Biochemistry Practical (2) PDF

Biochemistry Sampling PRACTICAL (2) DR. El-Sawy 1  Biochemistry Sampling Specimens :...

Biochemistry Sampling PRACTICAL (2) DR. El-Sawy 1  Biochemistry Sampling Specimens :  A specimen is any substance which is taken from the body for Def : testing in the laboratory. 1. Blood 2. Urine 3. Stool 4. CSF Examples : 5. Saliva 6. Semen 7. Respiratory (nasal swab, throat swab, sputum, tracheal and bronchial secretion) 8. Other body fluids (synovial, peritoneal, pleural & pericardial) Blood specimens: 1. Whole blood 2. Plasma 3. Serum includes all cellular the liquid portion of components (RBCs, WBCs, the liquid portion of blood blood (plasma) without platelets) and fluid components the clotting factors. DR. El-Sawy 2  Biochemistry Sampling Plasma separation:  A collecting tube containing anticoagulant is used to collect whole blood sample.  The cells are separated from the liquid supernatant by centrifugation Serum separation:  A collecting tube, without anticoagulant, is used to collect whole blood sample.  The blood is allowed to clot by leaving the sample at room temperature for 15-30 minutes.  The blood clot is removed by centrifuging the sample, and the resulting supernatant is the obtained serum. DR. El-Sawy 3  Biochemistry Sampling When to use whole blood, plasma or serum?  ABG  Blood culture Whole blood  Blood grouping  Hemoglobin  Coagulation tests Plasma  Clotting factors  Albumin  Creatinine Serum  Glucose  Lipid profile DR. El-Sawy 4  Biochemistry Sampling TYPES OF Collecting tubes: 1. Plain tube  NO anticoagulant, No additive Without 2. Serum separator tube (SST)  Contains clot activator & anticoagulant gel separator 1. Citrate 2. EDTA 3. Heparin With 4. Sodium citrate anticoagulant 5. Sodium fluoride  The choice of anticoagulant depends on the analysis that is to be carried out. Color Additives Purpose of use -  Serum separation for most RED biochemistry tests and  Clot activator YELLOW serology  Gel separator  Coagulation tests as PT, D.  Na citrate BLUE dime  CBC  EDTA PURPLE  HbA1C  ABG  Heparin  Ammonia GREEN  Electrolytes  Na fluoride  Estimation of Glucose level GREY DR. El-Sawy 5  Biochemistry Sampling Capillary  Required when only few drops of blood is needed  Used to measure arterial blood gases like oxygen, CO2 Arterial and pH Venous  Specimen of choice for most routine laboratory tests Sites 1. The cubital fossa (frequently selected): Superficial veins that are frequently selected for venipuncture at the cubital fossa include:  Basilic vein  Median cubital vein  Cephalic vein Because of its characteristics: a thick lumen and an easily visible confirmation. 2. Wrist and dorsum of the hands  also commonly used to perform venipuncture. DR. El-Sawy 6  Biochemistry Sampling METHODS Needle and Syringe Butterfly needle Evacuation tube system EQUIPMENT 1. Tourniquet 5. Sharps container (Safety box) 2. Gloves 6. Permanent ink pen 3. Syringe needle & syringe 7. Appropriate collection tubes 4. Alcohol & Gauze 8. Adhesive bandage or tape Precautions  Ensure that patient is in relaxed position: 1. Patient is sitting or lying down 2. Place arm at downward angle to prevent reflux 3. Remind patient to hold still  Verify patient conditions: fasting or non/medications DR. El-Sawy 7  Biochemistry Sampling Lab tests that require fasting: 1. Fasting blood glucose 5. Iron tests 2. HOMA-IR 6. Vit B12 3. C-peptide 7. Gamma glutamyl transferase 4. Lipid profile (triglycerides) Fasting means no food or drinks (except water) for 8-12 hours before taking the sample. Procedure steps : 1. Sensitization. 2. Tourniquet Application. 3. Site cleanse. 4. Equipment preparation. 5. Tourniquet reapplication and needle insertion. 6. Needle removal. 7. Blood transfer to collecting tube. 8. Collecting tube labeling. 9. Sample transport and processing. DR. El-Sawy 8  Biochemistry Sampling Sensitization  Wash your hands  Use alcohol-based hand sanitizers  Put on your gloves Tourniquet Application  Locate tourniquet 3 to 4 inches above venipuncture site (for vein visualization – increase amount of available blood)  tourniquet should be tight to impede venous return but not restrict arterial flow.  