A Standardized Method for Estimating the Carbon Footprint of Disposable Minimally Invasive Surgical Devices

Supplemental Digital Content is available in the text.

Abstract

Objective:

To propose a standardized methodology for estimating the embodied carbon footprint (CF) of disposable minimally-invasive surgical devices (MISDs) and their application in new benign prostatic hyperplasia (BPH) MISDs.

Summary of Background Data:

The estimation of the CO_2e emissions of disposable surgical devices is central to empowering the healthcare supply chain.

Methods:

The proposed methodology relied on a partial product lifecycle assessment and was restricted to a specific part of scope 3, which comprised the manufacturing of surgical device- and non–device-associated products (NDAPs), including packaging and user manual. The process-sum inventory method was used, which involves collecting data on all the component processes underpinning disposable MISDs. The seven latest disposable MISDs used worldwide for transurethral prostatic surgery were dismantled, and each piece was categorized, sorted into the appropriate raw material group, and weighed. The CF was estimated according to the following formula: activity data (weight of raw material) × emission factors of the corresponding raw material (kg CO_2e/kg).

Results:

The total weights of disposable packaging and user manuals ranged from 0.062 to 1.013 kg. Plastic was the most common and least emissive raw material (2.38 kg CO_2e/kg) identified. The estimated embodied CF of MISDs ranged from 0.07 to 3.3 kg CO_2e, of which 9% to 86% was attributed to NDAPs.

Conclusions:

This study described a simple and independent calculation method for estimating the embodied CF of MISDs. Using this method, our results showed a wide discrepancy in the estimated CO₂ emissions of the most recent disposable MISDs for transurethral BPH surgery. Thus, the lack of CF information should be of major concern in the development of future MISDs.

INTRODUCTION

Global warming has been gaining increasing attention and significance worldwide,¹ as climate change is becoming the greatest existential challenge of the 21st century.² Among all industries, the healthcare sector contributes considerably to global warming, accounting for 4.4% of the annual human-induced CO₂ net emissions.³ As such, surgical activities using massive amounts of energy and complex equipment, including innovative technologies, with their high carbon footprint (CF), are potential causes of global warming. However, until now, the impact of surgical activities on potential climate change has remained poorly investigated.⁴

Surgery has always been a playground for healthcare innovations.⁵ In this worthy pursuit of caregiving excellence, it has not been surprising to see a surge in minimally invasive treatment options in recent years. Therefore, operating rooms (ORs) are seeing the arrival of a plethora of novel disposable surgical devices. In urology, this technological boom has resulted in a growing list of disposable endoluminal scopes and surgical devices.

These disposable minimally-invasive surgical devices (MISDs), often made from nonbiodegradable materials (plastics, silicone, and various metals), have tended to lead to a throw-away culture in daily surgical practice that may be liable for the negative impacts on the environment.⁶ MISDs have recently been recognized as a major carbon hotspot.⁷ Unfortunately, the literature on this topic remains scarce, and the reported CF calculation methods are either country-specific or subject to uncertainty. In addition, transparent lifecycle assessment (LCA) data are not provided by manufacturers.

Obviously, knowing the CO₂ emissions of MISDs would help to improve our awareness and change our practices. Hence, heeding to our professional responsibility, we found it necessary to develop a reliable estimation method for the CF of disposable MISDs⁸ to provide evidence for consumers (both surgeons and patients). Moreover, while the subject is not yet considered by manufacturers, it seems essential that it is directly brought to the very heart of production and consumption considerations by surgeons.

The estimation of the CF of benign prostatic hyperplasia (BPH) surgery is important as it is one of the most common procedures performed worldwide in urology. Although available data on the use of each different MISDs per year and per country remain scarce, recent evidence supports an important shift in terms of surgical techniques, from reusable and simple instruments to single-use high-tech devices.^9–11

In the present study, we aimed to propose a standardized and simple methodology for estimating the embodied CF of disposable MISDs in a restricted cradle-to-gate focus. We sought to apply the process-sum inventory method to the most recent transurethral disposable MISDs used for treating BPH.¹²

