1. Introduction
Global healthcare services contribute an enormous 4.4% to the world’s Greenhouse Gas emissions, enough to place it fifth in the country carbon footprint ranking just after China, USA, India, and Russia [
1]. A large portion of these emissions comes from waste processes. For example, 590,000 tonnes of healthcare waste are produced annually in England alone, creating significant environmental impacts and a financial cost of over £700 m [
2]. In 2020, the NHS became the world’s first health system committed to a legally binding net zero emissions target [
3], recognising and solidifying the importance of reducing carbon emissions in healthcare.
The NHS Net Zero plan and similar global initiatives acknowledge that the current take-make-dispose linear economy marked with single-use devices (SUDs) is a significant contributor to climate impact [
4]. Fortunately, there are promising opportunities for improvement. A circular economy approach to retain value through reuse, remanufacturing, and recycling reduces premature device disposal and may lead to large emission and financial savings [
5,
6,
7]. However, remanufacturing comes with considerable challenges, as regulations understandably require that SUD medical devices are ‘reset’ before clearance for reuse (i.e., returned to a state substantially equivalent to a new device) [
8,
9].
Because of the stringent healthcare requirements, the medical remanufacturing process requires a series of resource-heavy steps (e.g., cleaning, sterilisation, testing) [
10]. Therefore, careful consideration of the environmental impacts is required to ensure that it would indeed reduce emissions compared to producing a new device. To support decisions regarding linear versus circular procurement strategies, Life Cycle Analysis (LCA) is often employed to systematically assess the environmental impacts [
11]. To ensure reliable results, comprehensive industry standards have been developed in recent years (e.g., ISO standards [
12] and NHS reporting guidelines [
13,
14]).
For remanufacturing to become a widely accepted practice, a collaboration between industry, legislation, and healthcare institutions is necessary. Previous studies have shown that successful remanufacturing is driven by engagement and support from all participating actors, who are largely motivated by triple bottom line benefits: profit, people, and planet [
15,
16]. With that in mind, in this article, we focus on evaluating the long-term emission savings of remanufactured electrophysiology catheters. They are a promising candidate for remanufacturing on a large scale because they have the potential for significant financial savings (up to £1.7 m annually in the UK [
17]), physician motivation is high (62% in 42 EU-based healthcare centres [
18]), and remanufacturing is promising (40% of ablation procedure emissions come from catheters [
19]).
In this article, we explore three research questions related to a circular remanufacturing approach for electrophysiology catheters:
- (i)
Can we validate the EP catheter remanufacturing results achieved by the Fraunhofer case study [
10]? (
Section 4.1)
- (ii)
To what extent do key life cycle parameters affect the overall emission results? (
Section 4.2)
- (iii)
How can we incorporate a realistic, industry-informed circular use of catheters to evaluate long-term emission savings? (
Section 4.3)
Contribution
The novelty of our work is the comprehensive and contextualised analysis of Life Cycle Analysis (LCA) emissions of medical single-use electrophysiology catheters, including the proposal of a long-term emission metric. Following on from the research questions laid out above, we identify three main objectives that this article addresses:
- (i)
To validate a previous case study on the environmental emissions of electrophysiology catheter remanufacturing [
10] by the prestigious Fraunhofer Institute.
We have developed a sophisticated, industry-informed Life Cycle Analysis model with the open source openLCA software [
20] for both virgin manufactured and remanufactured catheters (
Section 3).
- (ii)
To perform a sensitivity analysis of key life cycle parameters, showcasing the magnitude of impact that model uncertainty may have on the total emission results.
After carrying out a holistic evaluation of virgin and remanufactured catheter emissions, we analysed the impact of three key circular economy life parameters: the remanufacturing location, the catheter rejection rate, and the number of remanufacturing turns (
Section 4).
- (iii)
To propose a novel framework to assess the realistic, long-term emissions of adopting a circular economy approach with remanufactured medical devices.
