Cardiac Monitoring

 

TERMINAL LEARNING OBJECTIVE

Give the necessary medical equipment in a holding or ward setting. You are providing casualty care as part of an integrated team in a Minimal Care Ward. Conduct cardiac monitoring

INTRODUCTION

The electrocardiography (EKG) is a device used to measure cardiac electrical current.  Electrical currents will provide important information about heart contractions and can identify potential problems.  This device is key in the assessment of cardiopulmonary symptoms and can often indicate the urgency of treatment.

 

Basic Cardiac Monitoring

 

a.   Electrocardiogram (ECG)

 

   (1)  Graphic record of heartís electrical activity

 

   (2)  Body acts a  conductor of electricity and the heart is the largest generator of electrical energy

 

   (3)  Electrodes placed on the skin can detect total electrical activity within the heart

 

   (4)  Electrical impulses on the skin surface have very low voltage.  The ECG machine amplifies these impulses and records them on the ECG graph paper or on a monitor screen called an oscilloscope.

 

   (5)  Positive impulses appear as "upward" deflections on the graph paper or monitor screen

 

   (6)  Negative impulses appear as "downward" deflection on the graph paper or monitor screen

 

   (7)  Absence of any electrical impulse produces an isoelectric or "flat" line (asystole).

 

   (8)  "Artifacts" are deflections the ECG produced by factors other than the electrical activity of the heart.  Common causes are

 

      (a)  Muscle tremors

 

      (b)  Shivering

 

      (c)  Patient movement

 

      (d)  Loose electrodes

 

      (e)  60 cycle interference

 

      (f)   Machine malfunction

 

   (9)  Eliminate all artifacts before attempting to record an ECG

 

      (a)  Replace loose electrodes

 

      (b)  Cover patient with a blanket to prevent shivering

 

      (c)  Wipe oily skin or diaphoretic skin with alcohol and then attach leads to increase adherence to the skin

 

b.   ECG Leads

 

   (1)  Monitors heartís electrical activity by monitoring voltage change through electrodes placed at  various places on the body surface

 

   (2)  Each pair of electrodes is called a "lead"

 

   (3)  Basic cardiac monitoring uses only 3 leads

 

   (4)  Three types of ECG leads are

 

      (a)  Bipolar

 

      (b)  Augmented

 

      (c)  Precordial

 

   (5)  Bipolar leads are the most frequently used and have one positive electrode and one negative electrode

 

   (6)  Leads I, II and III commonly called limb leads are bipolar and are the most frequently used leads in basic cardiac monitoring

 

NOTE:  In the definitive care facility, 12 leads are normally used to detect a variety of conduction abnormalities, to include the presence and location of a myocardial infarction.  This technique requires the use of augmented limb leads and precordial leads and allows the examination of the heart in two planes.

 

   (7)  Bipolar leads provide only three views of the heartís electrical activity, which is adequate for detecting life-threatening dysrhythmias.

 

c.   Routine ECG monitoring

 

   (1)  Routine ECG monitoring generally uses only one lead

 

   (2)  Most commonly monitored leads are either Lead II or the modified chest lead 1 (MCL1), 

 

   (3)  Lead II is used more frequently because most of the heartís electrical current flows toward its positive axis.  This lead gives the best view of the ECG waves and best shows the heartís conduction systemís activity.

 

NOTE:  MCL is a special monitoring lead that some systems use selectively to help determine the origin of abnormal complexes such as premature beats.

 

d.   Lead placement

 

   (1)  Electrodes are place on the chest wall

 

   (2)  Positive lead is placed at the apex of the heart-usually a few inches below the left nipple.  Often the leads are marked for placement, RA (right arm), LA (left arm), etc.

 

   (3)  The negative electrode is place below the right clavicle

 

   (4)  The third electrode, the ground, is place somewhere on the left upper chest wall, usually below the left clavicle

 

e.   Advantages of single lead monitoring

 

   (1)  Simple system

 

   (2)  Provides rate of  the heartbeat

 

   (3)  Provides regularity of the heartbeat

 

   (4)  Provides conduction time of the impulse through the heart

 

   (5)  Detects  life threatening dysrhythmias

 

f.   Disadvantages of single lead monitoring

 

   (1)  Does not  provide the presence or location of an infarct

 

   (2)  Does not provide right-to-left differences in conduction or impulse formation

 

   (3)  Does not provide information on the quality or presence of pumping action

 

Perform a 12 Lead ECG

 

a.   Check equipment

 

   (1)  Ensure machine is turned on and allow ample time to warm up

 

   (2)  Inspect machine for any malfunctions

 

   (3)  Check machine's paper supply

 

   (4)  Ensure all equipment is on hand

 