METHODS

CF evaluation is based on the principles set forth by the ISO 14064 standard. The ISO (international organization for standardization) 14064 standard is part of the ISO 14000 series of International Standards for environmental management and provides a complementary set of tools for programs to quantify, monitor, report, and verify greenhouse gas (GHG) emissions. The methodologies applied in this study comply with this standard and are compatible with Greenhouse Gas Protocol guidance (https://ghgprotocol.org/Third-Party-Databases/Bilan-Carbone). CF is estimated based on GHG emissions, also referred to as CO₂ equivalent (CO_2e) emissions, as carbon dioxide comprises 80% of GHG emissions. To help delineate direct and indirect emission sources, improve transparency, and provide utility for different types of organizations and different types of climate policies and business goals, 3 “scopes” (scope 1, scope 2, and scope 3) are defined for GHG accounting and reporting purposes. The ISO 14064 standard categorizes GHG emissions into 3 separate scopes:

• Scope 1: Direct GHG emissions come from sources that are owned or controlled (direct emissions from stationary combustion, mobile combustion, direct process-related emissions, and direct fugitive emissions [leaks and other irregular releases of gases or vapors from a pressurized containment]).

• Scope 2: Indirect energy GHG emissions are those that come from the consumption of imported electricity and from consumed energy imported through a physical network (steam, heating, cooling, and compressed air).

• Scope 3: Other indirect GHG emissions are consequences of the activities of organizations, such as purchased products, capital equipment, waste generated from organizational activities, upstream transport, upstream leased assets, patient and healthcare worker transports, downstream transport, the use phase of the product, and the lifecycle of the product.

The different scopes help researchers assessing CF to understand more completely the total impact of a specific aspect of operations of a business or institution.¹³ Some are easier to measure than others, but for completeness in an ideal world, all 3 should be considered when possible.

Study Scope

The proposed methodology relied on a partial product LCA: a cradle-to-gate scenario from resource extraction to the factory gate.¹⁴ Thus, the focus of the study was restricted to a specific part of scope 3—the manufacturing of surgical devices, their packaging and their user manuals. This specific scope is the most reliable and easiest to use in the assessment of the worldwide external applicability of MISDs, as it does not consider the CO₂ emissions of the shipment, energy consumption (especially during use), and the lifecycle retreatment process (to ultimate disposal) of each device.

According to the Intergovernmental Panel on Climate Change, GHG emissions are expressed as a single unit: kg CO₂ equivalent (kg CO_2e), which represents the CF.

CF Estimation

To highlight the different factors that can impact the CF of disposable MISDs in this previously defined scope, we decided to split the analysis into 2 parts, as shown in the flow diagram (Fig. 1): an analysis on the device itself and that on non–device-associated products (NDAPs) comprised of packaging and user manuals. The embodied CF was defined by the CF from the device itself plus the CF from the NDAPs.

FIGURE 1.

Study protocol to assess the embodied carbon footprint of according to the scope of interest.

Analyses were performed by an independent laboratory (Sustainable Metrics) member of a network of independent accounting, audit, and consulting firms (https://www.crowe.com/fr/sustainable-metrics).

The process-sum inventory method was used, which involves collecting data on all the component processes underpinning the disposable MISDs of interest. GHG emissions were estimated according to the following formula:

CF estimation = GHG emissions = activity data × emission factors. The CF, or GHG emissions, is expressed in kg or g CO_2e.

The accuracy of CF estimation depended on the accuracy of 2 variables: activity data and emission factors.

Activity data are a quantitative measure of activity that results in GHG emissions. We defined activity data as the sum of the component parts inventoried in a manufactured MISD with its packaging and user manual. Thus, all devices were dismantled, and each piece was categorized and sorted into the appropriate raw material group based on human observation by 2 separate engineers; finally, each piece was weighed (in g or kg) with an analytical balance. The printed circuit board and liquids were measured in square meters (m²) and milliliters (mL), respectively. The percentage of each raw material was listed for each device based on the LCA methodology, as outlined by the ISO.¹⁵

An emission factor is a coefficient that allows for the conversion of activity data into GHG emissions. Emission factors include the extraction/production and transportation of every raw material and are directly given in kg CO_2e/kg. Emission factors are determined on a lifecycle basis; they were sourced from a public database (Base Carbone) as is required for carrying out carbon accounting analysis. This detailed free-access public database is administered by the French Environment and Energy Management Agency under the supervision of the Ministries of Research and Innovation, Ecological and Solidarity Transition and Higher Education. Examples of the emission factors of the most common raw materials are listed in Supplemental Figure 1, http://links.lww.com/AOSO/A57.

