Acute kidney injury after liver, heart, and lung transplants: dialysis modality, predictors of renal function recovery, and impact on survival

Risks and ways of preventing kidney dysfunction in drug-induced immunosuppression in solid organ recipients

Immunosuppressive therapy (IMT) is the cornerstone of treatment after transplantation. The goal of immunosuppression is to prevent acute and chronic rejection while maximizing patient survival and long-term graft function. However, the expected effects of IMT must be balanced against the major adverse effects of these drugs and their toxicity. The purpose of this review is to summarize world experience on current immunosuppressive strategies and to assess their effects on renal function.

Kidney disease in non-kidney solid organ transplantation

Kidney disease after non-kidney solid organ transplantation (NKSOT) is a common post-transplant complication associated with deleterious outcomes. Kidney disease, both acute kidney injury and chronic kidney disease (CKD) alike, emanates from multifactorial, summative pre-, peri- and post-transplant events. Several factors leading to kidney disease are shared amongst solid organ transplantation in addition to distinct mechanisms unique to individual transplant types. The aim of this review is to summarize the current literature describing kidney disease in NKSOT. We conducted a narrative review of pertinent studies on the subject, limiting our search to full text studies in the English language. Kidney disease after NKSOT is prevalent, particularly in intestinal and lung transplantation. Management strategies in the peri-operative and post-transplant periods including proteinuria management, calcineurin-inhibitor minimization/ sparing approaches, and nephrology referral can counteract CKD progression and/or aid in subsequent kidney after solid organ transplantation. Kidney disease after NKSOT is an important consideration in organ allocation practices, ethics of transplantation. Kidney disease after SOT is an incipient condition demanding further inquiry. While some truths have been revealed about this chronic disease, as we have aimed to describe in this review, continued multidisciplinary efforts are needed more than ever to combat this threat to patient and allograft survival.

Continuous Renal Replacement Therapy after Liver Transplantation: Peri-Operative Associated Factors and Impact on Survival

Continuous renal replacement therapy (CRRT) following orthotopic liver transplantation (OLT) is usually started for multifactorial reasons, with variable incidence among series. This paper presents a single-center retrospective observational study on the early use (within one week) of CRRT after consecutive cadaveric OLT from January 2008 to December 2016. Preoperative patient characteristics and intraoperative data were collected, and patients were divided into two groups (CRRT and no CRRT) to explore the factors associated with the use of CRRT. Repeated measurements of postoperative creatinine were analyzed with generalized estimating equation (GEE) models. Among 528 OLT patients, 75 (14.2%) were treated with CRRT at least once in the first week. Patients treated with CRRT showed lower survival in a Kaplan−Meier curve (log-rank p value < 0.01). Patients treated with CRRT had a more severe preoperative profile, with a significantly higher age, MELD, BUN, creatinine, and total bilirubin, as well as a longer surgery time and a higher number of transfusions of red blood cells, plasma, and platelets (all p values < 0.05). In a stepwise multiple analysis, the following characteristics remained independently associated with the use of CRRT: the MELD score OR 1.12 (95% CL: 1.07−1.16), p value < 0.001, and the preoperative value for blood urea nitrogen OR 1.016 (95% CL: 1.010−1.023), p value < 0.001. The early use of CRRT after OLT occurred at a low rate in this large cohort; however, it was associated with worse outcomes. Apart from the preoperative severity, repeated intraoperative hypotension episodes, which were likely modifiable or preventable, were associated with the increased use of CRRT and higher postoperative creatinine.

Application of machine learning in liver transplantation: a review

BACKGROUND

Machine learning (ML) has been increasingly applied in the health-care and liver transplant setting. The demand for liver transplantation continues to expand on an international scale, and with advanced aging and complex comorbidities, many challenges throughout the transplantation decision-making process must be better addressed. There exist massive datasets with hidden, non-linear relationships between demographic, clinical, laboratory, genetic, and imaging parameters that conventional methods fail to capitalize on when reviewing their predictive potential. Pre-transplant challenges include addressing efficacies of liver segmentation, hepatic steatosis assessment, and graft allocation. Post-transplant applications include predicting patient survival, graft rejection and failure, and post-operative morbidity risk.

