CSLB General Building (B) — All Questions

Where is the V1 electrode placed for a 12-lead EKG?

• a.Fifth intercostal space, left midclavicular line
• b.Fourth intercostal space, left sternal border
• c.Fifth intercostal space, right sternal border
• d.Fourth intercostal space, right sternal border✓

V1 sits in the fourth intercostal space at the right sternal border, and it is located by walking down from the sternal angle to the second rib, then counting the second, third, and fourth spaces. The fourth space at the left sternal border is V2. The fifth space at the left midclavicular line is V4, and there is no standard chest lead at the fifth space on the right sternal border.

A technician has correctly placed V1. Where does the V2 electrode go?

• a.Directly below V1 in the fifth intercostal space
• b.Midway between V1 and V4
• c.Fourth intercostal space, left sternal border✓
• d.Fifth intercostal space, left anterior axillary line

V2 is placed in the fourth intercostal space at the left sternal border, directly across the sternum from V1. The electrode placed midway between V2 and V4 is V3, and V3 is always positioned after V4 is located. The fifth space at the left anterior axillary line is V5.

Which chest electrode is placed in the fifth intercostal space at the left midclavicular line?

• a.V3
• b.V4✓
• c.V5
• d.V6

V4 is placed in the fifth intercostal space at the left midclavicular line, and it is located before V3 because V3 is defined as the midpoint between V2 and V4. V5 goes at the left anterior axillary line and V6 at the left midaxillary line, both level with V4 rather than following the rib spaces.

After placing V1, V2, and V4, where should the technician place V3?

• a.Midway between V2 and V4✓
• b.Midway between V1 and V2
• c.Directly below V2 in the fifth intercostal space
• d.At the left anterior axillary line level with V4

V3 is placed on a straight line halfway between V2 and V4, which is why V4 must be positioned first. Placing it between V1 and V2 would put it over the sternum. Dropping it straight down from V2 ignores the diagonal path of the chest wall, and the left anterior axillary line position is V5.

A technician is placing V5 on a 12-lead EKG. Which description is correct?

• a.Fifth intercostal space, left midaxillary line
• b.Sixth intercostal space, left anterior axillary line
• c.Fourth intercostal space, left anterior axillary line
• d.Left anterior axillary line, on the same horizontal level as V4✓

V5 is placed at the left anterior axillary line on the same horizontal plane as V4 rather than by counting rib spaces, because the chest wall curves and the horizontal alignment keeps V4, V5, and V6 comparable. The midaxillary line at that level is V6. Counting to the sixth space or the fourth space would place the electrode too low or too high.

Where is the V6 electrode placed?

• a.Left posterior axillary line, level with V4
• b.Sixth intercostal space, left midclavicular line
• c.Left midaxillary line, on the same horizontal level as V4 and V5✓
• d.Fifth intercostal space, right midaxillary line

V6 is placed at the left midaxillary line on the same horizontal plane as V4 and V5, completing the left lateral view of the heart. The posterior axillary line is used only for additional posterior leads such as V7. The right midaxillary line and the sixth space at the midclavicular line are not standard chest lead positions.

Where should the limb electrodes be placed for a standard 12-lead EKG?

• a.On the bony prominences of the wrists and ankles for the best signal
• b.On fleshy, non-muscular areas of the arms and lower legs, positioned symmetrically✓
• c.On the upper chest and abdomen for all four limb leads
• d.Anywhere convenient, since limb lead position does not affect the tracing

Limb electrodes belong on flat, fleshy areas of the arms and lower legs, placed symmetrically on the right and left, because bone conducts poorly and muscle bellies generate tremor artifact. Torso placement is acceptable only for continuous monitoring or when a limb is missing, and it must be documented because it alters the tracing. Limb position does affect amplitude and axis, so it is never arbitrary.

A 12-lead tracing shows an inverted P wave, inverted QRS, and inverted T wave in lead I, while the chest leads look normal. What is the most likely cause?

• a.The right arm and left arm electrodes are reversed✓
• b.The V1 and V2 electrodes are reversed
• c.The right leg electrode is loose
• d.The paper speed is set to 50 mm/sec

Reversing the right and left arm electrodes flips the polarity of lead I, producing a global inversion in that lead while the chest leads, which do not depend on arm placement, remain normal. Reversing V1 and V2 distorts only those chest leads. A loose right leg (ground) electrode causes baseline wander or noise rather than inversion, and a doubled paper speed stretches the complexes without inverting them.

