Heart Study

7/28/2019 Heart Study

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LOS ANGELES COUNTY+UNIVERSITY OF S)1J;fHERN C A L I F O R N ~ , ~ ~ I C A L CENTER\ " . ; 'DEPARTMENT OF EDUCATION A N l t ~ O ~ S U L T I ~ q . S E R V I C E S

~ ' ~ r , , ~ ~ . ~ , " i { ; ' . . J

INTRODUCTION TODYSRHYTHMIA RECOGNITIONSELF-STUDY MODULE

Prepared by:Gaye Lynn Miller, R.N., MS, CeRNSenior Nursing Instructor, Critical Care

Originating Date: 05/94Reyised: 01/95, 10/97, 05/99, 05/00


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., '.'. , ',. :.:,:. " .,'''''' '.:Introduction to DysSelf-Study Module "

TABLE OF CONTENTS

Purpose . 111Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111Anatomy of the Heart . 1-7Heart Chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Heart Valves and Circulation . 3Coronary Arteries . . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Review Section I . 5-7

lectrical Conduction System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-11Sinoatrial Node . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9

. 8-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11 'lectrical Waveforms on the ECG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-14P Wave ' . ' . 12QRS Waves . 13T Wave ' 14 Measurement of Intervals . 15-25PR Interval (PR!) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-19 RS Complex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22Practice Strips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-25 alculating the Heart Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26-3 1Practice Strips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 . i lDetermining the Rhythm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32-38Normal Sinus Rhythm . 32-35 fPractice Strips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-38Lead Placement . 39-46

Lead I . 39-40 ead II . 41-42Lead III . 42-43Review Section III . 44-46 I

Atrial Ventricular NodeBundle of HisRight and Left Bundle BranchesPurkinje FibersReview Section II

. 8-9. 8-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9 i


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Introduction to Dysrhythmia RecognitionSelf-Study Module

Determining the Lethal and Potentially Lethal D y s ~ h y t h m i a s 47-60Ventricular Fibrillation 47Ventricular Tachycardia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Asystole 49Symptomatic Bradycardia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Third Degree Heart Block 51Pulseless Electrical Activity 52Premature Ventricular Contraction (PVC) / 53Practice Strips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54-60

Interpreting ABGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62ABGs - Definition 62pH System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Respiratory System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Metabolic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Oxygenation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Treatment 64How to Interpret ABGs 65Practice ABGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '. . . . 67Answers to Practice ABGs 68

Electrolytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69PotassiumCalciumMagnesiumPractice QuestionsAnswers to Practice Questions

(

69707376. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

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Introduction to Dysrhythmia RecognitionSelf-Study Module To assist the participant in the recognition of life-threatening dysrhythmias and to preparethe first-time participant for the Intermediate Cardiac Life Support Program (ICLS).

IOBJECTIVES IAt the end of this self-learning module, the participant will be able to complete thefollowing with at least 80% accuracy:1. Identify the four chambers, the four valves, and the three major coronary arteries

of the heart. .2. Describe the conduction pathway of the heart.3. Distinguish the P, QRS, and T waveforms on the ECG tracing.4. Measure the PR interval and the QRS complex.5. Calculate the heart rate from the ECG tracing using one of the three methodsdiscussed.6. Identify normal sinus rhythm on the ECG tracing.7. Determine the correct ECG electrode placement on the patient.8. Select the appropriate lead with which to monitor the patient continuously.9. Identify the five lethal (life-threatening) dysrhythmias.10. Define and recognize a premature ventricular contraction (PVC).11. Identify the normal and abnormal ABG values to include pH, CO2, HC03 and p02'12. Discuss the interpretation ofABGs including normal ABGs, respiratory acidosis andmetabolic alkalosis. .13. Identify the three electrolytes that may cause lethal dysrhythmias when abnormal.14. Describe the appropriate treatment to correct the imbalance of these threeelectrolytes.

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IREFERENCES IDavis, D. (1992). Differential diai:nosis of arrhythmias. Philadelphia: Saunders.Grauer, K. (1998). A Practical Guide to ECG Interpretation. St. Louis: Mosby.Huszar, R. (1994). Basic dysrhythmias. St. Louis: Mosby.Lipman, B. & Coscio, T. (1994). ECG assessment and interpretation. Philadelphia:Davis.Marriott, H. (1996). Electrocardioi:raphy. Baltimore: Williams and Wilkins.Norman, A. (1989). Rapid ECG interpretation. a self-teachini: manual. New York:MacMillan.

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I ANATOMY OF THE HEART II HEART CHAMBERS IThe heart is a four chamber pump that supplies the body with blood containing oxygenand nutrients. The top two chambers are called the right atrium and the left atrium,they are divided by the atrial septal wall. The right atrium receives venous bloodfrom the body via the superior vena cava (SVC) and inferior vena cava (IVC) . Theleft atrium receives oxygenated blood from the pulmonary veins.

ATRIAAORTA

svc

PULMONARYVEINS

LEFf

IIVe1

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The bottom two chambers are the right ventricle and left ventricle which are dividedby the ventricular septal wall. The ventricular walls are thicker than the atrial walls,especially the left ventricle. The right ventricle is a volume pump and controls theamount of blood pumped to the left heart. It pumps blood from the right ventricle intothe pulmonary artery and usually operates under low pressure. The left ventricle is apressure pump and it pumps the blood into the aorta distributing it to the rest of thebody. It operates under higher pressure than the right side. .

