Katherine Barraclough is a Consultant Nephrologist at the Royal Melbourne Hospital, Melbourne, and an Associate Professor of the School of Medicine, University of Melbourne, Australia. Her research focuses on the relationship between human health and the natural environment and pathways to environmentally sustainable healthcare.
Writer: Amy Yau @amyaimei
Amy Yau is a 2nd year nephrology fellow at Mount Sinai Hospital. Her academic interests include hypertension, electrolyte disorders, and home dialysis modalities, and she is attentive to the responsibility that physician educators have as leaders.
Competitors for the Green Nephrology Region
Climate change. Sustainability. Environmentalism. No, we are not having a political discussion this year in NephMadness. In our “wild card” region, Green Nephrology, we discuss the future impact of climate change on kidney health through multi-order effects as well the environmental impact of dialysis.
Over the past 50 years, the mean global temperature has increased by 0.8° C.
Although this may not seem like much, this temperate change is directly accompanied by increased natural disasters, more severe and persistent heat waves and increased water shortages. We can expect more of these to come. This region explores the negative impacts of these changes on kidney health and healthcare delivery.
On the other side of the court, the utilization and disposal of healthcare resources takes a significant toll on our environment. There are an estimated 3.4 million patients worldwide on dialysis according to 2018 Fresenius annual report estimates, indicating a 6% increase from 2017. If we assume all were to receive conventional intermittent hemodialysis three times a week for four hours, this would consume approximately 265.2 billion liters of water, 2.75 billion KWh of power, and generate 1.06 trillion tons of disposable waste! We will delve into what these numbers mean and what we can do about it.
The current resources demanded by our dialysis treatments will become more expensive and less sustainable. A revolution in how we care for our patients is needed. However, it is not all doom and gloom. A green nephrology initiative in the United Kingdom (UK) is already saving approximately £7 million per year from water conservation alone. In 2010, DaVita piloted a solar hot water installation to preheat dialysis water which improved energy efficiency by 20%. As we look to the future, this region can SUSTAIN its momentum deep into the tournament and build a better world.
Climate Change and AKI vs Climate Change and CKD
Climate Change and AKI
The kidney is an amazing organ, helping to maintain internal homeostasis and protecting us from volume depletion and dehydration. Unfortunately, the rise in global temperature and the spate of heat waves can result in increased heat related kidney injuries through electrolyte abnormalities, rhabdomyolysis, and heat induced inflammation.
Rhabdomyolysis injury is related to direct acute tubular injury, while other forms of heat related acute kidney injury are thought to be related to ischemia and oxidative stress. Heat also brings increased incidence of nephrolithiasis. In the southeastern United States (US), there is a 50% higher prevalence of kidney stones than in the northwest, with a mean annual temperature difference of 8°C between the two climates. Poor hydration habits exacerbate hypovolemia, resulting in concentration of stone forming salts and, according to some estimates, by 2050, the US may see an increase of 1.6-2.2 million lifetime urolithiasis cases.
Let’s take a real-world example from a developed country: During a heat wave in July of 1995 in Chicago, there was a 388% increase in admissions for AKI in patients 65 years and older when compared to non-heat wave weeks. Unsurprisingly, discharge diagnoses for fluid and electrolyte disorders, acid/base disturbances, and volume depletion increased as well.
In a Canadian study looking at heat periods from 2005-2012 (defined as “3 consecutive days exceeding the 95th percentile of area-specific maximum temperature”), there were an additional 182 cases per 100,000 person years of AKI during warmer periods, with an odds ratio (OR) of 1.1. This was particularly pronounced in older individuals, and patients on diuretics and/or angiotensin converting enzyme inhibitors/angiotensin receptor blockers. Interestingly, the higher humidex periods (i.e. periods where the temperature felt higher) did not increase the OR. Recorded temperature needed to be higher.
