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Metal / Deposits - Organic Residues

Type of Surface Change

Colored deposits consisting of:

  • blood
  • proteins
  • drug residues

Origin & Causes        

in manual processing and ultrasonic cleaning:

  • Long interval between use and processing (i.e. preparation for reuse),
  • use of unsuitable instrument disinfectants,
  • use of contaminated cleaning and disinfecting agents,
  • insufficient rinsing after treatment,
  • presence of sound shadows (ultrasonic cleaning).

in mechanical (machine-based) processing:

  • Water feed temperature too high (exceeding 45°C) in first rinsing phase,
  • ineffective rinsing (insufficient water flow through or around the instruments, insufficient rinsing pressure, rinsing shadows), poor maintenance of cleaning/disinfecting apparatus, etc,
  • foam formation due to cleaning or disinfectant residues carried over from the ultrasound or immersion bath,
  • improper charging/loading due to use of wrong instrument trolley/trays, overloading, leaving instruments fully assembled, processing jointed instruments in closed condition.

Treatment Recommendations        

  • Recleaning with ultrasound
  • Targeted manual recleaning

Preventive Measures     

  • Remove coarse contamination immediately (see RKI recommendation in "Anforderung an die Hygiene bei der Aufbereitung von Medizinprodukten" [Hygiene requirements for the (sterile) processing of medical devices], item 2.2.1).
  • Shorten the interval between instrument use and processing for reuse (< 6 hours).
  • Use detergent-disinfectants for wet disposal.
  • Feed water temperature in machine processing: max. 45°C.

Risk Assessment        

Can lead to corrosion also in stainless steels because blood, for example, contains chloride ions. If present in higher concentrations, these ions cause pitting and/or possibly stress-crack corrosion.