Fluid dynamics in three 25‐gauge vitrectomy systems: principles for use in vitreoretinal surgery

Abstract

IntroductionSutureless 25-gauge pars plana vitrectomy has the potential to reduce the length of surgery and postoperative inflammation at the sclerotomy sites, thus decreasing patient discomfort postoperatively and hastening recovery (Chen 1996;Kwok et al. 1999;Jackson 2000;Lam et al. 2000;Rahman et al. 2000;Fujii et al. 2002a).This technology for vitrectomy, first described by De Juan & Hickingbotham (1990), has changed to facilitate transconjunctival sutureless vitrectomy (Fujii et al. 2002b). Smaller instrumentation has resulted in decreased infusion and aspiration rates, which may increase surgical time (Fujii et al. 2002b).Changes in pressure, resistance and cut rates with the smaller systems result in different types of vitrectomy. Many critical intraoperative situations in which the surgeon must select ideal surgical parameters require a solid comprehension of 25-gauge fluid dynamics.The purpose of the current study was to evaluate in vitro the infusion, aspiration and cutting rates of different 25-gauge vitrectomy systems to determine their respective physical characteristics during vitreoretinal surgery. Materials and MethodsThe infusion and aspiration rates of three 25-gauge systems made by Alcon Laboratories Inc. (Fort Worth, TX, USA), Bausch & Lomb Inc. (St Louis, MO, USA), and the Dutch Ophthalmic Research Centre (DORC, Zuidland, the Netherlands), respectively, were measured in vitro using a chronometer with 0.01-second accuracy. A precise weighing (to 0.01 g) high-speed (two samples ⁄ second) Ohaus Corporation balance (Pine Brook, NJ, USA) was used to measure 10 ml in a highaccuracy volume bottle. A stopwatch Wenzhou Lianying Teaching Instrument Co. Ltd precise chronometer (Wenzhou, China) was turned on and off when target weights (difference of 10 ml in balance) were showed. Infusion ratesThe infusion rates of 10 ml of balanced saline solution (BSS) were measured

Performance Analysis of Ultrahigh-Speed Vitreous Cutter System

“…3,15,17 In contrast, the vitreous flow rates showed an increasing trend for all gauges tested, comparing 1,000 CPM and 5,000 CPM with a maximum peak at 5,000 CPM for all gauges. Vitreous is classified as a gelatinous fluid, made up of 98% liquid and 2% protein, 3,18 containing chunks that can obstruct ANALYSIS OF ULTRAHIGH-SPEED VITREOUS CUTTERS RIBEIRO ET AL the cutter port and increase the resistance of the flow inside the aspiration tubing. As the cut rate increases at the same aspiration level, the vitreous chunks that are being cut become smaller and less resistant to aspiration, a feature that becomes more significant the smaller the gauge of the instrument.…”

“…Our methods have been described in detail elsewhere. 18,19 Briefly, each cutter was suspended in a vial of either water or porcine vitreous. The vitreous used for the experiments was carefully removed en bloc from porcine eyes enucleated ,12 hours postmortem (Sierra for Medical Science, Whittier, CA).…”

Vitrectomy Fluidics

“…Twenty-five-gauge maximum inflow will be less than 20-gauge maximum inflow [2]. This can be partially compensated for by increasing infusion pressures, but infusion inflow/outflow mismatch is far more likely to happen in a case where the infusion gauge is different from the outflow gauge, e.g.…”

A new infusion sustainer that stabilizes perfusion during sutureless 25-gauge vitrectomy

“…Recent studies of vitreous dynamics have found that performance, in terms of vitreous removal, differs among 20G, 23G and 25G systems [5], and that infusion and extrusion fluid rates differ among various 25G vitrectomy systems [6]. Currently, angled incision with trocars is a widely-used method for creating sclerotomies in T [7]; however, because of the poor stability of the infusion port, flow of infusion fluid into the anterior chamber during vitrectomy and flow of air into the anterior chamber during fluid-air exchange do occasionally occur.…”