Functions of The ECG Machines Questions and Answers Rated A

Functions of The ECG Machines Questions and Answers Rated A There are three basic functions Input, signal processing, and output display. Input Electrode placed on the skin direct the impulses to the ECG Machine Signal processing Occurs inside the ECG machine. And amplifies the electrical impulses and converts it into a mechanical action on the display. A complex collection of Transistors, Resistors and Circuitry amplify and prepare the signal for transfer to the output display. Output display If the printed ECG tracing. Controls Speed, gain an artifact filter are the three most important controls. Speed 25 mm per second is the most commonly used, use 50 mm per second if there is a rapid heartbeat. Gain Regulates the output or height of the ECG wave form. 10 Mm /m is the normal setting. Artifact Filter Between 40 Hz and 150 Hz is the normal setting. 40 Hz is normally used to reduce artifacts or abnormal marks on the ECG tracing due to muscle tremors or patient movements. LCD Display Area where you can view the patients information that you have entered and the ECG computer is displayed. Heart Rate Limits ECG machine can be set to interpret "Bradycardia" and "Tachycardia" An alarm will sounds if the heart rate goes above or below the number set. Stylus Creates the tracing on the ECG paper, which is treated to the heated stylus. When the heat is truned up the stylus will produce a darker tracing, and a lighter tracing when it is truned down. Standardization Ensures that the machine is recording correctly. 10 mms is the normal setting. Lead Selector Is used to run each lead individually or separately. Unique Quantities of the Heart ... Automaticity Is the ability of the heart to initiate an electrical impulse without being stimulated by another or independent source. Heart muscle tissue can initiate it's own electrical impulse. Conductivity Is the ability of the heart cells to receive and transmit an electrical impluse. Contractility Is the ability of the cardiac cells to shorten in response to an electrical stimulus. Excitability Is the ability of the heart muscle cells to respond to an impluse or stimulus. Deflections on an ECG Positive deflections are pointed upward and negative d eflections are pointed downwards P-wave Is the first positive deflection, usually upright and rounded. QRS complex ... Q-wave Negative deflection before the R-wave. R-wave First positive deflection in the QRS complex. S-Wave First negative deflection after the R-wave. T-wave Positive deflection following the QRS complex. U-wave Small positive deflection following the T-wave. Interpretations ... A. Rates Atrial and ventricular Atrial Rate Count the number of small boxes from the beginning of a P-wave to the beginning of the next P-wave and divide 1500 by that number. Ventricular Rate Count the number of small boxes from a R-wave and divided. Normal is 60 to 100 bpm Bradycardia Below 60 bpm Tachycardia Above 100 bpm B. Rhythm Either regular or irregular ( use plain paper and measures points of the R-wave) Irregular Rhythm Only if the Rhythm is more than 3 boxes off. An irregular Rhythm is Arrhythmia or Dysrhythmia. C. P-wave configurations ... Normal Upright and rounded. Peaked ... Notched ... Inverted or Negative ... Absent ... D. Intervals: P-R, QRS, and Q-T Multiple by .04 PR intervals .12 through .20 count the number of small boxes from the beginning of the P wave to the beginning of the QRS wave and multiply the number by .04. The PR interval is used to determine if a first, second or third AV block is present. First degree AV block Pri is greater than .20 remains consistent and the rhythm is regular. Second degree AV block PRI will vary from one measurement to the next, PRI will be progressively longer with each subsequent conducted P-wave until the QRS wave is dropped. The PRI will be short, then the cycle will begin again (MOBITZ 1.) The rhythm will be irregular. Third Degree Av Block The PRI will vary from one measurement to the next. PRI will be long (more then .20) followed by a short PRI. The atrial rate will be normal (60-100 bmp) but the ventricular rate will be between 20- 40 bpm. There will be more P-wave than QRS complexes. Measure all PR intervals on the EKG ... QRS complex (Intervals) .04- .12 Count the number of small boxes from the Q to the S and multiply by .04. QRS complex determines if a Bundle Branch Block is present. 1. Right Blundle Branch (RBBB) QRS is grater than .12 and positive. 2. Left Bundle Branch Block (LBBB) QRS is grater than .12 and negative. Q-T interval (Less than .40) Count the number of small boxes from Q-wave to the end of the T-wave and multiply by .04. A Q-T grater than .40 indicates Hypertrophy or Cardiomegaly. E. St Segment Determines Ischemia 1. Normal St Segment is flat 2. Elevated St Segment is above the isoelectric line. (Ischemia) 3. Depressed St Segment is below the isoelectric line. (Ischemia) F. T-wave ... 1. Positive Normal 2. Negative Injury G. U wave Appears in Hypokalemia (low potassium)