SOP Electrocardiographs

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HOSPITAL SHARED SERVICESIPM Procedure for Electrocardiographs (Major)

Last Revised: March 28, 1991

Author: HOSPITAL SHARED SERVICES

Interval Time Required

Major: 12 months 0.8 Hours

Minor: Hours

DESCRIPTION

HSS PRODURE #: B-1050

APPLICABLE TO: Electrocardiographs [11-407]

Electrocardiographs, Multi-Channel [11-411]

Electrocardiographs, Single-Channel [11-413]

ALSO CALLED: EKG units, ECG units, EKG machines

COMMONLY USED IN: Electrocardiography departments, most patient care areas

SCOPE: Applies to single- and multi-channel electrocardiographs typically used for recording an

electrocardiogram on paper; may also be adapted for some systems that digitally store data and laterprovide hard-copy tracings; not suitable for verifying performance of automated diagnostic

functions; does not apply to strip-chart recorders or direct writers, which should be inspected with

the ECG monitor or the defibrillator/monitor they are used in conjunction with (use the ECG

Monitors procedure and the Defibrillator/Monitors procedure, respectively)

SPECIAL PRECAUTIONS

Testing input isolation requires the use of a line voltage source. Although this source should include

a current-limiting resistor, use caution to avoid contact with any portions of the energized circuit.

TEST APPARATUS REQUIRED

G Leakage Current Meter/Safety Analy

G Ground Resistance Ohmmeter

G ECG Simulator, Variable Output/Rate

G Styluss Tension Gauge

SUPPLIES REQUIRED

G Contact Cleaner G Ruler, Metric, Transparent G Lubricant Specified by Mfr G Calipers,Drafting


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IPM Procedure for Electrocardiographs (Major), Page 2

QUALITATIVE TASKS

CHASSIS/HOUSING: Examine the exterior of the unit for cleanliness and general physical

condition. Be sure that plastic housings are intact, that all assembly hardware is present and tight,

and that there are no signs of spilled liquids or other serious abuse.

MOUNT: If the device is mounted on a stand or a cart, examine the condition of the mount. If it is

attached to a wall or rests on a shelf, check the security of this attachment.

CASTERS/BRAKES: If the device moves on casters, check their condition. Look for accumulations

of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the

operation of brakes and swivel locks, if the unit is so equipped.

AC PLUG/RECEPTACLE: Examine the AC power plug for damage. Attempt to wiggle the blades

to determine that they are secure. Shake nonmolded plugs and listen for rattles that could indicate

loose screws. If any damage is suspected, open the plug and inspect it.

LINE CORD: Inspect the cord for signs of damage. If it is damaged, replace the entire cord or, if the

damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug

with the same polarity as the old one. Also check line cords of battery chargers.

STRAIN RELIEFS: Examine the strain reliefs at both ends of the line cord. Be sure that they hold

the cord securely.

CIRCUIT BREAKER/FUSE: If the device has a switch-type circuit breaker, check that it moves

freely. If the device is protected by an external fuse, check its value and type against that marked on

the chassis, and ensure that an appropriate spare is provided.

CABLES: Inspect the cables and leads and their strain reliefs for general condition. Examine cables

carefully to detect breaks in the insulation and to ensure that they are gripped securely in the

connectors of each end to prevent rotation or other strain.

Connect the unit to an ECG simulator, and verify that an adequate trace is received at each patient

lead selection. [Checking all leads in some units will require either a 12-lead simulator or

connection and disconnection of every lead.] Flex the patient cable near each end to verify that there

are no intermittent faults.

CONNECTORS: Examine all cable connectors for general condition. Electrical contact pins or

surfaces should be straight and clean. Leads and electrodes should be firmly gripped in their

appropriate connectors.

ELECTRODES: Confirm that an adequate supply of electrodes is on hand, and check the electrodes'

physical condition.


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CONTROLS/SWITCHES: Before moving any controls and alarm limits, check their positions. If

any settings appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their

range), consider the possibility of inappropriate clinical use or of incipient device failure. Record

the settings of those controls that should be returned to their original positions following the

inspection.

Examine all controls and switches for physical condition, secure mounting, and correct motion.Check that control knobs have not slipped on their shafts. Where a control should operate against

fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane

switches for membrane damage (e.g., from fingernails, pens).

During the course of the inspection, check that each control and switch performs its proper

function.

BATTERY/CHARGER: Inspect the physical condition of batteries and battery connectors, if readily

accessible. Check operation of battery-operated power-loss alarms, if so equipped.