To further emphasize this relationship, we turn to Australia, where maximum temperatures have increased by 0.15° C per decade since 1950, and up to 0.21° C per decade in southern Australia. In Adelaide, Australia, there was a 10% increase in admissions for kidney primary diagnoses during heat waves with incidence rate ratios of 1.13 for individuals aged 15-64 years and 1.22 for patients at least 85 years of age. Proposed causes for the increased risk in the elderly included reduced eGFR, diminished sodium and water conservation leading to dehydration, and impaired thirst sensations.
Beyond direct heat-related injury, there are indirect effects of climate change that predispose individuals to AKI. As temperature warms, some vector borne diseases have an expanded distribution and accelerate their spread of disease, with some models estimating that 260-320 million more people by 2080 will be affected by malaria. In Africa, modelling has suggested a 10-fold increase in mosquito populations with every 0.1° C rise. In some scenarios, the population increase is attributed to mosquitoes feeding and breeding more in warmer temperatures and parasites and viruses completing incubation quicker in the female mosquito. One to five percent of individuals with malaria have AKI, but in severe malaria the incidence can increase to 60%. Another mosquito-borne disease, Dengue fever, is associated with AKI 11%-36% of the time, with a mortality of 9%-25%.
Additionally, rodent-borne diseases and diarrheal outbreaks are predicted to occur more frequently due to increases in extreme weather events such as flooding and increased rainfall. These are also expected to lead to increased AKI in affected regions.
Although these are projections, they frame this weather change in a different lens. All of a sudden, that 0.8° C increase translates into 108 times more mosquitoes, and that thought should certainly wake us up!
Climate Change and CKD
Environmental change has also been associated with CKD. Take, for example, the entity of CKD of unknown origin (CKDu) described in agricultural workers in Central America and similarly in Sri Lanka, India, and Egypt. The cause is likely multifactorial, but heat stress is thought to play a major role.
Because this was first described in young working men in Central America and later in other young men performing similarly strenuous work under hot conditions, it was hypothesized that the CKD resulted from recurrent episodes of AKI due to hypovolemia. When these patients were biopsied, the parenchyma demonstrated chronic tubulointerstitial disease, and some proposed that heat stress and dehydration may lead to acidified concentrated urine causing urate crystallization and tubular damage. Others suggested that the kidney injury may be due to hyperosmolality with activation of the vasopressin and aldose reductase/fructokinase pathway or low-grade rhabdomyolysis. There may be additional contribution from an infectious agent or a toxin from pesticides whose effect is more pronounced due to urinary concentration.
CKDu is highly prevalent in El Salvador followed by Nicaragua and Honduras, with the areas of highest mortality corresponding to the areas of highest average temperature. In El Salvador, kidney failure is now the second leading cause of death among working aged men.In Nicaragua, heat-related AKI increases the risk of CKD at 6 and 12 months:
Risk factors identified in brick layers in Nicaragua included performing increased oven work (ie, heat exposure) and low liquid intake (ie, dehydration). To strengthen the suspicion that access to water, dehydration, and possibly mode of rehydration play a role, poverty-stricken areas with low access to water and higher intake of sodas or other fructose containing drinks had higher incidences of disease.
Just as presumed heat-related AKI events increase the incidence of developing CKD, AKI from the indirect effects of climate change including vector borne illness, water shortages, and kidney stones also apply here. There’s no denying this matchup’s importance on the global stage and in this tournament!
Consumable Waste in HD vs Disposable Waste in HD
Consumable Waste in HD
Health care is resource-intensive, and nephrology is no exception. Let’s walk through a single standard dialysis treatment in Australia. This takes four hours and uses a dialysate flow rate of 500 mL per minute. Due to the inefficiency of reverse osmosis water filtration, one liter or more of source water per minute is required to prepare the dialysate, or 240 L over a four hour dialysis session. Adding in the volume of water used for priming, rinsing, and sterilization of the system results in 500 L of water use per treatment!
Typically, all water that does not end up as dialysate is lost to the drain – this can be as much as 380 L per treatment. Considering that average per capita domestic use is 160 L per day in Australia, most dialysis treatments are putting more than two days of water directly down the drain.
