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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1739_Библиотеки_им_академика_М_И_Перельмана.pdf
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A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
c. Customization and personalization: Artificial organs can be
customized according to each patient’s specic needs, ensuring a
perfect t and enhancing the overall success of the transplantation.
Personalized medicine takes a leap forward as articial organs can be
designed to match individual requirements.
Current and Future Developments
a. Artificial heart: Researchers are making remarkable progress in
developing articial hearts that can effectively replace failing human
hearts. These advancements offer hope to countless patients suffering
from heart failure and drastically improve their quality of life.
b. Articial kidneys: Chronic kidney disease affects millions worldwide,
with a limited supply of donor kidneys available for transplantation.
Articial kidneys, currently in the experimental stage, hold the potential
to transform the lives of those dependent on dialysis by providing a
long-term, sustainable solution.
c. Articial pancreas: Diabetes is a prevalent chronic disease that requires
constant monitoring and insulin administration. The development of
an articial pancreas holds the promise of revolutionizing diabetes
management, offering patients a more streamlined and autonomous
approach to insulin regulation.
With advancements in technology, articial organ transplantation holds
the key to transforming the lives of countless individuals suffering from
organ failure. The ongoing research and development in this eld pave the
way for a future where articial organs become a routine and accessible
option, improving patient outcomes and revolutionizing medical treatment
worldwide.
Recent Advances
Organ transplantation offers hope and extended lives to countless individuals
suffering from organ failure. In recent years, research in the eld of organ
transplantation has taken a signicant leap forward with the emergence of
3D bioprinting technology. This ground-breaking research conducted by
Organovo, a pioneering medical laboratory and Research Company, and the
potential of 3D bioprinting to revolutionize organ transplantation.
Advancements in Organ Transplantation
45
Dr Gopi Ayyaswamy
Organovo is an innovative medical laboratory and research company
dedicated to designing and developing functional, three-dimensional
human tissue for medical research and therapeutic applications.
Leveraging their cutting-edge NovoGen MMX Bioprinter, Organovo has
made signicant strides in the eld of 3D bioprinting, with a focus on
accelerating preclinical drug testing and discovery processes.
The Potential of 3D Bioprinting
a. Enhancing preclinical drug testing: Traditional drug testing methods
often involve animal models, which may not accurately mimic human
physiology. 3D bioprinting offers a more precise and human-relevant
approach, allowing researchers to create functional human tissues with
remarkable precision. This technology enables the testing of new drugs
on human tissue models, potentially reducing the reliance on animal
testing and improving the accuracy of preclinical studies.
b. Faster and cost-effective treatment development: By utilizing 3D
bioprinting technology, Organovo aims to expedite the drug discovery
process and develop treatments more rapidly. The ability to create
functional human tissues for testing enables researchers to observe the
effects of drugs on specic organs, leading to quicker identication of
potential treatments at a lower cost.
c. Surgical therapy and transplantation: While still in the early stages,
Organovo has long-term expectations that 3D bioprinting technology
could have signicant implications for surgical therapy and organ
transplantation. The ability to print functional human organs has the
potential to address the critical shortage of donor organs, providing
personalized and readily available organs for transplantation.
Present Advances and Future Prospects
Pioneering breakthroughs in tissue engineering: Organovo has been at
the forefront of pioneering research in the realm of tissue engineering,
achieving signicant milestones that have far-reaching implications.
Notably, they have successfully employed bio-printing techniques
to fabricate human liver tissue, a remarkable feat that opens up
unprecedented avenues for the study of liver diseases and the assessment
of drug toxicity. This accomplishment is a giant leap towards the
46
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
realization of a future where transplantable organs are manufactured
using 3D bioprinting technology.
Progress in vascularization challenges: An inherent challenge in the
endeavor to bioprint complex organs is the imperative need to establish
a functional vascular network within the tissue structure. This network
is essential to ensure an adequate blood supply to the fabricated organs.
The scientic community has been diligently engaged in the exploration
of various strategies to surmount this obstacle. The ultimate objective
is to engineer fully vascularized organs, equipped and ready for
transplantation. This pursuit represents an ambitious yet pivotal frontier
in the eld of organ transplantation.
Collaborative synergy: Organovo recognizes the importance of
collaborative synergy in advancing the frontiers of 3D bioprinting. In their
commitment to enhancing the technology’s efcacy and applicability, the
Advancements in Organ Transplantation
47
Dr Gopi Ayyaswamy
company actively forges partnerships with pharmaceutical companies and
academic institutions. These collaborations serve as vital conduits for the
renement and validation of their 3D bioprinting technology. By pooling
resources, knowledge, and expertise, these partnerships play a pivotal
role in ensuring that research ndings seamlessly transition into tangible
clinical applications.
Organovo’s research endeavors in 3D bioprinting herald a profound
paradigm shift in the landscape of organ transplantation. Their remarkable
achievements in fabricating functional human tissue models hold immense
promise in medical advancement. This innovative technology not only
accelerates drug discovery but also holds the potential to signicantly
reduce the exorbitant costs associated with treatment development.
Moreover, it brings us closer to addressing the perennial challenge of the
shortage of donor organs for transplantation.
While it is undeniable that challenges still lie ahead, the persistent
commitment to research and the collective efforts of the scientific
community in collaboration with Organovo are propelling the trajectory
of 3D bioprinting towards a future where personalized, readily available
organs for transplantation become a tangible reality. The transformative
potential of 3D bioprinting in organ transplantation has the power to
save innumerable lives and usher in a revolution in the realm of medical
treatment on a global scale.