Perform the inspection with the unit on battery power or operate the unit on battery power for

several minutes to check that the batteries are charged and can hold a charge. Check battery capacity

by activating the battery-test function or measuring the output voltage. When it is necessary toreplace a battery, label it with the date.

Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact,

charge the battery.

Some batteries require periodic deep discharges and recharging to maintain maximum battery

capacity. If this is recommended by the manufacturer, verify that it is being performed on schedule.

INDICATORS/DISPLAYS: During the course of the inspection, confirm the operation of all lights,

indicators, meters, and visual displays on the unit and the charger, if so equipped. Be sure that all

segments of a digital display function.

1 MV STEP RESPONSE: Depress and hold the 1 mV calibration button (or apply an external 1 mVpulse) for about 3 sec. The trace should exhibit a sharp, square-cornered leading edge that is neither

rounded nor spiked. [Up to 10% spike or overshoot is acceptable but will usually not be observed in

a unit that is functioning optimally (see Figure 1 in the ECRI IPM manual).] After 2 sec (50 mm of

paper at a speed of 25 mm/sec), the pulse should have decayed no more than half its original

amplitude (see Figure 2 in the ECRI IPM manual).

LABELING: Check that all necessary placards, labels, and instruction cards are present and legible.

ACCESSORIES: Verify that an adequate supply of electrodes and paper and a fuse are stored with

the device or in the nursing unit for those electrocardiographs that remain in a fixed location. A

spare patient cable and stylus (or pen) may be kept with units on crash carts.


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TRACE QUALITY: Observe the tracing with the unit in the standard lead select position (no input)

and in lead I with a simulated ECG signal applied. Verify compliance with the following criteria:

G The baseline should have constant thickness; it should be horizontal and not drift vertically. It

should be possible to move the baseline from the lower to the upper border of the chart paper

with the the vertical position control, except on those units where mechanical stops prevent

such travel. G The baseline should remain within 1 mm of its initial position upon pushing the reset control.

G If so equipped, the operator-adjustable stylus heat control should function and should not need

to be set near either extreme to obtain a satisfactory setting.

G All portions of a simulated ECG waveform should be clearly visible, including the P wave and

QRS.

G There should be no 60 Hz noise when the lead selector switch is set to the lead 0 or standard

position and the chart motor is activated.

PAPER TRANSPORT: Verify that the paper moves smoothly and without hesitation at all paper

speeds. Problems might be caused by the transport mechanism or by an excessively tightly wound

roll of paper. The paper should not drift sideways in the transport mechanism. If a formatted outputis used (i.e., unit prints a single formatted sheet for each electrocardiogram), verify that all

alphanumerics and tracings appear in the correct location and that the paper starts and stops at the

correct points.

PREVENTIVE MAINTENANCE

CLEAN EXTERIOR AND ACCESSORIES: Clean the exterior (including front panel controls), all

rollers, paper guides, and knife edges, as needed.

LUBRICATE RECORDER AND PAPER DRIVE: Lubricate the recorder mechanism and the paper

drive per the manufacturer's specifications.

CALIBRATE DAMPING AND STYLUS: Calibrate damping and stylus, as required. Use stylus

gauge to check tension.

QUANTITATIVE TASKS

GROUNDING RESISTANCE: Using an ohmmeter, electrical safety analyzer, or multimeter with

good resolution of fractional ohms, measure and record the resistance between the grounding pin of

the power cord and exposed (unpainted and not anodized) metal on the chassis.

CRITERION: 0.5

CHASSIS LEAKAGE CURRENT: Measure chassis leakage current to ground with the grounding

conductor of plug-connected equipment temporarily opened. Operate the device in all normal

modes, including on, standby, and off, and record the maximum leakage current.

CRITERION: 100 A


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CALIBRATION( GAIN ): This test determines the accuracy of the sensitivity control and of the

internal 1 mV calibration signal and requires the use of an external source of known amplitude (e.g.,

calibrated ECG simulator). If this calibration source is battery powered, check its output with a

precision voltmeter or similar instrument to confirm that the output is not affected by changing

battery voltage. An ECG simulator can be used, even if its output is not precisely 1 or 2 mV,

provided its amplitude is accurately known and appropriate corrections are made in interpreting theresults.

With sensitivity at 20 mm/mV, record a 1 mV pulse from the external reference generator and one

from the internal 1 mV calibration signal of the writer. For an externally generated pulse of exactly

1 mV, the tracing should be between 19 and 21 mm. Deviation greater than this can often be

corrected with the variable gain control (a screwdriver adjustment in many units). If the internally

generated pulse and a 1 mV external pulse produce tracings of heights that differ by more than 0.5

mm, the internal calibrator is not within the recommended 5% accuracy.

