To discover a patient resting heart beat a nurse often count the amount of beats in 15 seconds and then multi which expression shows how a nurse woucalculate a?

Question

A) a= 4b

B) a= b(60)

C) a= 4b(60

D) a= 4b/(60)

Answer 1

There are two "variables," that is, "unknowns" to solve for in this problem and there are two, "a" and "b" that are included in each of the possible answers.

 

"a" is what you are looking for, i.e., your answer. You learn this through experience in looking at these types of questions, and through experience in math. This of it this way: "a" is what you are solving for.

 

Heart or pulse rate (pulse = the number of pulses felt over an artery, whereas heart rate is the number of beats auscultated over the heart) is understood, described and recorded as the number of heartbeats, or more accurately, pulsations (felt) per minute.

 

If you count the number of heartbeats (pulsations, for example, over the radial artery) in 15 seconds, you would need to multiply this value (number of heartbeats or more accurately, pulsations) times 4 to find the number of heartbeats per minute (15 seconds X 4 = 60 seconds or 1 minute).

 

So, for example, if the number of heartbeats (pulsations) you count in 15 seconds = 20, and you multiply that number (20) by 4, you would get 80 - 80 pulsations per minute (60 seconds), that is, a pulse of 80, and if the pulse rate accurately reflects the heart rate, that is, every heart beat causes one pulsation (which it does not always do), your pulse rate would = your heart rate. Note: it is not uncommon for people to use these two terms interchangeably, but it is important to understand the difference between heart rate and pulse rate - they aren't always equal!

 

So, how do you express this in a mathematical equation?

 

You are given one variable in your question/problem, and that is "a."

 

If you scan the options for the correct answer, you will see that there is also a "b." What is "b?"

 

You can also see that "60" is part of the answer for three of these options, so ask yourself, what does "60" have to do with this?

 

60 is the number of seconds in a minute. Don't get misled by thinking 60 has to be a part of the answer!

 

We know that "a" represents the answer; "b" is another variable. What if we let "b" represent the number of heartbeats in 15 seconds? (I'm looking for a second unknown, or variable.)

 

Notice "b" is included in all four options, A - D.

 

After you count your pulse rate and determine that number, try "plugging" this number into your "b" in the first option. Does that make sense? It should, because we know that heartbeat (and pulse) is recorded in beats per minute. We know the number of beats (or pulsations) for 1/4 of a minute (15 seconds), so if we multiply that number, for example, 20 (beats or pulsations per minute) X 4, we will get the number of heartbeats per (one) minute.

 

Now, glance at the other options just for the mental exercise, and ask yourself, what do each of these equations mean?

 

If "b" is the number of heartbeats (or the pulse rate) in 15 seconds, 1/4 of a minute, would we multiply that number times 60 to get the number of heartbeats per minute? No.

 

Option C - if we multiply the number of heartbeats in 1/4 of a minute (15 seconds) times 4 -- so far that would be correct, and this option looks like option A, but what if we multiply that again by 60? No, that would be way too high! Just to "plug in" some sample values to see if it works, try using 20 again for the number of heartbeats in 15 seconds, 1/4 of a minute: 4(20)(60) = 4800! Wow! That is not a normal heart rate - remember, normal = 60-100, with a slow heart or pulse rate being as low as 40 and a high rate being 150 or so. Of course, your heart or pulse rate can go all the way down to 0 and can go higher than 150 with some cardiac dysrhythmias.

 

So, what about Option D? Well, first you would multiply your rate for 15 seconds times 4 - we'll use 20 again, just for the purposes of demonstration. That part's ok, and again, this looks like option A - but then in this option, you are asked to divide this product of 80 by 60. This can't be right - that would give us a heart rate of 1.3!

 

By working through each of these possible answers, I believe you can develop your critical thinking skills and build your confidence and test-taking skills.

 

Hope this helps!

 

One more thing - I have to say, I do not recommend checking a pulse or heart rate for just 15 seconds. 30 seconds would be minimum, then multiply by 2. It's best to check for a full minute to get the most accurate number since heart rate varies continuously. It is essential that you check it for at least a minute in some circumstances, such as before giving certain types of cardiac medications such as Digoxin.

 

Answer 2

If the nurse is counting the number of heartbeats in 15 seconds to discover the heartbeat per minute, she would take the number of beats in 15 seconds (b) and multiply it by 4.

 

There are 60 seconds in a minute, which is 15*4.

 

So the correct answer is A) a= 4b.

 

Hope this helps, Amandaa! ♥