Donors For Transplantation

There are two types of donors for the transplant: living donors and deceased donors. Donating an organ or a portion of an organ at the moment of death with the intention of transplanting it into another person is known as deceased organ donation.

A deceased donor is a person who has passed away by circulatory collapse or brain death. Individuals who are on ventilator support, have brain injuries, or are profoundly unconscious are eligible to donate organs for transplantation. It's critical to rule out muscle relaxants.

Various scenarios, such as extreme hypotension, hypothermia, and metabolic or hormonal disorders, must be checked out since they may exacerbate CNS depression and complicate the diagnosis of brain stem death.

Donor Death Declaration

2 physicians, who are not a part of organ recovery or transplantation team, certify that. One of them must be a consultant. 2 tests are needed to certify that.

Neurological Criteria For The Brain Death

All brain and brain stem function ought to end completely. The Apnea challenge ought to exist. Total loss of brain and brain stem function that is also irreversible is required.
Confirmatory testing, such as encephalograms, cerebral angiographies, and nuclear medicine brain scans, should be performed to ensure the diagnosis and rule out any potential uncertainty.

Absence of Cranial Nerve Reflexes

• Pupillary reflex
• Corneal reflex
• Pharyngeal and tracheal reflex
• Oculovestibular reflex 

Absence of Motor Response

It can also involve the lack of a motor response within the cranial nerve distribution to the appropriate stimulation of any somatic location, which is an indication of brain stem death. It involves the absence of a motor response to painful stimuli to the head or face.

Absence of Spontaneous Respiration

You must pre-ventilate at 100% of 02 for approximately five minutes before to the apnea test. Subsequently, the ventilator is turned off for approximately ten minutes to ensure that no breathing effort is made.  To ensure sufficient respiratory stimulation, the arterial PCO2 level should be about > 8 KPa (60 mmHg).

Even after the ventilator is disconnected, an endotracheal catheter is used to supply oxygen (6 liters per minute) in order to prevent hypoxia during the apnoeic interval.

Confirmatory Testing For The Determination Of Brain Death

• Cerebral angiography
• Electro encephalopathy
• Transcranial Doppler USG
• Cerebral Scintigraphy 

Donation After Circulatory Death

It usually happens when a potential donor is ventilator dependent and comatose but does not fulfill the requirements for brain death.  The absence of spontaneous respiration and sustained asystole for approximately five minutes serves as the declaration of death for the donation following circulatory death.

In addition to ex vivo perfusion, a double balloon-triple lumen catheter is used for in situ perfusion for the donation following circulating death.

Maastricht Classification

The Maastricht classification defines DCD categories according to the circumstances of the donor's death.

• Category 1: dead on arrival at hospital
• Category 2: resuscitation attempted without success
• Category 3: awaiting cardiac arrest after the withdrawal of the support
• Category 4: cardiac arrest while brain dead
• Category 5: cardiac arrest and unsuccessful resuscitation in the ICU.

Evaluation Of Deceased Donor 

The donor must be free of my type of transmissible infection and cancer. If cancer has been present within the previous five years, organ donation is strictly prohibited, with the exception of primary brain tumors, non-melanotic skin tumors, and cervical CIS.

Goals To Keep In Mind While Taking Care Of The Brain Dead Donor

Maintain a core temperature of 36.0°C to 37°C; a mean arterial pressure of greater than 70 mm Hg and a systolic pressure of greater than 100 mm Hg. The range of hemoglobin levels is 7–10 gldL.

Also Read: Tropical Infections And Infestations- Amoebiasis

Kidney Paired Donation

Incompatible pairs are sorted among other incompatible donor-recipient pairs; software matching methods are then used to find compatible matches.

Perfusion Solutions

• University of Wisconsin solution
• Euro Collins solution
• HTK (Histidine Tryptophan Ketoglutarate) solution.
• Glutathione: anti oxidant 
• Allopurinol: free radical scavenger
• Adenosine: precursor for energy metabolism
• Lactobionate: prevent cellular swelling and reperfusion injury 
• Raffinose and hydroxyethyl starch: help to reduce swelling of the endothelial cells and hence decreasing edema.

University of Wisconsin Solution

• Has catonic composition
• Increase potassium, decrease sodium- mimics intracellular levels to minimize diffusion down electrochemical gradient.
• K⁺-131 -So it needs to be flushed out before establishing circulation otherwise it may cause cardiac arrhythmia.

Factors Determining Organ Function After Transplantation

• Donor characteristics
  • Extremes of age
  • Presence of pre existing damage in transplanted organ
  • Hemodynamic and metabolic instability 
• Procurement related factors
  • Warm ischemia time
  • Type of preservation solution
  • Cold ischemia time
• Recipient Related factors
  • Technical factors that are related to the implantation
  • Hemodynamic and metabolic stability
  • Immunological factors
  • Presence of drugs that impair the transplant function.

Important Questions

Q. Is there any requirement of RH compatibility in the organ transplant? 

Ans. There is no need for Rhesus Antigen (RH) compatibility during organ transplantation. For the organ transplant, we do require both the human leukocyte antigen and the ABO blood type.

Q. What does 000 mismatch indicate? 

Ans. 000 mismatch indicates the complete match at loci of HLA - A,B and DR. 

Q. What is 021 mismatch?

Ans. 021 mismatch indicates the match at HLA -A loci. It is the complete mismatch at HLA -B. One mismatched DR antigens are found in this. 

Q. Which is the most common type of allograft rejection? 

Ans. Chronic rejection 

Q. Who can declare brain death of the patients?

Ans. Donor death can be declared by two medical professionals who are not involved in organ recovery or transplantation. A consultant doctor should be among the medical staff. To declare donor death, two tests are run.

Q. Can you do a transplant if you have an ABO incompatible donor?

Ans. Yes. It can be done by prior desensitization of the recipient by plasmapheresis which also removes ABO antibodies.

Also Read: Percutaneous Endoscopic Gastrostomy And Tracheostomy

Hope you found this blog helpful for your NEET SS General Surgery preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.