A tracing shows a uniform, thick, fuzzy baseline with small spikes occurring exactly 60 times per second across all leads. What is the most likely cause?

• a.The patient is shivering
• b.The electrodes are dried out
• c.The patient is breathing deeply
• d.Electrical interference from nearby powered equipment✓

Sixty-cycle interference is alternating current picked up from nearby electrical devices, cords, or fluorescent lights, and it produces a perfectly regular fuzzy band at 60 hertz in the affected leads. Shivering produces irregular jagged somatic tremor rather than a uniform pattern. Deep breathing causes a slow wandering baseline, and dried electrodes produce erratic noise or a flat trace in one lead.

An anxious, cold patient produces a tracing with irregular jagged spikes that obscure the small waveforms. What artifact is this and what is the best first correction?

• a.Wandering baseline; ask the patient to hold his breath
• b.AC interference; unplug nearby equipment
• c.Somatic tremor; warm and reposition the patient so the limbs are supported and relaxed✓
• d.Loose electrode; reapply the chest leads

Somatic tremor is muscle-movement artifact from shivering, tension, or involuntary motion, and it is corrected by warming the patient, supporting the arms and legs on the bed, and coaching him to relax. Wandering baseline drifts up and down slowly with respiration. AC interference is a uniform 60-cycle band, and a loose electrode affects only the lead it belongs to.

A tracing shows the baseline slowly drifting up and down in a wave pattern that matches the patient's breathing. What should the technician check first?

• a.Whether the machine is set to 50 mm/sec
• b.Whether the electrodes are loose, dried out, or applied over lotion or oil✓
• c.Whether the arm and leg electrodes are reversed
• d.Whether the standardization is set to 20 mm/mV

A wandering baseline is usually caused by poor electrode contact from loose tabs, dried gel, body lotion, oils, or sweat, and it is also worsened by deep respiration or cable tension. The fix is to clean and dry the skin, apply fresh electrodes, and secure the lead wires. Paper speed and standardization change the size or spacing of the complexes, and lead reversal changes polarity rather than causing drift.

What does the standardization mark on an EKG tracing indicate when it is 10 mm tall?

• a.The machine is calibrated so that 1 millivolt produces a 10 millimeter deflection✓
• b.The paper is running at 10 millimeters per second
• c.The patient's voltage is 10 times normal
• d.Each large box represents 10 milliseconds

Standard calibration is 10 mm per millivolt, printed as a rectangular standardization mark two large boxes tall at the start of the tracing, so that amplitudes can be compared between machines and over time. Paper speed is a separate setting of 25 mm/sec. The mark says nothing about the patient's own voltage, and each large box represents 0.20 second, not 10 milliseconds.

At the standard paper speed, how much time does one small box represent, and what is that speed?

• a.0.20 second at 25 mm/sec
• b.0.04 second at 50 mm/sec
• c.0.10 second at 25 mm/sec
• d.0.04 second at 25 mm/sec✓

Standard EKG paper runs at 25 millimeters per second, so each 1 mm small box equals 0.04 second and each 5 mm large box equals 0.20 second. The 0.20 second value belongs to the large box, not the small one. A speed of 50 mm/sec is a special setting used to spread out very fast rhythms, and 0.10 second does not correspond to any standard box.

How much time and voltage does one large box on standard EKG paper represent?

• a.0.04 second and 1 millimeter of height
• b.0.10 second and 10 millimeters of height
• c.0.20 second and 5 millimeters of height✓
• d.0.50 second and 5 millimeters of height

A large box is five small boxes across and five tall, so it represents 0.20 second horizontally and 5 millimeters, or 0.5 millivolt, vertically at standard calibration. The 0.04 second and 1 millimeter values describe a small box. The 0.10 and 0.50 second values do not match standard paper, where five large boxes equal one second.

A patient has a hairy chest and oily skin. What is the correct skin preparation before applying chest electrodes?

• a.Apply the electrodes over the hair and press firmly
• b.Clip the hair at each site, cleanse the skin with alcohol, let it dry, and gently abrade with a dry gauze✓
• c.Shave the entire chest with a razor and apply lotion to soothe the skin
• d.Wipe the chest with a povidone-iodine swab and apply electrodes while still wet

Good skin prep means clipping excess hair only at the electrode sites, cleansing with alcohol to remove oils, allowing the skin to dry completely, and lightly abrading with dry gauze to reduce resistance. Applying electrodes over hair or wet skin causes poor contact and wandering baseline. Lotion insulates the skin, and full shaving with a razor is unnecessary and risks nicks that break the skin barrier.