Our proposed framework models an industry-informed buy-back scheme to evaluate long-term remanufacturing emissions (
Section 4.3). We interpret the results in a healthcare context, taking industry stances and existing literature into account (
Section 5 and
Section 6).
3. Single-Use Catheter Life Cycles and Material Flows
Before analysing the environmental impacts, we provide a detailed Life Cycle Inventory (LCI). This illustrates the virgin manufactured and remanufactured catheter life cycle stages with a comprehensive description of material inputs and outputs. The start and end life cycle stages (i.e., cradle and grave) are dictated by the
functional unit. A functional unit is key in LCAs, as it defines one unit of the product or service being evaluated [
39]. In this paper, we determine it as the production, use (1-h long procedure), and disposal of one catheter. By choosing equivalent functional units for both the virgin and remanufactured scenarios, we may confidently and intuitively compare their emission results (even though catheter ‘production’ includes different processes) [
40].
To decide which inputs and outputs are contained in the system boundary, we use the quantitative rubric published by NHS guidelines (see
Section 2.3). Additionally, we outline the quantity, source, and data quality of each data point in this section, following the NHS guidance for life cycle reporting [
14].
Since component materials and processes may vary significantly based on the catheter model, Original Equipment Manufacturer (OEM), and remanufacturer, we selected representative product systems for the virgin and remanufactured life cycles. The inputs and outputs were largely informed by a 2021 EP catheter case study [
10] which was supplemented and updated with our primary data from NHS England and USA-based medical device remanufacturers AMDR and Innovative Health (see Section
Table 2). The primary data additionally influenced our catheter use and remanufacturing locations, which were set in the UK and the USA, respectively. To account for the possible bias introduced to our emission values by the chosen representation, we include a sensitivity analysis of key process parameters in our results analysis (
Section 4).
3.1. Virgin Manufactured Catheter
A catheter’s linear life cycle was tracked from the production from raw materials in the USA (cradle) to its waste disposal after use in the UK (grave), as shown in
Figure 2. Because we selected the cut-off model (see
Section 2.1), any energy recovered after incineration was not credited to the catheter’s life cycle.
Table 3 presents an overview of the process steps, and subsequent material flows per life stage.
3.1.1. Production Stage
The catheter production stage consisted of the raw resource extraction, component production, and device assembly steps. We assume that all components were produced in the same facility, which is also where the catheter was assembled.
A catheter was made up of a plug, handle, curvature, loop, and shaft, and weighed a total of 118.9 g. Plastic components were modelled following the case study [
10], which used a bill of materials provided by their collaborating remanufacturer, Vanguard AG. We assume that other materials were excluded because they do not significantly contribute to the catheter emissions, e.g., by the material cut-off rule presented in [
13]. Several proprietary plastics were not available in the Ecoinvent v3.8 dataset [
31] (PEI granulate and PA6). In these cases, we selected replacement materials that closely matched the manufacturing properties of the original plastics (polysulfone and polyamide, respectively). Most importantly, by ensuring a similar melting point, we expect to achieve high similarity in the overall plastic life cycle impacts on the modelled catheter. This is because the production process, undertaken at high temperatures, is one of the most energy and environmental impact-intensive stages of the material’s life (e.g., melting the plastic, pre-heating moulds and dies) [
33], while our replacements may influence other impact categories, they will create similar results for GHG emissions, our chosen climate impact (see
Section 2.5).
Once the components were manufactured (electricity and other input emissions are included in the material flows), electricity was required to assemble them into a completed catheter. Because this step was excluded in the original study, we calculated the assembly electricity as half of the electricity used to assemble and disassemble a used catheter during remanufacturing (see
Section 3.2).
3.1.2. Sterilisation and Packaging Stages
Before transportation to the user, all virgin manufactured catheters were sterilised with ethylene oxide gas. According to [
10], the material inputs given in
Table 3 were the main identifiable components from a safety sheet provided to the authors by Vanguard AG, a medical remanufacturer based in Germany. The data was also supported by AMDR’s primary data. Apart from the gas materials, electricity was also needed to complete the procedure (e.g., gas introduction and evacuation from the sterilisation chamber).
