Background
High blood pressure (BP) is very common in people with end stage kidney disease (ESKD) on dialysis. It is a risk factor for heart disease, which is the most common cause of death in people on dialysis. Managing high BP in people on dialysis is not always straightforward because of a lack of good quality research evidence on how and when to measure BP, what target BP to aim for, and how to best use different strategies to control BP with diet, exercise, dialysis techniques and medications.
How did we develop these guidelines?
These guidelines were developed by a broad group of experienced kidney care professionals. They went through existing research evidence to give guidance on how best to manage BP in people on dialysis. The guidelines group was divided into different topic areas. The recommendations and suggestions made by these groups are summarized below.
The topic areas were:
- How to measure BP
- What BP we should be aiming for
- Lifestyle measures and medications to help with BP control
- Modifications to dialysis and dialysate fluid
- Assessment of dry weight
- Considerations that apply to children and young people (CYP)
How should we measure blood pressure and what blood pressure should we be aiming for in adults on dialysis?
We found limited good quality information to tell us which BP measurement should be used in people on dialysis. Most research studies in haemodialysis patients have used ‘usual’ pre- and post-dialysis readings taken in the dialysis unit. These are often not very accurate. Also, both high and low ‘usual’ BP readings are associated with bad outcomes. This makes it difficult for kidney professionals to know how far we can safely lower BP. Finally, ‘usual’ pre- and post-dialysis readings are not good at predicting long term risks associated with high BP.
We suggest that usual BP readings should be used primarily to ensure safe delivery of haemodialysis. We encourage kidney care professionals to consider other ways of measuring BP in dialysis patients to help with long-term risks heart disease, stroke, etc. However, because usual pre- and post-dialysis readings are the most used readings in UK units, we make some suggestions about what these ‘usual’ readings should be.
These are:
- Aim for a pre-dialysis systolic (upper) reading of between 140 and 165 mmHg.
- For patients whose BP is stable during dialysis try to aim for the lower end of this range.
- For those with few or no other medical conditions, and in younger people, aiming for a BP lower than 140 may be appropriate.
Ambulatory blood pressure monitoring (ABPM) is the most accurate method for measuring BP. The downside of ABPM is that it involves wearing a monitor for 24 or 48 hours. Many people find this inconvenient. Because of difficulties associated with ABPM, we suggest that it is mainly used to diagnose high BP in adults on dialysis.
Home blood pressure monitoring (HBPM) – measurement by patients or carers of BP at home – is thought to be more accurate than usual readings for longer term BP management. However, some people may find taking readings burdensome. For those that use HBPM, we have suggested that we should aim for an average BP under 130 mmHg.
The alternative to HBPM may be to make sure BP is carefully measured in a standardized way within HD units and clinics, as recommended by international guidelines groups such as KDIGO. However, standardized measurements take more time and would be difficult to do regularly in busy HD units. We suggest that standardized BP readings could be carried out in an outpatient clinic.
What lifestyle measures help control BP?
We recommend that dialysis patients restrict their salt intake to no more than 5 grams (less than a level teaspoon full) per day. Renal dieticians can assist patients in how to calculate the salt content of various foods. There are benefits from taking regular exercise and we suggest that exercise is adopted wherever possible.
How may modifications of dialysis and dialysate fluid help?
Changing the type and duration of dialysis treatment or changing the composition of dialysis fluid may help to improve BP control. We suggest that those with high BP, increasing the duration of haemodialysis and using icodextrin (Extraneal) solution in peritoneal dialysis patients may help fluid management and BP control.
For those suffering from low BP during dialysis (intradialytic hypotension or IDH), lowering dialysis fluid temperature, frequent short dialysis, nighttime dialysis or home haemodialysis may be helpful. After ruling out other causes of IDH, a period of haemodialfiltration (HDF) may be tried. HDF combines haemodialysis with filtration, which allows the removal and replacement of fluid.
How should dry weight be determined?
Dialysis patients who have too much (overloaded) or too little fluid (dehydrated) in their circulation have worse outcomes. So it is important for dialysis staff to correctly assess each patient’s ‘fluid status’. The weight at which a patient has the correct amount of fluid in their body and they feel comfortable is called ‘target weight’ or ‘dry weight’. Keeping someone around their dry weight can help control BP and, in people on haemodialysis, reduce large BP changes and help avoid episodes of feeling unwell during dialysis.
It is not easy to determine exactly how overloaded or dehydrated a person is, and there are several ways to help dialysis staff in doing this. Clinical examination is most often used. There are several devices which may help to assess dry weight correctly. It is not clear whether one device or technique is better than others or better than clinical examination to do this.
We suggest that dialysis patients should be examined regularly to determine volume status. This information can then be used to decide a patient’s dry weight. This guides dialysis staff to know how much and how quickly fluid can be removed or added during dialysis sessions.
What medications help with blood pressure on dialysis?
Many people having dialysis will require BP lowering medications. The pros and cons of the various types of medications are beyond the scope of this summary. In brief, we suggest beta-blockers (e.g. bisoprolol) as first choice medication in haemodialysis patients, followed by calcium channel blockers (e.g. amlodipine). ACE inhibitors (e.g. ramipril) are recommended as first choice medication in those on peritoneal dialysis.
People on dialysis may be on medicines to manage BP that are not mentioned in this guideline. This does not mean they should not be used but it may be because there is little information from research studies. If you have any concerns about your medicines, then do not stop them. Instead, please talk to your kidney doctor, GP, kidney pharmacist or a member of the kidney team.
What is particularly important in Children & Young People (CYP)?
High BP is common in CYP on dialysis, and this can lead to long term changes to the heart. Unlike in the adult population, we do not have clear information from research that high BP directly leads to an increased risk of death from heart disease. Studies helping us to understand what the ideal BP should be for CYP on dialysis are very few. This makes it difficult to make any firm recommendations regarding suitable BP targets in this age group.
Normal BP in CYP varies by age, height and sex. Measurements are compared against existing groups of children of the same age, height and sex. To avoid large drops in BP during dialysis, it is suggested that BP should be kept near the 90th percentile of CYP of the same weight, height and sex.
The best way to monitor BP in CYP on dialysis requires more research. ABPM is very reliable in CYP and this should be performed at least once a year in all CYP on dialysis, once a minimum height of 120 cm has been reached. However, ABPM is not always practical and will need to be performed alongside measurements taken in the hospital and/or at home. As in adults receiving haemodialysis in hospital, BP should be checked before, during, and after each dialysis session, with regular physical examination to ensure correct estimation of dry weight.
Salt in the diet should be reduced to specific amounts recommended for age. Kidney dietitians can provide support with this. If lifestyle changes, such as being very careful with fluid and salt intake, are unsuccessful in controlling BP then doctors and nurses may consider giving medications to lower BP. This is particularly important if there is any evidence of damage to specific organs in the body due to high BP. When choosing which medication to use, there is not enough information to indicate that any one type of BP medication is better than another. Doctors and nurses need to think about the specific patient and how the drug works in their body.