A technician is setting up 5-lead telemetry monitoring. Which placement follows the standard color convention?

• a.White on the right shoulder, black on the left shoulder, green on the right lower abdomen, red on the left lower abdomen, brown on the chest✓
• b.White on the left shoulder, black on the right shoulder, red on the right lower abdomen, green on the left lower abdomen, brown on the chest
• c.All five electrodes across the upper chest in a row
• d.White and black on the legs, red and green on the arms, brown on the back

The standard 5-lead convention is white on the right upper chest, black on the left upper chest, green on the right lower chest or abdomen, red on the left lower chest or abdomen, and brown as the chest lead, remembered as white on right, smoke over fire, and clouds over grass. Swapping white and black reverses lead I. Clustering the electrodes together or moving them to the limbs destroys the intended vectors.

How many electrodes are applied for standard 3-lead cardiac monitoring, and what do they produce?

• a.Three electrodes producing all 12 leads
• b.Five electrodes producing leads I, II, and III
• c.Three electrodes producing leads I, II, and III✓
• d.Three electrodes producing leads V1 through V3

Three-lead monitoring uses three electrodes, usually right arm, left arm, and left leg positions, and generates the three bipolar limb leads I, II, and III, with lead II most often selected because it shows P waves well. Twelve leads require ten electrodes. Five-lead systems add a ground and a chest lead, and V1 through V3 are precordial leads that a 3-lead setup cannot produce.

The QRS complexes on a 12-lead tracing are so tall that they run off the paper and overlap the lead above. What is the appropriate action?

• a.Increase the paper speed to 50 mm/sec
• b.Change the standardization to half sensitivity (5 mm/mV) and document the change on the tracing✓
• c.Move the chest electrodes one intercostal space lower
• d.Reduce the gain until the complexes look like the patient's last EKG

When complexes are too tall to fit, the machine is switched to half standardization, so 1 millivolt produces a 5 millimeter deflection, and the change must be marked on the tracing so the physician can interpret amplitudes correctly. Increasing paper speed widens complexes but does not lower their height. Moving electrodes falsifies the anatomic view, and adjusting the gain to match a prior tracing is not an accepted practice.

A patient's heart rate is so fast that the complexes are crowded together and hard to measure. Which machine adjustment can help, and what must the technician remember?

• a.Reduce paper speed to 12.5 mm/sec; intervals will read the same
• b.Set standardization to 20 mm/mV; intervals will read the same
• c.Reduce paper speed to 10 mm/sec; intervals will double
• d.Increase paper speed to 50 mm/sec; each small box now equals 0.02 second and the change must be noted✓

Doubling the paper speed to 50 mm/sec spreads the complexes apart for easier measurement, but each small box then represents 0.02 second instead of 0.04 second, so the change must be documented or intervals will be misread. Slower speeds compress the tracing further. Standardization changes amplitude, not timing, and intervals never simply double without accounting for the new time scale.

What is the standard patient position for obtaining a resting 12-lead EKG?

• a.Supine with arms resting at the sides and legs uncrossed✓
• b.Sitting upright with the arms folded across the chest
• c.Standing with the arms extended
• d.Left lateral with the knees drawn up

The standard resting EKG is taken with the patient supine, arms relaxed at the sides, legs flat and uncrossed, so muscle tension and limb contact do not distort the tracing. Folded arms and crossed legs create somatic tremor and can bridge electrodes. Standing or lying on the side shifts the heart within the chest and changes the tracing, so any deviation must be documented.

A patient with severe shortness of breath cannot tolerate lying flat for a 12-lead EKG. What should the technician do?

• a.Refuse to perform the test until the patient can lie flat
• b.Lay the patient flat quickly and finish before symptoms worsen
• c.Raise the head of the bed to a semi-Fowler position, obtain the tracing, and document the position used✓
• d.Have the patient sit on the edge of the bed and hold the electrodes in place

Patient comfort and safety come first, so the head of the bed is raised to a tolerable semi-Fowler position, and the non-standard position is documented on the tracing because it can alter waveform amplitude and axis. Forcing a dyspneic patient flat risks harm. Refusing to test delays care, and holding electrodes by hand introduces motion artifact and unreliable contact.

A physician orders right-sided chest leads on a patient with a suspected right ventricular infarction. Which electrode position corresponds to V4R?