We assume that the packaging stage is carried out manually. Therefore, only the packaging materials are required as input to the model.
3.1.3. Transportation Stage
After production, sterilisation, and packaging, the catheters were transported from the remanufacturer in the USA to an NHS end user in the UK. There were two transportation stages: A representative 18,760 km container ship route between the USA and UK, and a 250 km lorry transport for the final distribution within the UK. The locations were updated from the case study, which used locations specific to their collaborators (USA and Germany, respectively).
3.1.4. Use Stage
A major update in our approach compared to [
10] is the inclusion of emissions generated during the use stage. As shown in
Table 1, NHS GHG modelling standards [
13] dictate that materials consumed by a medical device during the use stage should be included in the life cycle assessment. Electrophysiology catheters require only electricity to be operational. Therefore, we included a catheter’s average energy use. The total amount was calculated from the average length of an electrophysiology procedure (1-hour length, primary data from AMDR) and the average watts a catheter draws [
41]. Because electrophysiology catheters are single-use devices, they do not need regular maintenance before being used.
3.1.5. Incineration Stage
Medical devices are most commonly incinerated after disposal to reduce contamination risk. For the end-of-life incineration after one use, we assume that the waste management facility was in the vicinity of the user, and therefore exclude transportation to the incineration site.
3.2. Remanufactured Catheter
Compared to the virgin catheter, a remanufactured catheter has a circular life cycle as shown in
Figure 3. That starting life stage (cradle) is when a used catheter is transported from the previous user to the remanufacturer. The life cycle ends (grave) after a successfully remanufactured catheter is used by a healthcare provider.
The total weight of a remanufactured catheter is 118.9 g, the same as a virgin catheter.
Table 4 presents an overview of the material flows per life stage.
3.2.1. Transportation Stage
In a significant change from [
10], we have doubled the transportation route between the USA and the UK. The case study assumes that the used catheters and remanufactured catheters are transported in a single round trip. However, discussions with medical device remanufacturers AMDR and Innovative Health revealed that this does not reflect current industry practice. Each transport route has two stages: A representative 18,760 km container ship route between the USA and UK, and a 250 km lorry transport for the final distribution within the UK.
3.2.2. Remanufacturing Stage
The catheter remanufacturing stage consists of the disassembly, cleaning, reassembly, and testing steps. We assume that all processes take place in the same remanufacturing facility, and therefore do not include further transportation. Additionally, we assume that the electrophysiology catheter’s software does not have to be maintained. Used catheters that failed quality control at any point of the process or passed their cleared number of maximum turns reached their end of life. For simplicity, the modelled remanufacturing process does not include replacing faulty components.
A significant difference of our model to [
10] is the rejection rate. The case study assumes an almost 50% rejection rate. In other words, only one catheter is successfully reprocessed for every two used catheters that arrive at the remanufacturing facility. In comparison, medical device remanufacturers AMDR and Innovative Health confirmed that a 15% rejection rate more accurately reflects the current state of EP catheter remanufacturing in 2021.
3.2.3. Incineration Stage
As with the virgin catheter, we assume that incineration occurs near the healthcare provider and therefore exclude transportation to the waste management facility (see
Section 3.1).
3.2.4. Sterilisation and Packaging Stages
The gas sterilisation and packaging processes are assumed to be exactly the same as for a virgin single-use catheter (see
Section 3.1.2).
3.2.5. Use Stage
According to NHS regulations [
14], medical device remanufacturing must return a used catheter to its original state to classify it as a remanufactured single-use device. Consequently, we may assume that the use stage of a fully remanufactured catheter is the same as that of a virgin manufactured catheter (see
Section 3.1.4).
5. Discussion
Our extensive emission result analysis found that remanufacturing catheters reduces burden-free climate emissions by 60%.
