Cryogenics:
Freezing our way to a healthier life.
1. Executive Summary
The common misconception with cryogenics
is that it is often associated with science-fiction, i.e. an astronaut waking
up in space after years of cryo-sleep in his cryo-pod. While this image
portrayed may be true to a certain extent, the science of cryogenics runs much
deeper than that.
This paper examines the medical
applications of cryogenics in various medical fields such as oncology,
dermatology and surgical applications as well as its limitations and potential
for further development. It also seeks to discuss its more controversial
subset: Cryonics. It’s potential in prolonging lifespan, current technical
limitations and the ethical debate behind the science of cryonics.
2. Background/Introduction
The use of cold for medical treatments has been around for
hundreds of years, dating back to 3500 B.C. where it was used as a form of
therapy (Wang, 2006). Its applications have since evolved to range from its use
as a form of anaesthesia to treating of dementia to destroying cancerous
tumours and keloids (dermatology). (Wang, 2006; Rubinsky, 2000; Levy, 2009;
Goldenberg, 2013) Although not commonly used it is still recognized as a viable
and effective form of medical treatment. And with further technological
advancements that allows greater efficacy and accuracy of the treatment, it has
the potential to become an extremely viable tool in the treatment of cancerous
tumours
The more controversial side of cryogenics is cryonics. It is
essentially the science of “freezing” and “reanimation” of dead bodies in the
future with the hope that future technological and medical advancements will
eventually restore the body to full health, allowing the individual greater
lifespan or at least postponing death. However, science in cryonics is far from
complete and scientist will have to cross numerous major hurdles before
cryonics become viable. Then there is the ethical debate over “freezing” and
“reanimation” in the future. Concerns over the morality and socio-economic
impact of reviving someone from possibly hundreds of years ago were raised.
This paper seeks to examine the medical
applications of cryogenics in various medical fields such as oncology,
dermatology and surgical applications. It will also discuss the current
limitations on the use of cryogenics in surgeries and potential areas of
improvements. It also seeks to discuss its more controversial subset: Cryonics.
It will touch on the benefits of cryonics, such as prolonging lifespan of the
patient, avoiding death and also its current technical limitations and the
ethical debate behind the science of cryonics.
3. Historical Perspective
3.1 Cryosurgery
The use of cryo-technology in surgery in aptly named Cryosurgery.
It is the use of very low temperatures to destroy undesirable tissue, typically
cancerous tumours. (Nellis, 2009)
The first recorded use of cold as a therapeutic tool was recorded
in the Edwin Smith Papyrus, written at 3,500 B.C. Since then, there have been
various records of its many applications. A French army surgeon during the
Napoleon Wars, Baron de Larrey, used cold as a form of anaesthesia to perform
painless amputation in an era where alcohol was the only other alternative.
(Wang, 2006) Its use as an anaesthetic was further by physician like James
Arnott in the mid-nineteenth century. (Rubinsky, 2000) In 1791, a physician
Philip Pinel observed a case where a mentally ill patient was apparently cured
of his deluded mental state after being exposed to cold in an attempt to escape
his mental ward. Cold was also used to treat other malignancies and head
injuries. In 1938, Temple Fay, a neurosurgeon, introduced whole body
hypothermia to treat these ailments which resulted in a high success rate of
95.7% and low mortality rate of 11.2%. (Rubinsky, 2000)
In the mid-nineteenth century, the physician James Arnott(the same
as mentioned above) discovered that cancerous tumours that are exposed to low
temperatures(-12°C) are much less offensive after thawing. (Rubinsky, 2000) The
effect of low freezing on cells has been studied extensively. “Cell death
occurs when either very slow or very rapid cooling rates are used. Slow cooling
rates lead to the formation of extracellular ice while the intracellular fluid
remains, for a time, unfrozen. The difference in the osmotic pressure that
results causes water flow out of the cell, leading to death by dehydration.
Very rapid cooling rates are used in cryosurgery in order to cause the
formation of ice crystals in the intracellular fluid, rupturing the cell walls.”
(Nellis,
2009)
It has since been adapted into the field of oncology where this
technique was furthered to destroy cancerous tumour tissues located near the
surface of the skin and keloid scars which are benign, dermal,
fibroproliferative tumours. (Nellis, 2009)
Until that point in time the use of cold
in the treatment of patients were mainly focused on the physiological reaction
of the human body in reaction to low temperature. Although it has been also used
to treat cancerous tumours, it is mostly confined to the surface of the skin as
the cold was only able to penetrate up to a depth of several millimetres due to
limitations of available surgical tools.
However,
this paradigm was shifted when in 1961, a neurosurgeon, Irving Cooper built the
first cryosurgical probe that used liquid nitrogen as a coolant that is
applicable for surgical use. (Rubinsky, 2000; Wang, 2006) This probe has
allowed physicians to conduct minimally invasive surgeries to destroy
undesirable tissues that would be otherwise be inaccessible to traditional
cold-therapy. This has ushered in the modern era of cryosurgery.
3.2
Cryonics
In the 1960s, with the advances of cryosurgery came the advent of cryonics. It is the preservation and storage of legally dead humans using the process of vitrification in hopes that they can be revived in the future when medical advances will be able to restore their health and possibly youth.
