MMed thesis -
Faculty of Health Sciences / The field of organ and tissue transplantation has necessitated an improved
understanding of their associated pathophysiological pathways. Specific
areas of interest involve the changes that follow ischaemia and
derangement’s that accompany organ and tissue storage, reperfusion injury
and the “no-reflow” phenomenon. Strategies have been devised to
manipulate and modify these processes, improving tissue and organ survival
and function. These have involved the use of preservation solutions.
Although most research involves organ transplantation, these principles have
been translated and applied to various tissues, surgical flaps and
microvascular replantations. These studies have generally used the skin flap
as their model with little knowledge regarding muscle flaps, the most
vulnerable to the ischaemic process. This study targets the use of one such
preservation system and uses skeletal muscle as its tissue model.
The vascular anatomy of the rectus femoris muscle in the New Zealand
white rabbit was studied anatomically and radiologically and thus described.
The isolated rectus femoris muscle flap was harvested and perfused in-vitro
with cooled, oxygenated University of Wisconsin solution (UWS) using a
pulsatile renal perfusion pump. UWS was selected as it contains vital
additives important in cryopreservation of organs. Monitoring of various
physiological parameters was performed. The muscle was examined at 0, 4,
8, 12, 18 and 24 hours of extra-corporeal perfusion using warm and cold,
non-perfused controls. The contralateral muscle served as the control.
End-points were the percentage of muscle survival, as determined by a new
grading system of muscle ischaemia, based on 3 light and 7 electron
microscopic criteria.
The overall percentage of muscle survival (combined light and electron
microscopy scores) resulted in approximately 58% survival at 24 hours for
the perfused muscle versus 31% for the cold stored muscle. The stored
muscle had the same survival rate at 12 hours as did the perfused muscle at
24 hours. For all time periods beyond 4 to 8 hours, perfused muscle showed
statistically improved survival rates compared to the stored muscle. Eight
hours appears to be a crucial point beyond which survival in muscle
deteriorates to a much greater degree without perfusion.
Questions remain as to which method of preservation yields the best survival
benefit and, as yet, there is no “ideal” perfusate. The future involves
manipulating perfusion solutions and trying to arrest or reverse established
warm ischaemia. Success of free tissue transfers and replantations of musclecontaining
body parts may be enhanced. These techniques may also allow us
to effectively store previously harvested flaps and eventually, to enter the
realm of “banked” allograft tissue flaps.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/1863 |
| Date | 17 November 2006 |
| Creators | De Aguiar, Gavin |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 19070335 bytes, application/pdf, application/pdf |
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