A review of environmental and economic aspects of medical devices, illustrated with a comparative study of double-lumen tubes used for one-lung ventilation

When health care management considers implementing a new technology such as a medical device, it is crucial to take workflow, clinical outcome, economy, and environmental impacts into consideration in the decision-making process. This study outlines the knowledge status of this complex challenge via a systematic literature review (SLR). The SLR found 133 of 1570 screened publications that covered relevant frameworks for choosing hospital equipment (i.e., related economics, life cycle assessment, waste generation and health issues). Yet, just five publications addressed choosing single-use vs. reuse of tubes or similar types of equipment by economic and environmental considerations through a systematic quantitative approach. The SLR reveals few publicly available peer-reviewed studies for the optimal sustainable choice of equipment. This study assesses environmental impacts of carbon dioxide (CO2) emissions as CO2-equivalents and resource consumption of a single-use double-lumen tube (DLT) combined with a reusable bronchoscope were compared to a single-use DLT with an integrated single-use camera. Camera DLTs exclude or minimize the need for a bronchoscope to verify correct tube placement during one-lung ventilation. The life cycle assessment shows that the materials and energy used and needed for personnel protective equipment and cleaning of the reusable bronchoscope contribute significantly to CO2-equivalent emissions. To ensure the sustainable choice of equipment this aspect must not be overlooked. Secondly, future reuse of plastic waste materials from the use can contribute significantly to better environmental performance.


