The Greenhouse Gas Emissions Associated With Cardiothoracic Surgery

The impact of climate change on health is increasingly recognized as a major public health determinant, with the World Health Organization estimating that climate change may result in an excess of 250,000 deaths per year and could ultimately account for 8 million deaths worldwide.¹ Several studies within cardiothoracic surgery have found a deleterious effect of climate change and air pollution on patient outcomes, demonstrating the profound impact on cardiorespiratory health.² As a whole, health care is one of the major contributors to greenhouse gas (GHG) emissions across the globe, accounting for 4% to 10% of total emissions.¹ Within the health care system, surgical services are particularly resource intensive, accounting for 20% to 30% of hospital waste with waste streams that are particularly difficult to manage and environmentally harmful, largely owing to the requirements surrounding biologic wastes.³ Many systems have made a pledge with the Biden administration to reduce GHG emissions by 50% by 2030. Columbia University has pledged to reach net-zero emissions by 2050 across all of its New York campuses. As such, the issue of carbon emissions in health care has become the subject of increasing academic effort to raise awareness and to quantify emissions across the surgical specialties, although to date, literature in the field of cardiothoracic surgery is scarce. We aim to review the current status of research on GHG emissions associated with cardiothoracic surgery to highlight the current state of the field and avenues for future investigation.

Operative Emissions

As of this writing, the number of studies specifically examining the carbon emissions associated with cardiothoracic surgical procedures is limited. These studies take the form of a life cycle assessment, which is a standardized way of assessing the total emissions associated with a procedure or process. This includes all of the manufactured elements, the anesthetic gases, and the disposables and the energy utilization for that procedure, which can then be reported in kilograms of CO₂ or CO₂ equivalents (Figure). Grinberg and coworkers⁴ performed an analysis of GHG emissions associated with conventional cardiac procedures performed at a single center in France. They reviewed a total of 28 procedures including aortic valve replacements (n = 2), mitral valve replacements (n = 3), mitral valve repair (n = 8), and coronary artery bypass grafting (n = 8). They reported that an individual cardiac procedure was responsible for 124.3 kg of CO₂ emissions or roughly 10 times the average daily consumption of a French individual. In their analysis, disposables accounted for 86% of the carbon footprint associated with the procedures, and the cardiopulmonary bypass circuit accounted for 50% of that waste. Hubert and colleagues⁵ performed an analysis of the carbon emissions during elective coronary artery bypass grafting at a single US center. They estimated a total of 505.1 kg of CO₂ emitted per case, which is 4 times greater than the emissions reported in the French study. They also identified single-use items, particularly plastics, as the leading contributor to the procedural emissions. Of note, whereas transcatheter therapies have taken on an increasing role in the management of cardiothoracic disease, there has not been an investigation into the GHG emissions associated with these procedures. Ditac and colleagues⁶ performed an analysis of GHG emissions associated with catheter ablation for atrial fibrillation and reported a mean of 76.9 kg of CO₂ emissions per procedure. This is just 61% of the emissions associated with open surgical procedures performed in the same country as reported by Grinberg and coworkers. Although there is reason to believe that transcatheter therapies in general will be associated with decreased emissions, this is yet to be demonstrated in the literature. As of this writing, there have been no investigations into the GHG emissions associated specifically with thoracic surgery procedures.

Figure.

Elements that can be included in a life cycle assessment of a cardiothoracic surgery procedure. (CT, computed tomography; Echo, echocardiography; HVAC, heating, ventilation, and air conditioning; MRI, magnetic resonance imaging.)

We would be remiss not to first mention the work of the field of anesthesia as a whole, which has largely been leading the way on sustainability initiatives. Early work in the field highlighted the large contribution of anesthetic agents to GHG emissions.⁷ After this was identified, there was tremendous effort made to further understand the environmental impact of anesthetic gases and means of eliminating or minimizing this impact. Many anesthesia departments and health systems have incorporated the responsible use of anesthetic agents into their sustainability efforts, and this has led to the adoption of anesthetic strategies that benefit not only the environment but also patients.⁷ The surgical community must partner with anesthesia colleagues to promote these initiatives and to reinforce the need for sustainability initiatives within the operating theater.