• a.Fourth intercostal space, left sternal border
• b.Fifth intercostal space, right midclavicular line✓
• c.Fifth intercostal space, left midaxillary line
• d.Second intercostal space, right sternal border

Right-sided leads mirror the standard positions across the chest, so V4R sits in the fifth intercostal space at the right midclavicular line and is the single most useful lead for right ventricular infarction. The fourth space at the left sternal border is standard V2. The left midaxillary position is V6, and the second space at the right sternal border is not a chest electrode site.

A patient has a right below-the-knee amputation. How should the technician place the limb electrodes?

• a.Omit the right leg electrode entirely and run a 9-lead tracing
• b.Place both leg electrodes on the intact left leg, several inches apart
• c.Place the right leg electrode on the right arm
• d.Place the right leg electrode on the right lower torso and place the left leg electrode symmetrically, then document the modification✓

When a limb is missing, the electrode is moved to the nearest torso location on the same side and the opposite limb electrode is moved to match, keeping the tracing symmetric, and the modification is documented for the interpreting physician. Omitting an electrode prevents the machine from producing a valid tracing. Doubling up on one leg or moving a leg lead to an arm distorts the frontal-plane leads.

When performing a 12-lead EKG on a female patient with large breast tissue, where should the V4 and V5 electrodes be placed?

• a.Under the breast, directly on the chest wall at the correct anatomic landmarks✓
• b.On top of the breast tissue at approximately the right level
• c.Above the breast to avoid touching it
• d.On the back, opposite the usual positions

Chest electrodes are placed beneath the breast on the chest wall at the true anatomic landmarks, because breast tissue between the electrode and the heart reduces voltage and distorts the tracing. Placing electrodes on top of or above the breast produces inaccurate amplitudes. Back placement is used only for special posterior leads. The patient's privacy is protected with draping throughout.

On a 12-lead tracing, leads I, II, and aVR are clean, but lead III alone shows an erratic, noisy trace. What is the most likely cause?

• a.The patient is having a myocardial infarction affecting only the inferior wall
• b.The paper speed is incorrect
• c.A single electrode or lead wire connection is loose or dried out✓
• d.Alternating current interference from the room lighting

Artifact confined to one lead points to a problem with a specific electrode or lead wire, since each limb lead uses a different combination of electrodes; the fix is to reapply that electrode and reseat the wire. A true infarction produces recognizable ST or Q wave changes across a group of leads rather than random noise. Paper speed errors and AC interference affect the entire tracing, not one lead.

A technician opens a package of disposable electrodes and finds the conductive gel is dry and crusted. What should be done?

• a.Moisten the electrodes with tap water and use them
• b.Discard the package and open fresh electrodes within their expiration date✓
• c.Add alcohol to the gel to soften it
• d.Use them anyway and increase the machine gain to compensate

Dried electrodes cannot conduct properly and cause wandering baseline and false readings, so they are discarded and replaced with fresh, unexpired electrodes stored in a sealed package. Water and alcohol are not substitutes for conductive gel and alcohol actually increases resistance once it dries. Increasing gain amplifies the artifact along with the signal and does not fix the contact problem.

A tracing shows steady 60-cycle interference. Which troubleshooting sequence is most appropriate?

• a.Increase the paper speed and reprint
• b.Apply new electrodes and ask the patient to breathe deeply
• c.Switch the machine to half standardization
• d.Unplug nearby electrical equipment, move the cables away from power cords, verify the ground electrode, and confirm the patient is not touching metal✓

Sixty-cycle interference comes from surrounding alternating current, so the corrections are environmental: turn off or unplug nearby devices, separate the patient cable from power cords, verify a good ground electrode, and keep the patient from contacting the bed rails or other metal. Paper speed and standardization changes alter the display without removing the noise, and deep breathing worsens baseline wander rather than fixing interference.

Before beginning a shift, a technician inspects the EKG machine. Which finding requires the machine be removed from service?

• a.A frayed patient cable with exposed wire✓
• b.A paper roll that is about half full
• c.A standardization mark measuring exactly 10 millimeters
• d.Electrode tabs stored in a sealed, unexpired package

A frayed cable with exposed conductor is an electrical hazard and a source of artifact, so the machine is tagged and removed from service until repaired. A half-full paper roll is simply replaced or monitored. A 10 millimeter standardization mark is the correct calibration, and sealed unexpired electrodes are exactly what should be stocked.