Preharvest donor hyperoxia predicts good early graft function and longer graft survival after liver transplantation

Intraoperative Anesthetic Strategies to Mitigate Early Allograft Dysfunction After Orthotopic Liver Transplantation: A Narrative Review

Orthotopic liver transplantation (OLT) is the most effective treatment for patients with end-stage liver disease (ESLD). Hepatic insufficiency within a week of OLT, termed early allograft dysfunction (EAD), occurs in 20% to 25% of deceased donor OLT recipients and is associated with morbidity and mortality. Primary nonfunction (PNF), the most severe form of EAD, leads to death or retransplantation within 7 days. The etiology of EAD is multifactorial, including donor, recipient, and surgery-related factors, and largely driven by ischemia-reperfusion injury (IRI). IRI is an immunologic phenomenon characterized by dysregulation of cellular oxygen homeostasis and innate immune defenses in the allograft after temporary cessation (ischemia) and later restoration (reperfusion) of oxygen-rich blood flow. The rising global demand for OLT may lead to the use of marginal allografts, which are more susceptible to IRI, and thus lead to an increased incidence of EAD. It is thus imperative the anesthesiologist is knowledgeable about EAD, namely its pathophysiology and intraoperative strategies to mitigate its impact. Intraoperative strategies can be classified by 3 phases, specifically donor allograft procurement, storage, and recipient reperfusion. During procurement, the anesthesiologist can use pharmacologic preconditioning with volatile anesthetics, consider preharvest hyperoxemia, and attenuate the use of norepinephrine as able. The anesthesiologist can advocate for normothermic regional perfusion (NRP) and machine perfusion during allograft storage at their institution. During recipient reperfusion, the anesthesiologist can optimize oxygen exposure, consider adjunct anesthetics with antioxidant-like properties, and administer supplemental magnesium. Unfortunately, there is either mixed, little, or no data to support the routine use of many free radical scavengers. Given the sparse, limited, or at times conflicting evidence supporting some of these strategies, there are ample opportunities for more research to find intraoperative anesthetic strategies to mitigate the impact of EAD and improve postoperative outcomes in OLT recipients.

Using Rotational Thromboelastometry to Identify Early Allograft Dysfunction after Living Donor Liver Transplantation

Background: Diagnostic tests for early allograft dysfunction (EAD) after living donor liver transplantation (LDLT) vary widely. We aimed to evaluate the predictive value of rotational thromboelastometry (ROTEM)-derived parameters in EAD. Materials and Methods: A total of 121 patients were reviewed. The definition of EAD proposed by Olthoff et al. included the presence of any of the following at postoperative day 7: bilirubin level ≥ 10 mg/dL, INR ≥ 1.6, or serum AST or ALT levels > 2000 IU/L. All patients underwent ROTEM assay, which consisted of an extrinsically activated thromboelastometric test (EXTEM) before and 24 h after LDLT. Results: The 1-year/2-year OS were 68.%8/64.5% and 94.4%/90.8% for the EAD and non-EAD groups, respectively (p = 0.001). Two independent risks were identified for EAD, the postoperative clotting time (CT, p = 0.026) and time to maximum clot firmness (maximum clot firmness (MCF)-t, p = 0.009) on the EXTEM. CT yielded a specificity of 82.0% and negative predictive value of 83.0%, and MCF-t displayed a specificity of 76.4% and negative predictive value of 81.9% in diagnosing EAD. The use of the 24 h post-LDLT ROTEM increased the effectiveness of predicting overall survival (OS) compared to using the Olthoff’s EAD criteria alone (p < 0.001). Conclusion: We conclude that CT and MCF on EXTEM were independent predictors of EAD. The 24 h post-LDLT ROTEM can be used with conventional laboratory tests to diagnose EAD. It increases the effectiveness of predicting OS.

Donor Small-Droplet Macrovesicular Steatosis Affects Liver Transplant Outcome in HCV-Negative Recipients

BACKGROUND

No data are available on liver transplantation (LT) outcome and donor liver steatosis, classified as large droplet macrovesicular (Ld-MaS), small-droplet macrovesicular (Sd-MaS), and true microvesicular (MiS), taking into account the recipient Hepatitis C virus (HCV) status.

AIM

We investigate the impact of allograft steatosis reclassified according to the Brunt classification on early graft function and survival after LT.

METHODS

We retrospectively reviewed 204 consecutive preischemia biopsies of grafts transplanted in our center during the period 2001-2011 according to recipient HCV status.

