A patient has a heart rate of 75 bpm, an end diastolic volume of 150, and blood !


Question: A patient has a heart rate of 75 bpm, an end diastolic volume of 150, and blood pressure of 125/90.?
A recent posting on Answers posed the question : " A patient has a heart rate of 70 bpm, an ejection fraction of 75%, an end diastolic volume of 120, and a blood pressure of 120/90. What is the end systolic volume?"
The question having been amended to read 'stroke volume' instead of 'end systolic volume' the correct answer was 90 mls.

A subsequent test on the same patient showed a heart rate of 73 bpm, an end diastolic volume of 150 mls, with a BP reading of 120/85.

What as the ejection fraction on the second occasion?

Answers:

Very interesting. Kate is correct and you can do it that way.

But there's a much easier shortcut, because the two stroke volumes are in direct proportion to their respective pulse pressures, so the second stroke volume is 90 x 35/30, making the second stroke volume 105 mls.
So the new ejection fraction is 105/150, or 70%.
(Forgive me if I've got the sums wrong, -I'm hopeless at Math, - but the method is OK.)

As to Lawmed's supercilious (and wrong) answer, well, -perhaps he'd be well-advised to stick to Law, -rather than Med.?
What DO they teach them at Med-school these days? I wouldn't want him to help with my homework!



Perhaps you want to make some more amends. A heart rate of 73 bpm, an end diastolic volume of 150 mls, with a BP reading of 120/85 is not enough information to calculate EF. Or are you suggesting that everything has changed but the SV which we should assume is still 90??

Assuming that is the case, EF = SV/EDV, or 90/150, or .60, or 60%. Am I doing your homework for you??

My brain.



It seems straightforward to me. You've been given both the ratio of the two pulse rates, and the ratio of the two pulse pressures, so all you have to do is work out the two cardiac outputs and use Lowe's Law.

Note to Lawmed : No, the SV isn't unchanged. That would be a trivial answer to a perfectly valid question.




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