measurements with transpulmonary intermittent thermodilution, and continuous pulmonary thermodilution methods agree sufficiently with those performed intermittently with PAC to be considered interchangeable during LT. METHODS: We studied prospectively hemodynamic parameters of 72 consecutive patients undergoing LT. Each CI was obtained simultaneously with three different techniques: intermittent (PACi) and continuous (CCI) pulmonary artery thermodilution with PAC, and intermittent transpulmonary thermodilution (TPTD) with PiCCO2 in 8 time points of the procedure, obtaining 1350 paired measurements. Exclusion criteria was retransplantation. The statistical Bland Altman method for repeated measures was used to assess agreement, and polar plot methodology to evaluate trending ability. RESULTS: Analysis of agreement between PACi and TPTD measurements (N.=474 paired measurements) showed a bias of -0.42 L/min/m2, 95% limits of agreement (95%LoA) of ±1.5 L/min/m2 and percentage error of 45%. PACi-CCI comparisons (N.=431) showed bias of -0.02 L/min/m2, 95%LoA of ±1.96 L/min/m2, and percentage error of 64%. These results demonstrated questionable clinical agreement between PACi and TPTD, and no agreement between PACi and CCI. TPTD and CCI showed poor CO trending ability. CONCLUSION: Continuous pulmonary thermodilution with PAC is not an alternative monitoring method of CO. Transpulmonary thermodilution CO monitoring with PiCCO2 shows too questionable agreement with the clinical gold standard (PACi) being in the limit of acceptance to be considered interchangeable during liver transplantation.

Comparative study of nanocrystalline titanium dioxide obtained through sol-gel and sol-gel-hydrothermal synthesis.

TiO2 particles were prepared by sol-gel method alone and by sol-gel method combined with hydrothermal treatment. The structural and photocatalytic properties of the two series of photocatalysts were compared. XRD studies revealed that rutilization was faster in the series of photocatalysts, which had been additionally subjected to a hydrothermal process (SG-HT). The hydrothermally treated photocatalysts also displayed a higher specific surface area than those which had only been synthesized using the sol-gel process (SG) and subjected to low calcination temperatures of up to 873 K, while this tendency was inverted at higher temperatures. In accordance with the above observation, the hydrothermally treated series of photocatalysts had a lower particle size than the SG series calcined immediately after the sol-gel process up to 873 K, with this relation being inverted for the highest two temperatures which were studied (973 K and 1023 K) and which saw the commencement of rutilization. Increases in average particle size were observed for both series, with a polyhedral morphology seen as calcination temperature rose. FTIR studies highlighted the presence of the band at 2351 cm(-1) in the SG-HT photocatalysts, characteristic of surface-adsorbed CO2. This was not seen in the SG or P25 photocatalysts. In terms of photoreactivity, the best photocatalyst in the SG-HT series was that calcined at 923 K and in the SG series at 1023 K (SG-1023). Comparing these two photocatalysts and the commercial P25 photocatalyst, SG-1023 was found to be the most photoactive in both the photodegradation and the mineralization of phenol.

Degradation and detoxification of 4-nitrophenol by advanced oxidation technologies and bench-scale constructed wetlands.

The degradation and detoxification towards the duckweed Lemna minor of 4-nitrophenol (4NP) was studied by means of bench-scale constructed wetlands (CWs), TiO(2)-photocatalysis and Fenton + photoFenton reactions. The main goal of this work was to compare the three treatment techniques to evaluate their possible combination for the efficient, low cost treatment of 4NP effluents. In CWs, adsorption on the substrate of 4NP was found to achieve 34-45%. Low concentrations (up to 100 ppm) of 4NP were successfully treated by CWs in 8-12 h. The microbial degradation of 4NP started after a lag phase which was longer with higher initial concentrations of the pollutant. The greatest degradation rate was found to occur at initial concentrations of 4NP between 60 and 90 ppm. Solar TiO(2)-photocatalysis was faster than the CWs. The greatest removals in terms of mass of 4NP removed after 6 h of irradiation were found to occur at 4NP concentrations of about 200 ppm. Fenton reaction provided complete 4NP degradation up to 500 ppm in only 30 min but TOC was removed by only about 40%. The resulting toxicities were below 20% for initial 4NP concentrations below 300 ppm. It was the Fenton + photoFenton combination (180 min in total) that provided TOC reductions up to 80% and negative L. minor growth inhibition for almost all the 4NP concentrations tested. The combination of solar TiO(2)-photocatalysis (6 h) with CWs (16 h) was able to completely treat and detoxify 4NP effluents with concentrations as high as 200 ppm of the organic.

