Organ Donation Flashcards
(20 cards)
Organ donation definition
- Act of surgically transferring cells, tissue or organ from one site to another in same individual or different individual
- GRAFT is the implanted cell, tissue or organ.
- DONOR is an individual who provides the graft (living or deceased donor)
- RECIPIENT is an individual who receives the graft
Type of Transplantation
Source
• Autograft : Same individual, different site (SSG/ Flap)
• Allograft : Different individual, same species
• Xenograft : Different individual, different species
• Isograft : Different individual, genetically identical twins.
Graft
• Organ : Kidney, liver, heart, lung
• Tissue : Cornea, bone marrow
• Cell : Islet cells, blood transfusion
Implantation
• Orthotopic : Graft is placed in its anatomical site (Eg. Liver)
• Heterotopic : Graft is placed in a non-anatomical site (Eg. Kidney)
Types of Donor
Divided into:
a) Deceased Donor:
- Donation after brain stem death (DBD donor) / heart beating
- donation after cardiac death ( DCD donor) / non heart beating
b) Live organ donation
- Related or unrelated
1) DBD (Donation after brain death) or Heart beating donor (HBD)
▪ CVS functioning with good organ perfusion.
▪ Minimal warm ischemia before retrieval
2) DCD (Donation after cardiac death)/ Non heart beating donor (NHBD)
▪ 2 groups: (Maastricht Categories)
* Controlled DCD : Global cerebral dysfunction with functioning brain stem. Limited period of warm ischemia (15 mins)
* Uncontrolled DCD : Patient with circulatory arrest. Organ harvest 5 mins after death announcement. Prolonged period of warm ischemia
DCD donor: There are 5 (Maastricht) categories:
I- dead on arrival - uncontrolled
II- Failed resuscitation - uncontrolled
III- Awaiting cardiac arrest - controlled
IV-Cardiac arrest in a brain stem dead donor - controlled
V- Unexpected cardiac arrest in a critically ill patient
how is DCD/ Non heart beating donor (NHBD) grouped into?
▪ NHBD can be grouped according to the Maastricht classification as follows:
• category 1: dead on arrival at hospital;
• category 2: unsuccessful resuscitation in hospital;
• category 3: ‘awaiting cardiac arrest’ after withdrawal of support;
• category 4: cardiac arrest while brain dead.
Maastricht category 1 and 2 donors are sometimes referred to as uncontrolled NHBD.
The warm ischaemic time of kidneys from these two categories of donor is usually longer and less predictable than in the case of category 3 (controlled) donors.
The majority of NHBD organs used for transplantation are from category 3 donors.
Criteria for suitable Donor
Patient factor:
• Consented by next of kin for organ donation
• Organ is not damaged
• Bedside ABO blood group and HLA typing compatible
• Free of serious pathology
• Free of communicable diseases such as HIV, Hep B, Hep C
• Donor blood pressure, body temperature, circulation, water & electrolyte and oxygenation maintained
• Free from active infection
• Not in DIVC
• Organ characteristic suitable
• > 6 months < 70 years
Process for MATCHING & ALLOCATION of organs
General matching criteria (Criteria for organ recipient)
* Blood type, organ size, transplant waiting list, distance between recipient and donor
* Medical urgency of recipient
* HLA matching
Matching process has 5 steps
* Organ is donated : Information about the organ donor is sent to UNOS (Unrelated Transplant Approval Committee- UTAC in Malaysia)
* UTAC create list of recipients with biologic compatibility
* Transplant center notified of available organ
* Transplant team (Team of Procurement TOP) consider the organ for patient : Transplant team has 1 hour to make decision
* The organ is accepted or declined.
ASSESSMENT OF DONOR
Absolute contraindication:-
• HIV
• Creutzfeld Jacob Disease
• Hepatitis B ( in most countries)
• Active systemic sepsis
• Malignancy within 5years (except brain tumor, non melanotic skin tumor and carcinoma in situ (CIN) of cervix)
The chronological age of the donor is less important than the physiological function of the organs under consideration for transplantation. As a rough guide, acceptable donor age ranges for each of the commonly transplanted organs are:
• Kidney: > 2 years old
• Liver: no age limit
• Heart: 1-65 years
• Lung: 5-65years
• Pancreas: 5-65 years
Organ Procurement process
- Aim- preserving the functional integrity of the organs to be procured.
- Involved multidisciplinary = CTS, PRS, HPB, URO
- Careful monitoring and management of fluid balance is essential. Inotropic support is given and there may be a role for the use of tri-iodothyronine (T3) and argipressin.
- Freeze the organs = cardiac use cold cardioplegia, other organ can use saline ice flush
- Preservation of solution
◦ In Malaysia we use Custodiol® HTK Solution is intended for perfusion and flushing donor kidney, liver, heart, and pancreas prior to removal from the donor and for preserving these organs during hypothermic storage and transport to the recipient.