Introduction
Today's agenda on sustainable development challenges many aspects of approaches in society.The United Nations Sustainable Development Goals (Nations, 2015a) aim to provide a framework for those challenges that require a collaborative and joint focus from governments, the private sector, civil society, and people.These challenges include various environmental impacts such as those from climate change.A major task is to tackle climate change and mitigate its consequences, partly by swiftly reducing emissions of carbon dioxide (CO 2 ) and other greenhouse gases arising from our use of fossil fuels (Take urgent action to combat climate change & its impacts, 2015).
This must be pursued in parallel to other challenges.A key one is ensuring both responsible consumption and production given the increasing scarcity of resources.As case in point is the accelerating exploitation of known but limited reserves, e.g., rare earth metals in the production of electronics and other digital consumables (Nations, 2015b).
The consumption of various devices causes various environmental impacts originating from the use of natural resources, energy used in their production.The impacts arising from the use of devices may apply to different sectors, including the medical sector (Marshall et al., 2017).The consumption of scarce resources often occurs in the manufacturing of products for the economy, while CO 2 emissions are usually associated with the fossil fuels used in the production, transport, and utilization of a given product (Climate Change 2014 Synthesis Report Summary for Policymakers, 2014).
Mounting concern for the environment has also entered the healthcare sector.Hence, there is a now pressing need to better understand how various choice of products or medical operation and service contribute to environmental impact and map their impacts, when comparing different ways to perform the same medical operation or service.Recent studies have compared greenhouse gas emissions, calculated as CO 2 -equivalent emissions, for reusable and single-use bronchoscopes (Sørensen & Grüttner, 2018), reusable and singleuse ureteroscopes (Niall F. Davis et al., 2018aDavis et al., , 2018b)), environmental impacts of singleuse vs. reusable scissors (Ibbotson et al., 2013), and single-use vs. reusable anesthetic equipment McGain et al. (2017).
The introduction of single-use alternatives has stressed the need for robust comparisons of their potential environmental impacts (Campion et al., 2015).Discarding single-use devices intuitively causes concern among hospital staff, and people in general, who care about whether such a single-use is environmentally friendly (Marshall et al., 2017).Disposable products were initially intended for use in exceptional circumstances or conditions, to guarantee proper disinfection (e.g., during warfare, disasters, epidemics) (Tvede et al., 2012;Viana et al., 2016).Furthermore, concerns related to patient safety have led to the introduction of high-level disinfection (HLD) standards and procedures that have replaced simple sterilization.Specialized functions in hospitals can now clean and disinfect reusable devices (Gupta & Wang, 2009;McCahon & Whynes, 2015); (Perbet et al., 2017).Such developments have naturally led to the greater use of personal protective equipment (PPE) and specialized cleaning and disinfection equipment, which have increased their environmental burden and potentially their economic burden as well (McGain et al., 2017); (Larsen et al., 2019).Consequently, due to increasing labor costs, capital costs, repair costs, and energy requirements related to reprocessing reusable devices, single-use devices have become the preferred choice for numerous surgical cases within different hospital specialties (e.g., anesthesia, pulmonology, emergency care) (McGain et al., 2017); (Perbet et al., 2017); (Gupta & Wang, 2009); (Tvede et al., 2012); (McCahon & Whynes, 2015).Singleuse devices are often preferred in cases where availability and sterility are key factors for an optimized workflow.
The relationship between a product's life cycle (i.e., its design/production/use/endof-life) and its environmental burdens comprise a complex challenge.Hence, the decisions made in its design stages, for example, combined with certain external parameters, like context of use or end-of-life, can jointly influence its overall environmental impact (Moultrie et al., 2015).Methods to understand and support development toward better solutions have therefore been focus of interest for a long time, hence, e.g., Life cycle Assessment, Eco-design, Life Cycle Costing, and Circular Economy developed.
Concepts like the circular economy aim to improve companies' decision-making process and to reduce the negative environmental impacts of the products' life cycle.The overall goal is to design products and implement company approaches and policies that accommodate sustainability.The Ellen Macarthur Foundation frames the circular economy this way: "Circular economy is based on the principles of designing out waste and pollution, keeping products and materials in use, and regenerating natural systems" (Foundation, 2017).However, all environmental aspects are not always evident using principles as highlighted in the circular economy concept.An approach to clarify and be aware of the pitfalls in a specific context is to make a life cycle assessment to support the decision making.A complete life cycle assessment determines whether reuse or single use perform the best on various environmental parameters.(Haber & Fargnoli, 2021) have developed methods for addressing this challenge using product service system perspective in the medical sector.
The circular economy concept aims to link environmental performance to the design approach.(MacNeill et al., 2020) have studied the barriers to circularity in the medical device industry.They highlight perceptions regarding infection, behaviors of customers and manufacturers as well as regulatory structures to be barriers.Therefore, policy and market driven solutions are needed to transform the market.
Similarly, a disconnect between practice and reuse or recycling of medical waste is found by (Ordway et al., 2020), which confirms the balancing and management challenge.
However, various health economic aspects, including clinical outcomes, should also be very relevant to consider when assessing the relevant performance assessment dimensions in comparing single-use and reusable devices.Aspects of health economics seek to investigate all appropriate costs associated with using the device in question.
Reusable devices entail reprocessing costs-including disposable cleaning equipment, water and detergent consumption, and electricity usage, among others-ongoing repair and maintenance costs, capital investments, as well as labor costs.For single-use devices, the economic aspects include the device's price and the costs associated with discarding it after each procedure.The micro-costing method is often used to derived the most precise estimates of running costs, especially when assessing new medical devices (Xu et al., 2014).
Quantifying and balancing all perspectives are as mentioned previously an acknowledged challenge.
This study aims to determine the status, and knowledge of balancing and quantifying environmental, economic, and social aspects by a substantial literature search focused on the choice between single-use and reusable equipment in the medical sector, e.g., doublelumen tubes (DLTs) and similar medical equipment and their use.
Secondly, this study compares the specific choice of either using a single-use doublelumen tube (DLT) combined with a reusable bronchoscope were compared to a single-use DLT with an integrated single-use camera.This comparison is made on the environmental impacts of carbon dioxide (CO 2 ) emissions as CO 2 -equivalents and resource consumption.This study also explores scenarios with different levels of reuse of the plastics in the tubes to understand the future perspective of the investigated example of choice.
Combining the literature research and the current example aims to illustrate the aspects of the challenge for decision makers who wishes to aim for sustainable management.