SEPTUM

VENTRICLES

RIGHT VENTRICLE 7'

PULMONARYARTERY

LEFT

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Introduction to Dysrhythmia Recognitionelf-Study Module

IHEART VALVES AND CIRCULATION IDeoxygenated blood flows into the right atrium from the superior and inferior venacava. The blood then flows through the tricuspid valve into the right ventricle.Next, the blood is pumped through the pulmonic valve into the pulmonary artery.From here it flows to the lungs where oxygenation occurs.The oxygenated blood flows via the pulmonary veins to the left atrium where it ispumped through the mitral valve to the left ventricle. From the left ventricle theblood is pumped out through the aortic valve into the aorta and enters the systemic

HEART VALVES

PULMONICVALVE

TRICUSPID

circulation.

VALVE

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RightCoronaryArtery - . ; I f

Aorta

Left Main Artery


ICORONARY ARTERIES IThe heart muscle itself is fed by the coronary arteries These arteries branch from theaorta just above the aortic valve and lie on the outer surface of the heart. The threemain coronary arteries branch many times and extend through all three layers of theheart. (Outer - epicardial layer, middle - myocardial layer, and inner - endocardiallayer.) The three large coronary arteries are the Right Coronary Artery, the LeftCoronary Artery which divides into the Left Anterior Descending Coronary Arteryand the Circumflex Coronary Artery. Blockage of these arteries can cause abnormalrhythms or dysrhythmias.

CircumflexArtery

LeftAnteriorDescendinc \Artery -

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------ ---------------

------ -------


REVIEW SECTION I

1. The heart has four chambers, the top two chambers are called the _and the

2. The bottom two chambers are the and the

3. The right ventricle pumps blood into the and is a_______ pump.

4. The left ventricle pumps the blood into the and is a_______ pump.

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5. Label the following diagram:

m. _j

i.

------ .1.-..... . _ ~ h . - ~ - - - - - - - - -

c.

---..-----. f .

g.

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- - - - -- - - - - - -

JSelf-Study Module

6. The heart muscle is fed by the _ ~ . The threebranches are the _______________ , the _

and the

7. Blockage of these arteries can cause

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ANSWERS FOR REVIEW SECTION I1. Right atriumLeft atrium2. Right ventricleLeft ventricle3. Pulmonary arteryVolume4. AortaPressure5. a. Aortab. Pulmonary artery

c. Left atriumd. Aortic valvee. Pulmonary veinsf. Mitral valveg. Left ventricleh. Right ventricle1. Inferior vena cavaJ. Tricuspid valvek. Pulmonic valve1. Superior vena cavam. Right atrium

6. Coronary arteries'Right coronary arteryLeft anterior descending coronary arteryCircumflex coronary artery7. Abnormal rhythms (dysrhythmias)

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UIL. l U U ~ U U l l LV J JY :SU1Y UllIUa KecognltlOnSelf-Study Module

IELECTRICAL CONDUCTION SYSTEM IThe conduction system of the heart transmits electrical impulses through the heartcausing the muscle to contract.The conduction pathway includes the following:A. The Sinoatrial Node (SA node) is located at the SVC and right atrial junction. Itis known as the pacemaker of the heart and normally controls the heart rate andrhythm. SA node impulses cause the atria to depolarize (contract) generating 60100 beats per minute. From the SA node the impulses travel down theconduction pathway to the AV node.B. The Atrioventricular Node (AV node) is located on the floor of the right atriumnext to the tricuspid valve. It generates 40-60 beats per minute and controls the

number of impulses that enter the ventricles. The AV node delays the impulsesto allow time for the atria to contract and empty blood into the ventricles. Theseimpulses then travel to the bundle of His. I f the SA node is unable to function,the AV node may take over as the pacemaker.C. The Bundle of His is located at the beginning of the interventricular septum. Itconnects the AV node to the bundle branches and has no intrinsic rate.D. The Right and Left Bundle Branches are located in the interventricular septum.The right bundle branch carries impulses to the right ventricle and the left bundlebranch carries impulses to the left ventricle. They have no intrinsic rate.E. The Purkinje Fibers are a network of fibers at the end of each bundle branchwhich are dispersed throughout the ventricular wall (myocardium). As theheart's electrical impulses travel through these fibers ventricular contraction(depolarization) occurs. The Purkinje fibers have an intrinsic rate of 20-40 beatsper minute.

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AV NODE

RIGHT BUNDLE BRANCH

~ ~ L E F T BUNDLEBRANCH

I .

The Conduction System

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REVIEW OF SECTION II1. The node has an intrinsic rate of to- - - - - - . - - : - - - - beats per minute and is known as the of the heart.2. The node has an intrinsic rate of to - - , - - - - - = - - : beats per minute. It causes a delay in impulse transmission allowing the atria to________ and empty blood into the ventricles.3. The have an intrinsic rate of 20 to 40 beats perminute. They are dispersed throughout the - 4. Label the following diagram with the appropriate conduction system components:

a. . . . ; ~

b. - ~ ~ ~ - - - - e . ~ ~ - - - - - f .

c. ~ ~

d. - - . ; ; I I ~ ~ ~ ~ ~

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ANSWER FOR REVIEW SECTION II1. SA60-100

Pacemaker2. AV40-60Contract3. Purkinje fibersHeart muscle or myocardium4. a.b. SA nodeAV nodec.d.e.

