With the impact of the COVID-19 pandemic still threatening countries around the world, several pulmonary health clinics and test laboratories have seen temporary closure, infection control protocols have become stricter and respiratory product manufacturers have published additional guides and resources regarding device-based disease transmission. A successful approach to infection control and hygiene issues in the current climate is multi-layered and must be seen as such by both patients and healthcare professionals.
1. Infection control in the spirometry clinic: the big picture
COVID-19 is now another infectious disease amongst several others which poses a threat particularly to people who are already living with chronic respiratory illness. Individuals with cystic fibrosis, for example, are at the highest risk as they are more severely immunocompromised than other patient groups. Spirometry clinics, where lung function tests are performed to diagnose and monitor lung disease in patients, have become particularly critical settings during the COVID-19 pandemic. Contact with contaminated surfaces or equipment or with aerosol droplets travelling in the air are known routes of disease transmission. As such, respiratory laboratories have had to introduce additional cleaning and disinfection measures or have had to shutdown operations completely as seen in many parts of the world. Patients are naturally reluctant to visit these clinics and doctors who use spirometry as part of the care they must give have been left searching for alternative solutions. Hygiene and infection control in respiratory labs or clinics, however, is not just a matter of potentially contaminated devices or spaces and the role of factors such as the patients themselves, adherence to manufacture recommendations, smart device design and smart scheduling which make up the big picture must be recognised.
The ATS/ERS general rules
Although each clinic or facility will have its own infection control and hygiene protocols, there are fundamental basics which apply to and must be observed by all respiratory clinics. The updated guidelines for standardised spirometry (1) conjointly published by the American Thoracic Society (ATS) and European Respiratory Society (ERS) in 2019 states that operators and patients must wash their hands before and after testing/handling of equipment even if gloves are worn, single-use consumables such as mouthpieces or nose clips must be disposed correctly and immediately after use, a new set of consumables must be used for each new patient and all shared items and surfaces must be disinfected appropriately in between patients. The ATS/ERS highlights the fact that infection control cannot be guaranteed by protective equipment or equipment disinfection alone, and is an entire approach that must be practiced with every test and every patient.
The manufacturer’s rules
It can also not be emphasised enough that personnel responsible for device maintenance and hygiene adhere to the manufacturer’s guidelines regarding correct cleaning and disinfection of devices. The procedures and/or chemicals recommended by the manufacturer will be validated as effective for lowering the risk of cross-contamination of users through the re-use of their device. The validated methods and chemical agents protect not only the users but also the device as they are selected such that continual application does not damage the device or affect its performance.
The SpiroHome Clinic strictly requires users to complete separate cleaning and disinfection steps using disinfectant wipes and requires that each patient uses a new SpiroWay Disposable - the original mouthpiece accessory for the SpiroHome Clinic device. SpiroWay Disposable is an individually-packaged and single-use component that can be discarded after use with minimal operator contact after use. It was designed to line the entire airway of the spirometer so that any surface that comes into contact with a patients breath during a forced expiratory or inspiratory maneuver during testing, is actually completely disposed of after the test. The compact, portable and cordless SpiroHome Clinic can further be stored away from common-use spaces when not in use.
Further ATS/ERS recommendations
The 2019 ATS/ERS guidelines also mention additional measures that can be taken by clinics to further minimise the risks of disease transmission. Patients should be called just prior to their visit to check whether they have an active infectious condition such as tuberculosis or hemoptysis so that the clinic can either prepare accordingly or reschedule the appointment. Infectious patients can be tested at the end of the work-day or be tested is specially designated areas with appropriate ventilation minimising exposure to other patients and giving personnel sufficient time to properly disinfect equipment and surfaces.
2. Transmission via spirometers
The SARS-CoV-2 (COVID-19) pandemic has increased discussion around infection exposure through spirometry equipment. Although the involvement of spirometry equipment in clinical infection transmission was initially a grey area, research shows that reusable components within a spirometer's gas pathway can exhibit the lingering presence of microorganisms even after the device is reprocessed for use (2-4). Ultrasonic spirometers which generally utilise single-use disposable air flow tubing can avoid this problem (5). Poor device design inevitably leads to reprocessing difficulty and failed efficacy. Manufacturers are, however, always responsible for ensuring recommending validated reprocessing protocols that can be successfully applied by users. Device user manuals should not only provide detailed device reprocessing steps, but emphasise the difference between cleaning and disinfection. It is critical that device disinfection is preceded by a device cleaning. Cleaning involves the removal of surface debris which would otherwise hinder the reach and effectivity of disinfectant agents applied subsequently. Disinfection itself targets a specific kill rate for surface microorganisms and is used when devices are sensitive to sterilisation methods.