Study design
This study focused on two outcomes.The first outcome was to perform a literature review to investigate the current state of knowledge regarding the environmental and economic aspects of single-use vs. reusable medical equipment.Additionally, the literature review sought to identify potential research gaps within this topic, so as to include these aspects in the later discussion.
The second outcome was a carbon footprint analysis of using a camera DLT compared with using a conventional DLT-and-reusable bronchoscope.The aim here is to illustrate and exemplify the challenges of identifying the right choice to make for a device.The potential impact of reusing the plastic and cardboard in the waste handling is also investigated.
The functional unit chosen was one-lung operated patients, for whom single-lung ventilation was achieved using lung separation with a DLT.Two different scenarios to achieve one-lung ventilation were investigated: 1. Using a conventional DLT and a reusable bronchoscope to verify correct tube placement (i.e., the reference scenario) 2. Using a camera DLT (ETView Medical Ltd./Ambu A/S, Ballerup, Denmark), thus precluding the need for a bronchoscope to verify correct tube placement (i.e., the intervention scenario).

Literature review
A systematic literature review (SLR) was conducted to provide the accumulated knowledge on choosing between single-use and reuse devices in health care.More specifically, the literature was reviewed to identify research gaps and existing knowledge of the environmental and economic aspects of single-use vs. reusable medical devices.An SLR has four stages: planning stage (purpose and protocol), selection stage (literature search and screening), extraction stage (quality appraisal and data extraction), and an execution stage (analysis and findings and writing the review).
In the planning stage, the SLR's purpose was to identify the main aspects and conclusions deemed valid for choosing between single-use and reuse devices in health care.Here, the authors also agreed on a standard protocol regarding the review procedure, in part by identifying relevant databases and keywords for the study.
Studies were identified through literature searches.The searches considered all studies published until December 2021 in the databases used.The search was conducted in the electronic databases PubMed, Embase, Ei Compendex, and Web of Science.
The search was conducted using the following medical subject headings (MeSH) and keywords: The literature search yielded in total 1611 records, of which 41 were duplicates, thus leaving 1570 records.
To limit the scope of inquiry eight subjects of interest were chosen (listed below).The records abstracts were screened accordingly to the subjects listed (i.e., economics, life cycle assessment, waste generation and health issues).The subjects cover various aspects of how to make sustainable choices when buying equipment.
The screening step resulted in a total of 133 records (Appendix 1) that constituted the dataset for our study.
In the extraction stage, both quality appraisal and data extraction from the dataset was carried out.The dataset was categorized into the eight subject areas of interestlisted above-to determine which of those subject areas were covered in each publication, and to what extent.The number of publications as a function of publication year was also investigated.
1. Health economics 2. Economics and life cycle assessment 3. Life cycle assessment 4. Economics and waste reduction 5. Medical waste reduction 6. Economics and environment 7. Qualitative environmental and economic considerations 8. Considerations related to the reuse or single-use devices

Goal and Scope of Life cycle assessment/carbon footprint
Life cycle assessment (LCA) is a well-known and established method to assess the environmental impacts from a device or service (ISO/TC207/SC5, 2016).The use of natural resources, such as energy, land, minerals and metals, and outputs in the form of products, by-products, emissions, and waste, are quantified for all steps in the device's life cycle.While LCAs have been carried out on many food products and production systems (Poore & Nemecek, 2018), the approach is now being used extensively in many other fields of research.Yet, the use of LCA is relatively new in the healthcare industry.A 'carbon footprint' is a subset of a full LCA, in which only the climate impact is investigated.Due to the increasing interest in this subject, the International Organization for Standardization (ISO) has issued a standard describing the principles and framework for the LCA and carbon footprint of products (ISO/TC207/SC5, 2016).
The reusable bronchoscope's cleaning and disinfection must be included to fairly compare the camera DLT with the conventional DLT and a reusable bronchoscope.This comparison was done using the LCA approach, which sometimes also referred to as the 'cradle to grave approach'.This methodology to analyze environmental impacts is gaining popularity within the healthcare sector (Niall F. Davis et al., 2018aDavis et al., , 2018b)); (Campion et al., 2015); (Viana et al., 2016).This study's LCA approach is comparable to the ISO 14040 standards and complies with the transparency criteria in that standard.Such an analysis covers the whole life cycle of the products, production of raw materials, manufacturing to the extent possible from the data available, the use phase, and disposal/recovery.The impacts not included in this analysis are water-related impacts and toxicity impacts.The former are not considered relevant in this analysis, though water use may be appropriate in other contexts, e.g., Australia (McGain et al., 2017).The toxicity impacts, however, may be substantial due to the phthalates in the devices.It is not possible to quantify the toxicityrelated impacts because we lack information on their content of phthalates in the plastic materials.This aspect is, however, should be possible to quantify qualitatively.
Data on processing and material use impacts used for this study were pooled from Ecoinvent, using Simapro 9.0.0.5 (Sustainability, 2020).The background system chosen was a Danish context; that is, we used Danish heat and electricity production rates when waste is incinerated.Hospital waste is incinerated with 99% energy recovery in Denmark.These calculations were made using the International Reference Life Cycle Data System (ILCD).We should note that ILCD includes biogenic carbon.