Combining TiO2-photocatalysis and wetland reactors for the efficient treatment of pesticides.

In the present work the photocatalytic and biological degradation of two commercial mixtures of pesticides (Folimat and Ronstar) and two fungicides (pyrimethanil and triadimenol) has been studied. The evolution of some components of these commercial products (dicofol, tetradifon and oxadiazon) and that of the two fungicides has been monitored by means of HPLC, GC-MS, TOC and toxicity (Lemna minor toxicity test) measurements. The photocatalytic method was able to degrade dicofol, tetradifon, pyrimethanil, triadimenol and the components of Ronstar with the exception of oxadiazon. In addition to this, the photocatalytic method eliminated pyrimethanil toxicity and reduced that of triadimenol by a 90%, Ronstar by a 78% and Folimat by an 87%. Nevertheless, the wetland reactors alone could reduce the toxicity of only the former. Finally, the proper dosage of the water containing the pesticides to a photocatalytic reactor followed by a wetland reactor resulted to be the most successful strategy for the detoxification of the studied compounds and their mixtures.

Photocatalytic degradation of phenol and phenolic compounds Part I. Adsorption and FTIR study.

With the goal of predicting the photocatalytic behaviour of different phenolic compounds (catechol, resorcinol, phenol, m-cresol and o-cresol), their adsorption and interaction types with the TiO(2) Degussa P-25 surface were studied. Langmuir and Freundlich isotherms were applied in the adsorption studies. The obtained results indicated that catechol adsorption is much higher than those of the other phenolics and its interaction occurs preferentially through the formation of a catecholate monodentate. Resorcinol and the cresols interact by means of hydrogen bonds through the hydroxyl group, and their adsorption is much lower than that of catechol. Finally, phenol showed an intermediate behaviour, with a Langmuir adsorption constant, K(L), much lower than that of catechol, but a similar interaction. The interaction of the selected molecules with the catalyst surface was evaluated by means of FTIR experiments, which allowed us to determine the probability of OH radical attack to the aromatic ring.

Radial to femoral arterial blood pressure differences during liver transplantation.

This observational study compared femoral and radial arterial blood pressure in 72 patients undergoing liver transplant surgery. Simultaneous femoral and radial arterial blood pressures, cardiac index, core temperature and vasoconstrictor therapy were recorded at seven time points during the operation. No significant differences between radial and femoral pressures were found at the start of surgery. Femoral and radial systolic arterial blood pressures were statistically significantly different during liver reperfusion (mean (SD) arterial pressure = 92 (22) mmHg vs. 76 (22) mmHg, p < 0.01). Mean arterial blood pressures showed no statistically significant differences throughout the study. Vasoconstrictor drug administration was associated with a larger systolic pressure difference between femoral and radial arteries (28 (24) mmHg in patients being given vasoconstrictor drugs vs. 9 (19) mmHg in patients not needing vasoconstrictors during reperfusion, p < 0.001). In conclusion, differences in systolic arterial blood pressure occur between femoral and radial arterial monitoring sites during liver reperfusion, and in particular in patients being given vasoconstrictor therapy. Thus, if femoral arterial monitoring is not available, clinicians should rely on mean rather than systolic arterial pressure measurements from a radial artery catheter during liver transplantation.

Photocatalytic degradation of formaldehyde containing wastewater from veterinarian laboratories.