Right bundle branchPurkinje fibersBundle of Hisf. Left bundle branch

(

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ntroduction to Dysrhythmia RecognitionSelf-Study Module

I[ ELECTRICAL WAVEFORMS ONmE ECG I ,

Electrical impulses from the heart are recorded on EeG paper via electrodes and leadsplaced on the patient's chest. One normal heart beat contains three waveforms; the [P, QRS and T waves. ,PWAVE I

The P wave represents atrial depolarization (contraction). See illustration below. i\

13

IIII

III II II I

II I I III ,-I' ~ ~ I II II fI

Time in 0 0.2 0.4 0.6 0.8seconds


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IQRS WAVES I The QRS complex represents ventricular depolarization (contraction) on the

EeG. See illustration below.

. I Ir" I I

II I

I

I-' IQ I. IfI'Ie1-

Time in 0 0.2 0.4 0.6 0.8seconds The Q wave is the first negative (below baseline) waveform. The R wave is the first positive (above baseline) waveform. The S wave is the second negative waveform moving up to the baseline. The QRS complex is a bigger waveform than the P wave because the ventricleshave thicker walls than the atrial and therefore, a stronger contraction.

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i ' < ~ : " ~ " " ' ~ u . .....,"""", '&'V'&' '&' ' ' 'V .L- ' .J U.&.,J.,J.J u,.&..L.&. .... l .U ..."""''"''''v6.1...........1.'-',J. ..Self-Study Module

The T wave represents ventricular repolarization (resting time). See illustrationbelow.

I II I

I I III III II

,. I II I I~ I I II. II.1"

0.8.6.4.2ime in 0seconds During this phase (resting time) it may be easy to stimulate an early heartcontraction in some patients. This may cause dysrhythmias to occur.

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[ MEASUREMENT OF ECG WAVEFORMS

Time is measured horizontally on the EeG paper in the following manner: One small box represents .04 seconds .- One large box represents .20 seconds

(.04 one small box)

') 1 11 I I I I II I I I I II I I I I I II I I III I I I I I I I I II I I f I I I I I II I I I I I II I I I I II I I I I I I I II I I I I I f II I I I I I I I I rI I I I I I I I II I I I I I T I III I I I I I I I I II I I rr I I I I I I0- I t I I ~ l I I I I I I

1........ 1 I I ~ , I 1 I I I I, I 6[ I I III I I I ....". " I I I II I I I I I J, I I , I I I I II I I 'I I I I I II I t I I I I II I I I I I I I:. I I I I I I III I I I I I I

Time in 0 ">.t 0.4 0.6 0.8seconds (.20 one large box).- /

You will need ECG calipers to measure ECG intervals and complexes.

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IPR INTERVAL (PRJ) IIt is important to determine the length of the intervals/complexes to ensure that apatient's EeG is normal. The following section demonstrates how to measure the PRinterval (PRI) and the QRS complex.

The PRJ begins at the onset of the p wave and ends at the first wave of theQRS complex The PRJ represents the time for atrial depolarization Normal PRI is .12 to .20 seconds

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A PRJ of greater than .20 indicates abnormally slow conduction of impulses fromthe atrium to the ventricles and is called a heart block.

This PRJ is .20 - read on to learn how to do this! Place one point of your calipers at the beginning of the P wave and the other .,point at the beginning of the QRS complex. (The QRS complex begins at thepoint where the waveform leaves the baseline. This may be either above orbelow the isoelectric line [baseline].) See illustration below.

, I I I ! , I , I I I I I . , , , , II I : , . , , , , I , I I , , , ,, , I I , , I , ! I , I , !, I I , : , I , ,, I , I , , : I . I , ,I ! I ., , I I , , , I , , I I I ; I I , . , I , , : ,, I , I I I I , I ; : ; , I I I , . : . I , , , I t I , ; I I , , , , , , , I I I I , , I , I , , ,, I I , , I I , ..... I I , , "'" " , , I I I I ; _. I ' ' - ,-.; I I I I --r' " , t n' ' I I I , I . II I I ,. .

, I ; ,I , . I It. I i I , , II I I I I I I I , I I I I

, I , I, , ;

, ,: , , I I , I , I , I , I , . . , I , I I ! , , II I I I I I I , , I 1 I ; I I : . I I ' .t I I I I I , I I I I :, ; ; , , , . , I; I , I I ; I , , I , I , I , I I I , I I I ,

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Hold your calipers in this position and move them to the top of the ECG paper. Count the number of boxes that fit between each point of the calipers.

Calculate the PRI.

Remember each small box represents .04 seconds.

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In the example on page 18 the distance from the beginning of the p wave tobeginning of the QRS complex is 4 small boxes. the

To calculate the PRJ multiply the,number of boxes by .04 seconds (4 x .04.16) The PRJ is .16 seconds. =

This is a normal PRJ and represents normal conduction from the atrium to tventricle. he

III

,

= l4- .( 8

== 1?

== 1.6~ '1 0

= 11li-

IJ ~ ..... ," , I

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elf-Study Module

IQRS COMPLEX I The QRS begins at the point where the first wave of the complex leaves the

baseline and ends where the last wave of the complex returns to the baseline. This represents the time required for ventricular depolarization (contraction). The normal QRS is .06 to .10 seconds

I , . I I, I I II I, I I I I, I , II I I I,I , I : I,

I ,, , ; , II I : II ~ t

..... . ,I I I

I I I I; ,

I , II I I I IIr

I

'.' .I , ,

I II ; ; .. I, I, " I I I ; I, I , ; I I I ,

r I ; , I I I ; I I I I, I .

. , .t t t t1 ,

I I I nI ,

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I I I

I I . . . . , tl : " I fl

I Ii f j

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i I I, '

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I I .