Selection of Surgical Devices

In recent decades, novel MISDs have emerged in the armamentarium of BPH surgery.¹⁶ For the purposes of this study, the most recent disposable MISDs were chosen (Supplemental Figure 2 in the Supplementary Materials, http://links.lww.com/AOSO/A58):

• The bipolar loop: a system that uses a bipolar electric current generator to cut off small pieces of prostatic tissue.¹⁷

• The Greenlight 180-W MoXy fiber is used for the photovaporization of the prostate.¹⁸

• The holmium laser fiber and a morcellating blade (Piranha, Richard Wolf) are used for holmium enucleation of the prostate (HoLEP). The pulsed energy of a laser fiber is used for the enucleation of the adenoma, which is morcellated mechanically.¹⁹

• The prostatic urethral lift (UroLift) uses permanent implant nitinol anchors, connected with a nonabsorbable suture, to retract obstructing lobes. The device consists of a hand-held pistol grip to which a needle-shaped probe is attached. One pistol delivers only 1 implant, and at least 4 implants are necessary for 1 procedure.²⁰

• The convective water vapor treatment (Rezūm) uses water vapor thermal energy. Steam is injected into the prostate tissue, leading to necrosis with a disposable handpiece.¹⁶

• The temporary implantable nitinol device (iTIND) is a self-expandable nitinol temporary stent.¹⁶ Three elongated struts release outward pressure toward the prostatic tissue to induce prostatic tissue necrosis by ischemic pressure, leading to prostate reshaping and thus eliminating the prostatic obstruction.

• The Aquablation robotic handpiece (Aquabeam) is used in an image-guided robot-assisted semiautonomous procedure that uses a high-pressure saline jet stream to remove prostatic tissue.²¹

RESULTS

Raw Material Acquisition and Weights of Each Devices

The weights and material proportions between devices were widely heterogeneous. Disposable weights ranged from 3 to 584 g. The raw material analysis comprised plastic, steel, electronics, nylon, aluminum, copper, and nickel in various proportions (Fig. 2). Plastic was the most common material identified in all devices.

FIGURE 2.

Assessment of carbon footprint per device (grCO_2e) without packaging and user manual according to the weight of raw material. For each device, the weight of each raw material is represented. The yellow line shows the CO_2e emissions (grCO_2e) for each device. *Urolift raw material composition is presented for a single pistol/implant. HDPE indicates high-density polyethylene; LDPE, low density poly-ethylene; PS, polystyrene; PVC, polyvinyl chloride.

CO_2e Estimation of Each Device Without NDAP

In Figure 2, devices are ranked from highest to the lowest in terms of their CFs. Among the 2 heaviest-weighted devices, Rezūm was the most CO_2e-emissive device (2288 grCO_2e) due to the multiplicity of its components: electronics, electrical cable, and plastic.

Despite its technical simplicity, the disposable plasma loop was found to have the third highest CF (1204 grCO_2e) due to the manufacturing of cables designed to support a high electric amperage.

The greenlight laser fiber (387 grCO_2e) and single-staple Urolift system (545 grCO_2e) were estimated to have less CO_2e emissions from different sources (laser fiber for the first and mostly plastic for the second). Of note, from a surgical point of view, all the results from Urolift should be multiplied by 4, as, on average, at least 4 devices are used for 1 procedure.

The lowest use of raw materials was found for the iTind and HoLEP devices, which were also found to have the lowest estimated CO_2e value (11 and 69 grCO_2e, respectively) compared with the other devices. Nevertheless, we cannot conclude that the device’s weight is directly correlated to its CF, the type of raw material can impact much more than the weight as shown with the Plasma device.

Embodied CF Estimation of MISDs

To obtain an embodied CF estimation from the defined scope of each device, we added the CO_2e of their user manuals and packaging to the CO_2e estimation of the device itself in the estimation.

The weight of user manuals and consequently the CO_2e emission originating from them varied across devices and was higher for Aquabeam, Urolift (assuming the use of 4 implants) and Rezūm systems (Supplemental Table 1, http://links.lww.com/AOSO/A59). Packaging comprised mainly plastic and cardboard and accounted for more than 50% of the embodied CF for iTind (86%) and HoLEP (71%) (Fig. 3).