The photocatalytic destruction of methanol, formaline (mixture of formaldehyde, methanol and water) and formaline wastes from the preservation of vertinarian physiologic samples has been attempted by two different processes, at high concentrations of reagents and by dossification of reagents, varying pH in both. Experiment evolution has been monitored by measuring the organic matter such as TOC and formaldehyde concentrations [H2CO]. Also, methanol and methanol-formaldehyde interactions with the TiO2 surface have been analysed by FTIR spectroscopy. Results indicate that at high concentrations the catalyst surfacial alterations given by methoxy, formates or carbonates, according to the pH of the sample can profoundly affect catalyst behaviour. It has been established that reagent dossification is advantageous for enhancing photonic efficiency as it minimizes the adsorbate presence that hampers the photocatalytic process.

Autonomic neuropathy in end-stage cirrhotic patients and evolution after liver transplantation.

Autonomic neuropathy (AN), which is frequently observed in cirrhosis patients, has been associated with a higher mortality. We have prospectively evaluated the prevalence of AN, its relationship with the degree of liver dysfunction and circulatory disturbances, and the evolution of AN after liver transplantation (LT) in 62 end-stage liver cirrhosis patients. AN was evaluated by seven cardiovascular tests assessing sympathetic or parasympathetic function before and 6 months after LT. Patients were classified as showing absent (A), early (E), or definite dysfunction (D). AN appeared in 67.7% of cases (E: 24.2%, D: 43.5%) without relation to liver disease etiology. Parasympathetic dysfunction was more prevalent than sympathetic dysfunction (59.7% vs. 20.9%). AN was significantly related to Child-Pugh score. Hyperdynamic circulation was more marked in the D than the A group as shown by a greater cardiac output (CO)(9 vs. 7.3 L/min) and a lower peripheral resistance (SVR)(666 vs. 866 dyn.s.cm(-5)). Moreover, AN scores significantly correlated with CO and SVR. Overall the prevalence of AN decreased 6 months after LT (67.7% vs 48%) due to a significant reduction in definite AN (43.5 vs. 14.8%; P<.05). AN improved in 70% of cases after LT. Sympathetic dysfunction remained in only one patient. We conclude that AN is frequent in liver transplant candidates; its severity is associated with the degree of liver failure. Systemic circulatory disturbances seem to correlate with the severity of AN. AN is clearly improved by LT. The evaluation of AN may contribute to a better selection of LT recipients.

Autonomic neuropathy is associated with hemodynamic instability during human liver transplantation.

INTRODUCTION: End-stage liver disease is frequently associated with autonomic neuropathy (AN). The hemodynamic changes during liver transplantation (LT) require an adequate autonomic response to maintain cardiovascular stability. PATIENTS AND METHODS: Forty-one patients undergoing LT were evaluated for the influence of AN on the evolution after LT. AN was previously evaluated by seven cardiovascular tests assessing sympathetic (Sy) or parasympathetic (P) function. Patients were classified as absent (A), early (E), or definite dysfunction (D). A hemodynamic study was performed before and after vascular clampings. The analysis included the duration of LT, transfusion requirements, intra-operative artenal hypotensive episodes, incidence of postreperfusion syndrome (PRS), cardiac arrhythmias and vasoactive drug requirements. RESULTS: The hyperdynamic circulation worsened during surgery in D patients, as shown by a significantly increased cardiac output and a significantly decreased systemic vascular resistance. The incidence of PRS was greater in the AN group. Arterial hypotension during the neohepatic period was more frequent among patients with AN, more frequently requiring vasoconstrictor and inotropic therapy. CONCLUSIONS: AN is associated with hemodynamic impairment and with increased vasoactive drug requirements during liver transplantation, probably associated with impaired reflex vasoconstrictor responses to surgical manipulations and changes of blood volume. AN may be associated with a greater surgical risk during LT. Preoperative evaluation of AN may select a high-risk population of LT recipients.

Cardiac output by femoral arterial thermodilution-calibrated pulse contour analysis during liver transplantation: comparison with pulmonary artery thermodilution.