RESULTS

The median follow-up after LT was 7.5 years (range: 0.0-16.7). In negative recipients (n=122), graft loss was independently associated with graft Sd-MaS, in multivariable Cox regression models comprehending only pre-/intraoperative variables (HR=1.03, 95%CI=1.01-1.05; P=0.003) and when including indexes of early postoperative graft function (HR=1.04, 95%CI=1.02-1.06; P=0.001). Graft Sd-MaS>15% showed a risk for graft loss > 2.5-folds in both the models. Graft Sd-MaS>15% was associated with reduced graft ATP content and, only in HCV- recipients, with higher early post-LT serum AST peaks.

CONCLUSIONS

In HCV-negative recipients, allografts with >15% Sd-MaS have significantly reduced graft survival and show low ATP and higher AST peaks in the immediate posttransplant period. Donors with >15% Sd-MaS have significantly higher BMI, longer ICU stays, and lower PaO2.

Primary graft dysfunction of the liver: definitions, diagnostic criteria and risk factors

Primary graft dysfunction is a multifactorial syndrome with great impact on liver transplantation outcomes. This review article was based on studies published between January 1980 and June 2015 and retrieved from PubMed database using the following search terms: "primary graft dysfunction", "early allograft dysfunction", "primary non-function" and "liver transplantation". Graft dysfunction describes different grades of graft ischemia-reperfusion injury and can manifest as early allograft dysfunction or primary graft non-function, its most severe form. Donor-, surgery- and recipient-related factors have been associated with this syndrome. Primary graft dysfunction definition, diagnostic criteria and risk factors differ between studies. RESUMO A disfunção primária do enxerto hepático é uma síndrome multifatorial com grande impacto no resultado do transplante de fígado. Foi realizada uma ampla revisão da literatura, consultando a base de dados PubMed, em busca de estudos publicados entre janeiro de 1980 e junho de 2015. Os termos descritivos utilizados foram: "primary graft dysfunction", "early allograft dysfunction", "primary non-function" e "liver transplantation". A disfunção traduz graus diferentes da lesão de isquemia e reperfusão do órgão, e pode se manifestar como disfunção precoce ou, na forma mais grave, pelo não funcionamento primário do enxerto. Fatores relacionados ao doador, ao transplante e ao receptor contribuem para essa síndrome. Existem definições diferentes na literatura quanto ao diagnóstico e aos fatores de risco associados à disfunção primária.

Primary graft dysfunction after liver transplantation

BACKGROUND

Primary graft dysfunction (PGD) causes complications in liver transplantation, which result in poor prognosis. Recipients who develop PGD usually experience a longer intensive care unit and hospital stay and have higher mortality and graft loss rates compared with those without graft dysfunction. However, because of the lack of universally accepted definition, early diagnosis of graft dysfunction is difficult. Additionally, numerous factors affect the allograft function after transplantation, making the prediction of PGD more difficult. The present review was to analyze the literature available on PGD and to propose a definition.

DATA SOURCE

A search of PubMed (up to the end of 2012) for English-language articles relevant to PGD was performed to clarify the characteristics, risk factors, and possible treatments or interventions for PGD.

RESULTS

There is no pathological diagnostic standard; many documented definitions of PGD are different. Many factors, such as donor status, procurement and transplant process and recipient illness may affect the function of graft, and ischemia-reperfusion injury is considered the direct cause. Potential managements which are helpful to improve graft function were investigated. Some of them are promising.

CONCLUSIONS

Our analyses suggested that the definition of PGD should include one or more of the following variables: (1) bilirubin ≥ 10 mg/dL on postoperative day 7; (2) international normalized ratio ≥ 1.6 on postoperative day 7; and (3) alanine aminotransferase or aspartate aminotransferase >2000 IU/L within 7 postoperative days. Reducing risk factors may decrease the incidence of PGD. A majority of the recipients could recover from PGD; however, when the graft progresses into primary non-function, the patients need to be treated with re-transplantation.

Normobaric hyperoxia preconditioning ameliorates cisplatin nephrotoxicity

BACKGROUND

Cisplatin is a potent anticancer drug, but its nephrotoxicity limits the clinical use of it. To reduce the Cisplatin-induced nephrotoxicity, various interventions have been implicated. The aim of this study was to examine whether preconditioning with normobaric hyperoxia would prevent Cisplatin-induced nephrotoxicity in patient with solid tumor.