Bacterial/viral Filters (BVFs) and risk of cross-contamination
In light of the current pandemic, there is a recent push from some healthcare authorities for the utilisation of conventional in-line BVFs during spirometry. There is a belief by BVFs will provide protection against disease transmission during pulmonary function tests. BVF attachments to spirometers do create an extra physical boundary for the catchment of expelled air and other airway matter from a patient, however, a BVF that provides or claims 100% filtration efficacy does not and cannot exist for obvious reasons. Furthermore, using an in-line BVF during a spirometry test does not prevent an infectious patient from possibly contaminating the room, operator or other patients when coughing, sneezing etc. even before a spirometry test has started. The 2019 ATS/ERS guidelines draws attention to the potential for infection transmission in pulmonary function test laboratories in between test sessions (6).
BVF impact on device performance
There is also ignorance of the impact that conventional BVFs have on device performance and accuracy. The ATS/ERS has provided the maximum allowable resistance limits for airflow (1.5 cm H20 at 12L/S) (7) in spirometers. These limits may be breached when in-line filters are used. Moreover, device accuracy could still be affected by the resistance introduced by BVFs, particularly if they are not validated for use by the device manufacturer. The spirometry parameter peak expiratory flow (PEF), for example, is known to be the most sensitive to added resistance (8). It is therefore essential that operators utilise the correct, original, and validated accessories for spirometers, and understand that regardless filtration claims and device design, infection control in spirometry encompasses all of the concepts discussed previously.
3. Device design and efficacy
The SpiroHome Clinic is a multi-user device and is used with a disposable mouthpiece, the Spiroway Disposable. With multiple international design award for its unique and human-centred design, SpiroHome spirometers and mouthpieces are designed for performance accuracy and ease of maintenance for the user. Compact, portable and with no moving parts, the SpiroHome Clinic is easily cleaned, disinfected and stored between use.
The Spiroway Disposable - design
The Spiroway Disposable mouthpiece lines the entire gas (air) pathway of the spirometer that may be in contact with a patient’s breath. The Spiroway Disposable mouthpiece protects the device lumen from direct exposure to exhaled air, sputum or other bodily fluids expelled from the patient during a breathing maneuvre. In effect, the entire breath-contacting surfaces of the SpiroHome system is completely renewed for each patient and surface cleaning and disinfection is sufficient preparing the device for safe use by the next patient.
The Spiroway Disposable - efficacy
The fact that the SpiroWay Disposable is an open tube system with filtration meshes located parallel to airflow rather than perpendicular to it means that there is minimal resistance to or ‘tampering’ with the patient’s exhaled air and airflow characteristics can be more accurately measured and recorded by the system. Furthermore, the variability in filtration efficacy of commercially-available filters can be quite significant (9) and thus robust validation methods are necessary to support filtration claims. The efficacy of the in-built filters of the SpiroWay Disposable in minimising the risk of cross-contamination has been tested and validated by an independent testing laboratory. The mesh filters used on the SpiroWay Disposable can effectively (over 99%) bi-directionally filter the transfer of microorganisms across itself. The SpiroWay Disposable therefore provides comparable degrees of ‘protection’ to the device and user and does not introduce additional maintenance requirements for the operator or facility.
4. Remembering the basics
It is essential that in addition to this discussion, that operators and users of SpiroHome Clinic devices read, understand and fully apply the recommendations, precautions and warnings provided in the SpiroHome Clinic user manual. It is important to always remember and exercise the significance of complete hygiene and infection control in pulmonary function test settings, to refer to local and international guidelines for safe spirometry, and to use the device as recommended, for the safest outcome for both patients and staff.
The Inofab Health family is dedicated to bringing innovative, effective and safe clinical spirometry products and platforms to patients and healthcare professionals around the world.
- Graham BL, Steenbruggen I, Miller MR, et al. Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement. Am J Respir Crit Care Med. 2019;200(8):e70-e88.
- Houston K, Parry P, Smith AP. Have you looked into your spirometer recently? Breath 1981;12:10–1.
- Rutala D.R., Rutala W.A., Weber D.J., Thomann C.A. Infection risks associated with spirometry. Infect Control Hosp Epidemiol. 1991; 12: 89-92
- Marchant J., Little S.A., Bush A. Flow-volume curves in children with cystic fibrosis—a possible risk of cross-infection. Respir Med. 1994; 88: 235-236
- Singh V., Arya A., Mathur U.S. Bacteriology of spirometer tubing and evaluation of methodology to prevent transmission of infection.J Assoc Physicians India. 1993; 41: 193-194
- Heilmann M, Klocke M, Smaczny C, Ziesing S, Meissner E, Fabel H. Advances in lung function tests: ultrasound spirometry. Am J Respir Crit Care Med 1998;157:A704.
- Gardner, RM, Standardization of Spirometry: A Summary of Recommendations from the American Thoracic Society. Annals of Internal Medicine 1988 108:2, 217-220
- Johns DP, Ingram CM, Khov S, Rochford PD, Walters EH. Effect of breathing circuit resistance on the measurement of ventilatory function. Thorax. 1998;53(11):944-948. doi:10.1136/thx.53.11.944
- Canakis, A.‐M., Ho, B., Ho, S., Kovach, D., Matlow, A. and Coates, A.L. (2002), Do in‐line respiratory filters protect patients? comparing bacterial removal efficiency of six filters. Pediatr. Pulmonol., 34: 336-341. doi:10.1002/ppul.10171