Figure 10a compares our burden-free results
and
kg
eq (
Section 4.1) against the
Fraunhofer case study [
10]. The case study reports
and
kg
eq, representing a 50% emission reduction through remanufacturing. Even though the total emissions were slightly higher than what our models produced, we consider the results validated as the total and most category emissions follow the same trends. Furthermore, the discrepancies can be explained with the primary data updates we made, such as the lower-impact virgin plastic processing (replacement materials), lower remanufacturing waste emissions (reduced rejection rate) and the increased remanufacturing transport emissions (doubled transport rather than one round trip). Readers are referred to
Section 3 for details and justifications.
Emission metrics. However, burden-free results do not necessarily accurately reflect the realistic emissions.
Figure 10b visualises how the total emissions may change depending on the selected metric. For a fair comparison, all remanufactured emissions are calculated for the same scenario (
,
and
USA). Our proposed metric
comes the closest to accurately reflecting the real-world emissions, as it takes the
previous lives (burdened) and
long-term use of catheters into account. For the chosen Bad scenario, remanufacturing reduces climate emissions by 47% burden-free, 19% burdened, and 26% long-term, respectively.
Sensitivity analysis. Of course, these results may improve dramatically when the remanufacturing process is optimised. One of the main insights of our extensive sensitivity analysis (
Section 4.2) is the significant impact even relatively minor changes may have on the absolute and cumulative remanufacturing emissions. Higher remanufacturing efficiency (e.g., quality rejection rate, number of turns, location) may significantly reduce climate impact. In our best-case scenario, remanufacturing reduced climate emissions by 71% burden-free, 57% burdened, and 52% long-term, respectively.
Result uncertainty. Because Life Cycle Analysis (LCA) results are calculated from a model of the real-world product, LCA climate emissions should be considered as estimates. The uncertainty of the results may be categorised into three groups:
model,
scenario, and
parameter uncertainty [
44]. Throughout our study, we have attempted to address these concerns and improve the reliability of our results. Model uncertainty comes from the structure of the emission-calculating models themselves. We have addressed this by choosing highly-regarded software and background datasets openLCA and Ecoinvent v3.0. On the other hand, scenario uncertainty describes uncertainty introduced through LCA methodological choices such as the functional unit and system boundary. To minimise the introduced uncertainty, we have followed industry standards (e.g., ISO [
12] and NHS guidelines [
13,
14]). Finally, to address parameter uncertainty (i.e., data uncertainty), we have conducted a qualitative analysis of the data quality and included a comprehensive sensitivity analysis of high-impact life cycle parameters.
Versatility. Note that the systematic evaluation of virgin and remanufactured electrophysiology catheter emissions and the proposed long-term emission metric are versatile and not limited to electrophysiology catheters. In future, a similar approach could be taken to evaluate the life cycle emissions of other high-waste medical devices, as well as for circular economy approaches other than remanufacturing (e.g., recycling).
6. Related Work
As substantial individual contributors to environmental impacts, healthcare organisations and regulatory bodies worldwide have been investing in circular economy solutions [
4,
35,
36]. Compared to the current reliance on a linear, take-make-dispose model, a circular economy is defined by its principles to redesign, reduce, recover, recycle, and reuse (5R’s) resources to significantly extend their life before disposal [
45]. Remanufacturing is a promising technique which resets a used device to a “substantially equivalent” state as when it was first manufactured [
8,
9]. This approach is particularly impactful for single-use medical devices, which contribute significantly to the 590,000 tonnes of healthcare waste produced annually in England alone [
2] and have similar statistics globally. Regulated remanufacturing processes allow the devices to be legally reused, reducing both the consumption of rare raw resources and minimising the need for emission-heavy waste disposal treatments (e.g., incineration) [
46].
Apart from the environmental and financial benefits of a more circular single-use device economy, remanufacturing also has the potential to make expensive, multi-use medical devices more available to developing countries [
47]. By prolonging their life, devices discarded due to the fast-paced, technology-driven turnover in high-income countries may be repurposed. Multiple studies have argued that the required initial investment to ramp up remanufacturing capabilities would be offset quickly as the devices are safely reused [
48,
49].
