High blood pressure in Chronic Kidney Disease (CKD) requires an intensive treatment plan to effectively slow down progression to kidney failure.
What constitutes the treatment plan? How does it work? Must you take all those pills? How does your medical team devise your BP-lowering battleplan?
Find answers to all these questions and more, in today’s discussion below.
But first, a very brief recap on why your blood pressure rises in chronic kidney disease.
Kidneys regulate blood pressure by controlling the amount of sodium levels in the blood and the water that it attracts after it, via the Renin-Angiotensin-Aldosterone system (RAAS) – something that we have discussed in detail in our previous article here.
Fluid (water) content of blood directly has a bearing on the total blood volume. This naturally impacts two things:
The overall “pressure” that blood can exert on the walls of the blood vessel.
AND
The extent of “force” that the heart will need to apply to “pump blood out” or let blood in.
WHEN CHRONIC KIDNEY DISEASE HITS, IT RAISES OUR BLOOD PRESSURE BY:
Scarring and narrowing down our blood vessels, first the tiny ones within the kidneys that gradually spreads to other body parts over time. Narrowed blood vessels implies a tiny doorway. These require the blood to literally shove and push through even during regular flow.
Increase in pressure within tiny kidney filters due to unwanted taut, stiff blood vessels coming into the filters. This happens due to erroneous activation of the RAAS hormone system.
Abnormal increase in blood Sodium levels because the kidney filters are scarred to remove excess sodium from our blood adequately without the help of medicines.
The heart having to beat with greater force to pump blood out or let blood in due to extensive narrowing of blood vessels at numerous locations. This problem is further worsened in patients on long-term hemodialysis treatment.
Fluid overload in the body in advanced stages when unwell kidneys are unable to remove excess water from the body due to poor urine formation.
Armed with this basic knowledge, let us take you through the various BP-lowering strategies in CKD:
BLOOD PRESSURE LOWERING MEDICINES
Fancy name: Anti-hypertensives
As mentioned in the green box above, blood pressure lowering medication used in CKD patients work on three chief “therapeutic” targets:
1. Lowering blood sodium levels.
2. Countering Fluid Retention
3. Temporarily widening stiffened & narrowed blood vessels
Let’s take these up one by one.
Colour code in the image: Orange
HOW TO IDENTIFY?
Generic names that end with “-pril”
Eg: Ramipril, Enalepril, Lisinopril
This is the commonest and most effective medicine group used to fight high blood pressure in chronic kidney disease.
HOW DOES IT WORK?
ACEIs block the unnecessary, excessive activation of the RAAS hormone system. They do so by preventing the conversion of Angiotensin to Angiotensin-II by blocking the necessary enzyme ACE. This:
Prevents increase of blood pressure within kidney filters
Curbs sodium and fluid overload in the body
SIDE EFFECTS
1. Raspy, dry cough, especially at a specific time of the day on a regular basis.
Reason: Build-up of an allergen called Bradykinin due to blockade of ACE.
2. Disturbances in heart rhythm due to abnormal increase in Potassium levels in blood beyond 5.5 mEq/L. This must be monitored with regular blood tests and dose revision if necessary.
Colour Code in Image: Red
If you develop debilitating dry cough while on ACE-I medicines, your doctor will change your medicine to Angiotensin Receptor Blockers or ARBs.
HOW TO IDENTIFY?
Generic names that end with “-sartan”.
Example: Telmisartan, Olmesartan
HOW DOES IT WORK?
This brings about the same effect as ACE-I but without the cough. ARBs too, block the unnecessary, excessive activation of the RAAS hormone system. They do so by blocking Angiotensin-II from attaching to necessary locations in kidney filters that otherwise activate the RAAS hormone system. This:
Prevents increase of blood pressure within kidney filters
Curbs sodium and fluid overload in the body
SIDE EFFECTS
1. Abnormal increase in Potassium levels in blood beyond 5.5 mEq/L when taken in the long term. This can cause disturbances in your heart rhythm.
Hence, regular blood tests are a must to evaluate your Serum Potassium levels and avert such side effects with appropriate dose revision when necessary.
Colour code in the image: Violet
HOW TO IDENTIFY?
Generic name ends with “-one”;
Eg: Eplerenone, Spironolactone
HOW DOES IT WORK?
