Endotamponade medias

The demonstration of the potential of this stable and obviously excellently tolerated compound has inspired a great number of scientists to develop PFCLs as special tools for medical applications and to introduce therapies using the outstanding behaviours of PFCLs, like the well-known concepts of complete and partial liquid ventilation [4], oxygen support of the skin, wound treatment [5], artificial tears [6], and ocular endotamponade media [1], to name only a few. Until now, the mouse submersed in PFCLs is often used as an eye-catcher for the demonstration of the biocompatibility of PFCLs even in cases where the topic of the presentation is not reflected by this experiment. 

In ophthalmological application, this characteristic of the PFCLs is not used yet. In general, the products used are air equilibrated with the consequence that the oxygen partial pressure in the eye is increased from 15 Torr to 160 Torr and the CO2 partial pressure drops down from 50 Torr to 3 Torr initially. These differences are equilibrated intra-ocularly by diffusion processes, but the initial difference to the physiological level of gas concentration activates the constriction of the retinal vessels, resulting in an increase of the blood flow. In rabbit eyes, a damage of the retina could be attributed to this mechanism [38,39], On the other hand, endotamponade media with controlled levels of dissolved gases could not only avoid such a scenario but should also be useable for a therapeutic manipulation of the retinal perfusion. 

This was demonstrated by GC/MS measurements using a headspace sampler. Equivalent tissue segments of freshly enucleated and vitrectomised eyes of pig were prepared and rinsed for 30 min with PFD after a simulated VR surgery using different types of partially fluorinated liquids as endotamponade media. PFO was used as a reference. At the end of treatment, they were rinsed with PFD to clean the surfaces. 

Tissue penetration of endotamponade media should be avoided because of non-calculable side effects. One way to reduce the penetration rate is the use of branched species. In a similar experiment as described above, small pieces of fatty tissue and muscle tissue from pig were immersed in the test liquids for 15 min and then rinsed with PFD to clean the surfaces. Table 13 shows the reduced ratio of penetration of branched perfluorobutyl-butane in comparison to the linear form (044 perfluorobutyl-n-butane and 044v 1-perfluorbutyl-2-methyl-propane, own unpublished results). The relative penetration ratio was determined on the basis of the concentration of the two types of perfluorobutyl-butane indicated by GC/MS measurements. 

Winter et al. [41] could demonstrate that the intra-operative treatment of retinal detachments with PFCLs, followed by an exchange to intraocular gas, resulted in total coating of the retinal surface with the fatal effect of complete sealing, creating an interruption of essential transretinal exchange processes. Equivalent scenarios have to be taken into consideration in the situation of a completely filled eye or if the droplets of an endotamponade media show a non-spherical shape. 

In different medical disciplines, highly fluorinated liquids are directly used, like in the case of ocular endotamponades in ophthalmology, of gas carriers in liquid ventilation, or of preservation and transport media in transplantation medicine. For these applications, the highly fluorinated liquids are used in a purified form or as mixtures. The extraordinary... 

This chapter presents the state of the art of the use of highly fluorinated liquids in ophthalmology and perspectives of future applications in the eye. In different medical disciplines, the characteristics of these fluids are directly used, like in the case of ocular endotamponades in ophthalmology, of gas carriers in liquid ventilation, or of preservation and transport media in transplantation medicine [1-3]. For these applications, the highly fluorinated liquids are used in a purified form or as mixtures. The intended effect is created by the physicochemical characteristics themselves. The extraordinary behaviour of the fluorocarbon liquids (FCLs) requires specialised biocompatibility testing, adjusted to this class of components. 

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