Effects of repeated gas sterilization on closure rates of ameroid ring constrictors in vitro.

Objective: To determine the effect of repeated gas sterilization on rate of closure of ameroid ring constrictors in vitro.
Sample: Twenty-four 3.5-mm ameroid ring constrictors.
Procedures: Ameroid ring constrictors were allocated to 1 of 4 treatment groups (6/group) to undergo gas sterilization 0, 1, 5, or 10 times. After sterilization, constrictors were incubated in canine plasma at a protein concentration of 3 g/dL for 27 days. A digital camera was used to obtain images of the constrictors prior to and at various points during incubation, and lumen diameter was measured.
Results: Mean ± SD percentage of lumen closure for all groups of ameroid ring constrictors combined was 85.2 ± 1.6% at day 0 (prior to plasma incubation) and 95.4 ± 0.8% at day 27. Mean lumen area was 3.64 ± 0.43 mm(2) (95% confidence interval, 2.67 to 4.77 mm(2)) at day 0 and 1.32 ± 0.25 mm(2) (95% confidence interval, 0.76 to 2.04 mm(2)) at day 27. None of the ameroid ring constrictors had closed completely by day 27.
Conclusions and Clinical Relevance: Overall closure rates for ameroid ring constrictors appeared to be unaffected by repeated gas sterilization up to 10 times. Findings suggested that veterinary surgeons can resterilize ameroid ring constrictors up to 10 times with confidence that ring properties would remain suitable for clinical use.