Respiratory help therpy, Study notes of Nursing

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ECG

https://www.respiratorytherapy zone.com/ekg-study-guide/

Electrical Conduction

▪ (^) 2 basic myocardial cell groups of electrical conduction ▪ (^) Myocardial working cells ▪ (^) Generates physical contraction of heart muscles ▪ (^) Specialized pacemaker cells ▪ (^) Coordinates regular depolarization ▪ (^) Controls rate and rhythm ▪ (^) Primary characteristics ▪ (^) Automaticity ▪ (^) Excitability ▪ (^) Conductivity ▪ (^) Contractility

Normal Cardiac

Conduction

▪ (^) Sinoatrial node (SA) “natural pacemaker” ▪ (^) Atrioventricular node (AV) “backup pacemaker” ▪ (^) Bundle of His ▪ (^) Bundle branches ▪ (^) Purkinjie fibers

Know our waves

▪ (^) P wave = atrial depolarization ▪ (^) normal 2.5mm high ▪ (^) no longer than 3mm long ▪ (^) QRS wave = ventricular depolarization ▪ (^) not wider than 3mm ▪ (^) T wave = ventricular repolarization ▪ (^) can not see the atria repolarize due to QRS complex ▪ (^) Why is there a temporary delay at the AV node?

ECG paper passes at set speed of

25mm/sec

▪ (^) PR interval ▪ (^) start of P wave to start of QRS ▪ 0.12 to 0.20 seconds ▪ (^) longer time would mean an atrio- ventricular block ▪ (^) QRS duration ▪ (^) less than 0.12 seconds ▪ (^) QT interval ▪ 0.4 to 0.43 seconds ▪ (^) RR interval ▪ (^) 0.6 to 1.0 seconds

Time Voltage

Calculating rates

6 second method ▪ (^) Ensure strip is 6 seconds long ▪ (^) Count number of R waves ▪ (^) Times 10 ▪ (^) Better for irregular rhythms

Calculating rates

Big box (300) method ▪ (^) Find two R waves that fall on or close to a bold line ▪ (^) Count number of big boxes between them ▪ (^) Divide 300 by that number ▪ (^) Better for regular rhythms

P WAVE

▪ (^) Are P waves present? ▪ (^) Are they occurring regularly? ▪ (^) Is there one P wave present for each QRS? ▪ (^) Are the P waves smooth, rounded, and upright (positive) or inverted? ▪ (^) Do all the P waves look similar? ▪ (^) Sinus Rhythm ▪ (^) SA node pacing at regular intervals = P waves will also follow regular intervals

PR interval

▪ (^) Are the PR intervals greater than 0.20 seconds? ▪ (^) if yes = may be indication of a delay ▪ (^) electrical conduction or AV block ▪ (^) Are the PR intervals less than 0.12? ▪ (^) if yes = may be indication that impulse was outside of the normal route ▪ (^) Are PR intervals constant across the ECG strip? Normal is 0.12 to 0.20 seconds or 3-5 small boxes

ST segment

▪ (^) Begins – end of QRS Ends – onset of the T wave ▪ (^) ST segment elevation could indicate acute myocardial injury ▪ (^) Life-threatening ▪ (^) ST segment depression could indicate myocardial ischemia

Artifact

▪ (^) Defined as ECG waveforms from sources outside the heart ▪ (^) Patient movement ▪ (^) Loose or defective electrodes ▪ (^) Improper grounding ▪ (^) Faulty ECG apparatus Artifact can mimic certain lethal dysrhythmias. PATIENT ASSESSMENT IS CRITICAL!!!!!!!!!!!!

Sinus Tachycardia

▪ (^) Heart rate > 100 beats/min ▪ (^) resting adult patient ▪ (^) P wave ▪ (^) appropriately present before QRS ▪ (^) Appears just like normal sinus rhythm ▪ (^) Possible causes: ▪ (^) pain, fever, hypovolemia, hypoxemia, certain medications ▪ (^) Treatment – eliminate the cause ▪ (^) pain reliever, fever reducers, fluids, oxygen

Sinus Bradycardia

▪ (^) Heart rate < 60 beats/min ▪ (^) Does not differ from normal sinus rhythm other than rate ▪ (^) Only significant if patient is symptomatic ▪ (^) Hypotension ▪ (^) Fatigue ▪ (^) Lightheadedness ▪ (^) Common causes: ▪ (^) hypothermia, SA node abnormalities, intense athletic conditioning ▪ (^) Treatment if indicated (symptomatic) ▪ (^) atropine