CHAPTER 70 - CLINICAL MANAGEMENT OF THE ADULT KIDNEY TRANSPLANT RECIPIENT Flashcards
If acute CNI nephrotoxicity is suspected, our practice is to reduce the CNI dose and repeat a serum creatinine and drug level when?
within 48 to 96 hours
Indicators of diagnosis of acute CNI nephrotoxicity and acute rejection
Indicators of a diagnosis of acute CNI nephrotoxicity
- Severe tremor (neurotoxicity)
- A moderate increase in plasma creatinine (>25% over baseline)
- High trough blood CNI concentrations (e.g., cyclosporine >350 ng/mL or tacrolimus levels >15 ng/mL)
Indicators of a diagnosis of acute rejection
- low-grade fever
- allograft pain and tenderness
- Rapid, non-plateauing increases in plasma creatinine
- low drug concentrations
The treatment of acute CNI nephrotoxicity is
dose reduction
Histologic findings of acute CNI nephrotoxicity
Because acute CNI nephrotoxicity is mainly hemodynamic in origin, histology is frequently normal. However, with prolonged CNI toxicity tubular cell vacuolization and hyaline arteriolar thickening may be seen
The best studied non-HLA antibody implicated in graft injury
The best studied non-HLA antibody implicated in graft injury is probably the angiotensin II type 1-receptor activating antibody, the effects of which may be mitigated by angiotensin receptor blockade blocker therapy
Management of ABMR
Optimal treatment is yet to be established but.
The most commonly employed regimens for active ABMR include some combination of pulsed steroids, plasmapheresis, intravenous immunoglobulins, and anti-CD20 monoclonal antibody to suppress/remove DSA
Other therapies that have been used for active ABMR include C1 inhibition, eculizumab, bortezomib, and bortezomib plus conversion to belatacept
Which has poorer prognosis? ABMR or TCMR?
Active ABMR
Diagnosis of active ABMR requires the presence of (3)
- characteristic histological features which include microvascular inflammation (peritubular capillaritis and/or glomerulitis), intimal or transmural arteritis, thrombotic microangiopathy (TMA), and acute tubular necrosis
- evidence of recent antibody-endothelial interaction, usually identified using C4d staining of peritubular capillaries
- serologic evidence of antibody against donor HLA or other antigens
Therapeutic options for refractory T-cell mediated rejection (3)
- continuing maintenance immunosuppression in the hope that
kidney function will slowly improve - repeating a course of antilymphocyte antibody therapy
- switching from cyclosporine to tacrolimus if not already done
Refractory TCMR is generally defined as
Refractory TCMRis generally defined as TCMR resistant to treatment withanti-lymphocyte antibody. By definition, the patient hasalready received aggressive immunosuppression; the risksand benefits of further amplifying immunosuppressionshould be very carefully considered
This is the most commonly used depleting agent for steroid-resistant TCMR
ATG
Steroid-resistant TCMR is defined somewhat arbitrarily asfailure of improvement in urine output or plasma creatininewithin _____ of starting pulse treatment
5 days
Treated with depleting antibodies (but allograft biopsy must be done first prior to treatment)
Treatment of uncomplicated TCMR
- Short course of high dose steroids - methylprednisolone 250-500mg IV for 3-5 days; then tapering of oral steroids to maintenance dose
- review compliance to immunosuppresion (increased or changed)
Lymphocyte-depletingantibodies are highly effective in treating first rejectionepisodes but because of toxicity and cost, these agents areusually reserved for steroid-resistant cases or when there issevere rejection on the initial biopsy.
The presence of this cells in theinfiltrate suggests severe rejection
Eosinophils
but allergic interstitial nephritis should also be considered
Histologic findings fall belowthe threshold for Banff 1A TCMR
Borderline TCMR
A fairly frequent finding.
