The transient hyperaemic response (THR) is a novel way of assessing vascular reactivity that measures vasodilatory responses after 10-20 second periods of ischaemia. Previous studies have combined the THR test with measurements of microcirculatory perfusion using laser Doppler flowmetry in the of forearm skin of healthy volunteers. A database of over 1000 measurements in over 100 subjects was analysed to further establish the inter- and intra-individual variability of THR measurements. THR measurements of skin vascular reactivity were performed in laboratory experiments designed to explore the practicality of the test when investigating vascular reactivity in critical illness. Positive end-expiratory pressure caused fluctuations in skin perfusion but did not alter the THR. Both perfusion and THR could be manipulated by the iontophoresis of several drugs used in critical care, but the possibility of carrier solutions causing vasodilatory effects could not be ruled out. Norepinephrine was successfully iontophoresed into forearm skin and caused vasoconstriction which partially reversed the decreased THR caused by localised heating. A pilot study of cutaneous THR measurements in patients with evidence of systemic inflammation demonstrated decreases in vascular reactivity compared with the database of healthy volunteers, but the test was found to be less robust within intensive care than was anticipated. A retrospective analysis was performed of patients admitted to intensive care following a planned operation, or presumed to have sepsis, in order to evaluate the effects of prior administration of statins and other potentially vasoactive drugs. Previous research demonstrated associations between statin usage and improved outcome in bacteraemic patients. This analysis identified no benefit from prior statin usage. One hypothesis generated by this research was that the pleiotropic effects of different statins were not class effects. Further research designed to evaluate the effects of different statins on skin microvascular reactivity using the transient hyperaemic response is planned.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:559532 |
| Date | January 2011 |
| Creators | Beed, Martin |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/11927/ |
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