Reference scenario
One-lung ventilation (OLV) is an essential technique for most traditional thoracic surgeries.It refers to the mechanical separation of the two lungs, wherein only one lung is ventilated while the other is deflated (Rapchuk et al., 2017); (Massot et al., 2015).The most common OLV method is intubation with a double-lumen tube (DLT).Situations requiring OLV procedures are often lobectomies, biopsies due to the suspicion of cancer, and lung resections.The annual number of OLV procedures in Denmark is approximately 2,100 procedures (Sundhedsdatastyrelsen, 2020).Reusable bronchoscopes are used to check and ensure the correct placement of the DLT to secure the nonventilation of the lung to be operated on (Terjesen et al., 2017); (Koleva et al., 2013); (Communication, 2015); (Ofstead et al., 2017).Furthermore, it is the gold standard to check whether the tube placement is correct, by using a fiber-optic or video-enabled bronchoscope, or both, after the tube's insertion.Also, it is crucial to recheck its placement after shifting the patient's position into the final lateral surgical position, since doing so could increase the risk of tube displacement (Atul et al., 2015).Therefore, to ensure the accurate placement of the tube, a new DLT with a camera in the tip can be used.When using the DLT with the inbuilt camera, there is no longer any need for a reusable bronchoscope.It has been shown that it is clinically faster and easier to use the DLT with a camera, and a cost-effectiveness analysis demonstrated a cost-saving aspect to it, because the reusable bronchoscopes are only used in 4% of the cases (Larsen et al., 2019).
The reference scenario investigates the single-use conventional DLTs used together with a reusable bronchoscope (Fig. 1).A flow diagram of the reference scenario processes is shown in Fig. 2.
Reusable bronchoscopes require cleaning that uses high-level disinfection (HLD) as well as drying after every use.This study's evaluation of the impact from reprocessing reusable bronchoscopes is based on the procedure currently in use at the Odense University Hospital.The materials used for reprocessing is listed in Table 1.
• After using the bronchoscope is manually brought to the cleaning room.• After the manual cleaning, the table is cleaned using alcohol and napkins.All waste is put into a plastic waste bag and sent for incineration as part of the hospital waste.• After cleaning the bronchoscopes, each is placed inside a drying cabinet.It is left there to dry and stored overnight till its next use.One drying cabinet can hold eight endoscopes.

Intervention scenario
The intervention scenario investigated the single-use DLT with an integrated camera (VivaSight-DL, ETView Medical Ltd./Ambu A/S, Ballerup, Denmark).By having an integrated camera, the need for a bronchoscope to confirm correct tube placement is eliminated.It should be noted that a bronchoscope might still be required in certain cases (e.g., to check for a tumor mass further down in the lungs).The VivaSight tube is connected to a screen monitor (this monitor was not included in the assessment) (Fig. 3).A flow diagram of the processes and workflows for the intervention scenario using the VivaSight-DL is shown in Fig. 4 Table 2.

Energy recovery
All waste is incinerated as hazardous waste in a Danish hazardous waste incineration plant.
In the process, up to 99% of the energy is recovered as heat and electricity.

Disinfection before use
Tubes are presumed disinfected via cold sterilization with ethylene oxide.