So, how do we fix this? Importantly, while reverse osmosis ‘reject water’ is not currently legally allowed to be consumed by humans, it is in fact highly purified tap water that falls well within the limits set for potable water by multiple organizations including the World Health Organization (WHO).
Some countries like Australia have facilities where “reject water” is utilized for steam generation, hospital janitorial use, toilet flushing, landscaping, grounds keeping maintenance, and laundry. The authors of a study of a facility in Lyon, France, projected a likely financial return on investment from capturing and reusing reverse osmosis reject water of 5.8 years. They also note an example where a 3-way flow regulator valve on the reject water pipe reduced reverse osmosis water wastage from 1373 L to 917 L per year (an impressive 33% reduction!). Units need to factor these issues into architecture and building plans at the outset, as it is much easier to build water reuse systems up front than it is to retrofit existing plumbing.
Reuse of hemodialysis effluent is more difficult due to contact with blood and high conductivity. However, the effluent also contains high concentrations of nitrogen, potassium and phosphorus which makes it an ideal fertilizer. One study investigated the potential of treating then recycling hemodialysis effluent water for irrigation, landscaping and agricultural purposes. It showed that this was feasible and safe, but expensive. This cost plus the theoretical risk from blood contamination make it unlikely we will see this widespread reuse of hemodialysis effluent water any time soon. However, this may change as our climate warms further and global water resources become more scarce over time.
At first glance, peritoneal dialysis (PD) certainly uses less water than hemodialysis. A continuous ambulatory PD (CAPD) patient with four exchanges of 2.5 L daily uses 10 L of water per day. However, as with hemodialysis, several liters of source water (ie, tap water) are needed to generate the pure water that makes up the dialysate. The exact efficiency of this process is unclear. In addition, PD fluid comes packaged in plastic, which itself has a large water footprint, not to mention comes with its own price in disposable waste, which we will discuss separately.
Thinking about reusing and repurposing water is exceedingly important, as 10% of the worldwide population lives with serious water shortages and, in 2002, 21% of people in developing countries did not have sustained access to improved water. By 2050, water scarcity is predicted to impact two thirds of the world’s population.
Beyond water, we also need power. Annually, worldwide hemodialysis consumes an estimated 2.75 billion KWh of power. To put this number in perspective, a central air cooling unit running full blast in the summer would use about 100 kWh per month. Two dialysis treatments consume enough power to last an average 4-person home for one whole week. Solar power may be a saving grace, and we are seeing promising pilot programs in nephrology. In Australia, after 12 years of implementation of solar power to operate a four-chair home hemodialysis training facility (offering five hour sessions four days a week), the billing/reimbursement ratio is neutral and there is no net power consumption.
Importantly, the technology for solar power has improved and the cost has fallen since 2013 which means that the time to recoup costs in this setting would be much shorter than 12 years if the same solar system were installed today. Solar electricity generation may be of particular benefit in areas that are limited by power. For example, in sub-Saharan Africa, of the 11 countries surveyed, 26% of healthcare facilities had no energy and only 33% of hospitals had reliable electricity (defined as no outages for more than two hours).
And what about those pesky greenhouse gases? Eight percent of CO2 emissions in the US are from the healthcare system, and in the UK, the National Health System is responsible for 25% of public sector emissions. The carbon footprint of hemodialysis in Australia is 10.2 tons of CO2 equivalents per year, of which 35.7% is from pharmaceuticals and 23.4% is from medical equipment. In the UK, the annual carbon footprint of hemodialysis is 3.8 tons of CO2 equivalents per year, with the majority distributed between patient travel, energy use, and medical equipment (20%, 21%, and 37% respectively).
In China, a home PD patient who uses a daily dialysate dose of 8L is responsible for the release of approximately 1,400 kg CO2 equivalents of greenhouse gases annually, with the major contributing factor (~80%) being PD packaging materials. It is worth noting though that the study concerned did not consider the carbon impact of pharmaceutical use or transporting PD fluids from the place of manufacture to the point of care. Given that both are likely to be very significant contributors, we can assume 1,400 kg CO2 equivalents is likely to be a substantial underestimate. As this is directly tied to climate change issues in our first matchup, we should all be making efforts to reduce our carbon footprints.