AIM

In this review, we describe a comprehensive summary of ML applications in liver transplantation including the clinical context and how to overcome challenges for clinical implementation.

METHODS

Twenty-nine articles were identified from Ovid MEDLINE, MEDLINE Epub Ahead of Print and In-Process and Other Non-Indexed Citations, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials.

CONCLUSION

ML is vastly interrogated in liver transplantation with promising applications in pre- and post-transplant settings. Although challenges exist including site-specific training requirements, the demand for more multi-center studies, and optimization hurdles for clinical interpretability, the powerful potential of ML merits further exploration to enhance patient care.

Acute Kidney Injury After Liver Transplant: Incidence, Risk Factors, and Impact on Patient Outcomes

OBJECTIVES

Acute kidney injury is a frequent complication of liver transplant. Here, we assessed the rate and contributing factors of acute kidney injury and need for renal replacement therapy in patients undergoing liver transplant at a transplant center in Tehran, Iran.

MATERIAL AND METHODS

We identified all patients who underwent liver transplant at the Imam Khomeini Hospital Complex from March 2018 to March 2019 and who were followed for 3 months after transplant. Acute kidney injury was defined based on the Acute Kidney Injury Network criteria. We collected demographic and pretransplant, intraoperative, and posttransplant data. Univariable and multivariable models were applied to explore independent risk factors for acute kidney injury incidence and need for renal replacement therapy.

RESULTS

Our study included 173 deceased donor liver transplant recipients. Rates of incidence of acute kidney injury and need for renal replacement therapy were 68.2% and 14.5%, respectively. The 3-month mortality rate among those with severe and mild or moderate acute kidney injury was 44.0% (14/25) and 9.7% (9/ 93), respectively (P < .001). Multivariable analyses indicated that serum albumin (relative risk of 0.55; 95% confidence interval, 0.34-0.87; P = .021), baseline serum creatinine (relative risk of 2.11; 95% confidence interval, 1.56-2.90; P = .037), and intraoperative mean arterial pressure (relative risk of 0.76; 95% confidence interval, 0.63-0.82; P = .008) were independent factors for predicting posttransplant acute kidney injury. Independent risk factors for requiring renal replacement therapy were pretransplant serum creatinine (relative risk of 1.99; 95% confidence interval, 1.89-4.47; P = .044) and intraoperative vasopressor infusion (relative risk of 1.41; 95% confidence interval, 1.38-2.00; P = .021).

CONCLUSIONS

We found a high incidence of acute kidney injury among liver transplant recipients in our center. There was a significant association between severity of acute kidney injury and 3-month and in-hospital mortality.

Application of machine learning models for predicting acute kidney injury following donation after cardiac death liver transplantation

BACKGROUND

Acute kidney injury (AKI) is a common complication after liver transplantation (LT) and is an indicator of poor prognosis. The establishment of a more accurate preoperative prediction model of AKI could help to improve the prognosis of LT. Machine learning algorithms provide a potentially effective approach.

METHODS

A total of 493 patients with donation after cardiac death LT (DCDLT) were enrolled. AKI was defined according to the clinical practice guidelines of kidney disease: improving global outcomes (KDIGO). The clinical data of patients with AKI (AKI group) and without AKI (non-AKI group) were compared. With logistic regression analysis as a conventional model, four predictive machine learning models were developed using the following algorithms: random forest, support vector machine, classical decision tree, and conditional inference tree. The predictive power of these models was then evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

The incidence of AKI was 35.7% (176/493) during the follow-up period. Compared with the non-AKI group, the AKI group showed a remarkably lower survival rate (P < 0.001). The random forest model demonstrated the highest prediction accuracy of 0.79 with AUC of 0.850 [95% confidence interval (CI): 0.794-0.905], which was significantly higher than the AUCs of the other machine learning algorithms and logistic regression models (P < 0.001).