      (a)  Diskette

 

      (b)  Clean electrodes

 

b.   Gather information for electrocardiogram report

 

   (1)  Patient age

 

   (2)  Patient sex

 

   (3)  Race

 

   (4)  Weight

 

   (5)  Height

 

   (6)  Signature of requesting MD/PA

 

   (7)  Date and time of recording

 

   (8)  Patient diagnosis or reason for recording

 

   (9)  Current medications

 

(10)  Previous ECGs

 

(11)  Priority of processing

 

(12)  Patient identification

 

      (a)  Patient name and rank

 

      (b)  Social security number

 

      (c)  Company assignment if active duty

 

      (d)  Home phone number if retired

 

c.   Procedure for recording a standard 12-lead ECG

 

   (1)  Explain procedure to the patient

 

   (2)  Select electrode sites

 

      (a)  Arms - anterior forearm and biceps

 

      (b)  Legs - medial aspect of lower leg

 

      (c)  Chest positions

 

         1)  V1 - fourth intercostal space, right sternal

 

         2)  V2 - fourth intercostal space, left sternal

 

         3)  V3 - midway between V2 and V4

 

         4)  V4 - fifth intercostal space, midclavicular line

 

         5)  V5 - same level as V4, anterior axillary line

 

         6)  V6 - same level as V4 and V5, midaxillary line

 

      (d)  Special cases of placement

 

         1)  Amputees - place lead proximal to stump

 

         2)  Hairy skin surface - if hair is excessive, rub with alcohol

 

         3)  Female - place lead under breast

 

         4)  Exceptionally oily skin - rub with alcohol

 

         5)  Hard or scaly skin - rub with alcohol

 

         6)  Parkinson's disease

 

            a)  Place electrode high on limb

 

            b)  Elevating extremities in resting position may help control shaking

 

         7)  Skin rashes

 

            a) Find area without a rash

 

            b)  If possible, rub with alcohol

 

         8)  Metal particles embedded in skin - move electrode site

 

   (3)  Wipe selected area with alcohol before applying electrode

 

   (4)  Application of electrodes

 

      (a)  Ensure electrodes are not falling off patient

 

      (b)  Ensure patient cable is not twisted and not interfering with other leads

 

      (c)  Select flat, fleshy site on arms and legs, avoid bone

 

   (5)  Press record ECG button

 

      (a)  Remind patient to relax

 

      (b)  Check leads for contact

 

   (6)  Recognize a good ECG

 

      (a)  Sharp distinct baseline

 

      (b)  Free from artifact

 

      (c)  Centered on graph

 

   (7)  Disconnect ECG

 

      (a)  Disconnect patient

 

      (b)  Clean electrode surfaces as you remove them from the patient

 

d.   Identify general problems

 

   (1)  Muscle tremor

 

      (a)  Causes

 

         1)  Patient uncomfortable or cold

 

         2)  60-cycle interference

 

      (b)  Correction

 

         1)  Ensure patient comfort.  Provide a cover if room is cold.

 

         2)  Ensure patient is not holding anything in their hand

 

         3)  Ensure feet are not touching the wall or foot board

 

   (2)  60-cycle interference

 

      (a)  Causes

 

         1)  Ungrounded electrocardiograph

 

         2)  Ungrounded electrical outlet

 

         3)  Ungrounded equipment that is connected to same electrical outlet

 

      (b)  Correction

 

         1)  Change electrical outlets

 

         2)  Change electrocardiograph, if possible

 

         3)  Notify MD/PA and medical maintenance

 

   (3)  Wandering baseline

 

      (a)  Causes

 

         1)  Poor electrode contact

 

         2)  Cable pulling on electrodes

 

         3)  Cable moving with respirations

 

      (b)  Correction

 

         1)  Check electrodes to ensure good contact

 

         2)  Adjust patient cable and move electrocardiograph closer to patient

 

         3)  Move cable off abdomen and guide under patient's arm to stabilize from moving

 

Right Side and Posterior ECG's

 

a.   Right side and Posterior ECG's are recorded to aid the MD/PA in diagnosing the location of a myocardial infarction.

 

   (1)  Explain the procedure to the patient.

