Clinical Utility of a Risk-Adapted Protocol for the Evaluation of Coronary Artery Disease in Liver Transplant Recipients

The prevalence and management of coronary artery disease (CAD) in liver transplantation (LT) candidates are not well characterized. The aims of this study were to evaluate the impact on clinical outcomes of a specifically designed protocol for the management of asymptomatic CAD in LT candidates and to investigate noninvasive risk profiles for obstructive and nonobstructive CAD for 202 LT candidates. Those with high baseline cardiovascular risk (CVR; defined by the presence of classic CVR factors and/or decreased ejection fraction) received coronary angiography and significant arterial stenosis and were treated with percutaneous stents. Patients were followed up after LT until death or coronary event (CE). There were 78 patients who received coronary evaluation (62 direct angiography, 14 computed tomography coronary angiography, and 2 both). Of them, 39 (50%) patients had CAD of any severity, and 6 (7.7%) had significant lesions (5 were amenable to be treated with stents, whereas 1 patient had diffuse lesions which contraindicated the LT). Insulin-dependent diabetes was the only factor related to CAD of any severity (odds ratio, 3.44; 95% confidence interval [CI], 1.00-11.97). A total of 69 patients (46 with coronary evaluation) received LT. The incidence of CEs and overall survival after LT were similar between patients with and without coronary evaluation. Furthermore, no differences occurred between these groups in a multivariate competing risk model (subhazard ratio, 0.84; 95% CI, 0.27-2.61; P = 0.76). In conclusion, the application of an angiographic screening protocol of CAD in a selected high-risk Mediterranean population is safe and effective. The short- and medium-term incidence rates of CEs and death after LT in this population are similar to that observed in low-risk patients.

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.

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.

Haemodynamic monitoring and liver function evaluation by pulsion cold system Z-201 (PCS) during orthotopic liver transplantation

Pulsion cold system (PCS, COLD) is a haemodynamic monitoring system that allows measurement of cardiac output (CO), partial blood volumes, lung water, and liver function. The aim of the study was to evaluate this monitoring system during human orthotopic liver transplantation (OLT) for the following: (a) to determine agreement between CO measurements via pulmonary artery thermodilution (CO TDpa), and aortic transpulmonary thermodilution (CO TDa); (b) to compare the preload dates obtained with the COLD with central venous pressure (CVP) and pulmonary capillary wedge (PCWP); and (c) to assess the use of the plasma disappearance rate (PDR) of indocyanine green (ICG) as a measure of graft function. Fifteen consecutive patients undergoing OLT were studied. Each patient received a pulmonary artery catheter and a 5F aortic catheter with an integrated thermistor. The thermistor of the aortic catheter were connected to one computer system (COLD-Z201, Pulsion Medical Systems, Munich, Germany). Haemodynamic data were registered an all the phases of OLT. PDR was measured during surgery in 12 patients. Correlations between PDR and the other markers of graft function (transaminases, protrombine time, and bile production) were sought. The correlation coefficient between CO TDa (COLD) and CO TDpa was r = 0.766 (p < 0.001), and an additional analysis according to Bland-Altman was also performed. There was a better correlation between the cardiac index (determined by two monitoring systems) and the volume measurements than the correlation observed with pressure preload parameters. The best correlations were found between the cardiac index in the femoral artery and intrathoracic blood volume index (ITBVI) and pulmonary blood volume index (PBVI) (r = 0.79 and r = 0.72, respectively; p < 0.01). PDR measured in the group patients with bad early graft function were lower (13.6 +/- 2.7) than those in the group with a good graft function (21.6 +/- 9) (p < 0.05). The degree of discrepancy between femoral and pulmonary thermodilution cardiac output measures is very wide during OLT so as to make the techniques using the COLD machine clinically useless. On the other hand, the volumes measured by COLD, specially ITBVI and PBVI, are more useful to asses the pre-load than pressure measurements. In OLT, the PDR measured within the first few hours after liver reperfusion may become a useful tool for early diagnosis of primary graft dysfunction (PDF).

Presence of methylated arginine derivatives in orthotopic human liver transplantation: relevance for liver function

Orthotopic liver transplantation (OLT) is a frequent option in the treatment of liver diseases. During the cold ischemia period of the donor liver, there is an accumulation of metabolites that are potent inhibitors of the cytokine-inducible and endothelial nitric oxide synthase isoenzymes. We identified the presence of L-N-monomethylarginine and asymmetric dimethylarginine (ADMA) as the main inhibitors by means of analytic high-pressure liquid chromatography and mass spectrometry techniques. An average ADMA concentration of 450 micromol/L was measured in the preservation medium of donor livers with poor outcomes after OLT. A statistically significant relationship was observed between the concentration of methylated arginine derivatives in the graft and liver function after OLT. These data suggest that measurement of methylated arginine, released after liver protein catabolism, might provide an indication of functional status of the liver that can help the development of strategies intended to improve graft viability.

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.

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.