Volume-Decreasing Antihypertensive Meds: ACE and Diuretics

SimpleNursing Editorial Team Mar 9, 2018
Doctor's model of the human heart


Today, we will be focusing our senses on the difference between your volume-decreasing antihypertensive medications – ACE inhibitors and diuretics.

Usually, the challenge when dealing with volume-decreasing antihypertensive drugs is that it’s hard to tell them apart. Somewhere along your study session, there’s confusion between heart failure drugs and electrical conductivity drugs. Here, at Simple Nursing, we’ll put some sense to it the best possible way.

The Mechanisms

Technically, two mechanisms put pressure or increase stress on the heart,  namely:

  1. Heart rate = beats per minute, concerned with the contractions of the heart and cardiac output or blood flow
  2. Pressure = workload

To explain further how heart rate and pressure works, think of this scenario:

For example, you’re an accountant who works in a huge firm who is responsible for handling specific clients on a regular basis. So, let’s say you’re balancing books, doing taxes, and closing accounts. The work that you’ve done in an hour, that’s your rate.

On the other hand, the pressure depends on how much energy and time it needs for you to close an account. While there are accounts that are small which can quickly be closed after a few adjustments, there are large accounts that might need more out of you to finish. The effort that you’re exerting is your pressure or workload.

If there’s too much pressure acting on the heart, the rate is going to have a hard time to pump all that blood out. So, technically, it’s as simple as:

  • Heart rate = electrical conductivity/contractility
  • Pressure/workload = how much work the heart needs to do to push against the vascular system

Volume-Only Drugs

So, here, you should not think about drugs that affect the heart rate, electrical stimuli, contractility, and SA and AV nodes. The primary focus is on volume-only medications which directly affects in decreasing the pressure from the heart.

What are your volume-decreasing drugs?

  1. ACE inhibitors (“-pril) – mainly concerned with decreasing the fluid volume only by targeting the renin-angiotensin-aldosterone system (RAAS)

Side note: We have an extensive lecture on ACE inhibitors which introduces you to Club RAAS, involving primary characters like Aldos-Tyrone, Mr. Renin, and Angiotensin I and II. Check this lecture out; it’s a fun and informative discussion.

  1. Diuretics – helps the body to get rid of sodium and water, causing your clients pee a lot; thus, reducing the pressure on your vessel walls. There are three types of diuretics:
  • Loop diuretics – Furosemide (Lasix)
  • Potassium-sparing – Spironolactone (Aldactone)
  • Thiazides – Chlorothiazide (Diuril)

Diuretics mainly act on the distal tubules of the kidneys, the descending Loops of Henle, tapping into them to release fluid.

Client care: Watch out for the potassium level for those taking diuretics and your digitalis toxicity due to a low potassium level. Instruct clients who take diuretics to eat potassium-fortified foods.

Remember, when talking about volume-decreasing medications, only the volume is affected to decrease pressure. It has nothing to do with the rate or the electrical conductivity.

On a separate lecture, we will be thoroughly discussing the mechanism of loop diuretics. See you there!

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