Global warming applied to dialysis: Facts and figures

Abstract

Since its establishment in 1988, the Intergovernmental Panel on Climate Change, a United Nations body assessing the science related to climate change, has published several reports warning about global warming and emphasizing the fact that human activities clearly contribute to the observed climate changes. Indeed, in its last 2021 report [1], the panel notes once again that the global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years. The authors also consider that human-induced climate changes account for many of the weather and climate extreme fluctuations that we are experiencing, including heat waves, heavy rain events, floods and droughts. With time, global warming will not only change weather, but will also impact our way of life, affecting all aspects of the economy as well as the global health of populations. For a long time, climate changes have generated little concern among the scientific and medical communities, as suggested by a review of 11 944 climate abstracts from 1991 to 2011 matching the topics ‘global climate change’ or ‘global warming’, although the percentage of publications denying global warming in this review was extremely low [2]. This trend appears to have changed after 2015, as reported in a synthesis of systematic reviews of health impacts of climate change [3]. The collected reviews covered 10 health outcome categories, the three most common being infectious diseases, mortality and respiratory, cardiovascular or neurological outcomes. As mentioned by the authors, ‘most reviews suggested a deleterious impact of climate change on multiple adverse health outcomes, although the majority also called for more research’ [3]. Unexpectedly, healthcare itself represents an environmental burden that contributes to global climate changes. The impact of healthcare systems on the environment is estimated to range between 7% and 10% [4, 5]. Thus if nothing improves with time, at a certain point the fantastic benefits of recent medical developments might be offset by the health risks and the negative economic impacts caused by global warming. Nephrology does not escape from this duality, saving millions of lives through kidney replacement therapies (KRTs) but creating an important burden on the natural environment while running dialysis programmes. As with many other medical specialists, nephrologists are at the forefront of global warming health issues. Clinically they are increasingly exposed to the consequences of elevated temperatures induced by heat waves. Indeed, elevated temperatures can lead to severe dehydration and its consequences and increases in the severity and frequency of heat injuries, causing acute kidney diseases, including the newly defined clinical entity heat stress nephropathy [6]. This latter may actually represent one of the first epidemics due to global warming. In addition, nephrologists performing dialysis are faced with several major ecological challenges in their daily practice, as haemodialysis (HD) is a resource-hungry procedure consuming very high volumes of water (350–500 L of water per dialysis), producing substantial amounts of waste products (1.5–8 kg per dialysis) [7] and using a large amount of energy (∼7 kW per dialysis) [8]. For instance, in the dialysis centre of Lausanne University taking care of 80 HD patients, the 1-year consumption of water was calculated to be equivalent to the content of two Olympic-size swimming pools and 55 tons of wastes were produced [9]. Considering that >3.3 million patients receive KRT worldwide [10, 11], mainly HD (89%), it becomes increasingly urgent to reconsider the ecological impact of HD in all future developments and to implement new strategies to reduce water consumption, increase the availability of recyclable disposables and increase the use of renewable energies. One of the first initiatives to avoid wasting dialysis water came from Morocco, an arid country, where Tarrass et al. [12] demonstrated that HD wastewater could be cost-effectively recycled for irrigation use, such as watering gardens and landscape plantings. Agar (who commented on Tarrass et al.’s paper) [13] has published several papers promoting practical solutions that could be implemented in hospitals and dialysis centres in order to obtain a more ‘environment-friendly’ dialysis, renamed today as green dialysis [11, 14, 15]. Table 1 summarizes some of these suggestions. Today, the increased ecological awareness of the nephrology community as well as of industrial partners involved in the development of HD has resulted in some substantial improvements, mainly in terms of water consumption. For example, in the French NephroCare programme, the replacement of obsolete water treatment systems with more efficient devices enabled them to reduce the proportion of rejected water (from 60% to 20%), and with the introduction of the newest dialysis machines, the average water consumption per