FIGURE 3.

Embodied carbon footprint including the CO_2e emission of non–device-associated products in the MISD. Percentage of manufacturing, packaging, and user manual on total embodied carbon footprint are included for each device. The embodied CF emissions are shown in bold numerical values on the top of each histogram bar and are expressed in grCO_2e. *Urolift CF is presented for a single pistol/implant.

Plasma loop, Greenlight, and Rezum were found to have the highest CO_2e emissions attributed to device manufacturing with respectively 91%, 72%, and 69% of the embodied CF.

Overall, the iTIND and HoLEP devices were found to have the lowest embodied CF, with 76 and 235 g of CO_2e, respectively (Fig. 3 and Supplemental Table 1 in Supplementary Materials, http://links.lww.com/AOSO/A59).

DISCUSSION

The CF is an important and timely factor to investigate in the healthcare sector due to the growing concern of global warming. The increased use of disposable MISDs in recent years will necessarily increase the environmental impact and CF of our healthcare practices.^6,9,22

In the present study, we described a simple and reliable method for estimating the embodied CF of MISDs within their application in transurethral BPH surgery. Based on the raw material inventory combined with specific emission factors, this method could be applied to any disposable MISD to provide independent CO_2e estimation and should be investigated by manufacturers to provide more information regarding their medical devices.

More specifically, we found that the embodied CFs of disposable MISDs used to treat BPH ranged from 0.07 to 3.3 kg CO_2e, with the largest value being equivalent to driving up to 15 km in an average petrol car (https://ecoscore.be/en/info/ecoscore/co2). This result reflected our cradle-to-gate-specific scope, defined without even taking into account the portion from shipment and the total CF of the surgical use of these devices (including electricity consumption in the OR, other devices needed for the procedure and the anesthetic portion).

In ORs, the major consumer carbon emission hotspots are the energy used (electricity, gas, etc) and equipment/furniture.²³ Nevertheless, some studies have identified that disposable MISDs are of utmost concern in surgery.⁷ Herein, we highlighted a wide discrepancy in the global warming potential of the disposable MISDs used by urologists for the surgical management of BPH.

Although our estimation did not take into account the whole LCA (including the three scopes defined by the ISO 14064 standard), we showed the embodied CF mainly relies on the use of electric cables and electronics but plastic remains also one of the biggest contributors of the embodied CF (Fig. 2).

This finding can set the basis for an energy label from the most to least efficient disposable surgical product.

However, this study should not be considered an argument against innovative technologies. By understanding the negative effect that disposables pose, environmentally aware companies are emerging that reprocess single-use items; test them for safety, cleanliness, and performance; and then recycle them back into ORs for use.²⁴ Unfortunately, none of these MISDs devices for BPH surgery have been proposed for recycling.

The assessment of the CF has no impact if we are unable to consider the perspective of its reduction. The Paris Agreement has set the limit for the rise in global temperature at “well below 2 °C” by 2100. Moreover, the Intergovernmental Panel on Climate Change has affirmed that keeping global warming below 1.5 °C will require a reduction in GHG emissions of 70% to 80% by the second half of the century.

This overarching global objective as applied to our study should lead to a significant decrease in the CF, which will not be feasible without a relevant reduction roadmap.²⁵ The first main initiative will be to build a process of transparency of information and data sharing, particularly between users and manufacturers, to measure environmental impact with greater precision and reliability. The other initiative that could result in a rapid reduction in the CF should be reducing the quantity of materials and packaging, finding low-carbon substitution materials, developing reuse and recycling possibilities. Minimizing the material used and selecting reusable surgical instruments can mitigate emissions: from a 50% (with anesthetics included) to 70% (without anesthetics included) reduction per case.²⁶

Among the limitations of this study, the scope of this analysis was restricted to the embodied CF of each device. Scopes 1 and 2 and a part of the scope 3 described by the ISO 14064 standard were not estimated in this study.