CONCLUSIONS

The random forest model based on machine learning algorithms for predicting AKI occurring after DCDLT demonstrated stronger predictive power than other models in our study. This suggests that machine learning methods may provide feasible tools for forecasting AKI after DCDLT.

Acute kidney injury after lung transplantation: a narrative review

Acute kidney injury (AKI) is a commonly recognized complication after lung transplantation (LT) and is related to increased mortality and morbidity. With the improvement of survival after LT and the increasing number of lung transplant recipients, the detrimental impact of current management on renal function has become increasingly apparent. Multifarious risk factors in the perioperative setting contribute to the development of AKI, including the preoperative status and complications of the recipient, complex perioperative problems especially hemodynamic fluctuation, and exposure to nephrotoxic agents, mainly calcineurin inhibitors (CNIs) and antimicrobial drugs. Identification and minimization of the effects of these risk factors can relieve AKI severity and incidence in high-risk patients. Close monitoring of urine output and serum creatinine (sCr) levels and of specific biomarkers may promote early recognition of AKI and rapid nephrology intervention to improve outcomes. This review summarizes advances in the epidemiology, diagnostic criteria, biological markers of AKI, and further recommends appropriate treatment strategies for the long-term management of AKI related manifestations in lung transplant recipients. Future work will need to focus on developing more accurate measures of renal function and identifying patients before the occurrence of early renal damage. Combining renal protection strategies with the use of new biomarkers to develop early kidney risk identification and protection protocols is a promising idea that requires further investigation.

Acute kidney injury and chronic kidney disease after combined heart-liver transplant in patients with congenital heart disease: A retrospective case series

Although it is known that children undergoing heart transplantation are at increased risk for both AKI and CKD, renal function following CHLT remains understudied. All pediatric CHLT patients from 2006 to 2019 were included. The prevalence of AKI in the first 7 post-operative days, renal recovery at 30 post-operative days, and CKD were ascertained. AKI was defined as an increase in creatinine greater than 1.5 times baseline, and CKD, as an eCrCl less than 90 mL/min/1.73 m² . The need for RRT was also analyzed. 10 patients were included, with an average age of 20 years and an average listing time of 130 days. Preoperatively, the median eCrCl was 91.12 mL/min/m² (IQR 70.51, 127.75 min/mL/m² ). 5 (50%) patients had CKD, with 4 at stage 2 and 1 at stage 3. AKI occurred post-operatively in 3 of 9 (33%) patients: 2 at stage 1 and 1 at stage 2. 2 (67%) resolved by 7 days. Of the 5 patients who reached their 1-year follow-up, 1 (20%) had stage 3 CKD. Among 2 patients, neither had CKD at 5 years. One patient required RRT 2 weeks after CHLT. Despite an increased prevalence of preoperative CKD, patients undergoing CHLT have a lower AKI prevalence than those receiving an isolated heart or liver transplant. Of those with AKI, early renal recovery is common, although at 1 year CKD remains present in 20%. Among long-term survivors, normal renal function is achievable.

Acute kidney injury and chronic kidney disease after non-kidney solid organ transplantation

BACKGROUND

SOT is the treatment of choice for end-stage organ disease. Improved long-term survival after NKSOT has uncovered chronic morbidity including CKD. AKI is common after NKSOT and may be associated with long-term CKD.

METHODS

We performed a retrospective cohort study looking at AKI and CKD after pediatric heart (n = 109) or liver (n = 112) transplant. AKI was defined using KDIGO creatinine-based criteria. pAKI was AKI ≤ 7 days post-transplant; CKD_3-5 was eGFR < 60 mL/min/1.73 m² by modified Schwartz formula for > 3 months. We looked at the incidence of CKD_3-5 and the effect of perioperative pAKI on the slope of eGFR post-transplant.