◦ UW solution (university of Wisconsin)
◦ Euro-Collins Solution - Harvest keep in ice box with 0-4 degree Celcius
Warm ischaemic time:
- Liver and Pancreas : Max 30min of functional warm ishaemic time (Defined as hypotension below 50mmHg and O2 saturation below 70%)
- Kidney: 3 hours of functional warm ishaemia time
HTK= histidine-tryptophan-ketoglutarate (HTK)
Contents of Custodiol solution
Custodiol contentHTK solution for cardioplegia and multiorgan protection
1bag = 2000ml solution
Sodium chloride 15mmol/L
Potassium chloride 9mmol/L
Potassium hydrogen2-ketoglutarate 1.0mmol/L
Magnesium chloride x6 H2O 4mmol/L
Histidine X HCL X H20 18mmol/L
Histidine 180mmol/L
Tryptophan 2mmol/L
Mannitol 30mmol/L
Calcium chloride x2 H20 0.015mmol/L
Osmolarity = 300mosmol/kg
Store at 2-8degree Celcius
Maximum and optimal cold storage times for different organs
FACTORS DETERMINING ORGAN FUNCTION AFTER TRANSPLANT
- Donor’s Factors
◦ Extreme age
◦ Presence of pre-existing disease in the transplanted organ
◦ Haemodynamic and metabolic instability - Procurement related factors
* Warm ischaemic time
* Cold ischaemic time
* Type of preservation solution (UW can keep up to 24hours) - Recipient factors
◦ Technical factors relating to implantation
◦ Hemodynamic and metabolic stability
◦ Immunological factors
◦ Presence of drugs that impair transplant function
Transplant immunology
Transplant immunology divided into 2 components:
- Recognition
*Recipient immune system has to recognize transplanted tissue as foreign.
*3 types of antigens for recognition:- ABO blood group antigen.
▪ Incompatibility → hyperacute rejection.
▪ Rh system only on RBC & not important in organ transplant. - HLA antigen
▪ 2 types HLA I & II. Genes coded on MHC. - Minor histocompatibility antigen
▪ Minimal significance in organ transplant rejection.
- ABO blood group antigen.
- Antigen recognition
◦CD4 T cells (T helper cells) is most important in allo-recognition either direct or indirectly
▪ Direct : Donor APC present donor HLA to CD4 T cell.(analogy: Donor APC tu menyerah diri ke CD4)
▪ Indirect : Recipient APC present donor peptide to CD4 T cell. (analogy: recipient APC tangkap donor peptide tu and serah kat CD4)
- Effector
◦ 3 main pathway
1. Cellular cytotoxicity mediated by CD8 T cells2. Humoral response mediated by B lymphocyte 3. Delayed type hypersensitivity reaction (DTH) mediated by local inflammatory response
What are type of graft rejection?
Types of Tissues/ organs rejections
Prevention of tissue/graft rejection
- Tissue Matching
◦ Blood Grouping : ABO compatibility
◦ Cytotoxic antibody testing : HLA compatibility - Immunosuppressive drugs
What is Immunosuppressive drugs?
- Drugs used to prevent alloimmune response or reverse it if it becomes established.
- Principles
◦ Maximum immunosuppression initially & taper down later.
◦ Combination therapy/ triple therapy (CI, anti-proliferative, corticosteroid)
◦ Degree of suppression depend on type of transplant
◦ Maximized graft function while minimized side-effects. - Divided into
* Induction antibodies
* Calcineurin inhibitors ( Cyclosporin)
* Anti-proliferative
* corticosteroids
Site of action of immunosuppresive
Example of drugs:
- Cyclosporin ( inhibit early stages of lymphocystic proliferation)
- Azthioprine ( Inhibits DNA and RNA synthesis and can also block interleukin-2 production)
- Corticosteroid ( anti-inflammatory action alters the affector phases of rejection; hence high doses are used in treating acute rejection. Also inhibit interleukin-1 and hence prevent T lymphocytes proliferationn)
Side effects of Immunosuppressive
- Non specific
◦ Infections
▪ Viral = CMV, herpes simplex
▪ Bacteria = TB
▪ Fungal = Aspergilosis, Candida
▪ Protozoan = pneumocystic carinii◦ Malignancy
▪ Lymphoproliferative (Post transplant lymphoproliferative disorder (PTLD)) occur in 1-3%
▪ Skin tumor = Squamous cell carcinoma (incidence increase with age. 50% risk in 20years of transplant)
▪ Kaposis sarcoma (increase 300fold) - Specific
◦ Specific to drugs
◦ Commonly will cause nephrotoxicity and bone marrow suppression
Principles of Bioethics ( Ethics in Transplant)
PRINCIPLES OF BIOETHICS
• Beneficence : Doing good
• Non Maleficence : Do no harm
• Respect for autonomy : Right of the individual
• Justice : Fairness to all (Donor & recipient)
Different country system in organ donation
COUNTRY SYSTEM IN ORGAN DONATION
* Opt In : Donor require to give consent to be an organ donor.
* Opt out : Everyone are organ donor unless they opt out of organ donation. ( Singapore, Austria, France, Spain)
* Mandated choice: Everyone is compulsory to decide to be organ donor or not.
Overview of Organ preservation
