Dr. Jeremy F. Birch Profile

Dr. Jeremy F. Birch

at Leicester Univ

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Publications (2)

Proceedings Article | 12 September 2003 Paper

Haemostatic effects of laser tissue solder as a reinforcement to anastomoses with PTFE grafts

Jeremy Birch, Alexander Seifalian, Peter Bell

Proceedings Volume 4949, (2003) https://doi.org/10.1117/12.479368

KEYWORDS: Laser welding, Surgery, Laser tissue interaction, Laser therapeutics, Laser vision correction, Blood, Arteries, Semiconductor lasers, Medicine, Proteins

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Proceedings Article | 12 September 2003 Paper

Methylene blue solder re-absorption in microvascular anastomoses

Jeremy Birch, J. Hepplewhite, Malcolm Frier, Peter Bell

Proceedings Volume 4949, (2003) https://doi.org/10.1117/12.478326

KEYWORDS: Proteins, Surgery, Laser welding, Laser vision correction, Laser therapeutics, Adhesives, Iodine, Inflammation, Semiconductor lasers, Medicine

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Soldered vascular anastomoses have been reported using several chromophores but little is known of the optimal conditions for microvascular anastomosis. There are some indications of the optimal protein contents of a solder, and the effects of methylene blue on anastomotic strength. The effects of varying laser power density in vivo have also been described, showing a high rate of thrombosis with laser power over 22.9Wcm^-2. However no evidence exists to describe how long the solder remains at the site of the anastomosis. Oz et al reported that the fibrin used in their study had been almost completely removed by 90 days but without objective evidence of solder removal. In order to address the issue of solder re-absorption from the site of an anastomosis we used radio-labelled albumin (I-125) incorporated into methylene blue based solder. This was investigated in both the situation of the patent and thrombosed anastomosis with anastomoses formed at high and low power. Iodine-125 (half life: 60.2 days) was covalently bonded to porcine albumin and mixed with the solder solution. Radio-iodine has been used over many years to determine protein turnover using either I-125 or I-131. Iodine-125 labelled human albumin is regularly used as a radiopharmaceutical tool for the determination of plasma volume. Radio-iodine has the advantages of not affecting protein metabolism and the label is rapidly excreted after metabolic breakdown. Labelling with chromium (Cr-51) causes protein denaturation and is lost from the protein with time. Labelled albumin has been reported in human studies over a 21-day period, with similar results reported by Matthews. Most significantly McFarlane reported a different rate of catabolism of I-131 and I-125 over a 22-day period. The conclusion from this is that the rate of iodine clearance is a good indicator of protein catabolism. In parallel with the surgery a series of blank standards were prepared with a known mass of solder to correct for isotope decay and allow data interpretation in terms of the actual amount of the solder remaining after a particular time. The anastomoses were formed with a known amount of solder and allowed to continue for up to 60 days before being sacrificed. The explanted vessels were then placed into a gamma counter and the amount of solder remaining expressed as a percentage. In this way the proportion of albumin left at the site of the anastomosis could be determined. By changing the power density of the laser it has been shown that the patency of soldered microvascular anastomoses is altered. By doing this it was hoped to determine any effect thrombosis might have on solder re-absorption. In addition the explanted vessels were inspected for inflammation, patency and aneurysm formation.

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