Indeed, we did not estimate all production processes and shipments represented by energy consumption, generated waste, ancillary products, emissions to soil, etc. For now, these data are not available from respective companies and are different according to shipment destination or factory location. Therefore, this study stresses the need for the evaluation of the CF related to the entire production chain of devices. Thus, an effort toward transparency from companies is urgently needed to help us propose a complete overview of the CF of MISDs, from their production to their use in the operating field. Moreover, emission factors were sourced from a national database that might not be accurate for other countries. Therefore, future evaluations using our strategy should use their own country database.

We did not include the usage of devices in our estimation. Indeed, the global CF of surgical procedures can vary in terms of intraoperative time, hospitalization stay, or type of anesthesia. Due to the heterogeneity in terms of anesthesiology protocols, electricity production or hospital stays among countries and centers, this overall estimation was not possible in this study. The other scopes of CF analysis should remain the foundation for future studies in this field. We acknowledge that these variables are of utmost importance and will be evaluated in the next steps of our initiative to provide a better understanding of the environmental impact of surgical procedures. Prospective multicentric evaluations are required to obtain the best reflection of the CF of a certain procedure. Finally, although approximately 400,000 Urolift implants have been delivered worldwide since 2011,²⁷ the lack of data on the use of each MISDs per year and country hindered our study to provide a global CF overview. Nevertheless, the use of MISD in BPH surgery is rising. We expect further increasing usage of MISDs since they have been added to the American Urological Association and European Association of Urology guidelines for the surgical treatment of BPH.

One of the strengths of our study is its objective and streamlined methodology. Our analyses were performed by an independent laboratory and without any financial support, with the singular goal of evaluating environmental impact. The choice to focus only on surgical devices, without considering their production or use, was made to propose an objective and unbiased assessment of the baseline CF of surgical procedures.

We believe that our protocol for the evaluation of the CF of disposable MISDs will be useful for estimating the CF for every specific procedure requiring surgical devices. Hopefully, this study will push manufacturers to implement a standardized assessment of embodied CF for all the devices they produce. Indeed, the estimation of the CF should be performed and integrated into the device characteristics form at the time of application for premarket certification, such as Food and Drug Administration or European certification.

CONCLUSIONS

We described a simple, independent, and reliable methodology for estimating the embodied CF of MISDs. Using this method, we found a wide discrepancy in the estimated embodied CF of the most recent disposable MISDs for transurethral BPH surgery. It is incumbent upon us to foster awareness of the environmental impact of carbon emissions and choose surgical equipment responsibly. There is a need for embodied CF labeling on surgical devices to better inform sustainable surgical purchasing choices. Moreover, this study also highlights the urgent need for recycling programs and other manufacturing/packaging modifications. This could, in turn, result in manufacturing guidelines consistent with environmental expectations to control OR-related carbon emissions.

Supplementary Material

as9-2-e094-s001.pdf ^{(199.6KB, pdf)}

as9-2-e094-s002.pdf ^{(363.4KB, pdf)}

as9-2-e094-s003.pdf ^{(341.5KB, pdf)}

Appendix

This scientific committee is working on behalf of the French Association of Urology (AFU): Armand Chevrot, MD, Department of Urology, Nîmes Hospital, France; Amine Benchikh, MD, Department of Urology, Clinique les Martinets, Versailles, France; Aurelien Descazeaud, MD, PhD, Department of Urology, Limoges Hospital, Limoges, France; Emmanuel Dellanegra, MD, Department of Urology, Côtes d’Armor Hospital, Saint Brieuc, France; Jerome Gas, MD, Department of Urology, Toulouse Hospital, Toulouse, France; Nicolas Barry Delongchamps, MD, PhD, Department of Urology, Cochin Hospital, Paris, France; Hervé Baumert, MD, Department of Urology, Clinique de l’Alma, Paris, France; Marc Fourmarier, MD, Department of Urology, Aix en Provence Hospital, Aix en Provence, France; Sébastien Vincendeau, MD, Department of Urology, Saint Grégoire Hospital, Saint Grégoire, France; Pierre Etienne Théveniaud, MD, Department of Urology, Metz Hospital, Metz, France; Jonas Wilisch, MD, Department of Urology, Natecia Hospital, Lyon, France; Souhil Lebdai, MD, PhD, Department of Urology, Angers Hospital, Angers, France; Steeve Doizi, MD, Department of Urology, Georges Pompidou European Hospital, Paris, France.