[Dosage errors and their prevention in intraocular SF6 injection for endotamponade in pneumatic retinopexy and after vitrectomy].

Sulfur hexafluoride (SF6) is used for internal tamponade during retinal detachment surgery. It is usually injected into the eye by a plastic syringe either with a sharp needle or by using the infusion system during pars plana vitrectomy. Although several suggestions exist for the appropriate application of intraocular SF6 and other perfluocarbons, a sudden postoperative rise in tension or hypotonia has been observed repeatedly. We simulated the preparation and application of mixtures of sulfur hexafluoride and air and analyzed possible mistakes. SF6 was quantitatively analyzed by infrared spectroscopy. SF6 does not rapidly diffuse out of capped plastic syringes made of polypropylene, as commonly employed in the Federal Republic of Germany. SF6 and air mix completely during aspiration. If the volume of microporefilters or tubes being used for preparation and instillation of mixtures of SF6 and air is ignored, this may result in a 20% deviation in SF6 concentration. Silicone tubes, which are widely used for the influsion during pars plana vitrectomy, are not recommended for the application of SF6. SF6 and fluorcarbones diffuse through silicone tubes and absorb and desorbe in the tube. Infusion lines made of polyethylene or polyvinylchloride, e.g. butterflies, should be preferred.