Temperature control

Control of the temperature in the ultrasonic bath

The RKI guideline "Hygiene requirements for the reprocessing of medical devices"/1 describes the use of ultrasonic baths for chemical disinfection and/or cleaning in the reprocessing of medical instruments: "...
Since ultrasound can lead to temperature changes which may have negative effects on medical devices or cleaning performance, the operating temperature should be controlled on the device side (Cat. IB). ...". Here, category IB means: "The recommendations are considered effective by experts and on the basis of a consensus decision of the Hospital Hygiene Commission at the Robert Koch Institute and are based on well-founded evidence for their effectiveness. A classification of the corresponding recommendation in category IB can also be made if scientific studies may not have been carried out on this."/2. This recommendation is therefore not a normative or legislative requirement.

The demand for temperature control arose from the often unnecessary continuous operation of the ultrasonic baths, whereby the ultrasonic energy introduced led to an uncontrolled increase in temperature. If the ultrasonic bath is operated as intended according to the time specifications for disinfection and/or cleaning, i.e. only when ultrasound is emitted when the ultrasonic bath is loaded, the continuous heat supply is omitted. In addition, the metal instruments that are inserted draw heat from the bath.

There is a constant temperature equalisation. A significant temperature rise can only occur during operation for several hours. A commercially available electronic thermometer can be used to check the temperature during operation for several hours. This does not have to be ultrasound-proof, as the temperature measurement must be taken when the unit is switched off. Continuous temperature measurement during ultrasound emission is not necessary.

In principle, the following applies to ultrasonic baths without temperature display:
If short sonication times are observed and the ultrasonic bath is loaded immediately, an increase in temperature above 40 °C can be avoided permanently with a high degree of certainty; protein-containing compounds cannot coagulate and thus be removed safely. Therefore, we recommend disinfection and intensive cleaning in only 5 min with STAMMOPUR DR 8 after instrument dry deposition.

Retrofitting a temperature display is possible for older ultrasonic units with a separately installed tank. A retrofit kit is available for SONOREX built-in units for this purpose.

The newer SONOREX built-in units of the ZE-DT series have a built-in temperature control.

/1 Hygiene requirements for the reprocessing of medical devices; Bundesgesundheitsblatt; 2001 - 44: 1115-1126; Springer-Verlag

/2 Categories in the guideline for hospital hygiene and infection prevention; Published as a preface to the 16th delivery ( Feb. 2000) of the loose-leaf collection: guideline for hospital hygiene and infection prevention, Verlag Urban & Fischer, Munich.