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    PRACTICAL HAEMATOLOGY

    شاطر

    عمر النجاده
    مراقب عام المنتدى
    مراقب عام المنتدى

    ذكر
    عدد الرسائل : 630
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    البلد : اليمن
    القسم والمستوى : خريج / مختبرات طبــــيـــــه
    المزاج : طبيعــــــي
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    تاريخ التسجيل : 08/03/2008

    بطاقة الشخصية
    تخصصي: طب
    المحافظة: الحديدة

    PRACTICAL HAEMATOLOGY

    مُساهمة من طرف عمر النجاده في الأربعاء مايو 21, 2008 11:59 pm

    Introduction:-
    In the past humankind know about presence of blood, but a few centuries back science discovered that this blood circulates in our body. In Greek, Roman, and Unani medicine describe some disease due to blood abnormalities into: traumatic, inflammatory, infective, and neoplastic.
    DEFINATION OF BLOOD:
    Blood is a highly specialized (sterile) connective tissue, which circulate in a closed system of vessels as a liquid with red coulor, but in out this system a solid phase will perform, which we called plug or blood clot.

    Haematology: is the science that study the blood, and it's structure, function, disease, and the convenience between structure and the function.
    BLOOD COMPONENT:

    Mainly we can divide blood into two parts:
    [] Plasma [] Blood cells.
    The total amount of blood approximately 1/14 of the total body weight or 60-70 ml/each kilogram of body weight.
    Blood flows through every organ of the body providing effective communication between tissues.

    PLASMA:

    Plasma is a pale yellow fluid in which blood cells are suspended in.
    Plasma forms about 55% of blood volume and composed of 95%or more water, and many solutes including proteins, minerals, ions, organic materials, hormones, enzymes, products of digestion, and waste products.

    BLOOD CELL:

    1) Red blood cells (RBC).
    2) White blood cells (WBC).
    3) Platelets.

    FUNCTION OF BLOOD:

    [] Transportation and distribution:
    - oxygen transportation by haemoglobin from lungs to the tissues.
    - Blood also can transport the nutrents absorbed by the digestive system to the tissues for use or storage.
    - Hormones are carried from endocrine glands to the organs.
    - Wastes are transported from tissues for excretion e.g.: carbon , dioxide, urea, createnine,….
    [] Regulatory:
    - Plasma maintain the PH. of blood (7.35-7.45), and in the tissues .
    - Osmotic pressure in plasma is regulate by proteins and salts (sodium, chloride) to prevent excessive loss of fluids from the blood into tissues.
    - Regulation of the body temperature.
    [] Protective:
    - Platelets and coagulation factors control the blood loss by thrombous formation.
    - Leukocytes defend and produce antibodies and toxin against infection and tumor cells
    .
    HAEMATOPOIESIS:
    In normal healthy person there is a constant break down and new formation of cells, and the procedure of blood cells formation called Haematopoiesis.

    NORMAL SITES OF BLOOD FORMATION:
    - Fetus:
    * less than 2 months: in Yolk sac.
    * 2-7 months: in the liver and a few in the spleen.
    * Full term: in bone marrow for RBC, PLTs, and granulocytes, but lymphocytes and monocytes 0ccures in spleen, lymph nodes and lymphoid tissues (liver and bone marrow with less numbers).

    - After birth:
    Mainly from bone marrow even monocytes, except lymphocytes still from spleen and lymph tissues.
    - In adult:
    Main sites of haematopoiesis are the vertebrae, ribs, sternum, skull bones, pelvis, sacrum, and proximal ends of femur and humerus.
    Haematopoiesis can be sub-divided into 3 stages:
    1) Mesoblastic period.
    2) Hepatic period.
    3) Myeloid period
    ABNORMAL SITES OF HAEMATOPOIESIS:
    In certain disorders the fetal haematopoitic organs revert to their old function supported by the reticulum cells, this occurs when bone marrow can not fulfill the requirements or demand for new cells, this called EXTRA-MEDALLARY haematopoiesis, (Myeloid metaplasia).
    In some rare cases adrenal glands, cartilages, adipose tissues, intra thoracic areas, kidneys, and endo sternum can produce blood cells.