I I I

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f t

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: , I I

I I

I " I I

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t I I..... . ; Il ~ " , "

, I I ',

I I I I I

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Measure the QRS complex using themethod described on pages 17 and 18.

Multiply the number of small boxes by.04 seconds. The duration of the QRS complex is.08 seconds

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I~ = .u

;= 0RF .1 2

= 1 GI I = .2n-

h l l ~ =- III~ I - ~ I i " I l ~ ,~ "

I I ,

The above complex illustrates a normal QRS complex measuring .08 seconds.

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to Dysrhythmia Recognitionelf-Study Module

'.I I. . . . . . ' I I. '. . . -- ... . l.,I I. II III I I ,.. 1t ilI IIt. .. - - H

The complex above is two small boxes therefore it is .08 seconds, and representsnormal AV conduction.

The complex above is three small boxes therefore it is .12 seconds, which is .02seconds greater than normal. This represents abnormal AV conduction. A QRS complex longer than .10 represents abnormally slow conduction ofimpulse through the ventricles and indicates a block in the bundle branches.

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PRACTICE STRIPS

Complete the following practice strips:1.

PRJ __RS

Normal or abnormal conduction -----2.

PRJ _QRS _Normal or abnormal conduction-----

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Introduction to Dysrhythmia RecognitionSelf-Study Module 3.

~ .PRJ _QRS _Normal or abnormal conduction------4.

~ : . : ".-1 __ -J I ~ ' ~ ~ - ~ _ M:. . , . . . . ; . ~ .,"t,

, ~ . . , . - - ,.

PRJ _QRS _Normal or abnormal conduction ------

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- - ; . ~ ~ . ...--. __.. ':_ ..--... -"

~ = - ...... ~ - , " 1 \ 1 :1:=-:1:"

: r : : : : - - + ~ -;-.. ....:


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1. PRJQRSConduction

2. PRJQRSConduction

3. PRJQRSConduction

4. PRJQRSConduction

ANSWERS TO PRACTICE STRIPS

.12

.08Normal atrial and ventricular

.16

.06Normal atrial and ventricular.20.06Normal atrial and ventricular

.14

.16Abnormal ventricularVentricular conduction is slower than normal therefore, a bundlebranch block is present.

Do not be concerned if your PRJ or QRS complex measurements differ slightly fromthe above answers. I f your answers are within one small box you are correct.

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ICALCULATING HEART RATE IThe BeG is also used to calculate heart rate.There are various methods used. The following are three examples:Example A 300-150-100-75 method

Find an R wave that falls on or near a heavy black line on the BeG paper.This is where you start. Count the heavy black lines until you reach the next R wave. This will be300. Each heavy line corresponds with the number listed on the example below.

Start 30015010075 60I

', . .,

" ., I

. ," .j

, ,." I "

The heart rate is slightly faster than 60 beats per minute.

Remember normal heart rate is 60-100 beats per minute.

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Example B 6-second strip Each 3-second interval is marked by a vertical line at the top of the ECGpaper. Two of these 3-second intervals equal 6 seconds. Count the number of QRS complexes in a 6-second strip and multiply this x10. See example below.

" c l" L d SUOW'l Mt.mo. l j ~ ( - - - - - - - 1 0 ) c ~ 1 0 : 1 0 0 - - - - - - - - ~ ) .J

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Example C Small box method In one minute, 1500 small boxes go through the ECG machine. Count the number of small boxes from one R to the next R wave. Divide 1500 by that number and this will give you the heart rate. See example below.

~ ' = 1 0 0 15

Total number of small boxes in this strip is 15. Divide 1500 by 15 and this will give you 100 beats per minute. This method is useful when you do not have a 6-second strip. Not accurate when rhythm is irregular.

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PRACTICE STRIPSComplete the following practice strips:1.

_2.

_3.

Rate

Rate

Rate _

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4.

_ate

5. Use 300-150-100 method

_

6. Use the small box method

_

Rate

Rate

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ANSWERS TO PRACTICE STRIPS1. Rate 80 beats/minute2. Rate 110 beats/minute (tachycardia)3. Rate 90 beats/minute4. Rate 50 beats/minute (bradycardia)5. Rate 80 beats/minute6. Rate 125 beats/minute (tachycardia)

( 1500 = 125)12

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IDETERMINING TIIE RHYTIIM IINORMAL SINUS RHYTIIM IA. Criteria for sinus rhythm.

P waves all have the same configuration. QRS complexes all have the same configuration. The P to P interval (distance from one P wave to the next P wave) is thesame and does not vary. The R to R interval (distance from one R wave to the next R wave) is the

same and does not vary. All the above occurs throughout the entire ECG strip.

,......

~ : ' . .;+;

.- .. .... ...... ~

- ~ . , ' . ._......_+0- ..... ~ .. - .. , "' " ... ;. ;........ ,,"., .. . i . -' ~ r-., .. - f ~ ,.. ~ . ~ , .. .,-......

-.-

_ ...,"

The distance from P to P is regular--therefore the atrial rhythm is regular.

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B. (Cont'd)

P wave for each QRS P to P is regular R to R is regular PRI is .18 QRS is .08 Rate is 90 Interpretation: NSRc. I f regular sinus rhythm is less than 60 beats per minute, the rhythm is calledsinus bradycardia.

P wave for each QRS P to P is regular R to R is regular PRI is .14 QRS is .08 Rate is 50 Interpretation: Sinus bradycardia

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j" _" ' - ' ---' . " " " :J .-"


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- - . I . . . . . . . . . . " ' ' - ' ' ' ' ' ' ' ' U ~ l U U U l l Self-Study Module D. If regular sinus rhythm is greater than 100 beats per minute, the rhythm is calledsinus tachycardia.