Dr Gopi Ayyaswamy
Brain Stem Death
8
• Denition
• Coma
• Vegetative state
• Minimal responsive state
• Differences between coma and brain death
• Diagnostic criteria
• Glasgow Coma Scale
Definition
It is dened as an irreversible brain damage and loss of brain function,
as evidenced by cessation of breathing and other vital reflexes,
unresponsiveness to stimuli, absence of muscle activity, and a flat
electroencephalogram for a specic length of time.
Coma
When persons experience a brain injury, they can become unconscious. When
the unconscious state is prolonged, it is termed a “coma”. Coma is dened as
a state of unconsciousness from which the individual cannot be awakened, in
which the individual responds minimally or not at all to stimuli, and initiates
no voluntary activities. Patients in coma may be in deep coma or may survive
in what is termed a “vegetative state.” The difference between these two
groups is that a deep coma patient usually requires hospital care, while a
patient in a vegetative state may be released to the family for home care.
50
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
The individual in the vegetative state has a lot more lower-brain function,
and a bit more upper brain-stem function, than a patient in deep coma.
• A coma is a continued unconscious state that can occur as part of the
natural recovery for a person who has experienced a severe brain injury.
• While in a coma, a person can continue to heal and progress through
different states of consciousness.
• Persons who sustain a severe brain injury and experience coma can make
signicant improvements, but are often left with permanent physical,
cognitive, or behavioural impairments.
• A coma can last days, weeks, months, or indenitely. The length of a
coma cannot be accurately predicted or known.
Vegetative State
The term “vegetative state” (VS) is used to describe a severe brain injury
characterized by the presence of arousal without the ability to interact
with the environment. In a vegetative state:
• Eye opening may occur spontaneously or in response to stimulation.
• General responses to pain, such as increased heart rate, increased
respiration, posturing, or sweating, can be observed.
• Sleep-wake cycles, respiratory functions, and digestive functions gradually
return.
Diagnosing vegetative state relies on repetitive neurobehavioral
assessments as there is no specic test for its diagnosis.
Minimal Responsive State
Minimally responsive (MR) state is the term used for a severe traumatic
brain injury in which a person is no longer in a coma or a vegetative state.
Persons in a minimally responsive state demonstrate the following:
Minimal Responsive State
Minimal responsive state (MRS) refers to a severe traumatic brain
injury where the person has emerged from a coma or a vegetative state.
Individuals in a minimally responsive state exhibit the following:
Brain Stem Death
51
Dr Gopi Ayyaswamy
Primitive Reflexes
• Inconsistent ability to follow simple commands.
• Awareness of environmental stimulation.
• When assessing the meaningfulness or purposefulness of behaviour,
the frequency and conditions under which a response is made are
considered.
Brain Stem Death is Not the Same as Coma
Brain stem death should not be confused with coma or persistent vegetative
state. Coma is similar to deep sleep but lacks the ability to awaken and
become alert despite external stimuli. However, individuals in a coma
are alive, and there is potential for recovery. Persistent vegetative state
indicates the loss of higher brain functions, while the undamaged brain
stem continues to maintain essential functions such as heart rate and
respiration. Individuals in a vegetative state are alive and may recover to
some extent given sufcient time. Brain death, on the other hand, signies
the person has passed away.
Brain Death and Organ Donation
Brain death, a critical condition in which the brain ceases to function, is
typically diagnosed in the intensive care unit (ICU) while the individual
is being supported by a ventilator. Since the brain controls the process of
breathing, a person who is brain dead cannot breathe on their own. Unlike
other organs in the body, the brain is highly sensitive to the loss of blood
ow and oxygen, making it unable to sustain its function.
In contrast, organs such as the heart, liver, kidneys, and pancreas are
more resilient and can survive for longer periods without a constant
supply of blood ow and oxygen. However, to ensure the best chances
of successful transplantation, these organs require a consistent and
uninterrupted supply of blood and oxygen. This is where a ventilator
plays a crucial role.
By supplying the necessary oxygen to these organs, the ventilator
allows them to continue functioning and maintains their viability
for transplantation. It also provides a critical window of time for the
coordination of the organ donation process. During this period, medical
52
A Simple Introduction to Organ Transplant
Dr Gopi Ayyaswamy
Differences between coma and brain death
No. Topics Coma Brain Stem Death
1. Denition Coma is dened as a state of unconsciousness
from which the individual cannot be awakened, in
which the individual responds minimally or not at
all to stimuli, and initiates no voluntary activities.
Coma is similar to deep sleep, except that no
amount of external stimuli can prompt the brain
to become awake and alert. However, the person
is alive and recovery is possible.
Brain stem death means there
is “irreversible cessation of all
functions of the entire brain,
including the brain stem. A
patient determined to be brain
stem dead is legally and clinically
dead.
2. Glasgow Coma
Scale
Composite score of 3, considered the patients
are in coma.
Brain stem death patients are
usually scored less than 3.
(Contd.)
Brain Stem Death
53
Dr Gopi Ayyaswamy
Differences between coma and brain death (Contd.)
No. Topics Coma Brain Stem Death
3. Brain function A persistent vegetative state means the person
has lost higher brain functions, but their
undamaged brain stem still allows essential
functions like heart rate and respiration to
continue. A person in a vegetative state is alive
and may recover to some degree, given time.
In brain stem death, the entire
brain has died both the upper parts
of the brain and the lower parts of
the brain (brain stem). The brain
stem or lower brain is responsible
for the vegetative functions such as
breathing or sleeping and waking
up (sleep–wake cycles)
4. Conrmatory
tests
Eye examination, lab tests, EEG, CT and MRI,
physical examination, motor examination
EEG, cerebral blood ow study,
cerebral angiography, MRI,
transcranial Doppler, apnoea tests