PURPOSE: The continuous monitoring of the cardiac output during liver transplantation (LT) is an essential part of the intraoperative management of the patient's hemodynamics. To verify the accuracy of a new method based on femoral artery thermodilution-calibrated pulse contour analysis (PCCO) during LT, we compared the technique with the results of an intermittent pulmonary artery thermodilution method (ICO). METHOD: A prospective study included 314 paired cardiac output measurements at 10 sampling times in 35 patients undergoing LT. After initial calibration of the pulse contour analysis, no further recalibrations were performed. Bland and Altman's statistical method, one-way ANOVA, and one sample t tests were used for the analysis of the data. A P<.05 was considered significant. RESULTS: There was a small bias 0.18 L x min(-1) (6.29% from the ICO) for the whole sample of paired measurements, associated with 95% limits of agreement of +/-4.72 (68.89%) L x min(-1). The additional analysis showed comparable biases and limits of agreement for any single time in the study period. The difference PCCO-ICO showed a negative sign for ICO >10 L x min(-1) (P<.001) and a positive sign for ICO <5 L x min(-1) (P<.001). It was greater during infusion of a vasoactive drug (P<.001). CONCLUSION: The pulse contour analysis was found to be an unsatisfactory substitute for intermittent thermodilution measurement of cardiac output during the LT.

Highly concentrated phenolic wastewater treatment by heterogeneous and homogeneous photocatalysis: mechanism study by FTIR-ATR.

The degradation of high phenol concentrations (1 g/L) in water solutions by TiO2 photocatalysis and the photo-Fenton reaction has been studied. From the obtained data it may be suggested that degradation of phenol by TiO2-UV takes place onto the catalyst surface by means of peroxo-compounds formation. At low phenol concentrations other mechanism, the insertion of OH. radicals, may be favored. On the other hand, highly concentrated phenol aqueous solutions treatment by the photo-Fenton reaction gives rise to the formation of polyphenolic polymers. These seem to reduce the process rate. Degradation intermediates have been identified by HPLC and FTIR. The FTIR study of the catalyst surface has shown infrared bands attributable to different chemisorbed peroxo-compounds, formates, ortho-formates and carboxylates that can inactivate the catalyst.

Highly concentrated phenolic wastewater treatment by the photo-Fenton reaction, mechanism study by FTIR-ATR.

Phenol degradation by Photo-Fenton reaction has been studied in highly concentrated wastewaters and most intermediate species have been identified by Fourier Transform IR-Spectroscopy with ATR device. During the photodegradation of highly concentrated phenol solutions, the formation of dissolved and precipitate tannin has been observed. The possibility of a Fe3+-Pyrogallol complex formation, previous to the tannin formation, has been proposed too. The complex formation involving Fe3+ ions could be related to the observed Photo-Fenton activity decrease. Tannin formation inhibits the complete mineralization of phenol because *OH radicals attack will produce further condensation steps and the polymer size increase. This fact limits the applicability of the process for highly concentrated phenolic wastes mineralization. However, the tannin precipitation allows its separation from the solution by conventional filtration, and reduction of the corresponding dissolved organic carbon. These observations have been proved from the identification of primary degradation products, catechol and hydroquinone. Catechol is considered to be the first step for the formation of tannins. Degradation process for phenol, catechol and hydroquinone have been monitored by total organic carbon (TOC) measurements along the reaction time span. From these results, a global mechanism for the Photo-Fenton degradation of phenol is proposed.

The photocatalytic disinfection of urban waste waters.

In this paper we present the results of the photocatalytic disinfection of urban waste water. Two microbial groups, total coliforms and Streptococcus faecalis, have been used as indexes to test disinfection efficiencies. Different experimental parameters have been checked, such as the effect of TiO2, solar or UV-lamp light and pH. Disinfection of water samples has been achieved employing both UV-lamp and solar light in agreement with data shown by other authors. The higher disinfection rates obtained employing an UV-lamp may be explained by the stronger incident light intensity. Nevertheless no consistent differences have been found between TiO2-photocatalysis and direct solar or UV-lamp light irradiation at natural sample pH (7.8). At pH 5 the presence of TiO2 increases the relative inactivation rate compared with the absence of the catalyst. After the photocatalytic bacterial inactivation, the later bacterial reappearance was checked for total coliforms at natural pH and pH 5, with and without TiO2. Two h after the photocatalytic treatment, CFU increment was almost nill. But 24 and 48 h later an important bacterial CFU increment was observed. This CFU increment is slower after irradiation with TiO2 at pH 5 in non-air-purged samples.