Emissions from the Intensive Care Setting

Among the surgical subspecialties, cardiothoracic surgery is unique in that many of the patients require monitoring in the intensive care unit (ICU) in the immediate postoperative period. Such being the case, the emissions associated with intensive care warrant review. There are currently no publications into the specific emissions related to cardiothoracic surgery patients in the ICU. McGain and coworkers⁸ performed an analysis of the emissions associated with ICU care for the treatment of septic shock in a US and an Australian center. The average energy use in the US center was 272 kWh/d compared with 143 kWh/d in the Australian center, whereas the mean daily CO₂ emissions were 178 kg of CO₂ in the US center and 88 kg of CO₂ in the Australian center. Of note, both centers produced the same amount of average daily single-use waste—3.4 kg. All told, the daily treatment of septic shock in a US center was equivalent to the daily carbon footprint of 3.5 Americans, whereas the Australian center was equivalent to 1.5 Australians. Ghersin and coworkers investigated the unused medical waste in a single-center pediatric ICU in the United States, collecting 76 kg (167.5 pounds) of unused or opened materials in a 3-week period.⁹ Although they do not report the emissions associated with this waste, they did report the cost of unused disposed items to range from $1.02 for rigid suction catheters to as much as $500 for custom tracheostomy tubes.

Conclusions and Future Directions

This review of the environmental impact is meant to highlight the current state of the field but also to reinforce the need for further research into this field. Indeed, there is more that is unknown than known, and further data acquisition will be critical to informing any policy change. Furthermore, the breadth of this area of inquiry is expansive and could ultimately include regional differences in grid sustainability, energy utilization, and transportation-related emissions. The environmental impact of cardiothoracic surgical care, and health care more generally, can be reduced in ways that ultimately improve clinical care and the national health. Whereas more investigation is key, there are certain sustainability initiatives that have already begun to gain traction within the medical community with direct bearing on cardiothoracic surgery.

As noted before, disposable medical supplies represent a large proportion of the emissions associated with cardiothoracic surgical procedures.^4,5 A proportion of this waste is from materials packaging, which can be reduced without having an impact on patient outcomes. Packaging, however, represents only a fraction of the total waste from disposable medical supplies. Most of these supplies are made of plastics. Whereas future work could be aimed at the use of materials with a lower environmental cost, current efforts could be targeted at reducing the relatively low hanging fruit that is the high rate of disposal of unused materials. Cardiothoracic surgeons are also well positioned to work with hospital administration and medical suppliers to minimize this waste. Minimizing plastic waste is an important first step toward reducing the reliance on fossil fuels, which is another important target for the health care system. A second avenue of potential high impact would be improved efficiency in the segregation of medical waste and the optimization of recycling pathways, both of which have been shown to be suboptimal.¹⁰

Telehealth has also come to take on an increasingly prominent role in medical and surgical care, largely as a result of the COVID-19 pandemic. Telehealth offers many proposed benefits to patients, including reduced cost and increased access, and the use of telehealth for surgical patients can reduce the carbon emissions of preoperative and postoperative surgical care.

Physicians are uniquely positioned to lead the charge for a sustainable health care system. They should investigate the current programs underway at their own institutions and urge them to join the Biden administration’s Health Sector Climate Pledge if they have not done so and becoming a champion of sustainable initiatives in their own health care system and departments. This can include seeking out organizations, such as Practice Greenhealth, that have a proven track record of supporting initiatives such as “greening the operating room.” Physicians can further the cause by focusing academic pursuits to better quantifying their own practice’s contributions to waste and developing initiatives in their own hospital systems to mitigate this waste. This also represents an important opportunity for the next generation of clinicians to incorporate sustainability into their practice and as part of any academic, policy, or administrative efforts. Opportunities for this type of work will likely expand as the recently passed Inflation Reduction Act provides for billions in investments toward reducing the national carbon footprint.

Ultimately, this review highlights the lack of studies investigating the climate impact of cardiothoracic surgery in the operative and postoperative setting as well as the need for such studies. Whereas carbon emissions should not be the deciding factor in the treatment strategy for individual patients, one can imagine the relative emissions will play a role in the future when deciding between differing treatment options. Data acquisition, analysis, and provider education will be critical to informing this decision-making process. Just as cardiothoracic surgeons in the past have been leaders in tremendous advancements in the treatment of patients with cardiovascular and thoracic disease, they now have the opportunity to lead the way in addressing climate change, one of the next great threats to patients and providers alike.