METHODS

In a prospective study, 80 adult patients with solid tumor who were treated with Cisplatin between February 2011 and December 2011 were included. Forty-three patients were exposed to pure oxygen via non-rebreathing reservoir mask which increased the provided oxygen rate to 60% oxygen for 2 hours at 48, 24, and 6 hours before intravenous administration of Cisplatin and 37 patients received only Cisplatin as a control group. Estimated glomerular filtration rate (eGFR) calculated in all patients on day 1 before and on days 1, 3, 6, 30 after Cisplatin exposures.

RESULTS

Patients treated with Cisplatin and 60% oxygen showed a mild improvement in eGFR and mild reduction of serum creatinine after 30 days with statistically mild significant differences (p = 0.048).

CONCLUSION

This study showed that normobaric and intermittent precondition of 60% oxygen prior to Cisplatin treatment had an acute transient adverse effect on renal function; however, the improvement of renal function will be seen after 30 days. Thus, it may help to prevent Cisplatin nephrotoxicity.

Does living donor hyperoxia have an impact on kidney graft function after transplantation?

Background

Improvement in the outcome of organ transplantation is related to advances in patient selection criteria, organ preservation, operative techniques, perioperative care and efficacy of immunosuppressive agents.

Objectives

We aimed to evaluate the effects of higher levels of arterial PaO₂ in donors on DGF (delayed graft function).

Patients and Methods

Forty patients over 18 years old with stage 4-5 chronic kidney disease (CKD) who received a kidney from living donors were enrolled. They were randomly grouped in to the case (n = 17) and control (n = 23) groups and were followed for 2 weeks after transplantation. Donors were exposed to 60% oxygen for at least 2 hours with a face-mask (venture mask) for 2 consecutive days before transplantation until arterial oxygen pressure increased in arterial blood gas to 200 mmHg. Neutrophil gelatinase associated lipocalin (NGAL), Interleuk-18 (IL-18), tumor necrosis factor- α (TNF-α) and transforming growth factor–β (TGF-β) could be good biomarkers for early diagnosis of kidney injury in renal transplant recipients; we assessed kidney function with these biomarkers.

Results

Forty living kidney transplantations including 17 cases and 23 controls were performed; female gender was more prevalent in recipients (n = 16, 40%). The mean age of recipients was 36.1 ± 12.4 (18-67) years old. DGF was detected in 2 (5.95%) individuals, from whom one was in the case group and the other one in the control group. In the univariate analysis, there was no significant correlation between age and biomarkers in urine and serum unless for the second serum NGAL (P = 0.02, r = -0.06) and second urine IL 18 (P = 0.03, r = -0.5) which had a negative correlation, and first urine TNF α (P = 0.02, r = 0.7) which had a positive correlation.

Conclusions

Oxygen therapy in the case group had no significant impact on protection from DGF.

Short-time intermittent preexposure of living human donors to hyperoxia improves renal function in early posttransplant period: a double-blind randomized clinical trial

The purpose of this human study was to investigate the effect of oxygen pretreatment in living kidney donors on early renal function of transplanted kidney. Sixty living kidney donor individuals were assigned to receive either 8-10 L/min oxygen (Group I) by a non-rebreather mask with reservoir bag intermittently for one hour at four times (20, 16, 12, and 1 hours before transplantation) or air (Group II). After kidney transplantation, urine output, blood urea nitrogen (BUN), serum creatinine, need to additional diuretics (NTADs) in the first 24 hours after transplantation, delayed graft function (DGF), the creatinine clearance (CrCL) on 10th day, and duration of hospital stay from the first posttransplant day till normalization of renal function was recorded and compared in two groups. Mean CrCL in posttransplant day 10, NTAD after 24 hours of transplantation, and urine output during 6 hours after operation were significantly better in Group I compared with Group II (P < .05). Also, DGF during the first week after operation and duration of hospital stay was less in Group I compared with Group II. Intermittent exposure of human living kidney donor to hyperoxic environment may improve renal function following kidney transplantation.

Recommendations for the assessment and reporting of multivariable logistic regression in transplantation literature

Multivariable logistic regression is an important method to evaluate risk factors and prognosis in solid organ transplant literature. We aimed to assess the quality of this method in six major transplantation journals. Eleven analytical criteria and four documentation criteria were analyzed for each selected article that used logistic regression. A total of 106 studies (6%) out of 1,701 original articles used logistic regression analyses from January 1, 2005 to January 1, 2006. The analytical criteria and their respective reporting percentage among the six journals were: Linearity (25%); Beta coefficient (48%); Interaction tests (19%); Main estimates (98%); Ovefitting prevention (84%); Goodness-of-fit (3.8%); Multicolinearity (4.7%); Internal validation (3.8%); External validation (8.5%). The documentation criteria were reported as follows: Selection of independent variables (73%); Coding of variables (9%); Fitting procedures (49%); Statistical program (65%). No significant differences were found among different journals or between general versus subspecialty journals with respect to reporting quality. We found that the report of logistic regression is unsatisfactory in transplantation journals. Because our findings may have major consequences for the care of transplant patients and for the design of transplant clinical trials, we recommend a practical solution for the use and reporting of logistic regression in transplantation journals.