Transport
The tubes are assumed to move 12,000 km, carried by a Euro 6 freight lorry.This transport includes going from production site to the consumer and is based on the tube's production occurring in Europe.Table 3.

Literature search
The literature search yielded a total of 133 relevant studies.Of these, 40 records reported comparing the environmental impact of single-use and reusable medical devices.However, only a limited number (n = 5) of these studies sought to compare DLTs or endoscopes.Only one out of 5 studies compared both environmental and health economics data.Figure 5 depicts 133 studies grouped into different categories, to provide an overview; the blue color shows the relevant investigations related to medical devices in general.The orange color presents those studies comparing single-use and reusable medical devices, while the last column are studies addressing the environmental or economic impact associated with single-use versus reusable DLTs or endoscopes.Only the five studies comparing DLTs or endoscopes were explored in more detail.Baseline characteristics for these studies are presented in Table 3.An overview of all articles found are listed in Appendix 1.It is also evident from Fig. 5 that mainly single subject areas are covered, e.g., health economics or life cycle assessment or waste.
Finding the optimal sustainable approach or sustainable choice of equipment will depend on the combination of several aspects (economic, health, and environmental impacts).Thirty studies focused only on financial aspects; 11 studies covered both economics and life cycle assessment approaches; 10 out of 29 studies were found that analyzed the equipment's environmental impacts using a systematic quantitative method equivalent to a life cycle assessment.This illustrates a profound research gap.Evidently, the topic of waste reduction has been studied, for which 37 records were found, of which 13 addressing both economics and waste reduction.Figure 6 shows that in the last decade the number of publications investigating the topics of interest has increased over the preceding 27 years and especially the last 2 years.This trend illustrates the currently expanding focus on cost efficiency and the focus upon environmental aspects of using various medical devices.It illustrates the fact that the focus on these issues is relatively new in the healthcare industry and very pertinent.
As mentioned in the above introduction section, achieving sustainability requires the simultaneous consideration of economic and social aspects along with environmental impact.The SLR indicated that economic aspects have been researched, and waste generation optimization to similar extent, but few studies have inquired into a full life cycle assessment.
One analysis (McGain et al., 2017) revealed how the balance, as related to the global warming impact, between reuse and single-use choices of equipment depends on the background system (e.g., what sources supply the electricity used for washing and drying).Those authors also concluded that reuse in those assessed contexts resulted in a higher 10% CO 2 impact and more than a doubling of water use.
A review paper (Drew et al., 2021) on Life cycle assessment of surgical and anesthetic care find that most data show that single-use devices tends to result in higher contributions to environment.They also find examples of the opposite conclusion.
Only five studies could be found that aimed to quantify environmental impacts in combination with equipment choice for single-use vs. reusable products like tubes and scopes.They are listed in Table 3.An additional paper is listed which reports on a health economic analysis of the tubes used in the illustrative example of our study.
The literature review clearly indicates a research gap regarding comparing, quantifying the environmental impact, and balancing the choice between single-use and reusable DLTs and endoscopes devices in the health care sector, from both a health economics and an environmental perspective.It has become clear that minimal evidence exists on the subject with respect to comparing economic and environmental aspects when evaluating new interventions.
Only one study compared the economic aspects and environmental aspects of reusable vs. single-use laryngoscopes (Sherman et al., 2018).Two studies did perform a full life cycle assessment comparing single-use ureteroscopes vs. reusable ureteroscopes and single-use bronchoscopes vs. reusable bronchoscopes.Lastly, only one study has compared the health economics aspects of VivaSight-DL to a DLT in combination with a reusable bronchoscope.
A previous study (Larsen et al., 2019) found that VivaSight-DL is more cost-effective than using DLTs that are combined with a reusable bronchoscope.One reason for this is that VivaSight-DL, with its integrated camera, significantly reduces the need for a reusable bronchoscope; hence, any reprocessing of the bronchoscope was eliminated.Reprocessing reusable endoscopes is time-consuming and consists of various mandatory reprocessing steps to minimize any risk of bacterial residues contaminating the endoscope and being transferred to another patient during a procedure.The reprocessing of endoscopes also requires substantial amounts of detergent, water, and disposable PPE, all of which is relevant for a transparent comparison with the amount of waste associated with a fully disposable endoscope or DLT.
A recent study (Sørensen & Grüttner, 2018) compared reusable bronchoscopes to single-use bronchoscopes, finding that the CO 2 emissions were somewhat equivalent.In another study (N.F. Davis et al., 2018aDavis et al., , 2018b)), the total carbon footprint of the single-use ureteroscope Lithovue™ (4.43 kg CO 2 eq per case) was smaller than that for a reusable ureteroscope (4.47 kg CO 2 eq per case).

