EKG and Point-of-Care Testing
Perform a 12-lead EKG with correct lead placement, and run point-of-care tests within the rules that govern them.
By the end of this lesson you can
- Place electrodes correctly for a 12-lead EKG
- Recognize and correct artifact
- Perform common point-of-care tests correctly
- Explain what CLIA-waived testing requires
Lesson Notes
Read through the key concepts before you try the challenge.
Placing the precordial leads
Finding the fourth intercostal space
Place V1 through V6 accurately, since nothing downstream can correct a placement error.
- 1
Find the sternal angle — the ridge where the manubrium meets the body of the sternum.
This is the only reliable landmark, and everything else is counted from it. Estimating by eye is where the common one-space-too-high error starts, and that error is invisible on the finished tracing.
- 2
Slide laterally from the sternal angle to find the second intercostal space, then count down to the fourth.
The second rib attaches at the sternal angle, so the space just below it is the second intercostal space. Count down two more and you are at the fourth. Counting from the clavicle instead is unreliable.
- 3
Place V1 and V2 either side of the sternum in that fourth space, then V4 before V3.
V3 sits midway between V2 and V4, so V4 has to exist first. Placing V3 by eye before V4 is a common sequencing error that misplaces two leads instead of one.
- 4
Place V4 at the fifth intercostal space, midclavicular line — then V5 and V6 level with V4, not along the rib.
V5 and V6 follow the horizontal plane of V4, not the curve of the rib. Following the rib carries them downward and changes the waveform.
- 5
For a patient with breast tissue, place the electrode under it rather than over it.
Placing over breast tissue attenuates the signal and shifts the effective position. Explain what you are doing and why before you do it, and offer a chaperone.
Result: A tracing that reflects the heart's electrical activity rather than where the electrodes happened to land.
Count from the sternal angle, place V1, V2, then V4, then V3 between them. Nothing later can fix a misplaced lead.
Lead placement determines whether the tracing means anything
You perform an EKG on a medical unit at Lakeside Regional.
You place V1 and V2 one intercostal space too high — a common error, and invisible on the resulting tracing. The EKG shows changes suggesting a problem the patient does not have, and a clinician who cannot see where you placed the electrodes has no way to know.
Your task: Place leads precisely, because nothing downstream can correct a placement error.
| Lead | Position |
|---|---|
| V1 | Fourth intercostal space, right sternal border |
| V2 | Fourth intercostal space, left sternal border |
| V3 | Midway between V2 and V4 |
| V4 | Fifth intercostal space, midclavicular line |
| V5 | Level with V4, anterior axillary line |
| V6 | Level with V4, midaxillary line |
Limb electrodes go on the limbs — on fleshy areas, avoiding bone and major muscle. Place V1 and V2 first by locating the sternal angle and counting down to the fourth intercostal space, then V4, then V3 between them, then V5 and V6 level with V4. Placing V3 before V4 is a common cause of misplacement.
| Appearance | Cause | Fix |
|---|---|---|
| Wandering baseline | Movement, breathing, loose electrode | Re-secure electrodes; ask the patient to lie still |
| Fine, irregular fuzz | Muscle tremor, tension, cold | Warm the patient; support limbs; ask them to relax |
| Regular thick baseline | Electrical interference | Move away from equipment; check cables are not crossed |
| Flat line in one lead | Disconnected or dry electrode | Replace that electrode |
Point-of-care testing is governed by CLIA. Waived tests — glucose meters, urine dipsticks, rapid strep — may be performed by trained unlicensed personnel, but only exactly as the manufacturer specifies. Quality controls must be run at the required frequency and documented, and a failed control means patient testing stops on that system until it is resolved.
Your EKG tracing shows a wandering, drifting baseline. What is the most likely cause?
Challenge
Apply what you've learned in this lesson.
EKG placement is a hands-on skill requiring supervised practice and competency assessment.
- Draw a torso and mark all six precordial positions. Describe how you would locate the fourth intercostal space by palpation.
- For each artifact type, describe what you would see and the corrective action.
- Research why V1 and V2 placed one space too high produce misleading changes, and what those changes can be mistaken for.
- For a glucose meter you research, list every manufacturer requirement including control frequency and storage.
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