We usually treat borderline rejection
Histologic findings characteristic of TCMR (3)
Histologic findings characteristic of TCMR
1. mononuclear cell infiltration of the interstitium, mainly with T cells but also with some macrophages and plasma cells
2. tubulitis (infiltration of tubule epithelium by lymphocytes)
3. arteritis which manifests as infiltration of mononuclearcells beneath the endothelium
Vascular involvement reflectsmore severe rejection
This is a widely used schema for classifying rejection
Banff classification
Definitive diagnosis of acute rejection
In the era of modern immunosuppression, symptoms andsigns of acute rejection are rarely pronounced, but low-gradefever, oliguria, and graft pain or tenderness may occur. Mostcases of acute rejection are identified through surveillance monitoring of graft function. However, creatinine is a ratherlate and insensitive marker of renal injury. There is, therefore,a growing interest in development of early biomarkers ofimmune system activation. However, for now, the definitivediagnosis of acute rejection requires transplant biopsy
Acute rejection can occur anytime but mostly occurs when
1st 6 months posttransplant
Difference between renal artery thrombosis and renal vein thrombosis
Both present with abrupt onset of anuria and rapidly increasing plasma creatinine BUT
Renal artery thrombosis
- negligible graft pain
- Duplex studies: absent arterial and venous blood flow
- Renography or MR angiography: absent perfusion of the transplanted kidney
- Management: removal of infarcted kidney
Renal vein thrombosis
- Pain, tenderness, swelling inthe graft, and hematuria are more pronounced
- Severe complications such as embolizationor graft rupture and hemorrhage may occur.
- Duplex studies: absentrenal venous blood flow and characteristic highlyabnormal renal arterial waveforms
- MR venography: thrombus in the vein
- Management:Transplant nephrectomy and anticoagulation if extends beyond renal vein
The most common cause ofallograft loss in the first week.
Acute vascular thrombosis
Transplant renal artery or renal vein thrombosis usually occurs when?
in the first 72 hours but may be delayed for up to 10 weeks
These drugs will cayse functional preranal failure in the early posttransplant period
ACEi
ARBs
NSAIDs
Diarrhea is a common adverse effect of this immunosuppresant
Diarrhea is a common adverse effect of the MMF, especially when used with tacrolimus.
Primary measure of early and late transplant function
Primary measure of early and late transplant function remains the plasma creatinine concentration, despite its known limitation
This class of drug have been shown in experimental models to prevent ischemic injury and attenuate CNI-mediated renal vasoconstriction
Calcium channel blockers
These properties suggested that their administration to recipients or to the donor before organ retrieval might reduce the incidence and duration of ischemic ATN
Intraoperative mean arterial pressure should be maintained ________ in the recipient.
greater than 70 mm Hg
Treating the donor with this medication prior to organ retrieval has been shown to reduce the rate of DGF
dopamine
Graft injury can occur at this times (5)
Graft injury may occur
1. prior to donation
2. at retrieval
3. during transport
4. during transplant surgery
5. postoperatively
How will CNI cause acute decrease in GFR?
Cyclosporine and tacrolimus, especially in high doses or by intravenous route of administration, may result in an acute decrease in GFR through renal vasoconstriction, particularly of the afferent glomerular arteriole. Potentially, such vasomotor effects could exacerbate ischemic ATN. Acute CNI toxicity is now rare with the targeting of lower CNI levels. Caution should, however, be taken in the context of drug interactions that raise CNI levels.
How to diagnose accelerated acute rejection superimposed on ischemic ATN?
Accelerated acute rejection may be superimposed on ischemic ATN, in which case there may be no signs of rejection, or it may occur in an initially functioning allograft. Diagnosis is made by kidney biopsy in conjunction with crossmatch findings and DSA titers. Histology usually shows evidence of predominantly antibody rather than cell-mediated immune damage.
Refers to rejection occurring roughly 2 to 5 days after transplant
Accelerated acute rejection
Accelerated rejection occurs in recipients with pretransplant sensitization to donor alloantigen and is frequently associated with the presence of historic or low-titer pretransplant anti-donor antibody. Rapid post-transplant antibody production by memory B cells may represent an important mechanism for this phenomenon.