To make the required sustainable procurement decisions throughout a product value chain, decision makers need access to realistic, quantified climate impacts [
50]. Life Cycle Analysis (LCA) has been widely recognised as an effective tool to support sustainable decision-making by systematically evaluating a product system’s potential impacts over its entire life [
11]. Climate impact (also GHG emissions or carbon footprint) measured in kg
eq tends to be the most popular emission metric [
19,
51], presumably due to its widespread use across public, industry, and legislative communication around climate change. However, LCAs may be used to give a broad overview of multiple environmental factors instead, which may avoid over-optimising a particular indicator [
52]. The LCA modelling may have different purposes within the scope of sustainability: (i) To compare the impact efficiency of healthcare practices (e.g., healthcare waste management approaches [
53]), (ii) to inform product design (e.g., comparing single-use medical devices containing biopolymers vs. plastic equivalents [
54], and (iii) to inform procurement decisions (e.g., single-use vs. reusable bronchoscopes [
55]). Furthermore, called a Comparative LCA, such analysis may provide a robust and transparent comparison of two or more products [
56].
However, a significant limitation of LCAs is that they rely on a core, approximated model of a real-world product system [
57]. Therefore, the quality of the environmental impact measurements is subject to the quality of the representative model, which describes all material inputs and outputs that contribute to or stem from the product or service [
58]. This inherent challenge to the modelling process means that LCA models are very time-consuming and expensive to construct, often requiring long periods of extensive data collection throughout a product’s life cycle. The consequence is that few studies have been carried out on complex product systems. Popular healthcare candidates tend to be simple with relatively few components, for example, face masks [
59], surgical scissors [
60], and staplers [
61], to name a few. In contrast, electrical medical devices are rarely featured (e.g., bronchoscopes [
55]). Especially in the healthcare domain, proprietary design and materials in key components may make the data collection and LCA modelling process more complicated than usual.
In cases where product life cycle data is unavailable, assumptions and simplifications have to be made. Because LCAs may be highly sensitive to such choices as well as other modelling decisions (e.g., system boundary, reference unit, allocation strategy) [
62,
63,
64], recent years have seen an attempt to standardise LCA analysis through modelling standards (e.g., ISO regulations [
12,
28]) and reporting guidelines (e.g., NHS GHG accounting [
13,
14]). Consequently, current studies tend to include a report of the assumptions made [
21,
65,
66] and a sensitivity analysis of key life cycle parameters [
67,
68,
69]. The aim is to give the results and their interpretation a clear context and provide a measure of the uncertainty.
Given the uncertainty of LCA estimations and their importance in supporting significant shifts in sustainable medical device procurement, it is not unreasonable to expect studies to be frequently validated to ensure that the results are accurate. However, LCA result validation is rare because comparing absolute environmental impact results across studies is difficult even when common guidelines are followed [
70]. This is because the mentioned industry standards propose best practices in broad strokes but leave many details to the study designers, which may drastically influence the results. For example, there is currently no one-size-fits-all solution for incorporating circular life cycles in LCA models, nor a hard-and-fast rule for which life cycle parameters to consider when calculating long vs. short-term emissions. When validation is attempted, it often results in major impact discrepancies (e.g., −270–570% variation in a validation of 13 plastic recycling studies [
71]).
The challenges with LCA emission modelling illustrated above also apply to electrophysiology catheters, the medical device examined in this article. As a traditionally single-use medical device with significant rare-resource material components, they are a promising candidate for remanufacturing. To the best of our knowledge, only a handful of studies have assessed their environmental impacts, which we discuss in the following.