Fatal paradoxical air embolism during liver transplantation.

We describe a case of fatal paradoxical coronary air embolism during liver transplantation. The literature on the diagnosis and prophylaxis of paradoxical air embolism during liver transplantation is reviewed and discussed.

Presence of a nitric oxide synthase inhibitor in the graft efflux during reperfusion in human liver transplantation.

Involvement of the nitric oxide (NO) system in complications following human orthotopic liver transplants (OLT) has been reported, but the contribution of the graft to the modulation of the NO system during reperfusion in normal OLT has not been characterized. We have studied the contribution of the graft efflux to the modulation of the NO system in 20 consecutive OLT. We evaluated its effects on isolated vascular reactivity of the rabbit and on rat cultured macrophages stimulated with lipopolysaccharide (LPS). In none of the donor liver biopsies was expression of inducible NO synthase (iNOS) activity by Northern or Western blot analysis found. Graft efflux after the onset of liver reperfusion, but not pre-transplant patient plasma, reversibly inhibited the acetylcholine-induced relaxation of norepinephrine-contracted rabbit aortic rings. Moreover, graft efflux reversibly inhibited NO production in rat macrophages treated with LPS, as evidenced by both a decrease in nitrite plus nitrate formation and a decrease in the production of [14C]citrulline from [14C]arginine. Addition of a 10% dilution of graft efflux to cultured rat macrophages incubated with LPS increased iNOS mRNA levels, suggesting direct inhibition of the enzyme but not of its expression. These results cannot be ascribed to the depletion of arginine the iNOS substrate since they can be reproduced even in the presence of an excess (10 mM) of exogenously added arginine. No correlation was found between the iNOS inhibitory activity in each sample and the corresponding clinical parameters related to either the graft function after the OLT or the existence of post-reperfusion syndrome. Our results indicate the existence of a soluble factor in the graft efflux from human OLT that reversibly and unspecifically inhibits NOS activity. Its involvement in the physiology and/or pathology of human liver diseases deserves further study.

Response to clamping of the inferior vena cava as a factor for predicting postreperfusion syndrome during liver transplantation.

Postreperfusion syndrome (PRS) is an important cause of hemodynamic deterioration during orthotopic liver transplantation (OLT). We retrospectively studied 94 patients who had undergone OLT in an effort to establish whether the hemodynamic response to clamping of the inferior vena cava (IVC) could be used to predict hemodynamic behavior on reperfusion of the grafted liver. PRS was defined as a decrease in the mean arterial pressure of more than 30% below the baseline value for more than 1 min during the first 5 min after reperfusion of the graft. The patients were divided into two groups: those who developed PRS (PRS group) and those who did not (non-PRS group). We analyzed hemodynamic response before (dissection stage) and after (anhepatic stage) clamping of the IVC. Based on multivariate analysis methods (logistic regression), the percentage of change in the vascular resistance index from before clamping to after clamping of the IVC was an indicator of the risk of developing PRS, with an adjusted odds ratio of 1.04 for each unit of change (ENTER method, P = 0.01). In the non-PRS group, clamping of the IVC was followed by a 47.1% decrease in the cardiac index, compared with a 27.9% decrease in the PRS group (P < 0.05). The systemic vascular resistance index (SVRI) increased by 49% in the PRS group, as opposed to 85.7% in the non-PRS group (P < 0.05). PRS occurred in only 17.5% of patients in whom the SVRI increased by more than 50%. We conclude that the integrity of the vasoconstrictive response (increase in the peripheral vascular resistance greater than 50%) as measured immediately after clamping of the IVC correlates with occurrence of PRS.