RESULTS

pAKI was seen in 63% (n = 69) after heart and 38% (n = 43) after liver transplant. pAKI was associated with longer ICU and hospital stays. Cumulative incidence (95% CI) of CKD_3-5 at 60 months post-heart transplant was 40.9% (27.9%-57.1%) in patients with AKI vs 35.8% (17.1%-64.8%) in those without (P = NS). Post-liver transplant, the cumulative incidence of CKD_3-5 at 60 months was 0% in those without pAKI vs 10% (3.2%-29.3%) in those with (P = .01). Patients with pAKI had lower eGFR at last follow-up.

CONCLUSION

pAKI and CKD are common after NKSOT. Incidence of CKD is higher in those with pAKI. AKI episodes are associated with a drop in eGFR during follow-up. Identifying patients who have had AKI is an important first step in identifying those at risk of repeated AKI episodes. These patients would benefit from closer monitoring for CKD, lower nephrotoxic drug use, and follow-up with nephrology.

Prognostic Value of Creatinine Concentration and Glomerular Filtration Rate in Acute Kidney Injury Development in the Early Postoperative Period After Heart Transplantation

INTRODUCTION

Recipients of nonrenal organ transplants, including the heart, are at risk for developing acute kidney injury (AKI). This situation significantly jeopardized the outcome of patients. The most effective treatment is continuous renal replacement therapy (CRRT) AIM: The goal of this project is to verify the prognostic value of preoperative serum creatinine concentration and glomerular filtration rate (GFR), calculated by the Modification of Diet in Renal Disease formula, to determine the risk of renal failure after grafting RESULTS: In the group of 39 patients, CRRT was needed in 7 patients (17.9%; group K); 32 patients were in the control group (group C). The pretransplant creatinine level in group K was 133.7 ± 31.3 μmol/L and in group C was 160.8 ± 97.6 μmol/L; P = .47. We did not find a difference between groups in GFR: group K 51 ± 6mL/min/1.73 m² versus group C 43 ± 20 mL/min/1.73 m²; P = .65. Demographic data differed between groups. Patients in group C had significantly more often hypertension, diabetes mellitus, ischemic cardiomyopathy, and previous neurologic disorders and were male. Patients with CRRT had longer intensive care unit (ICU) stays after transplantation than the control population: 25 ± 19 versus 12 ± 10 days; P = .02. Other results showed that primary graft dysfunction occurred in 2 patients in group K and 6 in the control group; 1 needed extracorporeal membrane oxygenation support, and he died on the 12th day. The mean duration of renal replacement therapy was 9.8 days. There were 2 neurologic disorders-1 in each group-and 6 reoperations due to bleeding.

CONCLUSIONS

Developing AKI requiring CRRT after heart transplantation prolonged the length of ICU stays. Preoperative creatinine concentration and glomerular filtration rate do not predict AKI.

Predictors of renal replacement therapy after heart transplantation and its impact on long-term survival

BACKGROUND

Renal replacement therapy (RRT) after heart transplant (HT) is associated with worse prognosis. We aimed to identify predictors of RRT and the impact of this complication on long-term survival.

METHODS

Cohort study of HT patients. Univariate and multivariate competing-risk regression was performed to identify independent predictors of RRT. The cumulative incidence function was plotted for RRT. The Kaplan-Meier method was used to compare long-term survival.

RESULTS

We included 103 patients. At multivariate analysis, only the emergency status of HT (short-term mechanical circulatory support as a bridge to transplant), chronic kidney disease, and low oxygen delivery were independent predictors of RRT (subhazard ratio [SHR] 4.11, 95% CI 1.84-9.14; SHR 3.17, 95% CI 1.29-7.77; SHR 2.86, 95% CI 1.14-7.19, respectively). Elective HT patients that required RRT showed a significantly reduced survival comparable to patients with emergency HT and RRT (75% ± 13% vs. 67% ± 16%). The absence of RRT implied an excellent survival in patients with an emergency status of HT and elective HT (100% vs. 93% ± 4%).

CONCLUSION

The emergency status of HT, chronic kidney disease, and low oxygen delivery were independent predictors of RRT. The occurrence of RRT increases the risk of death in elective HT as much as in patients with an emergency status.

