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Ravi S. Singh, Brian P. Larsen, Judy E. Kim; Potential Technique to Prevent Retained Intraocular Perfluorocarbon Liquid after Pars Plana Vitrectomy Surgery. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2630.
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Perfluorocarbon liquids are used in vitreo-retinal surgery for retina tamponade because of their clarity, cohesiveness, high specific gravity and relative inertness. However, inadvertent intraocular retention after vitrectomy can lead to a low-grade inflammatory macrophage response, symptomatic floaters and potential long-term retinal toxicity. Since these liquids are volatile with high vapor pressure, we hypothesized that a direct fluid-free interface between perfluorocarbon liquid and humidified air during air-fluid exchange would enhance vaporization and ensure complete removal of perfluorocarbon.
Evaporation time of perfluoro-n-octane (PFO) liquid was measured in open air and closed pressurized system. A 4ml glass vial with a 20gauge inlet for humidified air and and 20gauge outlet vented to room air, was used to simulate intraoperative air-fluid exchange. Humidified air was insufflated using an airpump set to 20mmHg. Evaporation time of 1ml of PFO was measured in the absence and presence of a balanced salt solution(BSS) interface between PFO and air. The effect of postion of the inner orifice of the outlet relative to the air-PFO interface was also assessed.
1ml of PFO was completely evaporated from a 4ml glass vial with a 20mmHg inflow of humidified air and outlet vented to room air in 9 minutes and 13 seconds. Positioning the inner orifice of the outlet needle close to the air-PFO interface increased its evaporation by 45%. Addition of a thin layer of BSS on top of PFO completely prevented the evaporation of PFO.
A direct air-PFO liquid interface without intervening BSS promotes complete removal of PFO liquid owning to its high vapor pressure. Meticulous intraoperative aspiration of BSS layer on top of PFO liquid during initial air-fluid exchange and subsequent venting to room air after gross removal of all fluid from the posterior pole would promote evaporation of any remaining perflurocarbon liquid. BSS rinse at the conclusion of air fluid exchange may be counter-productive by creating a BSS interface over any remaining PFO liquid, which prevents evaporation of PFO.
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