Lab

Here are the simplified, concise definitions tailored for quick studying and flashcards:

### Venipuncture Basics & Equipment

* Why Venipuncture? Diagnostics, monitoring, therapy, and blood donations.

* Materials: Gloves, tourniquet, alcohol, needles, tubes, holder, gauze, bandages, sharps container.

* Tourniquet Placement: 3–4 inches above site; tight enough to pop veins without discomfort.

* Patient Fist: Make a fist, do not pump.

* Main Veins: Median cubital (preferred), cephalic, basilic.

* Site Prep: Clean in outward circles with alcohol; let air dry.

* **Insertion Angle:** 15–30 degrees with bevel up.

### Order of Draw

* Why it Matters: Prevents additive cross-contamination for accurate results.

* Sequence: Culture tubes \rightarrow Light blue \rightarrow Serum (red/gold/orange) \rightarrow Green \rightarrow Lavender \rightarrow White \rightarrow Gray.

* Blood Cultures Additive: Broth / SPS.

* Light Blue Additive & Test: Sodium citrate; coagulation (PT, PTT).

* Red Additive & Test: None/clot activator; chemistry, serology.

* Gold/Tiger (SST) Additive & Test: Clot activator + gel; routine chemistry.

* Green Additive & Test: Heparin; plasma chemistry.

* Lavender Additive & Test: EDTA; hematology (CBC), blood bank.

* Gray Additive & Test: Potassium oxalate/sodium fluoride; glucose, lactate.

### Troubleshooting & Complications

* **Max Attempts:** 2 attempts per phlebotomist.

* Missed Vein Causes: Shallow insertion, passed through vein, or bad anchor.

* Hematoma Causes: Needle went through vein, bad pressure, or fragile vein.

* Hematoma Action: Remove needle, apply firm pressure, elevate 2–5 min, ice.

* Syncope (Fainting) Action: Stop draw, lower head/lay patient down, apply cool compress.

* Rolling Veins Action: Anchor firmly below site, use larger vein, or use butterfly needle.

* Hemolysis Causes: Small needle, excessive force, or shaking tubes instead of gentle inversion.

### Calculations, Solutions, & Dilutions

* Weight/Volume %: \% (w/v) = (\text{solute mass} / \text{solution volume}) \times 100

* Molarity Formula: C_1V_1 = C_2V_2

* Simple Dilution (1:10): 1 part sample + 9 parts diluent

* Dilution Factor Rule: Multiply final result by the dilution factor reciprocal

* Serial Dilution: Stepwise dilution reducing concentration by a constant factor

### Lab Measurement & Pipetting

* Micropipette Ranges: P10, P20, P200, P1000

* Best Practice: Use a pipette where your volume is in the upper scale

* Pipetting Steps: Clean tip \rightarrow First stop before liquid \rightarrow Smooth release \rightarrow Dispense (first + second stop)

* Accuracy: Closeness to true value

* Precision: Consistency of repeated measurements

### Spectrophotometry & Total Protein

* Beer's Law: Concentration, color intensity, and absorbance increase together linearly

* **Wavelength:** 540 nm

* Blank Cuvette: Reagent only; used to zero the spectrophotometer

* Standard Curve: Graphs known concentrations vs. absorbance to find unknowns

* **High Unknown Action:** Dilute the sample, repeat assay, and multiply by dilution factor

### Microscope Use & Care

* Ocular Lens: 10x

* Objective Lenses: Scanning (4x), Low (10x), High (40x), Oil Immersion (100x)

* Working Distance: Decreases as magnification increases

* **Coarse Adjustment:** Never use at high power (40x/100x)

* **Blood Smear View:** Monolayer under 100x oil immersion

### Quality Control & Statistics

* Internal Controls: Tested internally with known values to ensure system accuracy

* External Controls: Proficiency testing from external sources to compare labs

* Levey-Jennings Chart: Graph tracking performance over time vs. mean and SD

* 1-2s Rule: > 2 SD from mean (**warning**)

* 1-3s Rule: > 3 SD from mean (**error**)

* 2-2s Rule: Two consecutive > 2 SD on same side (**systematic error**)

* Random Error: Unpredictable fluctuations (bubbles, pipetting, electrical)

* Systematic Error: Consistent bias (calibration drift, bad reagents)

* Shift vs. Trend: Shift is sudden jump; trend is gradual increase/decrease