 

   (2)  Select electrode sites

 

      (a)  Chest positions - V3R - 6R, are placed on the right side of the chest in the same locations as the Left side leads V3-6 would be placed.  V2R is therefore the same as V1

 

         1)  V1R - fourth intercostal space, left sternal border

 

         2)  V2R - fourth intercostal space, Right sternal border

 

         3)  V3R - midway between V2R and V4R

 

         4)  V4R - fifth intercostal space, midclavicular line

 

         5)  V5R - same level as V4R, anterior axillary line

 

         6)  V6R - same level as V4R and V5R, midaxillary line

 

      (b)  All other preparation and clean up steps of the procedure remain the same as for standard 12-lead ECG

 

b.   Posterior ECG's

 

   (1)  Explain the procedure to the patient

 

   (2)  Select electrode sites

 

      (a)  Leads for a posterior ECG are placed in a horizontal line across the back

 

      (b)  Back Positions - May be done with standard left-side ECG - V7, 8, 9 or with Right-sided ECG - V7R, 8R, 9R 

 

         1)  V7 - Posterior axillary line

 

         2)  V8 - Posterior Scapular line

 

         3)  V9 - Left border of the spine

 

         4)  V7R - Right posterior axillary line

 

         5)  V8R - Right posterior scapular line

 

         6)  V9R - Right border of the spine

 

      (c)  All other preparation and clean up steps of the procedure remain the same as for standard 12-lead ECG

 

Measure Pulse Oxygen Saturation

 

a.   Pulse oximetry defined

 

   (1)  The use of an oximeter to determine the oxygen saturation of blood (arterial = 2 or more arteries)

 

   (2)  Assess level of oxygen in the blood available to the body tissues

 

   (3)  Reflects percent of oxygen that is bound with hemoglobin in the blood

 

   (4)  Expressed as a percentage

 

      (a)  For example, 96% indicates 96% of the hemoglobin molecules are carrying oxygen molecules

 

      (b)  The more hemoglobin is saturated, the higher the percentage

 

      (c)  Normally over 90%

 

      (d)  An Arterial Blood Gas (ABG) is an invasive procedure that may also be used to measure  oxygen saturation of blood

 

   (5)  Pulse oximetry is accurate to +/- 2% for all readings over 70%

 

   (6)  Pulse oximetry is simple, painless, and has fewer risks than obtaining an ABG

 

b.      Pulse oximeter - how it works

 

   (1)  Probe with a Light-Emiting Diode (LED) connected by cable to an oximeter.

 

  (2)  Light waves emitted by LED are absorbed and reflected back by oxygenated and deoxygenated hemoglobin molecules

 

   (3)  Reflected light is processed by the oximeter, which calculated the oxygen saturation of blood

 

   (4)  The oximeter sensor probe is applied to

 

      (a)  Finger

 

      (b)  Toe

 

      (c)  Earlobe

 

      (d)  Bridge of the nose

 

c.   Considerations

 

   (1)  Patients at risk for unstable oxygen status

 

      (a)  Acute respiratory disease

 

      (b)  Chronic respiratory disease

 

      (c)  Ventilator dependence

 

      (d)  Chest pain

 

      (e)  Activity intolerance

 

      (f)   Recovery from general anesthesia

 

      (g)  Recovery from conscious sedation

 

      (h)  Traumatic injury to chest wall

 

      (i)   Changes in supplemental oxygen therapy

 

   (2)  Medications or treatments that may influence oxygen saturation

 

      (a)  Oxygen therapy

 

      (b)  Respiratory therapy

 

   (3)  Factors that influence oxygen saturation - abnormalities in type of amount of hemoglobin affect the ability of oxygen to be carried to the tissues.

 

   (4)  Factors likely to interfere with accuracy of pulse oximeter

 

      (a)  Skin pigmentation - darker pigments can result in false-high readings

 

      (b)  Jaundice

 

      (c)  Intravascular dyes

 

   (5)  Assess pertinent laboratory values, including hemoglobin and ABGs if available

 

      (a)  Anemia affects ability of oxygen to attach to hemoglobin molecule

 

      (b)  ABGs measure arterial oxygen saturation, which serves as a standard and provides a basis for comparison

 

   (6)  Determine client-specific sit appropriate to place pulse oximeter probe by measuring capillary refill

 

      (a)  Site must have adequate circulation

 

      (b)  Moisture, dark nail polish, and acrylic nails impede sensor detection of emitted light and produce falsely elevated arterial oxygen saturation levels

 

   (7)  Determine previous baseline from patient's records

 

d.      Application of pulse oximeter

 

   (1)  Select site and determine capillary refill

 

   (2)  Attach sensor probe to selected site

 

   (3)  Turn on oximeter

 

      (a)  Observe pulse waveform/intensity display

 

      (b)  Compare oximeter pulse rate with client's radial pulse

 

   (4)  Once oximeter reaches constant value, read arterial oxygen saturation on display

 

   (5)  Continually monitor arterial oxygen saturation levels

 

   (6)  Notify MD/PA of drastic changes

 

SUMMARY

The 91W should be able to set up 12-lead ECG.  These devices are essential in assessing the patient and could indicate severe problems that require immediate intervention.  Proper use of these devices is essential to prevent false, inaccurate results