Comparing the Efficiency of Fluid Infusion Systems for Pars Plana Vitrectomy.

PURPOSE

To compare the efficiency of infusion sets including distal tubing, infusion, and trocar cannulas (23G, 25G, 27G) of leading brands (Alcon, Bausch & Lomb, BVI, DORC, Optikon) in minimizing the intraocular pressure drop on aspiration. The study reports the pressure drop along infusion as a function of the flow rate and correlates performance to design.

METHODS

We measured the pressure drop of the distal silicone tubing, infusion cannula and trocar cannula, connected to a model eye and the corresponding flow rate. The piezometric height of the balanced salt solution (BSS) reservoir open to atmospheric pressure ranged from 10 to 120 cm above outlet. All infusion set components were measured in length and inner lumen diameter.

RESULTS

Pressure drop as a function of flow rate varied significantly: BVI and DORC proved more efficient at all gauges. Pressure drop at 10 mL/min flowrate varied between 9-16 mm Hg for 23G, 11-25 mm Hg for 25G, and 16-50 mm Hg for 27G. The tubing friction and kinetic energy loss, respectively responsible for the linear and quadratic component of the head-loss to flow rate parabolic function, also differed significantly.

CONCLUSIONS

Pressure drop secondary to flow rate varied by a factor of two among manufacturers. Excessive pressure drop during aspiration may lead to dangerous hypotony or force the surgeon to set anomalously high pressures at rest to avoid it. The present study gives useful insights to help improve infusion system performance.

TRANSLATIONAL RELEVANCE

A thorough understanding of head loss mechanisms along infusion sets allows the design of more efficient and safer infusion sets.