Relation of Preoperative and Postoperative Echocardiographic Parameters With Rejection and Mortality in Liver Transplant Patients

OBJECTIVES

Survival in liver transplant after end-stage liver disease is associated with major cardiac functions. In a significant number of patients with end-stage liver disease, cardiac dysfunctions may be observed, which can include high-output heart failure, cardiac valve disease, and pulmonary venous and arterial hypertension. All of these affect perioperative survival. The aim of our study was to determine whether preoperative and postoperative echocardiographic parameters, specifically right heart-related tricuspid regurgitation, estimated systolic pulmonary arterial pressure, and tricuspid annular plane systolic excursion, are associated with rejection and mortality in liver transplant patients.

MATERIALS AND METHODS

Adult patients (> 18 years old) who underwent liver transplant at our center between January 2011 and March 2017 were included in the study, with 64 patients retrospectively screened. The echocardiographic images that were taken immediately before and immediately after liver transplant were evaluated. The patients were divided into 2 groups according to rejection data and mortality. All parameters were analyzed for both variables.

RESULTS

For the 24 patients with liver rejection and 40 patients without liver rejection, there were no statistically significant differences in terms of demographic data, echocardiographic parameters, and laboratory data. However, when patients were evaluated according to survival, there was a statistically significant difference between these 2 groups concerning the echocardiography parameters of systolic pulmonary arterial pressure (P = .005), tricuspid annular plane systolic excursion (P = .001), and postoperative right ventricular width (P = .01).

CONCLUSIONS

Echocardiography, being a simple and easily accessible technique that is reliable in excluding pulmonary hypertension diagnosis, can be used as a guide in the evaluation of right ventricular function and tricuspid regurgitation, particularly in patients who are not hemodynamically stable before and after liver transplant.

Predictors of renal function recovery among patients undergoing renal replacement therapy following orthotopic liver transplantation

Renal dysfunction frequently occurs during the periods preceding and following orthotopic liver transplantation (OLT), and in many cases, renal replacement therapy (RRT) is required. Information regarding the duration of RRT and the rate of kidney function recovery after OLT is crucial for transplant program management. We evaluated a sample of 155 stable patients undergoing post-intensive care hemodialysis (HD) from a patient population of 908 adults who underwent OLT. We investigated the average time to renal function recovery (duration of RRT required) and determined the risk factors for remaining on dialysis > 90 days after OLT. Log-rank tests were used for univariate analysis, and Cox proportional hazards models were used to identify factors associated with the risk of remaining on HD. The results of our analysis showed that of the 155 patients, 28% had pre-OLT diabetes mellitus, 21% had pre-OLT hypertension, and 40% had viral hepatitis. Among the patients, the median MELD (Model for End-Stage Liver Disease) score was 27 (interquartile range [IQR] 22-35). When they were listed for liver transplantation, 32% of the patients had serum creatinine (Scr) levels > 1.5 mg/dL or were on HD, and 50% had serum creatinine (Scr) levels > 1.5 mg/dL or were on HD at the time of OLT. Of the transplanted patients, 25% underwent pre-OLT intermittent HD, and 14% and 41% underwent continuous renal replacement therapy (CRRT) pre-OLT and post-OLT, respectively. At 90 days post-OLT, 118 (76%) patients had been taken off dialysis, and 16 (10%) patients had died while undergoing HD. The median recovery time of these post-OLT patients was 33 (IQR 27–39) days. In the multivariate analysis, fulminant hepatic failure as the cause of liver disease (p<0.001), the absence of pre-OLT hypertension (p = 0.016), a lower intraoperative fresh-frozen plasma (FFP) transfusion volume (p = 0.019) and not undergoing pre-OLT intermittent HD (p = 0.032) were associated with performing RRT for less than 90 days. Therefore, a high proportion of OLT patients showed improved renal function after OLT, and those who were diagnosed with fulminant hepatic failure, had no pre-OLT hypertension, received a lower transfused volume of intraoperative FFP and did not undergo pre-OLT intermittent HD had a higher probability of recovery.