After reading this, there should be no doubt that we need to conserve our resources. Simple concepts like reusing water and conserving power were taught to all of us in grade school. Let’s turn now to what we’re putting into landfills or burning into our atmosphere.
Disposable Waste in HD
Think about the waste you dispose of daily – IT IS A LOT. If you think plastic straws are a problem, then wait until we get into dialysis waste. According to the Environmental Protection Agency, the average American produces around 2 kg of garbage a day.
When it comes to dialysis, in the UK each hemodialysis treatment produces 2.5 kg of waste, of which 38% is plastic. This equates to 390 kg of trash per person per year, mostly consisting of plastic tubing, used dialyzers, syringes, medications, and packaging. Accounting for plastic alone, the waste generated by dialysis units worldwide is an estimated 625 kilo tons of plastic per year. Only 23-28% of non-hazardous hemodialysis waste is recyclable, and the financial cost of waste disposal is high, ranging from $2.70-$21 per session. Of note, PD is far from a game-changing solution. Each treatment with four daily exchanges creates 1.69 kg of disposable plastic waste, and given that PD is a daily therapy, this equates to more waste per year than HD. As the majority of plastic is polyvinylchloride (PVC), this poses another problem. Medical waste is burned in many places, and the burning of PVC is associated with production of chlorinated organic compounds which are toxic to plant and animal life.
What are some solutions? Dialyzer reuse was initially practiced as a cost-saving measure, and in some areas is still in place. However, in most countries, including Japan, Australia, Germany, France, and Italy, dialyzers are not reused, and in the US reuse is overall diminishing. For instance, in 2012, a US Centers for Disease Control survey indicated 24% of facilities reuse dialyzers. Currently, there is no reuse in the US as there are no Food and Drug Administration (FDA)-approved reuse dialyzers produced. Each additional use of the dialyzer increases risk of bloodstream infections by 7%, and the use of a filter more than 6 times is associated with a 7-fold increased risk. Reuse of dialyzers and lines can expose staff to harmful sterilizing chemicals, and the presence of these chemicals in waste water is also an environmental problem. No studies exist to establish if plastic (ie, used dialyzer) or chemical water waste is a larger environmental problem in hemodialysis.
Despite this dismal introduction, there are bright spots of hope. In the UK and Australia, for example, the focus is on reducing waste at the production point. Segregating nonclinical waste from clinical waste is not only better for the environment, but also reduces disposal costs. Hospitals and patient areas that have trained staff to do this have reduced clinical waste by 30% in the UK, and a study from Italy has shown that it only takes one additional minute per session to separate hazardous and non-hazardous waste at the time of waste generation. Recycling packaging material is a no-brainer, and countries like the UK put the onus on the producer to recover and recycle the material.
What about repurposing this trash? Already, recycled plastic and plastic bottles are being used as bricks for building houses around the world and, similarly, in Europe, trials are underway to reprocess plastic waste through autoclaving shredded items to make sterile confetti that can be used to create new plastic items or to redirect it to industry for reuse. Early analyses show the cost-benefit is comparable to current methods. An Australian Engineering team is collaborating with nephrologists to use shredded plastic waste from dialysis units as an incorporative product into concrete. This project is not only finding a use for the disposable waste, but preliminary studies also suggest that it might lead to a more durable and water-proof concrete well suited for wet environments.
These matchups should resonate with all of us, but may particularly ring true for nephrologists. Our kidneys maintain homeostasis and provide internal balance day in and day out. Just as these magnificent organs maintain a stable ecosystem inside the human body, we as deliverers of healthcare need to be aware of how healthcare impacts the environment around us. We should strive to keep the earth’s oceans and atmosphere in balance, just as the kidneys keep us in balance.
How to Claim CME and MOC
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The CME and MOC activity will expire on June 13th, 2020.