Can a humid storage environment of surgical instruments before reprocessing increase patient safety and durability of instruments?

Background: National and international guidelines recommend reprocessing of medical instruments to commence as soon as possible post-surgery; furthermore, they recommend that transport and storage of surgical instruments postoperatively occurs in a moist, humid atmosphere. The concern is that a dry storage environment results in deterioration of instruments. Aim: To evaluate whether residual protein or corrosion is associated with storage environment (dry or humid), holding time or number of treatment cycles. Methods: The range of protein residue and corrosion were tested on surgical instruments contaminated with human blood amended Enterococcus faecalis ATCC 29212. Subsequently instruments were stored for 6, 12 and 24 h in dry or humid conditions. After one, 25 and 50 reprocessing cycles, instruments were examined for protein residues using the o-phthaldialdehyde (OPA) method or corrosion using stereomicroscopy, scanning electron microscopy and energy dispersive spectroscopy. Findings: Protein residue found on instruments was 21.5–54.0 μg and corrosion corresponded to 0–5% of the inspected area. No associations between storage environment and protein residue (adjusted mean difference = 0.48, 95% confidence interval: -0.42, 1.37, P=0.30) or corrosion (P=0.20) were identified. Higher numbers of treatment cycles showed higher amounts of corrosion (mean: 1 _cycle = 0.06%, 25 _cycles = 0.52% and 50 _cycles = 1.45%). In contrast, higher numbers of treatment cycles showed lower amounts of protein residue (P<0.001). We found both lower protein residue concentration and lower corrosion rating at 12 h compared with 6 and 24 h holding time. Conclusion: Cleanliness and durability of instruments before reprocessing seems not to be affected by storage environment or holding time but instead by number of treatment cycles.