Cyclosporine A alters expression of renal microRNAs: New insights into calcineurin inhibitor nephrotoxicity

Calcineurin inhibitors are powerful immunosuppressants that revolutionized organ transplantation. However, non-immune effects of the calcineurin inhibitor, such as cyclosporine A (CsA), have significantly hindered their use. Specifically, nephrotoxicity, which is associated with tubulointerstitial fibrosis, inflammation, and podocyte damage, affects up to half of all transplant patients. Calcineurin is involved in many aspects of kidney development and function; therefore, mechanisms of CsA-induced nephrotoxicity are complex and not yet fully understood. MicroRNAs are short non-coding RNAs that regulate protein-coding RNA expression through post-translational repression of target messenger RNAs. MicroRNA dysregulation is known to be involved in kidney diseases including fibrosis. In this study, we compared the renal microRNA expression profiles between mice that received CsA (20 mg/kg) or vehicle daily for six weeks. The results demonstrate that CsA induces significant changes in renal microRNA expression profile. We used combined criteria of False Discovery Rate (≤0.1), fold change (≥2) and median signal strength (≥50) and identified 76 differencially expressed microRNAs. This approach identified microRNAs previously linked to renal fibrosis that includes let-7d, miR-21, miR-29, miR-30, miR-130, miR-192, and miR-200 as well as microRNAs that have not been reported to be related to nephrotoxicity or immunosuppression. Pathway analysis of microRNA/mRNA changes highlights the Wnt, TGF-β, mTOR, and VEGF pathways. The mRNA expression profiles were compared in the same samples. The change of mRNA and microRNA profiles showed close correlations. To validate that the observed microRNA and mRNA expression level changes in mice kidney tissue were directly related to CsA treatment, the expression change induced by CsA treatment of three microRNAs (miR-21, miR-186, and miR-709) and three mRNAs (BMPR1a, SMURF1 and SMAD7) were compared in HEK293 cell line. A similar trend of expression level change was induced by CsA treatment in all selected microRNAs and mRNAs in the in vitro cell model. These data provide a roadmap for future work to study the role of the known and novel candidate microRNAs in the mechanism of nephrotoxicity and their further therapeutic potential.

Disrupted Renal Mitochondrial Homeostasis after Liver Transplantation in Rats

BACKGROUND

Suppressed mitochondrial biogenesis (MB) contributes to acute kidney injury (AKI) after many insults. AKI occurs frequently after liver transplantation (LT) and increases mortality. This study investigated whether disrupted mitochondrial homeostasis plays a role in AKI after LT.

METHODS

Livers were explanted from Lewis rats and implanted after 18 h cold storage. Kidney and blood were collected 18 h after LT.

RESULTS

In the kidney, oxidative phosphorylation (OXPHOS) proteins ATP synthase-β and NADH dehydrogenase-3 decreased 44% and 81%, respectively, with marked reduction in associated mRNAs. Renal PGC-1α, the major regulator of MB, decreased 57% with lower mRNA and increased acetylation, indicating inhibited synthesis and suppressed activation. Mitochondrial transcription factor-A, which controls mtDNA replication and transcription, protein and mRNA decreased 66% and 68%, respectively, which was associated with 64% decreases in mtDNA. Mitochondrial fission proteins Drp-1 and Fis-1 and mitochondrial fusion protein mitofusin-1 all decreased markedly. In contrast, PTEN-induced putative kinase 1 and microtubule-associated protein 1A/1B-light chain 3 increased markedly after LT, indicating enhanced mitophagy. Concurrently, 18- and 13-fold increases in neutrophil gelatinase-associated lipocalin and cleaved caspase-3 occurred in renal tissue. Both serum creatinine and blood urea nitrogen increased >2 fold. Mild to moderate histological changes were observed in the kidney, including loss of brush border, vacuolization of tubular cells in the cortex, cast formation and necrosis in some proximal tubular cells. Finally, myeloperoxidase and ED-1 also increased, indicating inflammation.

CONCLUSION

Suppression of MB, inhibition of mitochondrial fission/fusion and enhancement of mitophagy occur in the kidneys of recipients of liver grafts after long cold storage, which may contribute to the occurrence of AKI and increased mortality after LT.