Life cycle assessment and carbon footprint of DLTs.
The results are summarized in Fig. 7. Figure 7 shows the results for the categories chosen and the two tube systems are presented beside each other.
A general pattern is discernable, one that is related to energy consumption.The reusable scope, which requires washing after each use, seems to exert a considerable environmental burden.The single-use shows higher impacts related to resource consumption.It is related to the fact that for every time a tube is used there is use of materials, fossil as well as minerals.The single use tube includes a camera and a chip.The metals or minerals in the tube will be lost as waste.If a product includes rare resources, this could be a problematic loss of resources.To better understand this pattern, the breakdown of the different contributors to the environmental impact is depicted in Fig. 8, since this enables their closer examination.Furthermore, the uncertainty and sensitivity of these results must be assessed.This study compares single-use DLTs with an integrated camera (VivaSight-DL) to singleuse DLTs without a camera used in combination with a flexible, reusable bronchoscope.Figure 8 shows that the VivaSight-DL has a carbon footprint of 1.25 kg CO 2 eq in the contextual framework assessed in this study.A comparable tube for single-use, combined with flexible reusable scope that undergoes cleaning and drying before reused, has a total carbon footprint of 2.1 kg CO 2 eq under the current framework assessed.Figure 8 shows that the amount of material (mainly plastic types) used to make the tubes is the main contributing factor followed by the incineration of their packaging and PET.Secondly, the material and energy use needed for the washing and handling during the cleaning of scopes slated for reuse have a significant, extra impact on their carbon footprint.
Figure 8 shows the breakdown of the carbon footprint in the systems including drying and storage.From those results, it is also evident that the energy used for drying and storing is significant but not the sole factor determining the overall totals.
To investigate the detail of reuse of packaging further, some more detailed scenarios have been made.According to (PlasticEurope, 2019), the proportion of plastics collected for recycling now averages 32.4% in EU member states.(Miljøstyrelsen, 2018) has estimated the actual recycling rate in DK to be 19%, even though more than 40% of plastic is collected.In the future, it may be possible to attain a higher recycling rate, especially if the products are designed with their recycling in mind, and waste collection systems are customized to better handle them (Moultrie et al., 2015).This is not the case today of hospital plastic waste, which is in Dansih context incinerated.
Figure 9 shows the effect of the carbon footprint of recycling between 100 and 25% of the plastics.The carbon footprint for the combined scenario can with full recycling get reduced to 0.6 kg CO2 eq.The single use scenario can get reduced to 0.3 kg CO2 eq.The reuse of plastics is especially challenging and presently still undergoing further development and refinement.Assuming 100% recycling of plastics is a very high level of recycling and not the case for most waste collection systems as of today.In the future, however, it may be a possible reachable target.Yet, some development within a design for reuse of materials and collection systems must be developed.

Sensitivity and Uncertainty
Based on the obtained dataset and specific scenarios evaluated here, our results uncovered a carbon footprint for single-use device that is comparable in size to that of the multipleuse device.

Data on the production and materials of tubes and scopes
It is evident from the breakdown of contributors that the amounts of plastic used in the various parts of the tubes play an important role.The durability of a product is also a function of the material quality and amounts used to make it.But the analysis indicates that the optimal use of this material is vital for the overall carbon footprint or other environmental impacts since the material used for either protective wear or equipment is a significant contributor (> 50%) to the product's carbon footprint.
The amount of paper and cardboard used also significantly impacts the total carbon footprint of the scenarios examined.This effect, however, is mostly related to products' disposal.The emissions generated from incineration augments the CO 2 impact, whereas if the material is reused, it replaces production of new cardboard and thus reduces the CO 2 impact.

