Association of pre-transplant blood pressure with post-transplant outcomes

Correlation Between Serum Transaminase Levels and Estimated Glomerular Filtration Rate After Living-Donor Kidney Transplantation

BACKGROUND

There is a risk of hypoperfusion during kidney transplantation surgery owing to patients' underlying disease and ischemia-reperfusion injury; further, hypoperfusion may cause injury to major organs. We hypothesized that the decrease in blood pressure after ischemia-reperfusion injury during kidney transplantation may be associated with indicators of liver injury and kidney graft function.

METHODS

Data regarding living-donor kidney transplantations performed at our institution between 2018 and 2022 were retrospectively evaluated. Exclusion criteria included pediatric recipients or donors aged <18 years, multiple organ transplantation, and elevated postoperative serum transaminase levels. Correlations among blood pressure, serum transaminase levels on postoperative days 3 to 5, and estimated glomerular filtration rate (eGFR) on postoperative days 7 and 14 were analyzed. Further, a subgroup analysis was performed based on eGFR.

RESULTS

A total of 276 patients were included in the final analysis. Serum transaminase levels were significantly negatively correlated with eGFR (partial correlation coefficient-0.26, P < .001). The postreperfusion decrease in blood pressure was not correlated with serum transaminase levels. However, the postreperfusion decrease in blood pressure and baseline blood pressure correlated with the eGFR (partial correlation coefficient = -0.18, P = .004).

CONCLUSION

These findings indicate a correlation between intraoperative liver injury and kidney graft function, suggesting the importance of intraoperative management of organ perfusion. Since postreperfusion blood pressure changes did not significantly correlate with liver injury indicators, it is important to consider other causative factors for hypoperfusion in major organs during living-donor kidney transplantation, including microcirculatory failure and organ congestion-related ischemia/reperfusion.

Defining optimal blood pressure control for pre-transplant end-stage renal disease patients: scoping review

BACKGROUND

Strict blood pressure control is essential to prevent cardiovascular disease and is associated with decreased mortality. However, in patients with end-stage renal disease awaiting renal transplantation, the level of optimal blood pressure control is not yet defined.

METHODS

Following the PRISMA Extension for Scoping Reviews, we searched MEDLINE and EMBASE for all peer-reviewed articles using keywords including 'end-stage renal disease', 'blood pressure', and 'pre-transplant' from their inception to 7 August 2022.

RESULTS

Seven observational studies, including one population-based study, were included in the review. Most studies investigated factors associated with post-transplant graft failure or mortality. There was considerable heterogeneity in defining optimal pre-transplant blood pressure measurement frequency among studies (average of three measurements vs. single measurement). One study suggested that low pre-transplant diastolic blood pressure (<50 mmHg) was associated with lower odds of delayed graft failure and mortality. Two studies noted that pre-transplant hypertension, or clinical criteria of hypertension that were present prior to transplant, was associated with post-transplant adverse outcomes. In contrast, one study noted that pre-transplant sustained hypotension with mean blood pressure <80 mmHg, was associated with a higher frequency of delayed graft failure.

CONCLUSION

This systematic review summarizes the current evidence regarding the relationship between pre-transplant blood pressure control and post-transplant outcomes in end-stage renal disease patients. While the results from the included studies are mixed, more stringent blood pressure control than currently practiced may be beneficial to decrease graft failure and mortality in this patient population.

Pretransplant characteristics of kidney transplant recipients that predict posttransplant outcome

Better characterization of the potential kidney transplant recipient using novel biomarkers, for example, pretransplant plasma endotrophin, will lead to improved outcome after transplantation. This mini-review will focus on current knowledge about pretransplant recipients’ characteristics, biomarkers, and immunology. Clinical characteristics of recipients including age, obesity, blood pressure, comorbidities, and estimated survival scores have been introduced for prediction of recipient and allograft survival. The pretransplant immunologic risk assessment include histocompatibility leukocyte antigens (HLAs), anti-HLA donor-specific antibodies, HLA-DQ mismatch, and non-HLA antibodies. Recently, there has been the hope that pretransplant determination of markers can further improve the prediction of posttransplant complications, both short-term and long-term outcomes including rejections, allograft loss, and mortality. Higher pretransplant plasma endotrophin levels were independently associated with posttransplant acute allograft injury in three prospective European cohorts. Elevated numbers of non-synonymous single-nucleotide polymorphism mismatch have been associated with increased allograft loss in a multivariable analysis. It is concluded that there is a need for integration of clinical characteristics and novel molecular and immunological markers to improve future transplant medicine to reach better diagnostic decisions tailored to the individual patient.