As
extremely low temperatures will damage cells tissues (refer to above), long
term preservation using traditional freezing method is not viable. Instead,
cryonics achieves this goal via a process called vitrification where the blood
of the subject is replaced with an organ-preservation solution which will
prevent organ/tissue damage during preservation. The patient is then
transferred to a tank filled with liquid nitrogen for preservation. (Knight,
2008)
4. Current Situation
4.1Cryosurgery
Procedure:
Cryosurgery is currently used as a form of minimally invasive
surgical technique to remove undesirable tissues. (Rubinsky, 2000) It is a
safer, less invasive and intrusive as compared to the traditional scalpel or
open surgeries. In comparison between procedures such as the laparoscopic renal
cryoablation (use of cryosurgical probe) against the traditional laparoscopic partial nephrectomy (use of scalpel) to remove small renal
tumor, the cryoablation procedure is often associated with lesser blood loss
and a shorter hospitalization period for the patient with the same rate of
success.
(Levy, 2010)
There is also increasing recognition for the use of cryosurgery as its benefits outweigh traditional treatments. In 1996, the use of cryoablation in the treatment of prostate cancer is traditionally seen as a last resort for patients who had failed radiation therapy. With the technological advances in the field of cryosurgery, its application have now expanded to the treatment of early stage prostate cancer with similar success rate as traditional radiotherapy but minus the complications from exposure to radiation. (Levy, 2010)
However, there are limitations to this procedure. From the report
of “Current state of urological cryosurgery: prostate and kidney” by Levy, D.,
Avallone, A., & Jones, J. (2010), data collected indicates that the
efficacy of the cryosurgical procedure is comparable to radiotherapy in the
early stages of prostate cancer. In the later stages, the data skews heavily in
favour of traditional radiotherapy in comparison of biochemical Disease-Free Survival
(bDFS) periods and Prostate Specific Antigen (PSA) levels. This shows the
procedure’s limitation in treating locally advanced disease.
Equipment:
Currently most cryosurgeries involve the use of the cryosurgical probe. However, the traditional probes were bulky and unwieldy. Also, in using liquid nitrogen as a coolant, the system’s operational period is severely limited to the supply of liquid nitrogen. Furthermore, there are various safety concerns when handling liquid nitrogen and in using liquid nitrogen means that the operating room has to be constantly ventilated to prevent a build-up of nitrogen gas. (Nellis, 2009)
In view of such limitations, the cryosurgical probe
was revamped drastically when multi-component working fluids (i.e. mixed gas)
were introduced which provided for better refrigeration capability and smaller
pressure required by the probe. The result was a smaller, more portable machine
that provides more cooling power, can operate indefinitely and does not require
ventilation. (Nellis, 2009)
Another
revolutionary advance in cryosurgery was pioneered by Onik, a radiologist, and
Rubinsky, an engineer, who introduced the use of image monitoring devices such
as X-ray, Magnetic Resonance Imaging (MRI) and ultrasound into cryosurgery.
Such tools have provided surgeons with the ability to observe and monitor the
exact rate and extent of freezing of tissue matter during surgery. (Rubinsky,
2000) Thus allowing greater surgical precision and greatly enhances patient
safety during the procedure.
4.2 Cryonics
People
who are involved in cryonics call themselves cryonicists. Cryonicists believe
that death can be beaten using cryonics. Terminally ill patients, like cancer
patients, who have ran out of options for treatment can simply freeze
themselves till some point in the future where the biomedical science has
advance enough to treat whatever ailments that would’ve killed them. They would
simply be woken out of “suspension”, be cured of the disease and continue to
live a healthy normal life. The justification here is that since the person
will die anyway, cryonics offer a way, however slim, out. Providing the patient
a chance for survival in the future.
Another
option would be the preservation of the brain. Since it's the memories,
characteristics, experiences contained inside the brain that essentially makes
up the person, preserving only the brain would essentially be preserving the
person’s entire conscience. Then, the cryonics patient will have to be in
“suspense” until such a time when a body can be grown to transplant the
patient’s brain. (Shaw, 2009)
This
is accomplished through the process of vitrification (as mentioned above). With
the current technological level, it is possible to preserve the body without
causing much damage to the organ tissue. However, it is the “reanimation” that
poses significant technical difficulties.
With
the present level of technology, it is impossible “reanimate” cryonic patients
without causing significant damage at a cellular level due to the side effects
of cryo-preservation. To repair the damage would require advanced
nano-technology and stem cell therapy that we do not yet possess. (Knight,
2008)
There
are currently also ethical issues regarding cryonics. (TBA)
5. Future Considerations
5.1 Cryosurgery
Even with today’s technology, there are still limitations to the
refrigeration power of cryosurgical probes. Several probes are still needed to
destroy cancerous tumours of substantial size, suggesting the limitations of
currents technologies. Chemical additives could be added in the procedure to
further enhance the freezing process.
(Nellis, 2009) It
is also suggested that using computing models to optimize placement of probes
could serve as a viable solution. (Levy, 2010)
Another consideration is the freezing process of the procedure.
The freezing is usually confined only to around the tip of the probe with the
freezing process gradually slowing as it spreads outward due to greater insulation
from the frozen cells. The inability to control such process is further
complicated by blood perfusion or the presence of large blood vessels near the probe.
One solution suggested would be to adopt real-time computer simulations of the
surgery. However that would require significant amount of computing power that
we do not yet possess.
(Nellis, 2009)
5.2
Cryonics
(TBA)
Conclusion
References
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