Management of hyperacute rejection
Transplant nephrectomy
Clinical manifestation of classic hyperacute rejection
In classic hyperacute rejection, cyanosis and mottling of the kidney and anuria occur minutes after the vascular anastomosis is established. Disseminated intravascular coagulopathy may occur.
Histology shows widespread small vessel endothelial damage and thrombosis, usually with neutrophils incorporated into the thrombus
Anti-HLA class I antibodies are formed in response to (3):
previous transplantation
blood transfusion
pregnancy
Caused by preformed recipient antibodies reacting with antigens on the endothelium of the allograft, resulting in activation of the complement and coagulation cascades
Hyperacute rejection
These antibodies are usually directed against antigens of the ABO blood group system or against HLA class I antigens.
Less commonly, hyperacute rejection is caused by antibodies directed against donor HLA class II antigens or endothelial or monocyte antigens (the last two are not detected in the standard crossmatch)
Why does acute rejection occurs more frequently in allografts with delayed versus immediate function?
The postulated mechanism is that ischemia-reperfusion injury increases the immunogenicity of the allograft, thereby predisposing to acute rejection
Management of uncomplicated ATN posttransplant
Management of the patient during this period is supportive. When early hemodialysis is required, minimal anticoagulation should be used to reduce the risk of postsurgical bleeding. Intradialytic hypotension should also be avoided in order to prevent further renal ischemic injury. Peritoneal dialysis may be successfully continued posttransplant, although should be avoided if the peritoneum was opened at the time of surgery. Early postoperative treatments should be performed with low volume exchanges.
The natural history of uncomplicated ATN
Spontaneous resolution.
Usually, improvements in urine output begin from 5 to 10 days after transplant, but ATN may persist for weeks.
On reanal imaging,there is intact allograft perfusion and absence of obstruction. On histology, there is tubular cell damage and necrosis. Patchy interstitial mononuclear cell infiltrates with no tubulitis may be present.
ATN
Describe the resistive index in transplant kidney ultrasound in the setting of intrarenal graft dysfunction
Standard ultrasonography is commonly used to assess potential surgical complications in the immediate postoperative period. Ultrasonography can be performed quickly, is inexpensive and noninvasive, and is usually effective in identifying postrenal causes of kidney failure. Duplex sonography is also useful in assessing the graft’s arterial and venous blood flow. The resistive index (RI) is often reported in transplant kidney ultrasounds and is elevated in the setting of intrarenal graft dysfunction. However, a raised RI does not discriminate between ATN and rejection and is therefore of limited diagnostic utility.
The most common cause of DGF
Although the causes of DGF include prerenal, intrarenal, and postrenal insults, ischemic acute tubular necrosis (ATN) is by far the most common cause of DGF
Define slow graft function
SGF defines a group of recipients with moderate early graft dysfunction. One commonly employed definition of SGF is a plasma creatinine level greater than 3 mg/dL at 1 week posttransplant
Delayed graft function is defined as
DGF is usually defined by the need for one or more dialysis treatments within the first posttransplant week
Excellent allograft function is manifested by (2):
Excellent allograft function is manifest by:
1. ample urine output
2. rapidly falling plasma creatinine concentration
A surrogate measure for both donor nephron mass, as well as recipient metabolic demand
Body surface area has been used as a surrogate measure for both donor nephron mass, as well as recipient metabolic demand.
The principal reasons for sensitization (3)
Previous transplants
pregnancy
blood transfusion
This is responsible for more than 50% of graft failures in elderly
Death with a functioning allograft
Common causes of graft loss in the very young and in elderly
In the very young:
1. technical causes of graft loss such as vessel thrombosis
2. Acute rejection
In the elderly:
1. Death with a functioning allograft - responsible for more than 50% of graft failures
In general, allograft survival rates are poorer in what ages?
