(41C) Basic EKG Calculations

11302019, 02:43 PM
Post: #1




(41C) Basic EKG Calculations
Introduction
The program calculates the following: * Lead II magnification, in mm * The mean axis deviation * The mean axis magnitude Given: * Lead I positive deflection, in mm * Lead III negative deflection, in mm The mean axis deviation and magnitude are calculated by a rectangular conversion by the following coordinates: X: Lead I positive deflection  Lead I negative deflection Y: Net Lead I deflection * 0.5774 + Net Lead III deflection * 1.1547 Mean axis deviation: θ  57° The program also: * Converts between the heart rate (rpm) and the RR interval * Use either parameter to calculate the QT interval, in seconds heart rate = 60/RR QT interval = √(RR)*0.39 The program is a translation of HP 67/HP 97 Basic EKG Determination, which itself is a translation of Steven A. Conrad's HP65 program (HP65 Users' Library Program). See the source listed below. Notes: 1. Clear the assignments of keys A (Σ+) through E (LN) before running the program. This must be done outside the programming environment. Clear assignments to keys by ASN (blank) (designated key). Example: Clear assignment from A: [ shift ] (ASN) [ALPHA] [ALPHA] [ Σ+ ] 2. Running EKG will turn the User Keyboard on. 3. The program will set the calculator to degrees mode. 4. This program was entered on an HP 41C, and it should work on any simulator and Swiss Micros DM41. Instructions: 1. Run EKG. 2. Determine Lead I net deviation and store it to register 01: (in User's Mode) positive deviation Lead I [ENTER] negative deviation Lead I ( A ) 3. Determine Lead II net deviation, storing net Lead III net deviation to register 03 and Lead II net deviation to register 02: (in User's Mode) positive deviation Lead III [ENTER] negative deviation Lead III ( B ) Result: Lead II net deviation 4. Compute Mean Axis: (in User's Mode) ( C ) deviation is displayed [ R/S ] magnitude is displayed 5a. Convert heart rate to RR: (in User's Mode) heart rate (bpm) ( D ) or 5b. Convert RR to heart rate: (in User's Mode) RR ( D ) 6. Compute QT. (in User's Mode) ( E ) HP 41C/DM41 Program: EKG Code:
Example I+ = 2.8 mm, I = 1.1 mm III+ = 2.5 mm, III = 1.4 mm Heart Rate = 86 bpm Keystrokes: XEQ "EKG" (User Mode is On) 2.8 [ENTER] 1.1 ( A ) Display: III: 1.7000 2.5 [ENTER] 1.4 ( B ) Display: II: 2.8000 ( C ) Display: DEV=4.0516 [ R/S ] Display: MAG=2.8214 86 (D) Display: RR=0.6977 (E) Display: QT=0.3258 Source: "Basic EKG Determinations" HP67/97 User's Library Solutions: Cardiac. Hewlett Packard. Corvallis, OR. (no date given, but I estimate this to be circa 1974) Blog Link: http://edspi31415.blogspot.com/2019/11/h...tions.html 

01182020, 01:31 AM
Post: #2




RE: (41C) Basic EKG Calculations
Hi...
Could you answer me: The Deviation is the QRS axis? Best Regards Nelson Dinamarco 

01182020, 11:52 PM
Post: #3




RE: (41C) Basic EKG Calculations
According to the program notes, the axis deviation is in reference of the mean electric axis of the QRS complex.


01192020, 01:55 AM
Post: #4




RE: (41C) Basic EKG Calculations
HI,
Thanks for the answer and the post! I'll program my CALC and try some EKG. Let you know when done Regards. Nelson Dinamarco Nelson Dinamarco 

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