Acute kidney injury after orthotopic liver transplantation

Acute kidney injury (AKI), one of the most frequent complications in the early period after liver transplantation, causes serious obstacles in the management of these patients affecting their outcomes. We studied retrospectively 79 subjects who underwent orthotopic liver transplantation (OLT). AKI was defined as an elevation of serum creatinine 1.5 times above baseline or an absolute serum creatinine level > 2 mg/dL. Our aim was to analyze the incidence, correlation with prior renal impairment, outcomes of AKI after OLT. Twenty-two patients (29.3%) developed AKI after OLT with 31.81% of the requiring renal replacement therapy. Among patients with AKI the duration of mechanical ventilation was prolonged (P = .001), length of stay in the intensive care unit was greater (P = .001), infections were more common (P = .016), and 30-day and 1-year mortality rates higher (P = .018). Logistic regression analysis showed post-OLT AKI to be an independent risk factor for 1-year mortality after OLT.

Natriuretic peptides in the management of solid organ transplantation associated acute kidney injury: a systematic review and meta-analysis

Randomized controlled trials involving natriuretic peptide administration in solid organ transplantation setting have shown inconsistent effects for renal endpoints. We conducted a systematic review and meta-analysis of these trials to ascertain the role of natriuretic peptides in the management of solid organ transplantation associated acute kidney injury (AKI). MEDLINE, EMBASE, and Google scholar were searched independently by two authors for randomized trials evaluating renal effects of natriuretic peptides in solid organ transplantation settings. Two reviewers independently assessed the studies for eligibility and extracted the relevant data. The pooled estimate showed that natriuretic peptide administration is associated with a reduction in AKI requiring dialysis (odds ratio = 0.50 [0.26–0.97]), a statistically nonsignificant trend toward improvement in posttransplant creatinine clearance (weighted mean difference = 5.5 mL/min, [−1.3 to 12.2 mL/min]), and reduction in renal replacement requirement duration (weighted mean difference −44.0 hours, [−60.5 to −27.5 hours]). There were no mortality events and no adverse events related to natriuretic peptides. In conclusion, administration of natriuretic peptides in solid organ transplantation may be associated with significant improvements in renal outcomes. These observations need to be confirmed in an adequately powered, prospective multicenter study.

Recovery from AKI and short- and long-term outcomes after lung transplantation

BACKGROUND AND OBJECTIVES

Patients with AKI after lung transplantation are at increased risk for CKD and death. Whether patients who completely recover from AKI have improved long-term outcome compared with patients who do not completely recover remains unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study retrospectively evaluated data on 657 patients who underwent lung transplantation from 1997 to 2009. Outcomes analyzed were the incidence of renal recovery after AKI and the association of this recovery with short- and long-term mortality. AKI was defined by an absolute increase in serum creatinine of ≥0.3 mg/dl or a percent increase in serum creatinine of ≥50% from baseline at any time during the first 2 weeks after transplantation.

RESULTS

Four hundred twenty-four (65%) patients experienced AKI in the first 2 weeks after transplantation. Of these patients, complete renal recovery occurred in 142 (33%) patients. The incidence of in-hospital complications was similar between patients who recovered renal function and patients without recovery. At 1 year, the cumulative incidence of CKD was 14% and 22% (P=0.10) and patient survival rate was 81% and 76% (P=0.20) in patients with complete recovery from AKI and patients without recovery, respectively. Patients with completely recovered AKI had similar risk-adjusted long-term mortality compared with patients who did not recover (hazard ratio [95% confidence interval]=1.42 [1.15-2.05] versus 1.53 [1.01-2.00]).

CONCLUSIONS

Patients who recover completely from early AKI after lung transplantation have a similar risk for CKD and long-term mortality compared with patients who do not recover.

