Monday, April 10, 2017

HP Prime: Fick Cardiac Output (The Blog Turns Six!)



HP Prime:  Fick Cardiac Output  (The Blog Turns Six!)

A Special Note

Happy sixth birthday to my mathematics blog!   And a big reason why blog has turned six on April 11, 2017 is because of all of you readers!  Words can’t explain how appreciated I am. 

Thank you!  Cheers to everyone!

Fun fact:  The most popular blog entry is my TI-36X Pro review (my fourth blog entry, 4/27/2011).  Link:  http://edspi31415.blogspot.com/2011/04/ti-36-pro-review.html

Now let’s get to today’s subject. 

Fick Cardiac Output Equations

The program FICK will calculate:

* CO: Cardiac Output (L/min)
* SV: Stroke Volume (ml)
* CI:  Cardiac Index (L/(min/m^2))
* SI:  Stroke Index (ml/m^2)

Given the following inputs:

* Ca:  Arterial blood oxygen (O2) content percentage
* CvO2:  Venous blood oxygen (O2) content percentage
* VO2:  Oxygen compulsion (in ml per pure oxygen gas per minute, STPD)
* HR:  Heart Rate in beats per minute (BPM)
* Height in cm
* Weight in kg

STPD: Standard Temperature Pressure Density

Conversion factors:  1 in = 2.54 cm, 12 in = 1 ft, 1 lb = 0.45359237 kg

Formulas: 

CO = VO2 / (10 * (Ca - CvO2))
SV = CO * 1000/HR
CI = CO/BSA
SI = SV/BSA

BSA:  body surface area, measured in cm^3.  There are several formulas, but the Fick program uses the simple approximation formula:

BSA = √(weight * height)/60

HP Prime Program FICK

EXPORT FICK()
BEGIN
// Fick Cardiac Output
// HP 65, 1972
// EWS 2017-04-10

// inputs
LOCAL ca,cv,vo,hr,h,w;
INPUT({ca,cv,vo,hr,h,w},
"Fick Cardiac Output",
{"Ca O_2:","C_v O_2:","VO_2:","HR:",
"Height:","Weight:"},
{"Arterial blood (%)",
"Venous blood (%)",
"O_2 compulsion (ml/min)",
"Heart Rate (BPM)",
"Height (cm)",
"Weight (kg)"});

// calculation
LOCAL co:=vo/(10*(ca-cv));
LOCAL sv:=co*1000/hr;
// simple BSA
LOCAL bsa:=√(w*h)/60;
LOCAL ci:=co/bsa;
LOCAL si:=sv/bsa;

// output
PRINT();
PRINT("Cardiac Output (l/min)");
PRINT(co);
PRINT("Stroke Volume (ml)");
PRINT(sv);
PRINT("Cardiac Index (L/(min/m^2))");
PRINT(ci);
PRINT("Stroke Index (ml/m^2)");
PRINT(si);

END;

Example:

Inputs:



* Ca:  19%
* CvO2:  15%
* VO2:  250 ml/min
* HR:  64
* Height: 5 ft 11 in, 180.34 cm
* Weight 196 lb, 88.90410452 kg

Results:

* CO: 6.25 L/min
* SV: 97.65625 ml
* CI:  2.96158586825 L/(min/m^2)
* SI:  46.2747791914 ml/m^2

Source:

Hewlett Packard.  HP-67/97 User’s Library Solutions: Cardiac Corvallis, OR 1976  pg. 20

Here’s to many more years!

Eddie

This blog is property of Edward Shore, 2017.
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