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.