Next, record 1 mV pulses, either from the internal calibrator or the reference generator, at

sensitivity settings of 2.5, 5, 10, and 20 mm/mV.

At each setting, the trace should double in height (within 5%). Because of the difficulty in

resolving small errors, investigate any deviation of more than 0.5 mm.CRITERION: 5% or 0.5 mm

LINEARITY: Apply a calibrated 2 mV input to the writer. Record the deflection at 10 mm/mV. It

should be twice the deflection (within 5%) observed for a 1 mV signal.

CRITERION: 5%

PAPER SPEED: Use an ECG simulator set to 60 bpm or a signal or pulse generator set to 1 Hz that

has been set or calibrated with a counter. If the interval between pulses is not within 10 msec at a

pulse interval of 1,000 msec, an appropriate correction should be made in calculating paper speed.

The speed should be accurate to within 2%. At a chart speed of 25 mm/sec and a pulse interval of

1,000 msec (60 bpm on an ECG simulator), the distance between the first and last of five successivepeaks should be 100 2 mm; at a chart speed of 50 mm/sec, the distance between the first and last of

five successive peaks should be 200 4 mm.

CRITERION: 2% = 0.5mm @ 25mm/sec @ 60BPM; R to R

GAIN VS BASELINE POSITION: Vary the centering or position control to change baseline

position. Using the internal calibration button, generate a pulse with the baseline set at the bottom

margin of the chart, another with the baseline at the middle of the chart, and a third with the baseline

as close to the top margin of the paper as possible while still allowing the pulse to remain on the

ruled chart. The height of the

calibration pulse should not vary more than 0.5 mm with baseline position.

CRITERION: Gain Variation, 0.5 mm

RETURN TO BASELINE POSITION: Check that trace returns to baseline after each cal pulse

CRITERION: Variation, 0.1 mm ;1/10th major division

DAMPING, HIGH FREQUENCY(1MV PULSE)

CRITERION: 0.5mm Overshoot @ 2cm Pulse Height

INSTO BALLANCE(BETWEEN LEADS): Many units have adjustment so that trace is blanked

(signal is shorted) between leads. Check to verify that trace remains centered between leads.


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HOSPITAL SHARED SERVICESIPM Form for Electrocardiographs (Major)(B-1050)

Work Order No.:

Manufacturer:

Location:

Model:

Control No:

Serial:

SPECIAL PRECAUTIONS

Testing input isolation requires the use of a line voltage source. Although this source should include

a current-limiting resistor, use caution to avoid contact with any portions of the energized circuit.

TEST APPARATUS REQUIRED

G Leakage Current Meter/Safety Analy G Styluss Tension Gauge

G Ground Resistance Ohmmeter

G ECG Simulator, Variable Output/Rate

SUPPLIES REQUIRED

G Contact Cleaner G Ruler, Metric, Transparent

G Lubricant Specified by Mfr G Calipers, Drafting

QUALITATIVE TASKS

G Chassis/Housing G Electrodes

G Mount G Controls/Switches

G Casters/Brakes G Battery/Charger

G AC Plug/Receptacle G Indicators/Displays

G Line Cord G 1 mV Step Response

G Strain Reliefs G Labeling

G Circuit Breaker/Fuse G Accessories

G Cables G Trace Quality

G Connectors G Paper Transport

PREVENTIVE MAINTENANCE

G Clean Exterior and Accessories G Calibrate Damping and Stylus

G Lubricate Recorder and Paper Drive


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QUANTITATIVE TASKS

Task Description/Criterion Set Indicd MeasuredPass Fail

Grounding Resistance

0.5

Chassis Leakage Current 100 A

Work Order No.: Control No.:

Task Description/Criterion Set Indicd Measured Pass Fail

Calibration ( Gain )

5% or 0.5 mm

Linearity

5%

Paper Speed

2% = 0.5mm @ 25mm/sec @ 60BPM; R to R

Gain vs Baseline Position

Gain Variation, 0.5 mm

Return to Baseline Position

Variation, 0.1 mm ;1/10th major division

Damping, High Frequency(1mV pulse)

0.5mm Overshoot @ 2cm Pulse Height

Insto Ballance(between leads)

SUMMARY

G Service Required G Removed from Use G Acceptable for Use

Completed by: Date IPM Time Repair Time

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SOP Electrocardiographs