The MRB group of medicines “blocks the workspace” of Aldosterone hormone in the RAAS hormonal system. This helps to reduce the blood pressure by:
Reducing the blood pressure within kidney filters
Preventing excessive Sodium retention
Counters Fluid overload in the body
SIDE EFFECT
1. Abnormal increase in Serum (blood) Potassium levels especially if used with ACE-I or ARB.
Colour code in the image: Green
HOW TO IDENTIFY?
Generic name ends with “-thiazide”, “-thalidone” or “-semide”;
Eg: Hydrochlorothiazide, Chlorthalidone, Furosemide, Torsemide
HOW DOES IT WORK?
Diuretics are “water pills”. They help your unwell kidneys to remove excess fluids from your body via urine. Some of these medicines also increase removal of excess Sodium from the body. Since sodium attracts water with it, removing sodium further removes excess fluid from the body.
This counters fluid overload in your body and helps to keep your blood pressure in check.
SIDE EFFECTS
1. Abnormal fall in blood Sodium levels
2. Abnormal fall in blood Potassium levels
3. Dehydration (volume depletion)
Now, blood vessel wall dynamics play an essential role in regulating your blood pressure. So, we also have certain classes of BP lowering medicines that focus on the biochemistry of Blood vessel walls.
Blood vessels have way too many “holes” in them!
No, really! These pores are what make them “responsive” by letting all minerals and hormones impact its dynamics.
When we talk about minerals, Calcium makes for an essential mention. Yes, you read that right. Calcium doesn’t just strengthen your bones and teeth. It helps your blood vessels remain adequately taut for delivering blood to all tissues at the right amount of pressure. However, in patients with excessively stiff blood vessels and thereby, high blood pressure, “barring” some of that calcium actually helps relieve the excess load on blood vessels. So, we have medicines called “Calcium Channel Blockers”!
Colour Code in the image: Dark blue
HOW TO IDENTIFY?
Generic names that end with “-dipine”;
Eg: Amlodipine, Nifedipine
HOW DOES IT WORK?
Calcium channel blockers or CCBs work by preventing the entry of Calcium within heart muscle and blood vessel wall. Calcium normally makes the heart pump harder and makes blood vessels taut. Blocking it reverses these effects.
This effectively reduces your blood pressure by:
Widening Blood Vessels
Reducing the need for your heart to pump blood with excessive force by relaxing the heart muscle as well
SIDE EFFECT
1. Swollen feet & ankles due to fluid build-up (in ways unrelated to kidney failure).
Further on, there are numerous “miniature locks” located along the entire length of blood vessel walls where certain hormones can “fit like a chemical key” to bring about the desired effect on vessel movement. Based on the “shape” of the lock and the “effect brought about by unlocking it, there are different names such as Alpha sites or Beta sites.
Beta sites narrow down a blood vessel & raise your BP when unlocked with their chemical key. So, medicines that will jam the beta sites and block their chemical keys from fitting in will “prevent the rise of your BP”. Such medicines are called Beta Blockers.
Colour Code in the image: Purple
HOW DOES IT WORK?
This is a diverse class of medicines. The segment of Beta blockers (shown in purple in the image) that helps in BP control works in two ways:
They block Beta sites in blood vessels and prevent the blood vessel from narrowing down.
They also help to reduce how fast your heart beats.
Examples: Metoprolol, Atenolol, Carvedilol etc.
SIDE EFFECT:
1. Slowdown of your heart rhythm
On the other hand, Alpha sites of blood vessels are such that they relax a blood vessel wall and widen your arteries and veins when “unlocked”. This reduces your BP when its chemical key fits in. In other words, medicines that resemble the chemical key for Alpha sites will reduce your BP. These medicines are called “Alpha Agonists” as explained below:
Colour Code in the image: Green
These drugs are supportive measure and not used very frequently unless in special cases like pregnancy in CKD patients.
HOW DOES IT WORK?
These medicines directly help widen stiff blood vessels and help restore normal BP.
Examples: Clonidine, Guanfacine
SIDE EFFECTS:
1. Extreme tiredness
2. Slowdown of heart rhythm
A
With time, scientists wondered if there were other minerals that could “balance out” the blood vessel stiffening action of Calcium in normal health. Soon enough, they found their answer in minerals like “Potassium” that actually help blood vessels relax.
So, preparing medicines that would “enhance the entry of potassium” into blood vessels looked like a good way to reduce blood pressure.
Enter, “Direct Vasodilators”.
Colour Code in the image: Pink
HOW DOES IT WORK?