Recipient pre-existing chronic hypotension is associated with delayed graft function and inferior graft survival in kidney transplantation from elderly donors

BACKGROUND

Pre-existing chronic hypotension affects a percentage of kidney transplanted patients (KTs). Although a relationship with delayed graft function (DGF) has been hypothesized, available data are still scarce and inconclusive.

METHODS

A monocentric retrospective observational study was performed on 1127 consecutive KTs from brain death donors over 11 years (2003-2013), classified according to their pre-transplant Mean Blood Pressure (MBP) as hypotensive (MBP < 80 mmHg) or normal-hypertensive (MBP ≥ 80 mmHg, with or without effective antihypertensive therapy).

RESULTS

Univariate analysis showed that a pre-existing hypotension is associated to DGF occurrence (p<0.01; OR for KTs with MBP < 80 mmHg, 4.5; 95% confidence interval [CI], 2.7 to 7.5). Chronic hypotension remained a major predictive factor for DGF development in the logistic regression model adjusted for all DGF determinants. Adjunctive evaluations on paired grafts performed in two different recipients (one hypotensive and the other one normal-hypertensive) confirmed this assumption. Although graft survival was only associated with DGF but not with chronic hypotension in the overall population, stratification according to donor age revealed that death-censored graft survival was significantly lower in hypotensive patients who received a KT from >50 years old donor.

CONCLUSIONS

Our findings suggest that pre-existing recipient hypotension, and the subsequent hypotension-related DGF, could be considered a significant detrimental factor, especially when elderly donors are involved in the transplant procedure.

Blood Pressure Management After Reperfusion in Living-Donor Kidney Transplantation

BACKGROUND

The central focus of anesthesia management in kidney transplantation is to avoid hypotensive episodes and maintain adequate perfusion pressure to the graft. However, it is not clear whether there is an optimal systolic blood pressure (SBP) level after reperfusion for living-donor transplant outcomes. The aim of this study is to investigate the effect of SBP after reperfusion on early graft function in living-donor kidney transplantation.

METHODS

We retrospectively analyzed 315 patients who underwent living-donor kidney transplantation from January 2013 to December 2017. We divided the patients into 4 groups according to SBP after reperfusion and compared the postoperative estimated glomerular filtration rate and creatinine.

RESULTS

There were no differences in the postoperative recovery of kidney graft function in the first 7 postoperative days among the 4 SBP groups after reperfusion. However, the urine output after reperfusion was significantly less in the group with SBP < 140 mm Hg after reperfusion compared with the remaining 3 groups in a multivariate analysis (P = .04).

CONCLUSIONS

No significant differences in early graft function were observed among the 4 SBP groups. SBP ≥ 140 mm Hg after reperfusion, which is linked to greater urine output, can be beneficial in terms of long-term graft survival and mortality.

Approach and Management of Hypertension After Kidney Transplantation

Hypertension is one of the most common cardiovascular co-morbidities after successful kidney transplantation. It commonly occurs in patients with other metabolic diseases, such as diabetes mellitus, hyperlipidemia, and obesity. The pathogenesis of post-transplant hypertension is complex and is a result of the interplay between immunological and non-immunological factors. Post-transplant hypertension can be divided into immediate, early, and late post-transplant periods. This classification can help clinicians determine the etiology and provide the appropriate management for these complex patients. Volume overload from intravenous fluid administration is common during the immediate post-transplant period and commonly contributes to hypertension seen early after transplantation. Immunosuppressive medications and donor kidneys are associated with post-transplant hypertension occurring at any time point after transplantation. Transplant renal artery stenosis (TRAS) and obstructive sleep apnea (OSA) are recognized but common and treatable causes of resistant hypertension post-transplantation. During late post-transplant period, chronic renal allograft dysfunction becomes an additional cause of hypertension. As these patients develop more substantial chronic kidney disease affecting their allografts, fibroblast growth factor 23 (FGF23) increases and is associated with increased cardiovascular and all-cause mortality in kidney transplant recipients. The exact relationship between increased FGF23 and post-transplant hypertension remains poorly understood. Blood pressure (BP) targets and management involve both non-pharmacologic and pharmacologic treatment and should be individualized. Until strong evidence in the kidney transplant population exists, a BP of <130/80 mmHg is a reasonable target. Similar to complete renal denervation in non-transplant patients, bilateral native nephrectomy is another treatment option for resistant post-transplant hypertension. Native renal denervation offers promising outcomes for controlling resistant hypertension with no significant procedure-related complications. This review addresses the epidemiology, pathogenesis, and specific etiologies of post-transplant hypertension including TRAS, calcineurin inhibitor effects, OSA, and failed native kidney. The cardiovascular and survival outcomes related to post-transplant hypertension and the utility of 24-h blood pressure monitoring will be briefly discussed. Antihypertensive medications and their mechanism of actions relevant to kidney transplantation will be highlighted. A summary of guidelines from different professional societies for BP targets and antihypertensive medications as well as non-pharmacological interventions, including bilateral native nephrectomy and native renal denervation, will be reviewed.