In a recent study, Leung et al. found that circular mapping catheters could be remanufactured to their original functionality and efficiently reused in healthcare centres without complications [
17]. According to their calculations, over £30,000 were saved across only 100 procedures. They estimate that up to £1.7 m may be saved annually in the UK if half of all circular mapping catheter procedures (5000–10,000) were carried out with remanufactured catheters instead. The paper concludes that catheter remanufacturing is a highly cost-efficient process that may be implemented without compromising patient safety. Additionally, Ditac et al. modelled the carbon footprint of atrial fibrillation catheter ablation procedures from catheter production to surgery, covering all processes carried out in the operating room [
19]. The authors found that catheters contributed almost 40% of total Greenhouse Gas (GHG) emissions during the procedure, 26% of emissions came from the anaesthesia and other pharmaceutical drugs, and the remaining 34% were emitted by other disposable materials during surgery. Since more than a third of ablation GHG emissions are released during material mining and catheter production, the results suggest that catheter remanufacturing could potentially significantly reduce their environmental impact.
A survey of 278 physicians from 42 European healthcare centres revealed a high motivation to reduce the environmental impact of EP procedures (62% of responses) [
18]. However, Boussuge-Roze et al. report that only 15% of catheters are remanufactured and identify multiple barriers that must be addressed before the process can become more widespread. These are mainly at an institutional, processing, and regulatory level and highlight the need for a collaborative approach between healthcare, industry, and legislation. Schulte et al. provide an incentive for catheter remanufacturing by quantifying the emission reductions with a comparative LCA analysis of virgin manufactured and remanufactured single-use electrophysiology catheters [
10]. They find that remanufacturing reduces GHG emissions by 51% per turn when classifying the used catheter at the start of the remanufacturing process as burden-free (i.e., not considering previous lives). They also include a circularity metric to take multiple remanufactured catheter lives into account, which can be critical to interpret LCA results accurately [
72].
Even with widely-accepted standards for LCA analysis in place, LCA methodology for healthcare faces open questions. Significant challenges include (i) how to address data unavailability (e.g., due to proprietary materials and processes), (ii) how to address the consequent uncertainty, and (iii) how to translate the absolute LCA emission results into actionable insights for industry and healthcare practitioners. To address these points in our comprehensive study of electrophysiology catheters, we validate a case study from the literature, conduct an extensive results analysis including a sensitivity analysis of key parameters, and propose a novel metric that calculates realistic emissions by taking long-term use statistics of the device into account.
7. Conclusions
In this article, we carried out a comprehensive analysis of the climate impact and carbon emissions of virgin manufactured and remanufactured electrophysiology catheters, validating and expanding on a previous case study by the prestigious Fraunhofer Institute with a holistic sensitivity analysis and long-term emission analysis. Our emission framework is based on Life Cycle Analysis (LCA) models.
According to our models, remanufacturing catheters achieved 60% burden-free per turn emission reductions (1.53 to 0.61 kg eq). However, our results have shown that burden-free results do not necessarily reflect real-world emissions. Therefore, we have included a range of emission metrics, including a novel long-term emission metric. When taking a remanufactured catheter’s previous lives into account, the emission reduction drops slightly to 57% burdened per life reductions (−0.87 kg eq). Including long-term remanufacturing use statistics changes the results to up to 48% cumulative reductions (−0.73 kg eq).
Our comprehensive results analysis concluded in three primary insights:
- (i)
Remanufacturing is a promising circular economy approach to reduce the climate impact of single-use electrophysiology catheters.
- (ii)
Sensitivity analysis has shown that parameters across the product chain may have major impacts on environmental emissions (e.g., up to 66% reduction with an improved remanufacturing rejection rate). Therefore, our study encourages a collaborative approach to remanufacturing by all actors throughout the value chain.
- (iii)
Furthermore, finally, the distinction between burden-free (no previous lives) and burdened emissions (taking previous lives into account) is necessary to fully understand how emissions may be attributed to catheter turns over its entire life. Additionally, long-term use statistics should be incorporated into the emission metrics for more accurate results.
In future, we would like to expand our LCA models by removing the need for simplified assumptions that we had to make due to data availability. Additionally, since our proposed emissions framework is device-agnostic, it would be beneficial to analyse the emissions of other high-waste medical devices to inform the developing circular economy and net zero goal in healthcare.