Disinfection
Minimising infection risk in ultrasound
Point of care ultrasound has become an indispensable tool in ICUs and Emergency Departments, but with studies identifying high levels of contamination on ultrasound probes, how can healthcare providers minimise the infection risks and improve safety for patients? Olivier Mazille calls for improvement and standardisation of disinfection processes.
Ultrasound is a versatile medical technology that has become ubiquitous throughout healthcare. The use of diagnostic ultrasound in the United Kingdom has increased steadily in recent years with the number of procedures in England rising from 7.7 million in 2013 to 10.2 million in 2019.1
Reprocessing of ultrasound
probes is also evolving, as facilities move away from manual processes towards automated systems that require less hands-on time, while still being safe and effective for point of care use. For all point of care reprocessing, there are factors that facilities and healthcare staff should consider to maximise the safety and efficiency of disinfection workflows.
The emergence of point of care ultrasound As ultrasound devices become smaller and more portable, the role of ultrasound as a diagnostic tool, at point of care, is becoming more established. Point of care ultrasound (PoCUS) is an indispensable tool for triage and management in acute care environments like intensive care units and emergency
Critical
Device contacts sterile tissue or the bloodstream
Sterilisation
Semi-Critical Device contacts mucous
membranes or non-intact skin
Non-Critical Device only contacts
intact skin Figure 1. The Spaulding Classification
High level disinfection
departments.2,3 Other specialties including
obstetrics and gynaecology, urology and general practice are also benefitting from PoCUS.4-6 Alongside this increase in the use of PoCUS comes a greater focus on the importance of standardisation of medical device reprocessing workflows. For ultrasound probes, this means applying the Spaulding classification to each ultrasound probe before use on a patient (Figure 1). The Spaulding classification divides infection
transmission risk based on the type of patient tissue the device will contact during use, which determines the level of disinfection. If sterilisation of critical devices is not possible, such as with ultrasound probes, they can minimally undergo HLD and be used with a sterile sheath.7,8
Applying Spaulding The Spaulding classification system is a rational approach to disinfection and sterilisation of medical devices that contact the patient. This universally accepted classification scheme has been retained, refined and successfully implemented in clinical settings for over
50 years. It also forms the basis of national standards and guidelines around medical device reprocessing.7-12 Spaulding divides infection transmission risk based on the type of patient tissue the device will contact during use. As ultrasound machinery becomes more portable and PoCUS becomes more widespread, consistently applying Spaulding to each use of a probe remains essential. Ultrasound probes used at point of care are often shared between rooms, departments or operators, and used in a range of procedures requiring different levels of disinfection. For example, the same probe might be used as a non-critical device in a diagnostic scan on intact skin, then later as a critical device during an invasive procedure. In the first scenario, the probe requires only low-level disinfection. But in the second procedure, the probe is classed as critical and requires high- level disinfection and the use of a sterile sheath at a minimum.7,8
Infection risk from ultrasound Ultrasound probes contact a range of hazards during use, putting them at high risk of becoming contaminated with pathogens. A study in emergency rooms and intensive care units found that over 50% of ultrasound probes had blood contamination.13
In other
settings, over 90% of transvaginal ultrasound probes have been found to be contaminated with bacteria after use.14,15
Even after low-
Low level disinfection
level disinfection with wipes and sprays, probes can be contaminated with viruses and bacteria, including pathogens that can cause sexually transmitted infections like human papillomavirus (HPV) and Chlamydia trachomatis.16,17
A landmark epidemiological study by the
Scottish health authority reported an increased risk of infection in the 30 days following an endocavitary ultrasound scan, where low-level disinfection was the practised standard of
March 2023 I
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