    PRE-ANALYSIS MANAGEMENT
    The clinical laboratory is useful to assist in diagnosis, and management of patient.

    A test request is a request for a consultative services, to generate a laboratory report using to make a clinical judgments.
    - Understanding of the test process and procedures, collection, and handling enables the laboratory staff to achieve more nearly optimal conditions and consequently to improve the accuracy and precision of each measurement.

    REASONS FOR ORDERING LAB. REQUEST:
    1) To confirm a clinical impression or diagnosis.
    2) To rule out a diagnosis.
    3) To monitor therapy.
    4) To establish prognosis.
    5) To screen for or detect disease.

    TEST REQUESTATION:
    The physician initiates the test request by writing an order for lab. examinations in the patient medical chart/record.
    - The orders are carry out to an appropriate lab. request form by the nursing station or secretary unit.
    - Each laboratory form has a list of test with reference intervals and a space for the result.
    - Patient data (demographics) include, patient name, sex, age, date of admission, date of test ordering, room number,……..
    must be clearly writing on the request, or patient's addressograph plate or computerized label are stamped onto the request.
    - The requests are given to the collect unit or to the phlebotomist /nurse to draw the specimen, specimen tube must be labeled be for the specimen is drawn.
    It is essential to follow strict quality control procedures through all stages of test request to avoid several possible errors, such as, incorrect or missing test entering, ……
    - All requests should have a full, clear patient data, and correct sample labeling.
    - Samples quantity and anticoagulant should be suitable, and with no haemolysis, or clot.

    BLOOD SPECIMEN COLLECTION:

    [A] SKIN PUNCTURE:

    Skin puncture is the method of choice in pediatric patients, especially infants.
    - Skin puncture can be used in adults with:
    * extreme obesity.
    * sever burn.
    * thrombotic tendencies.
    Technique:
    1) select an appropriate puncture site, lateral or medial plantar heel surface for infants, in older infants the palmer surface of the last digit of the second, third, or forth fingers (big toe, and ear lobe can be used).
    -The site of puncture must not be edematous or a previous puncture site.
    2) Warm the puncture site with a warm moist towel, and clean the puncture site with 70%of aqueous isopropanol solution, allow the area to dray.
    3) Make the puncture with a sterile lancet with blade no longer than 2.4 mm.
    4) Discard the first drop of blood by wiping it away with a sterile pad.
    5)collect the specimen in a suitable container (oral aspiration of blood is discouraged for a safety reasons ).
    5)label the specimen container.


    VENOUS PUNCTURE:

    Technique:
    1) Identify the patient by checking identification card against the request, ask the conscious patient his/her full name and birth date (do not draw any specimen without properly identification).
    2) If fasting specimen is required , confirm that the fasting order has been followed.
    3) Inform the patient, what is to be done and reassure the patient to avoid as much tension as possible.
    4) Position the patient properly for easy, comfortable access to the antecubital fossa.
    5) Assemble equipments and supply (tubes, tourniquet, syringes…..).
    6) Ask the patient to make a fist –to make the veins more palpable – then select a suitable vein (veins of atecubital fossa , in particular the median and cephalic veins are preferred), wrist , ankle, and hands veins may also be used.
    If one arm has an intravenous line , use the other arm to draw a blood sample.
    7) Clean the venipuncture site with 70%isopropyl alcohol solution in a circular motion and allow the area to dray.
    8)apply a tourniquet above the puncture site, "never leave the tourniquet longer than 1min.
    9) Use your thumb and middle finger or thumb and the index finger, to anchor the vein.
    10) Enter the skin with the bevel of the needle at 15 degree angle, to the arm with the arm, with the bevel up , insert the needle smoothly, and fairly fast.
    - If using a syringe pull pack on the barrel with a slow until the blood flows into the syringe (do not pull back too quickly to avoid the haemolysis or collapsing the vein).
    - If using a vacutainer, as soon as the needle is in the vein ease the tube fore ward in the holder, at the same time hold the needle firmly in place.
    11) At the end of the collection release the tourniquet.
    12) After all blood samples have been drawn, have the patient relax his fist.
    13) Place a clean, sterile, dray cotton ball over the site and withdraw the needle , and apply a pressure to the site , and bandage the arm.
    14) Mix the blood with the anticoagulant.
    15) Check the patient condition e.g.: whither he is faint, bleeding is under control,…..
    16) Dispose the contaminated materials.