P wave for each QRS P to P is regular R to R is regular PRIis.14 QRS is .08 Rate is 110 Interpretation: Sinus tachycardiaE. I f regular sinus rhythm is 60 to 100 beats per minute but the P to P and R to Rare slightly irregular, the rhythm is called sinus arrhythmia.,

t,, ..,..co .

P wave for each QRS P to P is irregular R to R is irregular PRIis .12 QRS is .08 Rate is 80 Interpretation: Sinus arrhythmia36

~ i i l l i i ' i ' "

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PRACTICE STRIPS1.

P wave per QRS: _P to P: _R to R: _PRI: _QRS:Rate: ----------Interpretation:

2.


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3.

P wave per QRS: _P to P:RtoR : - -- - - -- - - PRI: _QRS:Rate: ----------Interpretation:

4.


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ANSWER TO PRACTICE STRIPS1. P wave present for each QRS

Il

II1,

P to P: RegularR to R: RegularPRJ: .12QRS: .08Rate: 70Interpretation: Normal sinus rhythm

2. P wave present for each QRSP to P: RegularR to R: RegularPRI: .14QRS: .06Rate: 130Interpretation: Sinus tachycardia

3. P wave present for each QRSP to P: RegularR to R: RegularPRI: .16QRS: .08Rate: 50Interpretation: Sinus bradycardia

4. P wave present for each QRSP to P: IrregularR to R: IrregularPRJ: .12QRS: .08Rate: 60Interpretation: Sinus arrhythmia

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I ECG ELECTRODE and LEAD PLACEMENT IThe ECG electrodes and leads must be correctly placed on the patient's chest in orderto interpret the ECG rhythm accurately.Each lead reviewed provides a different picture of the electrical activity in the heart.The ECG configuration will be different depending on which lead is used to interpretthe rhythm.The three electrodes are placed in the positions noted on the diagram below. Right ofthe sternum, placed below the right clavicle, left of the sternum, placed below the leftclavicle and the third electrode is placed on the left at approximately the seventh rib.The white color-coded lead hooks up to the right electrode, the black color-coded leadhooks up to the left upper electrode and the red or green lead hooks up to the leftlower electrode.

o ElectrodeL - ~ (cable with coloredcoded end)

The lead (cable) snaps/hooks onto the electrode

If the BCG monitor is turned on to the Lead I, the R electrode becomes negative andthe L upper electrode is positive. The left lower electrode is the ground.

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The electrical impulses travel from the negative lead toward the positive lead. Therefore the EeG waves are upright in lead 1.

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The right-sided electrode is negative. The left-lower electrode is positive. The left-upper electrode is the ground.

When the ECG monitor is viewinglead II the electrical impulsestravel from the negative leadtoward the positive lead.-R

+L Therefore the ECG waves are

upright in lead II.II

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--


The right-sided electrode is the ground. The left-upper electrode is negative. The left-lower electrode is positive.

43

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III When the EeG monitor is viewing lead III the electrical impulses travel from thenegative lead toward the positive lead.

- L upper~ + L lower

Because of this positioning the EeG complex may be biphasic (some portion ofwave is positive and some portion is negative) or it may be upright.

* When using a three-lead system, the preferred lead to monitor your patient would belead II.

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'-------' '----

L E A D I ~ / ' \ I/-

2.

BeG Complex:

~

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' - . - - - /

,-

3.

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REVIEW SECTION IIILabel the following diagrams. For each lead indicate the location of the positive, negative and ground electrode. State whether the complex in that lead is normally positive, negative, or biphasic. Label the color of each lead. Indicate the direction the electrical impulses normally travel.



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toduction to Dysrhythmia Recognitioni-Study Module

ANSWERS TO REVIEW SECTION

1.

ECG waveform is upright

2. LE%,'(1(.1


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3.

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BeG waveform is uprightor biphasic

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etion to Dysrhythmia Recognitiondy Module

I DETERMINING THE LETHAL DYSRHYTHMIAS I..e following dysrhythmias will be discussed:

) Ventricular Fibrillation Symptomatic Bradycardia/Third Degree Heart BlockVentricular Tachycardia Pulseless Electrical Activity (PEA)Asystole Premature Ventricular Contraction (PVC)

~ N E N T R I C U L A R FIBRILLATION*'i

efinition: Total disorganization of the heart's electrical activity associated with signsd symptoms of no pulse, no blood pressure. Chaotic rhythm No identifiable BeG waveforms Ventricular contractions are absent, the heart is fibrillating (looks like a bagof wiggly worms). It can appear large and coarse or small and fine. (See illustrations below.)

~ I ! .

i

II ii 1'1:II

Coarse Ventricular Fibrillation

Fine Ventricular Fibrillation48


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1.J1;;1l-..>LUUy IV.lUUUIC

IVENTRICULAR TACHYCARDIA IDefinition: a rapid ventricular rate associated with signs and symptoms ofcardiovascular collapse, e. g., low BP, high HR.

Heart rate is 150 beats/minute or greater. P wave difficult to see (may appear sporadically). QRS complexes are wide and bizarre (usually> .12) and look alike. Usually regular rhythm, i.e., R to R is regular.

f t ...


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IASYSTOLE IDefinition: Electrical activity is absent. A straight line is usually present on the EeG.

Always check two different leads On the monitor to verify this rhythm.