In general, allograft survival rates are poorer in those at theextremes of age, that is, younger than 18 or older than 65 years of age
In the very young, technical causes of graft loss such as vessel thrombosis are relatively more common.Acute rejection is also a more common cause of allograft loss; conversely, death with a functioning graft is relatively rare. Death with a functioning allograft is a much more common cause of graft loss in the elderly (responsible for more than 50% of graft failures). Conversely, acute rejection may be less common. Thus, although randomized controlled trials are not available to definitively inform practice, it seems reasonable, in general, to use less aggressive immunosup-pression in the elderly.
Which is inferior when it comes to short-term outcomes: donation after cardiac death or donation after brain death?
DCD.
Short-term outcomes (such as rates of DGF and primary non-function) are inferior to those seen with brain dead donors.However, long-term outcomes of DCD organs (from donors <50 years old) are similar to those from standard deceased donors.
Uncontrolled and controlled donors after cardiac death are described as
Uncontrolled donors are either unsuccessfully resuscitated or present dead on arrival to hospital
Controlled donors suffer a cardiac arrest following the withdrawal of life support in the intensive care unit or operating room immediately prior to donation.
The duration of warm ischemia time is likely to be significantly greater in the setting of uncontrolled donation.
Donation after cardiac death can be sub-classified as (2)
Controlled
Uncontrolled
In orderto maximize the utility of the deceased donor organ supply,deceased donor kidneys with this KDPI score are to be allocatedto candidates with the highest posttransplant life expectancy
The KDPI isexpressed as a percentile score with 0% and 100% signifyingexcellent quality and marginal organs, respectively. In orderto maximize the utility of the deceased donor organ supply,deceased donor kidneys with a KDPI < 20% are to be allocatedto candidates with the highest posttransplant life expectancy,as judged by the 4-variable estimated posttransplant survival(EPTS) score. Older candidates, for whom long waiting timesrepresent a barrier to transplantation, who would previouslyhave agreed to receipt of an ECD kidney, may now choose toaccept deceased donor kidneys with a high KDPI value (>85%).
This is calculated using10 donor characteristics thatg is used in thenew Kidney Allocation System that has replacedthe standard and expanded criteria deceased donor categorieswith a single pool of kidneys
In the US, the new Kidney Allocation System has replacedthe standard and expanded criteria deceased donor categorieswith a single pool of kidneys graded using the kidney donorprofile index (KDPI). The KDPI score is calculated using10 donor characteristics and is a modified version of thepredictive tool first described by Rao et al.329
The KDPI isexpressed as a percentile score with 0% and 100% signifyingexcellent quality and marginal organs, respectively. In orderto maximize the utility of the deceased donor organ supply,deceased donor kidneys with a KDPI < 20% are to be allocatedto candidates with the highest posttransplant life expectancy,as judged by the 4-variable estimated posttransplant survival(EPTS) score. Older candidates, for whom long waiting timesrepresent a barrier to transplantation, who would previouslyhave agreed to receipt of an ECD kidney, may now choose toaccept deceased donor kidneys with a high KDPI value (>85%).
Survival of ECD kidneys is,on average, shorter for two general reasons:
Survival of ECD kidneys is,on average, shorter for two general reasons:
1. The baselineGFR of these kidneys is likely lower
2. Tend to be transplanted into older recipients, who have higherrates of posttransplant death
Expanded Criteria Donor kidneys are defined by donor characteristics that are associated with (4):
This includes donors who are:
1. 60 years or older
2. Donors aged 50 to 59 with two of the following criteria:
- CVA as cause of death
- history of hypertension
- terminal creatinine > 1.5 mg/dL
Donor characteristics that are associated with a70% greater risk of allograft failure when compared to areference group of non hypertensive donors of age 10 to 39years, whose cause of death was not cerebrovascular accident(CVA) and whose terminal creatinine is less than 1.5 mg/dL
The bestradiologic technique for determining the site of obstruction post transplant
Percutaneous antegrade pyelography is the bestradiologic technique for determining the site of obstructionand can be combined with interventional endourologictechniques. In expert hands, endourologic techniques (e.g.,balloon dilation, stenting) may be effective in treating uretericstenosis and stricture
Ultrasound finding of urinary tract obstruction post transplant
Worsening hydronephrosis showed in serial scans
Intrinsic (3) and extrinsic (2) causes of urinary tract obstruction post KT
Intrinsic causes
1. poor implantation ofthe ureter into the bladder
2. intraluminal blood clots or sloughmaterial
3. fibrosis of the ureter due to ischemia or rejection
Extrinsic causes
1. enlarged prostate in elderlymen (causing bladder outlet obstruction)
2. Compressionby a lymphocele or other fluid collection
Rarely, calculicause transplant urinary tract obstruction
Urinary tract obstruction can occur at any time after transplantation but most commonly occur when?