    [C] ARTERIAL PUNCTURE:
    Arterial blood is used to measure oxygen, carbon dioxide , and measuring PH.,…
    Arterial punctures are technically more difficult to perform.
    Technique:
    1) Select the puncture site, the radial artery is the most common site, if the ulnar artery is is absent, do not puncture the radial artery (use the Allen test to make sure of collateral circulation ).
    The femoral artery and the brachial artery, at the antecubital fossa provide alternative sites for puncture, scalp arteries are used in infant.
    2) Anesthetized the puncture site if necessary, prepare the syringe by aspirate an anticoagulant (usually heparin).
    3) Record the patient temperature and perform Allen test (for radial artery puncture) as follow:
    - compress the radial and ulnar arteries at the wrist until the palm of the hand becomes blanched.
    - Release the pressure from ulnar artery and observe that the hand becomes flushed, if the hand remains blanched DO NOT puncture the radial artery.
    4) Clean the site, place a finger over the artery and puncture the skin 5-10mm. distal to the finger .
    - Blood rushing into the needle, or pull back on the plunger and obtain the required amount of the blood.
    5) Quickly withdraw the needle and syringe , place a sterile cotton ball or dry gauze over the puncture site.
    6) Apply firm pressure for at least 5 min.
    7) Expel any air bubble from the syringe.
    Remove the needle and cap it with a tight – fitting Luer cap and mix the anticoagulant by gentile inversing of the syringe.
    9) label the sample and place it in an ice/ice water bath.
    10) Transport the sample on ice immediately to the lab.

    * Drawing problems:
    Occasionally, the phlebotomists are unable to obtain blood by ordinary venipuncture.
    - In some cases a skin puncture may suffice, if not, a physician draws the specimen using most commonly the femoral vain or jugular vain in children.

    REAGENTS:

    Reagent contain chemicals exist in varying degrees of purity. – all reagent should have a label identify the concentration , purity, amount, and compounds,….
    - Reagents or chemicals arrived into lab. with a certain guarantee of purity ;once the seal is broken, the guaranteed analysis is strictly in the hands of the receiving lab.
    - Definite steps must be taken to ensure that the reagent/ chemicals are handdeled under optimal condition.
    - It extremely important to read the label for proper storage .
    - Never sample directly from the reagent bottle.
    - It essential that each lab. first evaluate a kit / reagent according to an established protocol, then monitor kit/reagent performance by appropriate quality control procedures.
    - In generally distilled water and deionized water most commonly used to prepare reagents.
    - The College of American Pathologist has drawn up specification and methods of quality control for reagent water.
    * Three grades of water are defined:
    ▫ Type I reagent water:
    For procedures which require maximum water purity
    - preparation of standard solutions
    - ultra microchemical onalysis.
    - measurement of nanogram or sub nanogram concentration.
    ▫ Type II reagent water:
    For most lab. testing, in chemistry, haematology, immunology, and other clinical tests.
    ▫ Type III reagent water:
    For most qualitative testing, most procedure in urinalysis, parasitology and for washing glass ware.
    * carbon dioxide free water is used in gasses such as Co2 , ammonia and O2 may affect analysis.


    .