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ISYMPTOMATIC BRADYCARDIA IDefinition: Same as sinus bradycardia except the patient has a low blood pressure andis restless or lethargic Therapy or treatment is the same as Third Degree Heart Block.

r t:-:- '_._ .. '._._-=......: ~ . -.........,..: _ : { ~ :

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~ ~ ~ _ = , .... " ' c ~ & _


ITHIRD DEGREE HEART BLOCK IDefinition: This rhythm represents complete absence of conduction between the atriaand the ventricles. It may also be called complete heart block.

The AV node is not functioning. Atrial impulses from SA node are not getting through to the ventricles sothe Purkinje fibers must become the pacemaker for the ventricles. P waves are present but do not correlate with ventricular activity.Therefore, there is no relationship between the p wave and qrs complex. P to P and R to R intervals are usually constant but share no relationshipwith each other. Ventricular rate is usually less than 40.

mil

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{" .q/\iIntroduction to Dysrhythmia Recognition;::;-;, (" Self-Study Module \ '

' \IPULSELESS ELECTRICAL ACTIVITY (PEA)DefInition: A normal ECG rhythm is present on the monitor indicating electricalactivity but mechanical activity is absent (no contractions).

Blood is not being pumped out of the heart, therefore the patient will haveno pulse. Even though the ECG shows NSR the patient has no pulse.

_ ~ I - ~ f : - ' I - ~ _ J _ : ~ f 8 ~ r : __ ~ ' ~ _ J 1.', : ~ i - : > ~ _ ~ ' ~ . ! - J ' - ~ ! F: -- ~ : - _ ~ : : = : - : .,. - =--= .. - = l = = = ~ - - ~ b . ; ~ l : - ~ L = - 1 - __ __ If:- ; ; - - : ; ~ - : : - ~ : ; ] ~ - ~ - ~ : li=!:..:"::.+-'-.1- . r - - ' - . + - F ' - - ' - j F - = ~ - : - I ,-..=J:=.:=:_='.="--'--'-J+' ,. -- , - - r - - - -- - I --I:::.T -j .- - - . - , - - --I-f--- -=1===1='- I-e...: --I--- - . ~ . '.-, 1--"- , ' -1 - - - -4 -- ,r--:i -f - f - - - - l - I - r--- -, -- - l, 1 r-

:c::j iCc:' : : ~ : :._:. = = - ~ - _ . - = -_:/-=..:. - - , J - - ' - - " - " ~ f = f:-+=i'-:-='E .--=-- I=:.-=r-'=::-- = f : ~ '-=:=:::: g ~ * - i - ' - - - ' : r-:'. ; ~ - ~ ; ; ~ : . ~ ' ~ ~ ~ : ~ ~ - ~ ' ~ : ~ = i i ~ i ~ ~ ~ ~ ~ g ; , I ~ ~ ~ : = T ~ ; ; ~ ~ ~ ~ ~ ~ ~ - = .. I: .. '. :::1= .:==:jc.--: == i1 '==1=, "'::=:-=t I [==*=t==.:: :1 :=d = ~ l = t : = I = = - ' : : . . : : : = l = ~ L - - : - - - = - ! I-:=r=-::s--.-:-l

"'" , ' ; I - ~ ! : = ~ , : ,--::=+'=1 ...=' =.=F---.'" : . ~ t _ - ' - - ' . - : I!-::-+--:-t,;;: --/:.-----!::::A:, 1 = t = ~ J \ t I - ~ ,-,--f::::c:h,-.:' e = ~ : : C i I : : i.. -v r-r---'o.. - ,r . . ... : - ~ . . . . , .- l = r - . . . ~ . r - : ' - - : ' ~ . . . . . . . . . ..-'T .. ~ ' ~ ~ i ~ 1 ~ ~ 7 E ~ , ~ j ~ C ~ T ~ 4 = - f ~ t = t i ~ I T ~ f : : i 2 C - ! i : i ~ '"

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oduction to Dysrhythmia Recognition,.If.Studv Module

~ R E M A T U R E VENTRICULAR CONTRACTION (pVC) IDefinition: An irritable focus in the ventricles causing early or prematuredepolarization (contraction).

The PVC will cause the ECG rhythm to be irregular. PVCs may also increase the heart rate. The QRS is bizarre looking and wider than .12. Frequent PVCs (greater than 6 per minute) are often treated withLidocaine. PVCs that are multifocal (do not look alike) are more serious than unifocalPVCs (look the same).

W:U:lt I II \Unifocal

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PRACTICE STRIPSIdentify the dysrhythmia1.

2.

t

3.

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,troduction to Dysrhythmia Recognition"elf-Study Module

4.

I

5. The patient has no pulse.

6.

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ANSWERS TO PRACTICE STRIPS1. Ventricular tachycardia (V-tach)2. Asystole3. Ventricular fibrillation (V-fib)4. Complete heart block/bradycardia (3 AVB)5. Pulseless electrical activity (PEA)6. V-fib7. V-tach8. Asystole9. Sinus rhythm with a pair of PVCs10. Complete heart block11. Sinus rhythm with one PVC12. V-fib13. V-tach14. Sinus rhythm with multifocal PVCs

1

15. V-tach16. PEA

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IINTERPRETING ABGs IIABGs - DEFINITION 'I Blood sample taken from an artery to determine:

Acid-base status (PH)OxygenationVentilation Normal values

pHpC02HC03p02O2 Sat

= 7.35-7.45= 35-45 mmHg= 23-25 mEq/L= 80-100 mmHg= 95-100%

!PHSYSTEM I Reflects the acidity or alkalinity of a solution Reflects alteration in respiratory and metabolic processes