An improvement of carotid intima-media thickness and pulse wave velocity in renal transplant recipients

Background

Renal transplantation can significantly improve the quality of life of patients with end stage renal disease (ESRD) who would otherwise require dialysis. Renal transplant (RT) recipients have higher risks of cardiovascular disease compared with general population. The carotid intima-media thickness (CIMT) and pulse wave velocity (PWV) have been used as the important predicting factor of vascular arteriosclerosis. Therefore, this study was to investigate the improvement of carotid intima-media thickness and pulse wave velocity in renal transplant recipients.

Methods

Thirty-one patients with chronic kidney disease being treated with hemodialysis, 31 renal transplant recipients and 84 healthy control subjects were included to have the clinical evaluations and ultrasonography of bilateral carotid arteries. CIMT and PWV were independently measured by two ultrasonographers using the technique of ultrasonic radiofrequency tracking and correlated with arteriosclerosis risk factors. The progression of CIMT and PWV with age were analyzed by linear regression models, and the slopes of curves were compared using Z test.

Results

Compared with the patients on hemodialysis, the CIMT was significantly lower in renal transplant recipients and healthy control. The PWV were higher in hemodialysis patients and renal transplant recipients than that of the subjects in control group. The progression is CIMT positively corelated with age and cumulative duration in renal transplant recipients and hemodialysis patients. In both hemodialysis patients and renal transplant recipients, age and cumulative time on dialysis were all positively correlated with the increase of PWV as well.

Conclusions

Carotid intima-media thickness and pulse wave velocity is the predicting factors of developing arteriosclerosis, which were improved in renal transplant recipients.

Electronic supplementary material

The online version of this article (10.1186/s12880-018-0263-7) contains supplementary material, which is available to authorized users.

Predictive Score for Posttransplantation Outcomes

BACKGROUND

Most current scoring tools to predict allograft and patient survival upon kidney transplantion are based on variables collected posttransplantation. We developed a novel score to predict posttransplant outcomes using pretransplant information including routine laboratory data available before or at the time of transplantation.

METHODS

Linking the 5-year patient data of a large dialysis organization to the Scientific Registry of Transplant Recipients, we identified 15 125 hemodialysis patients who underwent first deceased transplantion. Prediction models were developed using Cox models for (a) mortality, (b) allograft loss (death censored), and (c) combined death or transplant failure. The cohort was randomly divided into a two thirds set (Nd = 10 083) for model development and a one third set (Nv = 5042) for validation. Model predictive discrimination was assessed using the index of concordance, or C statistic, which accounts for censoring in time-to-event models (a-c). We used the bootstrap method to assess model overfitting and calibration using the development dataset.

RESULTS

Patients were 50 ± 13 years of age and included 39% women, 15% African Americans, and 36% persons with diabetes. For prediction of posttransplant mortality and graft loss, 10 predictors were used (recipients' age, cause and length of end-stage renal disease, hemoglobin, albumin, selected comorbidities, race and type of insurance as well as donor age, diabetes status, extended criterion donor kidney, and number of HLA mismatches). The new model (www.TransplantScore.com) showed the overall best discrimination (C-statistics, 0.70; 95% confidence interval [95% CI], 0.67-0.73 for mortality; 0.63; 95% CI, 0.60-0.66 for graft failure; 0.63; 95% CI, 0.61-0.66 for combined outcome).

CONCLUSIONS

The new prediction tool, using data available before the time of transplantation, predicts relevant clinical outcomes and may perform better to predict patients' graft survival than currently used tools.