Early postoperative period
Urinary tract obstruction can occur at any time after transplantation but most commonly occur when?
Early postoperative period
Managemet of urine leaks post transplant
Bladder catheter may be inserted to decompress the urinary tract
many, however, require urgent surgical exploration and repair
This is the best test to demonstrate abladder leak post transplant
Cystography
This allows precise diagnosis and localization of proximalurinary leaks post transplant
Antegrade pyelography allows precise diagnosis and localization of proximalurinary leaks
Urine leaks posttransplant occur at the level of (3)
Renal calyx
ureter
bladder
This drug has been shown to successfully treat and prevent recurrent atypical HUS post KT
Eculizumab has beenshown to successfully treat and prevent recurrent atypicalHUS and post-kidney transplant ‘prophylactic’ eculizumabrepresents a viable, if expensive, option for preventing diseaserecurrence
Transplantation should be deferred until this disease isquiescent for at least 6 months becaue the atypical form of this disease has high recurrence (as high as 80%)
Recurrence of classic(diarrhea-associated) HUS/TTP is uncommon. However,transplantation should still be deferred until the disease isquiescent for at least 6 months. In contrast, recurrence ofatypical (non–diarrhea-associated) HUS/TTP, particularly ifinherited, has been reported to be as high as 80%
Patients with recurrent anti-GBM disease with allograftdysfunction should be treated with (2)
Patients with allograftdysfunction should be treated with plasmapheresis andcyclophosphamide
Here, the recipient with abnormaltype IV collagen produces antibodies against the previously“unseen” normal α5 chain NC1 domain in the basementmembrane of the transplanted kidney.
De novo anti GBM disease can occur in recipientswith Alport syndrome. Here, the recipient with abnormaltype IV collagen produces antibodies against the previously“unseen” normal α5 chain NC1 domain in the basementmembrane of the transplanted kidney.
Patients with allograftdysfunction should be treated with plasmapheresis andcyclophosphamide.
De novo anti GBM disease can occur in transplant recipientswith
De novo anti GBM disease can occur in recipientswith Alport syndrome. Here, the recipient with abnormaltype IV collagen produces antibodies against the previously“unseen” normal α5 chain NC1 domain in the basementmembrane of the transplanted kidney.
Patients with allograftdysfunction should be treated with plasmapheresis andcyclophosphamide.
In order to prevent recurrence of anti-GBM disease post transplant, these 2 criteria must be fulfilled
Before transplantation, patients with ESRD due to antiglomerular basement membrane (GBM) disease should generally be ondialysis for at least 6 months and have negative anti-GBMserology. If these criteria are fulfilled, posttransplant recurrence is rare.
Kidney biopsy finding of recurrent FSGS post transplant
This may not show FSGS lesions per se,but the electron microscopic demonstration of diffuse footprocess effacement is present
Manifestion of recurrent FSGS post transplant
Proteinuria - hours to weeks after transplant
Becauseof the poor prognosis of delayed treatment, patients withprimary FSGS should be monitored after transplantation fornew-onset proteinuria. Early biopsy is indicated in those whodevelop proteinuria; this may not show FSGS lesions per se,but the electron microscopic demonstration of diffuse footprocess effacement is present
Recurrence rate of primary FSGS post transplant
30% - spodic FSGS
rare - familial FSGS