Respiratory - controls CO2 (acid) t CO2 = pH acidotic CO2 = t pH alkalosisMetabolic - kidney controls HC03 (base) t HC03 = t pH alkalosis HC03 = pH acidotic

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ITREATMENT1. Respiratory

a. Respiratory acidosis caused by hypoventilation pC02 > 45 mmHgTreat the cause - e.g., decreased respiratory rate

Hyperventilate with bag-va1ve-mask (ambu bag)b. Respiratory alkalosis caused by hyperventilation.

pC02 < 35 mmHgTreat the cause - e.g., increased respiratory rate caused by pain or anxiety

Breathe into "brown" bagRelieve pain or anxiety2. Metabolic system

a. Metabolic acidosis caused by a loss of bicarbonate (HC03) or retention ofmetabolic acids HC03 < 22Treat underlying cause, i.e., diabetes, diarrhea

Give bicarb replacement only if pH < 7.10 and HC03 < 10b. Metabolic alkalosis caused by an increase in the intake of HC03 or from

Increased loss of metabolic acids HC03 > 26 ITreat underlying cause, i.e., vomiting, chloride depletion Iive chloride, replace electrolytes

II

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l

,(';Introduction to Dysrhythmia Recognition,:Self-Study Module

3. OxygenationIa. Decreased oxygenation

P02 < 80 O2 Sat < 92Treat with:

Oxygen administrationIncrease FP2Intubate/ventilate

[ HOW TO INTERPRET ABGs I1. Look at pH - increased, decreased or normal.2. Look at pC02 - increased, decreased or normal.3. Look at HC03- - increased, decreased or normal.4. Look at oxygenation P02, O2 sat.Examples1. pH 7.39pCOz 38HC03- 23pOz 100

Oz Sat 98%2. pH 7.52pC02 ,.30HC03- 24pOz 88

Oz Sat 96%3. pH "/\7.49pCOz 35HC03- 1128pOz 85

Oz Sat 97%

NormalNormalNormalNormalNormalIncreased (alkalotic)Decreased (alkalotic)NormalNormalNormalIncreased (alkalotic)NormalIncreased (alkalotic)NormalNormal

Interpretation: NOnrull ABGsTreatment: None

Interpretation: Respiratory AlkalosisTreatment: "Brown "bag treatmentif awake

Interpretation: Metabolic AlkalosisTreatment: Treat the cause

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IntroductIOn to Dysrhythmia RecognitionSelf-Study Module

4. pHpC02HC03p0 2O2 Sat

7.2056237286%

' DecreasedIncreasedNormalDecreasedDecreased

(acidotic)(acidotic)(hypoxemia)

Interpretation: Respiratory Acidosiswith hypoxemiaTreatment: Hyperventilate withambu bag and ensurepatient is receiving100% O2 (or as closeas possible)

5. pHpC02HCO-3p0 2O2 Sat

7 . 0 5 < ~ 395 JI9895%

DecreasedNormalDecreasedNormalNormal

(acidotic)(acidotic)

Interpretation: Metabolic AcidosisTreatment: Treat the cause

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1. pH 7.25pC02 55HC03 23p0 2 54O2 Sat 80%

2. pH 7.50pC02 39HCO3 28p0 2 8002 Sat 95%

PRACTICE ABGs .

Interpretation: _Treatment: _

Interpretation: _Treatment: _...,....;.. _

"

3. pH 7.43 mrerynmtioo: _pC02 37HCO-3 25 Treatment: _pO;:! 8802 Sat 97%

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1. pH 7.25 DecreasedpCO2 55 IncreasedHC03- 23 Normalp02 54 DecreasedO2 Sat 80% Decreased

2. pH 7.50 IncreasedpC02 39 NormalHC03- 28 Increasedp02 80 NormalO2 Sat 95% Normal

3. pH 7.43 NormalpC02 37 NormalHC03- 25 Normal88 NormalO2 Sat 97% Normalp02

I

I


ANSWERS TO PRACTICE ABGs

(acidotic)(acidotic)(hypoxemia)

Interpretation:Treatment:

(alkalosis)(alkalosis)



Respiratory Acidosiswith hypoxemiaHyperventilate withambu bag and ensurepatient is receivingI()()% O2Metabolic AlkalosisTreat the cause

Normal ABGsNone

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ELECTROLYTES

This chapter includes a brief discussion of three electrolytes which, when they becomeabnormal or imbalanced may prevent resolution of a lethal dysrhythmia.IELECTROLYTES1. Potassium (K+) 3.6-5.2 mEq/L

Promotes transmission of impulses through the heart's conduction system Aids in the regulation of acid-base balance Promotes contractility of heart musclesa. Hyperkalemia (K+ > 5.2 mEq/L)

Causes:Renal diseaseExcessive administration of KCI

Signs and Symptoms:~ u s c l e weakllessECG changes ~ peaked T wavesSlowing of conduction and decrease in excitability therefore adecrease in contractility

Treatment:Treat underlying causesCheck K+ levelSevere K+ > 6.5 mEq/LGive CaCl2 or calcium gluconate, LV. insulin, NaCH03,Kayexlate, or dialysis (depends on patient diagnoses and situation

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b. Hypokalemia (K+ < 3.6 mEq/L) Causes:

Loss of K+ through: GJ diarrhea, vomiting Skin, extreme sweating Stress - Release of epinephrine promotes entry of K+ intocells from extracellular space

Signs and Symptoms:Fatigue, leg cramps

reflexes, muscle tone'Disrupts cellular integrity in heart - damages muscleDysrhythmias occur due to irritable muscle, usually ventriculardysrhythmias (PVCs, V-tach, V-fib)