These medicines work through “mineral channels” and not the alpha or beta sites that we mentioned above.
These meds make your blood vessel wall more porous to Potassium which is known to relax your blood vessels and reduces your BP. Since there is NO lock and key method involved in this process, pharma experts have named these meds as “direct vasodilators (vaso = vessel + dilator = to dilate or widen)
Eg: Hydralazine, Minoxidil
SIDE EFFECTS
1. Swelling of feet & ankles due to fluid buildup
2. Excessive hair growth in face & body (hirsutism)
Further, these drugs are always used as a supportive measure, never used on their own in CKD patients and ALWAYS with caution.
That is because in advanced chronic kidney disease, scarring of kidney filters also messes up their ability to flush out excess Potassium from your body. Using these medicines may disturb the potassium balance further. This could negatively impact your heart rhythm.
If you have chronic kidney disease without other associated medical conditions, your doctor starts you on one BP lowering medicine first. The choice of drug is based on:
Whether you are at the “pre-dialysis” stage or have already started Dialysis.
Certain clinical and lab markers.
With time, however, as CKD progresses, the need for starting you on a combination therapy for your blood pressure control becomes necessary.
FOR PRE-DIALYSIS PATIENTS:
ACE-I or ARB is the preferred drug to treat high blood pressure in CKD. These medicines are never given together else they can harm your kidney itself.
If ACE-I or ARB alone don’t provide adequate BP control, or there are associated heart complications, your doctor would usually start a Calcium Channel Blocker (CCB) to relax blood vessels all over the body and reduce the pressure on the heart.
In advanced stages in pre-dialysis patients, a Diuretic (Water Pill) becomes necessary to relieve fluid overload in your body.
FOR PATIENTS ON DIALYSIS:
Hypertension in Hemodialysis is due to the added adverse effect of the procedure on the heart muscle in the backdrop of all other mechanisms in CKD that raise your BP.
But because Hemodialysis actually helps to treat & rid you of excess Sodium levels in your blood, it partially takes care of the side effect of unwanted RAAS hormone cascade activation.
So, the approach here is to help your heart muscles first.
Beta blockers like Atenolol actively help effectively relax your heart muscles directly. This is preferred in many centers. This choice is based on established evidence from clinical trials and KDIGO norms.
In patients on long term hemodialysis & a poor pumping capacity of the heart, doctors may add a calcium channel blocker (CCB) both to relax heart muscles further and widen blood vessels. This greatly reduces the strain on the Heart.
In a subset of cases where even Hemodialysis fails to remove excess sodium fromthe bloodstream adequately, ACE-I or ARB makes it back to the BP medicines list in combination with the above medication.
RESEARCH UPDATE (21.07.2020)
As per a study conducted to compare the efficacy of various BP-lowering meds for patients on maintenance dialysis , Beta Blockers, ACE Inhibitors & Mineallocorticoid Blockers reduce the upper BP number (Systolic BP) most effectively. This means, these medicines are more effective in easing out the effort your heart needs to make to pump blood, than other options.
However, both ACE Inhibitors & Mineallocorticoid Blockers tend to reduce BP aggressively and make a patient feel dizzy. Patients stick to Beta Blocker class of medicines better.
These findings were published in the Clinical Journal of American Society of Nephrology (CJASN).
Stress is understandably, quite common with chronic diseases for more reasons than one. However, it increases the circulation of hormones like adrenaline & cortisol in your bloodstream. These hormones keep your blood vessels taut & raise your blood pressure.
While other reasons that increase your blood pressure in CKD are beyond your control, stress-reduction is something that you are the best candidate to help yourself with.
Practicing meditation with deep breathing techniques (Pranayama) is a great way to beat that stress. When you take deep, controlled breaths actively, you create a positive Oxygen balance in your body:
Oxygen helps relax your blood vessel walls throughout your body. This widens your blood vessels & partially helps to lower your blood pressure.
In the long term, such deep breathing techniques also curb the unnecessary release of stress hormones like cortisol & remove the negative impact of chronic stress on blood vessel dynamics.
Fat is a tissue that is made of living, breathing & actively metabolizing cells. If you happen to have a greater fat content, it simply means you have more blood vessels to cater to these cells. That reflects on your overall blood volume. Greater blood volume with narrowed blood vessels and a compromised kidney function in CKD not only raise your blood pressure, but also spell burdensome for your unwell kidneys.