Maximum time is one minute  Ask the patient to make a fist (the veins become more prominent, making them easier to locate)  Palpate the area with the tip of the index finger  Vein enhancement: message arm upward from wrist  Then release the tourniquet and ask the patient to open fist Site cleanse  Clean the site with a gauze pad soaked with 70% isopropyl alcohol or a commercially prepared alcohol prep pad (by a circular motion cleanse from inside to outside)  Allow to air dry, 30–60 seconds (assemble syringe and needle in this period)  Failure to let alcohol dry causes a stinging sensation for patient DR. El-Sawy 9  Biochemistry Sampling Equipment preparation  Select a syringe and needle size compatible with age of the patient, the size and condition of the patient’s veins and the amount of blood to be collected.  Attach the needle to the syringe but do not remove the needle sheath (cap) at this time.  To ensure that it moves freely, move the plunger back and forth slightly a few times Tourniquet reapplication and needle insertion  Reapply the tourniquet (help needle entry), being careful not to touch the cleaned area.  Remove the needle cap and visually inspect the needle.  At this time the patient is asked to again make a fist.  The nondominant hand is used to anchor the vein, with the thumb 1-2 inches below the site and other fingers on the back of the patient arm  The collection equipment is held and the needle inserted using dominant hand.  Insert the needle (bevel up), 15-30 degree angle  Establishment of blood flow is normally indicated by blood in hub of syringe.  In some cases blood will not flow until the syringe plunger is pulled back.  Release the tourniquet and ask patient to open the fist, so that blood flow returns to normal  A syringe is filled by slowly and steadily pulling back on the plunger until the barrel is filled to the appropriate level DR. El-Sawy 10  Biochemistry Sampling Needle removal  Withdraw the needle from the vein while simultaneously applying pressure to the site with your free hand, for 3 to 5 minutes or until the bleeding stops  Do not ask the patient to bend the arm up. The arm should be kept extended or even raised.  Apply an adhesive gauze or tape on the site  A needle must be promptly discarded in a safety box Never bend or recap needle  When transfer is complete, the syringe also must be discarded in safety box  If recapping needle is absolutely necessary: 1. Never recap needle with both hands 2. Use a one-handed technique Blood transfer to collecting tube  Select tubes according to the tests that have been ordered.  Transfer sample from syringe to the tube.  If the tube contains an additive, mix it by gently inverting it several times.  (Lack of, delayed, or inadequate mixing can lead to clot formation and necessitate recollection of the specimen)  Do not shake or vigorously mix blood specimens, as this can cause haemolysis  Nonadditive tubes do not require mixing. DR. El-Sawy 11  Biochemistry Sampling Collecting tube labeling  Tubes must be labeled in the presence of the patient immediately after blood collection  Label information: 1. Patient’s first and last name 2. Patient’s ID number 3. Date and time of collection 4. Collector’s initials 5. Additional information (e.g. fasting) Sample transport and processing  Rapid delivery to the laboratory protects specimen integrity.  Follow handling requirements (Place specimens that must be cooled (e.g., ammonia) in crushed ice slurry  Wrap specimens that require protection from light (e.g., bilirubin) in aluminum foil or other light-blocking material).  Plasma and serum separation within 2 hours of collection DR. El-Sawy 12  Biochemistry Sampling NOTE Don’t Forget to : 1- Dispose  all contaminated materials in the proper biohazard containers or according to facility protocol. 2- Discard  other used disposable items in the regular trash. 3- Remove gloves  aseptically and discard them 4- Sanitize your hands Complications of blood collection Fainting Hematoma Petechiae Bleeding Seizures DR. El-Sawy 13