Energy use and protective wear
The main uncertainty stems from uncertain empirical data for the energy use needed for one washing cycle and the storage of the devices in a ventilated cabinet.It was only possible to find technical data on the maximum energy use for the washing process and the storage cabinets.The energy used for this washing was assumed to be 0.65 kWh for one washing cycle carrying two scopes.The energy used for the storage of eight scopes was assumed to 43.2 kWh.The uncertainty due to unavailable data is significant.The effect of having 50%-90% less energy used for the washing reduces the contribution to 0.1 kg CO 2 eq.Given the fraction of energy use contributing to the carbon footprint (= 0.2 kg CO2 eq), this will still favor the single-use tube if the recycling of paper, cardboard, and plastics are not enforced somehow.
It is also essential to note that a major contributor to the total carbon footprint is the use of protective wear and other materials for the washing and drying procedure, similar to the findings of (Sørensen & Grüttner, 2018).It follows that if it becomes possible to handle several scopes per set of protective wear, for instance, this should lead to a substantial reduction in the total carbon footprint for reusable equipment.

Recycling of paper, cardboard, and plastics
However, compared with model at hand, if paper, cardboard, and plastic can be fully reutilized, and the energy use for washing and storage is reduced by 50% (down to 20 kWh), both tube systems are almost on par in terms of their carbon footprint.

Transport
The model at hand presumed the products are produced in Europe and transported by truck.The environmental impact of other modes of transport, such as flying the same products to Europe from Asia, will introduce a significant difference.According to one study (Wernet, 2016), the CO 2 eq emission for lorry transport (Euro 6) is 0,0923 kg CO 2 eq per tkm and 1,17 kg CO 2 eq per tkm for airfreight.That difference is at least tenfold greater, which surely would dominate a similar breakdown of results if the context used instead was airfreight transport.

Discussion
Single-use equipment is becoming more and more popular, chiefly due to the avoided risk of cross-contamination and patient-to-patient infections.Some evidence has been sought to address the health economics and environmental impact of implementing these new technologies, especially on large scale.
In the first part of this study a literature review was carried out to assess the status and gaps existed within this topic, especially when comparing single-use and reusable medical equipment, such as DLTs or endoscopes.We found five studies on environmental impact exist on those products as well as one resent review paper (Drew et al., 2021).Our literature search show there has been a significant increase in papers over the last 27 years on waste amounts and handling, health economics as well as the life cycle assessment of various aspects of health care.The topic on quantifying and comparing reuse and single use products combined with the economic aspects was covered in only five combined.The number of papers within the topic subjects in the literature search increased significantly in 2020 and 2021.This underlines the topic to be of increasing and significant interest as well relevant for more investigation.
In this study, we assessed a particular scenario, by comparing two different DLTs for OLV.Our findings nonetheless demonstrate a research gap regarding studies that investigate the environmental impact of single-use vs. reusable medical devices.
Our study did compare single-use DLTs with an integrated camera (VivaSight-DL) to single-use DLTs without a camera used in combination with a flexible, reusable bronchoscope.We found that VivaSight-DL has a carbon footprint of 1.25 kg CO 2 eq in the contextual framework assessed in this study.A comparable tube for single-use, combined with flexible reusable scope that undergoes cleaning and drying before reused, has a total carbon footprint of 2.1 kg CO 2 eq under the current framework assessed.And showed a significant potential to reduce the carbon footprint by increasing the recycling of packaging and plastics to between 0.6 kg CO 2 eq and 0.3 kg CO 2 eq depending on scenario.
The main uncertainties of our results are related to energy use for washing and drying, which significantly contribute to the carbon footprint.Such uncertainty admittedly makes it difficult to say, at this point, whether one solution is better than the other.The example at hand illustrates one of the important and critical points to be aware of when chosen between single-use and reuse equipment.The energy use for processing and the material uses as, e.g., for PPE is significant during reprocessing for reuse, this may become a significant contributor and change the balance between reuse or single-use to the benefit of single-use.The energy consumption in the current case, may be very uncertain in the current example and may change in the future energy system.The type of energy providers influences the carbon footprint.This is also mentioned by (McGain et al., 2020).However uncertain, the total contribution to carbon footprint is significant in this case.Focusing on the handling and process and, e.g., handle more than one or 2 items for reprocessing at the same time may reduce the influence of the mentioned aspects as, e.g., described in (Sørensen & Grüttner, 2018).
Another specific detail to be aware of in relation to environmental impact of using specific products is transport via air freight during production and distribution on the market.Air freight may influence the balance significantly.That type of carbon footprint impact will be distributed over times of uses and is therefore to the benefit of reused devices.
Nevertheless, the single-use tube does offer benefits with respect to toxicity effects because it does not contain phthalates.Using single-use tubes and equipment does generate more waste that reusable tubes.That is off course a benefit for applying the reusable framework.The handling of waste is space-and time-consuming (Lopes et al., 2019).The environmental impacts related to a device's waste is, in some cases, possible to avoid if that waste is used for either heat and electricity production, or it is reused as illustrated in this study.
While the data presented in this study are informative for decision-makers and future environmental studies, there are several limitations that should be considered.One is that no data related to the content of phthalates was included.Secondly, significant uncertainties in the statistics used for electricity consumption prevented a firm overall conclusion for the comparison between a single-use product and reusable one.
Thirdly, no cost data was collected specifically for this study, since a previous costeffectiveness analysis was already carried out comparing the same interventions described here, albeit only from a hospital perspective.Thus, no cost data were added to the environmental aspects of this study.