Hence, however cliched it may sound, it is important to put in that extra effort to cut down your body fat. Increases the longevity of your kidneys despite CKD.
Ask your doctor to help you devise a suitable exercise plan for your age and individual general health status.
As a general rule, avoid high intensity training and limit/avoid cardios unless you have good heart health or have been pursuing a cardio fitness routine all your life. Considering the “out-of-breath” sensation that frequently accompanies CKD, slower exercises like Pilates & Yoga are good options.
NOTE:
Please do not start any exercise regimen without prior advice from your medical team or necessary supervision, especially if you have any associated heart, lung or bone disease.
All Blood pressure advisories ask you to “lower your salt intake” to help keep your BP in control. Why do you think they do so?
Common salt, condiments & many common preservatives used in store-bought packed food contain huge quantities of sodium. Now whatever we eat, drink or inhale shows right up in our bloodstream. While in normal health, your kidneys kindly flush all the excess sodium out of your body, scarred kidney filters in CKD are unable to do so. As a result, your blood sodium levels exceed healthy limits. We know how Sodium being a water-attracting mineral holds excess water in your blood. This can increase your blood volume & your blood pressure over time.
Why invite additional trouble for your already unwell kidneys, right? Cutting your Sodium intake is an easy way to prevent your BP from overshooting.
We have prepared a Sodium guide based on clinical guidelines for you to refer to. Find the links below:
THE COMPLETE SODIUM GUIDE FOR CKD
SODIUM CONTENT IN FLAVOURING & CONDIMENTS
While these guides serve as a generalized yardstick, we recommend you consult your dietitian (preferably a Renal Dietitian) to get your customized Sodium plan based on your age, activity levels, geography of residence and dietary preference.
We explained in the above section here how it is important to maintain a healthy body weight for good BP control.
In addition to devising an individualized exercise plan, ask your dietitian to guide you on the appropriate fat & carbohydrate intake that’s right for you to help you achieve your healthy bodyweight target without compromising on necessary nutrition.
Tobacco has loads of Nicotine in it. This is a chemical that damages blood vessels, scars them and narrows them permanently, be it through smoking tobacco, chewing tobacco leaves or nicotine gums.
So, smoking only worsens the problem of extensive narrowing blood vessels as a result of Chronic Kidney Disease. Quit smoking as early on as you can, to help with more effective management of your own blood pressure.
For all you alcohol connoisseurs out there, here’s a tiny matter of concern. Did you realize alcohol is basically “fermented sugar (carbohydrate)” of the plant product that it is derived from? Say for instance:
Wine from grapes (everybody knows that!)
Whiskey and Scotch come from barley, corn or wheat
Vodka comes from Potatoes
Rum & Beer come from Sugarcane!
This simply means every peg you take, stuffs you with those unwanted calories that turn into fat tissue if you don’t adequately burn them off. We have covered in the sections above how high fat content can increase blood pressure in the long run in the backdrop of compromised kidney function in CKD patients.
More importantly, there is a direct effect of alcohol on your blood pressure. Immediately after drinking alcohol your BP drops by widening your healthy blood vessels. Something that you feel as “getting high”. However, drinking regularly for a few years permanently damages the blood vessels in the liver. This raises something called the portal Blood pressure within the Liver. A high Portal BP ultimately forces the blood to return at a higher pressure back to the heart. This raises the lower number of your BP reading known as the Diastolic BP.
This is something that you can control, right? So, if your alcohol intake is frequent or heavy, you would do well to reduce it.
CONCLUSION
So, that was a comprehensive insight on what your blood pressure treatment plan when CKD homes in your body. The crux of the matter is:
Take all your medicines on time, make a note of instances and talk to your medical team if you get any unusual symptoms after taking your medication.
Further, try to stick to a Renal Diet Plan to help limit your Sodium, Carb & Fat intake — things that increase your BP.
Stick to a regular exercise plan. Ask your medical team to help you devise a regimen that helps you stay active without impacting your heart health adversely.
Quit smoking. Just do it. There is NO alternative other than kicking that (cigarette) butt out of your life.
Work towards limiting your alcohol intake to once a week. But if you are on any other medication that reacts adversely with Alcohol, your doctors may ask you to avoid drinking completely.
Reference:
1. Clinical Pharmacology of Antihypertensive Therapy for the Treatment of Hypertension in CKD
https://cjasn.asnjournals.org/content/14/5/757
