Abstract
Healthcare-associated infection is a global concern and imposes a huge economic burden on the health industry. Anaesthesiologists must be aware of their role in mitigating infection at the work place. This chapter looks at the potential sources and causes of infection and how an anaesthetic event may result in cross-infection. Good practices including hand-washing, decontamination of equipment and maintenance of work surfaces and anaesthetic machines between cases are described. Terminologies such as single use, single patient use, reusable equipment, decontamination and sterilisation are defined. Management of reusable components of video and direct laryngoscopes and the use, maintenance and transport of flexible optical bronchoscopes are discussed. We hope this chapter would be of use to the career anaesthesiologists and also to trainees preparing for their certificate exams.
Anaesthetic equipment and machines can be potential sources of cross-contamination of microbiological pathogens and hence causes of healthcare-associated infections (HAIs), which are an important concern across the world. Anaesthetists must take an active role in reducing cross-contamination. This chapter gives a brief insight into the processes involved and ways of preventing cross-contamination.
Healthcare-Associated Infection (HAI)
HAI has a negative impact on the health industry, with an estimated 300,000 cases per annum in the National Health Service (NHS) in England with respiratory tract infection the commonest. Scrupulous hand hygiene has been emphasised for reducing HAI. In the USA an estimated 1 million HAIs are reported annually, which is approximately 1 in 20 patient admissions with an annual cost of 30 billion dollars. Australia does not have a national surveillance for HAIs and therefore reports low figures of 165,000 per year which may not reflect the true scale of the problem. New Zealand has started a national trial to assess the extent of HAIs to help introduce corrective measures.
Bacteria top the list of causes of HIAs but they may also be caused by viruses, prions and fungi. Hepatitis A, B, C and the human immunodeficiency virus (HIV) are all potentially important viruses that may be transmitted between patients. Coronavirus-19 and its implications for anaesthetic practice is discussed in detail in the next chapter.
Prions are transmissible disease-causing proteinaceous particles. As they lack nucleic acid, they are resistant to almost all standard decontamination and sterilisation methods. Despite their resistance to sterilisation, cleaning with detergents is an important aspect of prion decontamination as it will wash away the hydrophobic prions reducing their numbers to low safe levels. Prions are the cause of variant Creutzfeldt–Jakob disease (vCJD), which was a disease of great concern in the UK in the 1980s to 1990s. It is a rare disease but necessitates the use of single-use equipment for surgical and anaesthetic procedures to minimise risk of transmission. Local policies based on national guidance must be followed diligently.
Decontamination Methods
The definitions of decontamination and the various components of decontamination used here are taken from the Medicines Healthcare products Regulatory Agency’s (MHRA) Microbiology advisory committee glossary of terms.
Decontamination
Decontamination is a broad term that includes cleaning, disinfection and sterilisation. It effectively removes contaminants or infectious agents that may potentially cause harm.
Cleaning
Cleaning, using detergents and water, is an important step that removes organic debris from equipment and is the only method of removing prions. Disinfection and sterilisation are only effective after cleaning has reduced the bioburden (i.e. amount of organic debris on the contaminated equipment).
Disinfection
Disinfection is a process used to reduce the number of viable infectious agents, but which may not necessarily inactivate some microbial agents, such as certain viruses and bacterial spores. Disinfection does not achieve the same reduction in microbial contamination levels as sterilisation. Effect of different decontamination methods on various vectors of infection is shown in Figure 37.1.
Figure 37.1 Effectiveness of various agents against four important infectious agents. Prions cannot be destroyed by any of the agents, they can only be removed by washing and cleaning with water and detergents. X, not effective; #, mildly effective; ##, fairly effective; ###, strongly effective. Act H2O2, activated hydrogen peroxide, NaDCC = Sodium dichloroisocyanurate. *Cleaning is an essential process to remove all debris. Without this decontamination will not be effective. Cleaning with detergents is currently the only way of reducing prion proteins from the surface of equipment.
A high-level disinfectant is a chemical agent that can kill bacteria, viruses and spores. It is only sporicidal under certain conditions.
Sterilisation
Sterilisation indicates the elimination of all pathogens including spores. For a medical device to be labelled sterile, the theoretical probability of there being a viable microorganism present on the device should be equal to or less than 1 × 10−6.
Steam sterilisation is performed at temperatures above 120 °C and most anaesthetic equipment including videolaryngoscopes and flexible optical bronchoscopes (FOBs) cannot withstand such temperatures.
Reusable FOBs can be sterilised using low temperature sterilisers such as gas plasma or hydrogen peroxide sterilisers that are as effective as steam sterilisers against spores and mycobacterium (Figure 37.1). A select few videolaryngoscopes can also be similarly sterilised.
Ethylene oxide sterilisation is a slow process, but it is often used at an industrial level for equipment (including single-use devices) that are delivered sterile.
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