CC LAB PIPETTES, PLASMA SERUM, BLOOD COLLECTION

pipette

Volumetric equipment used extensively in the Clinical Chemistry laboratory.

pipette

Calibrated to contain or deliver specific volume of fluid from one vessel to another.

pipette

GLASS PIPETTES vs. SEMI-AUTOMATIC MICROPIPETTORS.

Glass Pipettes — Design — To contain (TC)

Holds but does not deliver the exact volume.

To contain (TC) — Examples —

Sahli, Lang-Levy, glass micropipette.

Glass Pipettes — Design — To deliver (TD)

Delivers but does not hold the exact volume.

To deliver (TD) — Examples

Volumetric, Ostwald-Folin, Serologic, Mohr.

Blow-out (BO) pipettes

Remaining liquid is expelled out with an aspirator.

Blow-out (BO) pipettes — Examples

Ostwald-Folin, Serologic.

Self-draining (SD) pipettes

Allowed to be drained by gravity.

Self-draining (SD) pipettes — Examples

Volumetric, Mohr.

V – Volumetric — Type —

T – Transferring (bulb in center).

V – Volumetric — Drainage

SD

V – Volumetric — Design

TD

V – Volumetric — Graduation Marks

Single capacity mark.

O – Ostwald-Folin — Type

T – Transferring (bulb near tip).

O – Ostwald-Folin — Drainage

BO

O – Ostwald-Folin — Design

TD

O – Ostwald-Folin — Graduation Marks

Single capacity mark.

S – Serologic — Type

M – Measuring.

S – Serologic — Drainage

BO.

S – Serologic — Design

TD

S – Serologic — Graduation Marks

Graduated down to the tip.

M – Mohr — Type

M – Measuring.

M – Mohr — Drainage

SD

M – Mohr — Design

TD

M – Mohr — Graduation Marks

Graduated between 2 marks.

Air displacement

Uses an air cushion.

Air displacement — Piston

Piston does not touch the liquid.

Air displacement — Tips

Tips are disposed.

Air displacement — Samples

For low density or aqueous samples.

Air displacement — Use

Used in semi-automatic aspirations.

Positive displacement

Uses no air cushion.

Positive displacement — Piston

Piston touches the liquid.

Positive displacement — Tips

Tips are rinsed.

Positive displacement — Samples

For high density or viscous samples

Positive displacement — Use

Used in discrete automated systems.

Plasma

Pale yellow.

Plasma — Blood condition

Anti-coagulated blood.

Plasma — Clotting

Unclotted.

Plasma — Cells

Cells not attached together.

Plasma — Fibrinogen

Fibrinogen is present.

Plasma — Fibrinogen form

Fibrinogen is the inactive form.

Plasma — Preparation

Shorter time to prepare.

Plasma — Centrifugation

Can centrifuge immediately.

Plasma — Layer

Plasma + Buffy Coat + RBC.

Plasma — Analyte concentration

Analyte in plasma is higher in analyte.

Serum

Clear to pale yellow.

Serum — Blood condition

Coagulated blood.

Serum — Clotting

Clotted.

Serum — Cells

Cells attached together.

Serum — Fibrinogen

Fibrinogen is absent.

Serum — Preparation

Longer time to prepare.

Serum — Preparation before centrifugation

Let it clot before centrifugation.

Serum — Layer

Serum + clot → cell blood cells.

Icterus

Associated with a yellow-colored specimen.

Icterus — Liver

Liver affected.

Icterus — Hemolytic conditions

Hemolytic conditions.

Icterus — Main association

Bilirubin-related discoloration of the specimen.

Lipemia — Appearance

Cloudy / turbid.

Lipemia

Associated with lipids.

Lipemia — Fasting

Fasting sample but did not fast.

Chylomicrons

Lipoprotein that makes sample turbid.

Lipemia — Cause of turbidity

Increased lipids / chylomicrons.

Hemolysis — Appearance

Red / pink color.

Hemolysis

Excess hemoglobin.

Hemolysis — In vitro

Outside the realm of the patient.

Hemolysis — In vivo

Inside the patient.

Intravascular hemolysis

Inside the vein.

Intravascular hemolysis — Specimen appearance

Causes red/pink color.

Extravascular hemolysis

By other organs (spleen, liver).

Extravascular hemolysis — Specimen appearance

Does not cause red/pink color.

Blood pressure cuff in place of tourniquet

Inflate to 40-60 mmHg (as long as below the patient’s diastolic BP).

Blood pressure cuff — Pressure

40-60 mmHg.

Blood pressure cuff — Limitation

As long as below the patient’s diastolic BP.

Routine antiseptic

70% isopropyl alcohol.

Culture antiseptic

70% isopropyl alcohol followed by chlorhexidine/iodophor/povidone iodine.

Ethanol assay antiseptic

Benzalkonium chloride (Zephiran).

EDTA — Mechanism of calcium removal

Removes calcium via chelation.

Citrate — Mechanism of calcium removal

Removes calcium via chelation.

Oxalate — Mechanism of calcium removal

Removes calcium via precipitation.

Calcium — Importance

Calcium is an essential component of the coagulation cascade.

Thixotropic gel separator — TDM

Tubes with thixotropic gel separator are not recommended for therapeutic drug monitoring (TDM).

Thixotropic gel separator — Reason

These can absorb drug metabolites, hence causing falsely ↓ results.

Gray top tubes — Anticoagulant

Potassium oxalate.

Gray top tubes — Anti-glycolytic agent

Sodium fluoride or iodoacetate.

Sodium fluoride — Effect on urease

Sodium fluoride inhibits urease.

Sodium fluoride — When BUN is measured with glucose

For such cases where BUN has to be measured along with glucose, iodoacetate is preferred.

Capillary blood samples for blood gas analysis (BGA)

Must be arterialized by warming (≤ 42 °C).

Radial artery — Needle angle

45° needle angle.

Brachial artery — Needle angle

45° needle angle.

Femoral artery — Needle angle

90° needle angle.

Factors affecting tube quality

Temperature, altitude, humidity, and light.

Humidity — Cause of effect on tube quality —

Due to water vapor differential.

↑ Humidity

Water vapor migrates into the tube.

↓ Humidity

Water vapor migrates from the tube.

Light — Tube affected

Affects CTAD (citric acid, theophylline, adenosine, dipyridamole) tubes containing a photosensitive additive.

CTAD

Citric acid, theophylline, adenosine, dipyridamole.

Pre-analytical variables — Uncontrollable

Age, gender, race, underlying conditions.

Controllable pre-analytical variables

Diurnal variation, posture, exercise, stress, smoking, diet, specimen quality, and specimen handling.