EKG Basics
What does the P wave represent on an EKG?
Atrial depolarization (atrial contraction)
What does the QRS complex represent?
Ventricular depolarization (ventricles contracting)
What vein is preferred for venipuncture?
Median cubital vein
What is the first tube in the venipuncture order of draw?
Yellow (SPS for blood cultures)
What should you do with a tube after collecting if it has an anticoagulant?
Invert gently to mix (5–10 times depending on tube)
Where is the V6 lead placed?
5th intercostal space, left midaxillary line
What does a T wave represent?
Ventricular repolarization (ventricles relaxing)
At what angle should you insert the needle for venipuncture?
15–30°
What tube color is used for coagulation tests (PT, INR, aPTT)?
Light Blue; sodium citrate
What does lipemic serum indicate?
Excess fat (lipids) in the blood sample
What is the normal paper speed for an EKG?
25 mm/sec
What is a wandering baseline usually caused by?
Patient movement, loose electrodes, or breathing pattern
What should you do if a patient feels faint during venipuncture?
Stop immediately, remove the needle, lay the patient down, and elevate legs if possible
What tube color and additive are used for CBC tests?
Lavender; EDTA
What does hemolysis look like in a blood sample, and what can cause it?
Pink/red serum; caused by shaking tubes, small needles, or prolonged tourniquet use
What is the standard gain (sensitivity) for an EKG?
10 mm/mV
What should you do if you see muscle (somatic) artifact during an EKG?
Ask the patient to relax and stay still
What is the maximum time a tourniquet can remain on the arm?
1 minute
What is the correct order of draw for these tubes: Lavender, Green, Red, Light Blue?
Light Blue → Red → Green → Lavender
Why is it important to fill the light blue tube completely?
Ensures correct blood-to-additive ratio for coagulation tests
Which lead is most commonly used for continuous heart monitoring because it gives the most upright QRS?
Lead II
A flat line (isoelectric line) on all leads usually means what?
A loose or disconnected lead (check equipment first)
Define phlebitis.
Inflammation of a vein, sometimes caused by repeated venipuncture
What does the gray tube test for, and what is its additive?
Glucose or alcohol testing; Sodium fluoride & Potassium oxalate
A patient reports tingling and numbness during venipuncture. What should you do?
Stop immediately and select another site to prevent nerve damage