Conclusion
The aim of determining the status, and knowledge of balancing and quantifying environmental, economic, and social aspects in the context of medical devices was pursued.The key findings confirmed via the dearth of publicly published scientific studies addressing the process and procedure and facts involved for sustainably choosing medical equipment.
Further, the example used in this study for the particular devices of single use versus multiple use equipment demonstrated several key parameters to consider in making such choices.
The first key thing learned here is to consider the total material use product/products in question, or possible reuse.The material use must include all material, e.g., also material used for the processing of reuse itself.The current example shows significant contribution form PPE. This focus is of course eminent when considering waste materials and amounts.
Secondly, one should consider energy usage for the reprocessing impact when reusing products, since these may have an underappreciated but considerable impact on the total environmental impact of using a product.Therefore, a reusable device may not be the best choice once all other parameters are duly considered (economy and health).
Especially, this specific point of using either energy or significantly extra material when processing for reuse is where concept like circular economy may result in misinterpretation and therefore needs support from a life cycle assessment to quantify understanding exactly this point.This is a type of detail, where the circular economy concept, may result in a wrong priority and need support from, e.g., life cycle assessment.
The third key learning is when focusing on circular single-use products-where the materials are reused either via reprocessing of new types of products or back into the same type of product-is shown to be a possible way forward in terms of minimizing their overall environmental impact.Nevertheless, that is based on the ability to achieve the same quality or comparable quality of the reprocessed material.

Fig. 1
Fig. 1 Reusable bronchoscopes and the single-use double-lumen tube Fig. 2 Flow diagram of reference scenario processes and workflow using a conventional tube and reusable bronchoscope

Fig. 3
Fig.3The VivaSight DLT with its integrated camera.The monitor is reusable and can be used for several types of endoscopes; therefore, it was NOT included in this study's analysis is 2.1 kW.The heating unit uses 1.5 kW; the compressor uses 300 W; UV light uses 15 W. The total energy use is based on the values listed and estimated at 43.2 kWh per day to keep eight scopes dry and stored safely.

Fig. 5 Fig. 6
Fig. 5 Number of studies divided into different overview categories

Fig. 7 Fig. 8
Fig. 7Results for the life cycle assessment of the two types of scopes in use today, for which waste is incinerated

Fig. 9
Fig. 9 Carbon footprint comparison of recycling vs. incineration of waste

Table 2
Materials use for the VivaSight DL (single-use tube)

Table 3
Baseline characteristics for studies comparing single-use vs. reusable equipment