Treatment:Check K+ levelAdminister K+ (20 mEq KCl/hr per LV.)Monitor ECGWatch for respiratory arrest

2. Calcium (Ca++) 8.8 - 10.3 mg/dL Maintains hardness of bones and teeth Promotes muscle contractions - skeletal and cardiac

Works directly on contractile force of cardiac musclesa. HypercaIcemia(> 10.3 mg/dL)

Occurs when rate of Ca++ entry into serum exceeds kidney excretion Causes:

Hyperparathyroidism and malignancyt GJ absorption - Vit D overdose and t Ca++ supplements

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Signs and Symptoms: neuromuscular irritabilityWeakness, fatigue

GI - Nausea, vomiting, t gastric secretionRenal failure cardiac action potential causing short repolarization period,V-fib can occur hereAsystole at Ca++ levels L 18.0 mg/dL

Treatment:Usually for Ca++ levels> 12.0 mg/dLNormal saline and loop diureticsMaintain urine output 200-300 cc/hrLasix q 2-4hPhosphate administration (Phosphate binds Ca++)

b. Hypocalcemia 8.8 mg/dL) Causes:

H y p o p a r a t h y r o i d i s ~ intestinal absorptionCa++ deficient dietImpaired Vit D metabolismChronic diarrhea

Small bowel diseaseExcessive Ca++ loss Massive infections or bums Alkalosis Administration large amount citrated blood (Bank Blood) ETOH

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Introduction to Dysrhythmia Recognition.Self-Study Module

Signs and Symptoms:Neuro Muscle cramping Seizures Personality changes - depressiont irritable confusion Finger numbness/tinglingRespiratory Stridor Spasm (brQ!!.


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. l . uuuuu \ , .UUU Uy:SlllyLnnua KecognltlonSelf-Study Module

3. Magnesium(Mg++) 1.7 - 2.3 mg/dL Promotes contraction of cardiac muscles Activates enzymes for cellular metabolisma. Hypermagnesemia (> 2.3 mg/dL)

Causes:Renal failureLaxatives, antacids

Signs and Symptoms:Cardiovascular (CV) Bradycardia SA, AV nodal blocks Complete heart block

, Hypotension Vasodilation

Flushing Sweating

CNS Drowiness Coma at Mg++ levels 2.. 12-15 mg/dLRespiratory Respiratory center depressionGl Nausea, vomiting Sensation of thirstRenal Renal failure

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Treatment:Check Mg++ levelEliminate causeLoop diuretics, normal saline infusionCalcium gluconate to antagonize symptomsDialysis if due to renal failure

b. Hypomagnesemia 1.7 mg/dL)Causes:

Diuretic therapyDigitalisMalnutritionChronic alcoholismColitis

Signs and Symptoms:Neuro

Mood changes, confusionPeripheral nerve irritabilityTremors, convulsions, tetany

Cardiovascular (CV)Dysrhythmias

PVCsSVTV-fib, V-tach, or Torsade de pointesGI Anorexia, nausea, vomitingSensation abdominal distention

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Treatment:Check Mg ++ levelMonitor levels daily on patients at riskMg++ replacement Dietary - mild symptoms 1.V. for symptomatic patient

Monitor other electrolytes as well I f K+, Mg++ - correct Mg++ first

Code situationFor V-tach: Give 1-2 gm Mg++ diluted in 10 ml DsW Administer over 1-2 minutesFor V-Fib Give 1-2 gm Mg++ IVP

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PRACTICE QUESTIONS

1. K+ < 3.2 mEq/L is dangerous because it can cause:a. Ventricular dysrhythmiasb. Teeth to fall outc. Seizuresd. Depression

2. Treatment of low K+ would be to administer:a. Phosphateb. PO fluidsc. LV. KCId. Antacids

3. Hypocalcemia especially levels < 8.8 mg/dL can cause:.

a. Increase in Vitamin Db. Decreased contractility of a r d i a ~ musclec. Renal failured. Mood changes, relaxed, calm

4. Treatment of low Ca++ would be to administer:a. Phosphateb. Normal salinec. Vitamin C supplementsd. Calcium gluconate PO or I.V.

5. Hypomagnesemia especially levels < 1.7 mg/dL are dangerous because it cancause:a. Weak deep knee reflexesb. Respiratory depressionc. Torsade de pointes .d. Sensation of thirst

6. Treatment of low Mg++ in a code situation would be to administer:a. Mg 1-2 gm IVP over 1-2 minb. Lasix 80 mg IVPc. Normal saline 500 cc bolusd. CaCI to increase hypotension

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- -- - - - ....... .. - J ~ . & . . & . & J ..I..I..I..l.a .I.""",,,",V!)l11LIUllSelf-Study Module

7. Mr. C. is admitted complaining of nausea and vomiting., He is confused and hisBeG shows Torsade de pointes. His medical history shows that he has been ondigitalis for several years. The cause of these symptoms most likely would be:a. Hypomagnesemiab. Hypercalcemiac. Hypophosphatemiad. Hypokalemia

8. Mrs. J. is admitted with a history of renal disease. She has been complaining ofmuscle weakness and lightheadedness. Her BCG shows peaked T waves. Thesesymptoms most likely would be caused by:a. Hypokalemiab. Hypomagnesemiac. Hyperkalemiad. Hypercalcemia

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ANSWERS TO PRACTICE QUESTIONS

1. a2. c3. b4. d5. c6. a7. a8. c

Heart Study

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