The great potential of "green" dialysis

Professor Beige, why does the carbon footprint of global healthcare systems need to be improved?

It is generally estimated that the entire healthcare system accounts for around ten per cent of the global CO2 footprint. It is not yet known exactly how big a part nephrology plays in this. But if you consider that there are around 80,000 dialysis patients requiring long-term treatment in Germany, and that haemodialysis is a method that a person performs three times a week throughout their life, then that is a very large CO2 footprint in terms of energy, water and medication.

My personal motivation was Bill Gates' book ’How to avoid a climate disaster’. In it, he recommends looking in your own personal environment to see where there is a point with more than ten per cent of your own CO2 footprint and tackling it there. In my professional environment, dialysis, this is the case.

Can you illustrate this with figures?

We consume around 6 to 10 kW/h of electricity and around 200 litres of water per Hämodialysis. Converted into CO2, that is
6 to 7 tonnes per year and patient. This is roughly equivalent to his private CO2 consumption. In other words, the patient doubles their CO2 footprint through dialysis.

To stay with Bill Gates: that's significantly more than 10 per cent.

What is meant by basic dialysis?

This is just a buzzword. It's about making dialysis more ecological. If the goal of greenhouse gas neutrality by 2050 set by the United Nations Framework Convention on Climate Change (UNFCCC) in Paris is to be achieved, dialysis is one of the many and, above all, effective levers. Whereby the most effective lever is of course to save dialysis years through prevention.

What does green, i.e. sustainable, dialysis look like?

In my dialysis centre, we consumed around 6.5 tonnes of CO2 in 2014. Thanks to photovoltaics with 15 to 20 per cent CO2 savings with 40 per cent electricity savings and the collective transport of patients with 5 per cent savings as well as changed water management, we are now down to around 3.8 tonnes. We are therefore not that far away from the milestone target of halving greenhouse gases by 2030.

If we consistently implement this kind of multimodal approach, the seemingly distant target of 2050 is actually achievable.

In your publication for the DGfN, you mention a concentrate mixing plant for dialysis, could you please briefly explain this?

In old systems, the electrolytes required for dialysis are supplied as a liquid concentrate in a tank. This means that they are transported around the world by the tonne and are then stored in huge tanks in the cellars of dialysis centres. We have only been using dry dialysis concentrates for ten years now. We then produce the required liquid, the dialysate, ourselves on site using fresh water, thus saving 80 per cent of the tonnage.

How much water is needed for dialysis?

Patient requires 200 to 300 litres of raw water to produce 120 litres of ultrapure water for dialysate. The wastewater from this ultrapure water production could be used as so-called grey water for laundry, toilet flushing or green plants. However, this does not happen in Germany. We can also use less dialysate and therefore less water for dialysis. Of course, this has medical limits. But it is not clear where these are. We now want to find out. So far, we have tended to operate in the ‚luxury sector‘. Here at the dialysis centre, we have already reduced dialysate and therefore water consumption by 15 percent, with no impact on patients.

How do you measure these medical effects of saving water?

This is a good question, because there is no single value to determine this. That is why we are currently asking dialysis patients about their well-being using standardised questionnaires as part of a research programme. We want to obtain standardised assessment scales and a dialysis quality system. We urgently need to combine ecological measures with medical quality research.

What investments do the individual measures mean and, on the other hand, what savings will result from them?

The photovoltaic system really pays off. If you assume that a system costs around 1000 euros per installed kW/h, then you are investing around 100,000 euros for a 100 kW system. However, we recouped this sum after five to six years - and the electricity is used directly by our dialysis centre, so we don't have any storage requirements or costs.

When we installed the concentrate mixing plant in 2010, it was a consciously ecological decision. But such a purchase is entirely feasible. It is roughly equivalent to two dialysis machines and has not only environmental but also operating and practical advantages.

Are there any other ideas for more sustainability in dialysis?

There is still great potential for savings in heat recovery. The dialysis solution has to be heated to body temperature, in our case from around 10 °C to 36 °C. That's a lot of heating energy. That's a lot of heating energy. In the immediate return flow, the water is still 36 °C. New dialysis systems correctly utilise this heat via built-in heat pumps. After that, however, the waste water is still 26 °C warm. A value from which the geothermal energy is boosted. We could utilise this. Unfortunately, there are still no systems for dialysis centres in this respect. Furthermore, we still have blind spots: We know nothing about the life cycle assessment of the drugs and tubing systems used because we have not yet received any information about this from the manufacturers. In the DGfN community, we therefore agree that we should favour manufacturers with a reasonable life cycle assessment.

What impact do your measures have on patients, staff and dialysis centres?

For patients, it is sometimes not so convenient to travel by shared taxi, as they have more waiting and travelling time. Nothing changes in the dialysis procedure, neither for the patients nor for the staff. But we have to look at the technical and medical outcome in terms of quality control. We also do a lot of educational work and promote resource-saving home dialysis and, in particular, peritoneal dialysis.

Could you please explain that briefly?

In contrast to haemodialysis, the abdominal cavity is used as a dialysis room. Several times a day, patients allow a sterile dialysis solution to flow into the abdominal cavity via a catheter in the abdomen. The toxins, electrolytes and excess fluid in the blood diffuse into this solution in the abdominal cavity. The dialysis solution containing toxins is then replaced by a fresh solution. The advantage of the procedure is that it uses gravity, therefore does not require electricity, and uses only 10 litres of water per day. However, the solution comes in disposable plastic bags. The total CO2 footprint of peritoneal dialysis is estimated to be 1 to 2 tonnes of CO2 equivalent per year - in contrast to 4 to 10 tonnes in the case of hämodialysis in the centre. In purely medical terms, the procedure may be suitable for up to 60 to 80 per cent of dialysis patients. But in Germany, only 8 per cent use it. By comparison, the figure in Australia is 40 per cent.

Are there other approaches for other specialist areas?

The measures themselves are tailored to dialysis - except for the photovoltaic system. But a superordinate carbon footprint monitoring system and a continuous improvement process based on it as a proven management technique makes sense everywhere. We need to incorporate the ecological aspects into a constantly evolving quality management system. We do this here at the centre and anyone can do the same. To this end, we have set up the portal carbonfootprintdialysis for the field of dialysis, where centres can analyse their measures free of charge. Our aim is to integrate this into the company systems and then be able to measure and, if necessary, improve each individual dialysis.

Article from "medizin & technik" from 21/02/2023