A single nucleotide polymorphism of Toll-like receptor 4 identifies the risk of developing graft failure after liver transplantation

BACKGROUND & AIMS

While studies in animal models have linked Toll-like receptor (TLR) 4 signaling to the pathophysiology of ischemia/reperfusion (IR) injury and liver fibrosis, the relevance of TLR4 activation after human liver transplantation is unknown. The TLR4 single nucleotide polymorphism (SNP) D299G is situated within the extracellular domain and diminishes receptor binding to danger-associated molecular patterns.

METHODS

We studied the influence of TLR4 D299G on IR injury and graft survival in 430 deceased donor LT recipients. Compared with livers expressing wild-type (WT) alleles, livers with a TLR4 loss-of-function allele were significantly more likely to have initial good graft function (IGGF) (OR 2.20, p=0.01). In contrast, there was no effect of recipient TLR4 genotype on the rate of IGGF.

RESULTS

The effect of TLR4 D299G on long-term graft survival was analyzed based on hepatitis C virus (HCV) serostatus. In HCV infected recipients, multivariate Cox regression analysis demonstrated a significant association between the presence of recipient, but not donor TLR4 D299G and long-term graft failure (HR 2.48, CI 1.28-4.81; p=0.007). There was no difference in graft survival between TLR4 mutant and WT recipients among non-HCV infected recipients.

CONCLUSIONS

Collectively, these results demonstrate the differential effects of donor and recipient TLR4 signaling in human liver transplantation. Donor TLR4 contributed to sterile injury following cold preservation and the recipient TLR4 genotype was linked with poor allograft survival among HCV infected recipients.

Complement component C3 allotypes and outcomes in liver transplantation

The complement system has been implicated in the pathogenesis of liver diseases. Human complement component C3 (C3) exists as 2 allotypes, fast (F) and slow (S). We conducted a study to address the influence of these alleles on ischemia-reperfusion (IR) injury and graft survival in liver transplant recipients. Four hundred thirty patients receiving liver transplants from 2000 to 2004 were included. C3 allotypes of 296 donor-recipient pairs were determined and correlated with clinical outcomes. Four groups were analyzed according to the C3 genotype: C3 SS donor and recipient, C3 FS or C3 FF donor and C3 SS recipient, C3 SS donor and C3 FS or C3 FF recipient, and C3 FS or C3 FF donor and recipient. Baseline characteristics of the 4 groups were similar. The mean follow-up time was 4.3 +/- 2.2 years. The 4 groups had similar rates of IR injury (P = 0.16). The hazard ratios for liver allograft survival in the C3 SS donor and recipient group in comparison with the other 3 groups (C3 FS or C3 FF donor and C3 SS recipient, C3 SS donor and C3 FS or C3 FF recipient, and C3 FS or C3 FF donor and recipient) were not significantly different: 1.13 (P = 0.60), 0.99 (P = 0.97), and 1.02 (P = 0.95), respectively. In conclusion, donor and recipient C3 genotypes are not associated with liver transplantation outcomes.

Pre-treatment with hyperoxia before coronary artery bypass grafting - effects on myocardial injury and inflammatory response

BACKGROUND

In experimental studies, exposure to hyperoxia for a limited time before ischaemia induces a low-grade systemic oxidative stress and evokes an (ischaemic) preconditioning-like effect of the myocardium. We hypothesised that hyperoxia before cardioplegia could protect the myocardium against necrosis and stunning caused by ischaemia-reperfusion.

METHODS

Forty patients undergoing coronary artery bypass grafting were randomly exposed to an oxygen fraction of 0.4 or > 0.96 in inspired air on an average of 120 min before cardioplegia. Blood for troponin I, creatine kinase-MB, lactate, glutathione and interleukin-6 was sampled from arterial and coronary sinus cannulae during 20 min of reperfusion. Additional arterial samples were drawn 60 min after declamping and in the first post-operative morning. The cardiac index and right and left ventricular stroke work indices were measured before sternotomy and up to 12 h post-operatively.