Withholding and withdrawing renal support in acute kidney injury

Management of critically ill patients with acute kidney injury (AKI) is mainly limited to supportive therapy, with dialysis as one of the main components. Whether or not to offer dialysis and when to withdraw dialysis is a one of the many choices physicians face in daily clinical practice. Withholding or withdrawing renal replacement therapy is a complex decision and depends on many interacting factors, which are unique for each patient and their families and for the care team. An evidence-based guideline with nine specific recommendations for managing patients has been available however is infrequently employed to help clinical decision making. In this review, we discuss the important issues affecting decisions to withhold or withdraw dialysis in AKI patients and provide an approach for making these decisions for patient management.

Implications of acute kidney injury after heart transplantation: what a surgeon should know

OBJECTIVE

Data regarding risks and consequences of acute kidney injury (AKI) after cardiac transplantation are dismissingly few and unclear. This study defined the incidence, risk factors and prognostic implication of AKI in a single-center cohort operated on between January 1999 and December 2008.

METHODS

Data from 307 consecutive recipients (mean age: 47.42 ± 13.58, 20.5% female, 18.9% diabetics, 19.5% with previous cardiac operations, 26.4% hospitalized, 78.4 ± 33.7 ml min(-1) preoperative glomerular filtration rate (eGFR)) were analyzed using multivariable logistic regression modeling. AKI was defined according to RIFLE (Risk, Injury, and Failure; and Loss, and End-stage kidney disease) criteria.

RESULTS

RIFLE scores of I or F were detected in 14%, and continuous venovenous hemofiltration was needed in 6.1%. Risk factors for AKI were: previous cardiac operation (odds ratio (OR) 2.35; 95% confidence interval (CI), 1.11-4.9), blood transfusion (OR 1.08; 95% CI, 1.011-1.16), troponin I release >10 (OR 1.031; 95% CI, 1.001-1.064), length of ischemic time (OR 1.008; 95% CI, 1.011-1.16). Overall hospital mortality averaged 7.8% and overall 1-year mortality was 10.4%; both mortality rates increased with each RIFLE stratification (Normal 3.4%, RIFLE R = 7.1%; RIFLE I = 25.7%; and RIFLE F = 37.5% and Normal 5.6%, RIFLE R = 11.8%, RIFLE I = 25.7%, and RIFLE F = 37.5%, respectively). AKI proved independent predictors of both early and 1-year mortality. The burden of AKI significantly affected 1-year kidney function (Δ preoperative GFR-1-year GFR in AKI vs no AKI = -25.872 ± 22.54 vs -7.968 ± 34.18, p = 0.015).

CONCLUSIONS

AKI is a highly prevalent and prognostically important complication. Some of the risk factors for AKI identified may be modifiable.

[Medical complications of lung transplantation]

In 2010, lung transplantation is a valuable therapeutic option for a number of patients suffering from of end-stage non-neoplastic pulmonary diseases. The patients frequently regain a very good quality of life, however, long-term survival is often hampered by the development of complications such as the bronchiolitis obliterans syndrome, metabolic and infectious complications. As the bronchiolitis obliterans syndrome is the first cause of death in the medium and long term, an intense immunosuppressive treatment is maintained for life in order to prevent or stabilize this complication. The immunosuppression on the other hand induces a number of potentially severe complications including metabolic complications, infections and malignancies. The most frequent metabolic complications are arterial hypertension, chronic renal insufficiency, diabetes, hyperlipidemia and osteoporosis. Bacterial, viral and fungal infections are the second cause of mortality. They are to be considered as medical emergencies and require urgent assessment and targeted therapy after microbiologic specimens have been obtained. They should not, under any circumstances, be treated empirically and it has also to be kept in mind that the lung transplant recipient may present several concomitant infections. The most frequent malignancies are skin cancers, the post-transplant lymphoproliferative disorders, Kaposi's sarcoma and some types of bronchogenic carcinomas, head/neck and digestive cancers. Lung transplantation is no longer an exceptional procedure; thus, the pulmonologist will be confronted with such patients and should be able to recognize the symptoms and signs of the principal non-surgical complications. The goal of this review is to give a general overview of the most frequently encountered complications. Their assessment and treatment, though, will most often require the input of other specialists and a multidisciplinary and transversal approach.