The COVID-19 pandemic has forced healthcare facilities to increase the scope and implementation of their infection control and hygiene procedures. 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.
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.
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.
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.
Bacterial/viral Filters (BVFs) and risk of cross-contamination
With the current SARS-CoV-2 (COVID-19) pandemic there has been increased discussion around the risk of contracting an infectious disease through contact specifically with spirometry equipment. Although the involvement of spirometry equipment in clinical infection transmission was initially undetermined in literature, recent research has found that spirometry devices which have reusable components in parts of the device airway have shown tendency to exhibit the lingering presence of microorganisms (2-4) after device reprocessing. Interestingly, research has shown that ultrasonic spirometers which generally utilise disposable air flow tubing can successfully avoid this problem (5). Although poor device design inevitably contributes to the possibility of failed reprocessing techniques, manufacturers are still responsible for ensuring that the methods and agents they recommend are validated and can be successfully repeated by users. In fact, device user manuals should provide details for correct reprocessing but also alert users to the importance of certain concepts such as the difference between cleaning and disinfection. For example, it is critical that disinfection of a device is preceded by a cleaning step. The cleaning step removes any debris from device surfaces and is important as microorganisms may be hide within debris matter, ultimately hindering the reach and effectivity of the disinfectant agents applied in the next step.
There is specific recent discussion, however, around the use of conventional BVFs during spirometry tests. There is a push from some healthcare providers for the utilisation of conventional in-line BVFs due to their belief that they provide extra protection for patients and healthcare workers. This is despite the fact that currently there are no BVFs on the market which can provide or claim 100% filtration efficacy. This is also despite the fact using an in-line BVF does not account for an infectious patient possibly contaminating anything in the room, including the operator, through coughing, sneezing or even breathing normally, 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 not only during test procedures, but also in between test sessions (6).
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.
The Spiroway Disposable - design and efficacy
The Spirohome Clinic is a multi-user device and is used with a disposable mouthpiece, the Spiroway Disposable. As part of Spirohome’s safe spirometry approach, and as required by global authorities in spirometry testing, a new mouthpiece must be used for each patient testing with a Spirohome Clinic device. 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 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. Concepts around added airway resistance to devices was discussed in the previous section. In this way, the Spirohome Disposable can both protect the body of the device to patient breath exposure whilst also analysing it as accurately as possible.
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.
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