RESULTS

Troponin I, creatine kinase-MB and lactate did not differ between the groups. Hyperoxic pre-treatment had no impact on the post-operative haemodynamic indices measured with the thermodilution pulmonary artery catheter. More oxidised glutathione was released in the hyperoxia group in the first minute of reperfusion (P = 0.015). Hyperoxic pre-treatment abolished the myocardial release of interleukin-6 during 20 min of reperfusion (P = 0.021 vs. controls). In the first post-operative morning, interleukin-6 was higher in the hyperoxia group [127.0 (86.0-140.0) vs. 85.2 pg/ml (66.6-94.5 pg/ml); P = 0.016].

CONCLUSIONS

Exposure to >96% oxygen before cardioplegia did not attenuate ischaemia-reperfusion injury of the heart in patients undergoing coronary artery bypass grafting. The only potentially beneficial effect observed was the decreased transmyocardial release of interleukin-6.

Liver transplantation()

Orthotopic liver transplantation (OLT) involves the substitution of a diseased native liver with a normal liver (or part of one) taken from a deceased or living donor. Considered an experimental procedure through the 1980s, OLT is now regarded as the treatment of choice for a number of otherwise irreversible forms of acute and chronic liver disease.The first human liver transplantation was performed in the United States in 1963 by Prof. T.E. Starzl of the University of Colorado. The first OLT to be performed in Italy was done in 1982 by Prof. R. Cortesini. The procedure was successfully performed at the Policlinico Umberto I of the University of Rome (La Sapienza).The paper reports the indications for liver transplantation, donor selection and organ allocation in our experience, surgical technique, immunosuppression, complications and results of liver transplantation in our center.

Optimal perioperative oxygen administration

PURPOSE OF REVIEW

During anesthesia and surgery oxygen is routinely administered to all patients. Inspired oxygen concentrations, however, vary between 30 and 100%, and oxygen is often administered in a seemingly random manner. During the last decade it has been shown in several randomized trials that perioperative supplemental oxygen administration might improve outcome after certain surgical procedures. The purpose of this review is to provide an overview about the benefits and risks of supplemental oxygen administration in the perioperative period.

RECENT FINDINGS

Supplemental oxygen improves immune function. Furthermore, 80% inspired oxygen fraction almost doubles subcutaneous tissue oxygen tension and halves the rate of postoperative wound infections. Some studies have shown that supplemental oxygen also decreases the rate of postoperative nausea and vomiting after laparoscopic and open abdominal surgical procedures. Preconditioning with oxygen might improve organ function after liver transplantation and outcome after spinal ischemic insults. Supplemental perioperative oxygen administration is not associated with clinically important side effects.

SUMMARY

Supplemental oxygen administration during the perioperative period might be a simple, inexpensive and well-tolerated treatment option to improve patient outcome. The optimal inspired oxygen concentration still needs to be evaluated.

High preoperative recipient plasma 7beta-hydroxycholesterol is associated with initial poor graft function after liver transplantation

Oxidative stress is implicated in the pathogenesis of hepatic ischemia-reperfusion injury, a major determinant of initial poor graft function (IPGF) after orthotopic liver transplantation (OLT). We prospectively investigated the association between the recipient plasma preoperative oxidative stress and the occurrence of IPGF after deceased-donor OLT and indirectly studied the source-hepatic or extra-hepatic-of systemic oxidative stress in vivo in cirrhosis. We used a recently developed specific and sensitive mass spectrometry assay to measure 7beta-hydroxycholesterol and 7-ketocholesterol (oxysterols), markers of oxidative stress, in biological matrices. At univariate analysis, preoperative recipient 7beta-hydroxycholesterol plasma concentration was significantly higher in transplants with subsequent IPGF (n = 9) compared with those with initial good graft function (IGGF; n = 23) [mean +/- SD: 30.63 +/- 26.42 and 11.57 +/- 15.76 ng/mL, respectively] (P = 0.017). In a logistic regression model, which included also the Model for End-Stage Liver Disease (MELD) score, 7beta-hydroxycholesterol plasma concentration was an independent predictor of IPGF with an odds ratio of 1.17 (95% CI, 1.02-1.33, P = 0.028). Patients with cirrhosis (n = 32) had increased oxysterol plasma levels compared with healthy controls (n = 49); livers with cirrhosis (n = 21), however, had oxysterol content comparable with normal livers obtained from organ donors (n = 19). Oxysterols persisted elevated in plasma 1 month after OLT (n = 23). In conclusion, cirrhosis presents upregulated systemic oxidative stress likely of extrahepatic source that is associated with graft failure after OLT.