    _________________

    عمر النجاده
    مراقب عام المنتدى
    مراقب عام المنتدى

    ذكر
    عدد الرسائل : 630
    العمر : 29
    البلد : اليمن
    القسم والمستوى : خريج / مختبرات طبــــيـــــه
    المزاج : طبيعــــــي
    العضوية : 107
    أختر علم دولتك :
      :
    السٌّمعَة : 0
    نقاط : 202
    تاريخ التسجيل : 08/03/2008

    بطاقة الشخصية
    تخصصي: طب
    المحافظة: الحديدة

    رد: PRACTICAL HAEMATOLOGY

    مُساهمة من طرف عمر النجاده في الخميس مايو 22, 2008 12:00 am

    SOME METHODOLGY PRINCIBLS USED IN CLINICAL LABORATORY

    □ PHOTOMERTRY:
    Photometric measurement defined as measurement of light intensity of multiple wave length.
    SPECTROPHOTOMETRY: meant measurement of light intensity in a much narrower wave length range.
    □ FLAME PHOTOMETRY:
    Heat energy of a flame makes the electrons in an atom excited and being unstable, then the electrons give up their excess energy to the environment as they change from the higher energy state (level) to a lower energy state as light, the light may consist of one or more than one energy level, therefore many different wave lengths; these wave lengths are individually characteristic for each element.
    □ FLUOROMERTRY:
    Fluorescence is a physical energy process that occurs when certain compounds absorb electromagnetic radiation and become excited, and then return to energy level slightly higher than or equal to their original energy level , the energy given off is less than or equal to that absorbed, and wave length will be longer or equal to that absorbed for excitation.
    □ TURBIDIMETRY:
    Turbidimetry measures the amount of light blocked by particulate matter as light passes through the cuvette.
    □ POTENTIOMETRY:
    The measurement of the potential voltage between two electrodes in solution from the basis for a variety of measurement that can be used to quantitate concentration of substance of interest.
    □ ION SELECTIVE ELECTRODES (ISE):
    There are three different basic ISE. Classes:
    - Ion selective glass.
    - Solid state electode.
    - Liqud ion exchange membranes.
    □ CHROMATOGRAPHY:
    The purpose of chromatography involves separation of a mixture on the basis of specific difference of the physical – chemical characteristics of the components.

    * steps involved in requesting, performing, and evaluating a measured quantity :
    (I) Physician request a quantitative measurement of a constituent in biological specimen.
    (II) Laboratory personnel perform the assay:
    A. Pre-instrumental phase
    1- preparation of the patient.
    2- obtain the specimen
    3- processing the specimen
    4- storing the specimen prior the measuring steps.
    B. Instrumental phase
    1- dispending a sample aliquot into a reaction vessel
    2- combining the sample with one or more reagent
    3- recording some physical/chemical consequence of the reaction
    4- calculate the value of the quantity measured
    C. Post-instrumental phase
    1- lab. staff accept the value (result) as being of good quality
    2- the report is sent to the requesting physician
    (III) Physician evaluates the report:
    A. physician assesses whether the measurement could be consistent with other known patient information
    B. the physician makes a clinical decision at least partially based on the report measurement.

    INTRODUCTION TO QUALITY CONTROL
    Clinical laboratories perform quantitative, semiquantitative, and quantitative tests on a variety of biologic specimens.
    The basic principles on quality controls were set by Shewhart in 1931, the ways in which these basic principles have been extended to develop systems of quality assurance have been revered by Grannis (1977).
    The immediate aim of quality control is assure that the end product of the analytical values regularly produced by a clinical laboratory are sufficiently reliable for their intended use, and to assure that the laboratory procedure analytical values that meet acceptable standard of precision, and accuracy at all times.
    To attainment of these aims requires that all lab. personnel, technologists, supervisors, and directors be knowledgeable of the causes of the analytical inaccuracies and of the techniques that available for their detection, correction, and control.
    Quality control in laboratory medicine has been defined as the study of those errors which are responsibility of the laboratory to recognize and minimize them.
    An alternative term "quality assurance" has been used to represent the techniques available to ensure with a specified degree of the confidence that the result reported by the laboratory is correct.
    In order to have such confidence, the laboratory director must be assured that there is both "precision control and accuracy control" performed.
    Quality control can be divided into two major types: Internal QC, and External QC.
    ANTICOAGULANTS
    1)E.D.T.A.:
    Ethylen diamine tetra acitic acid:
    - Acts as chelating agent by removal of calcium ions.
    - The most widely common used anticoagulant for haematologic procedures.
    - Useful for CBC, blood films, platelets count (because it prevents platelets clumping).
    - EDTA. Is not useful for factor V and VIII assay.
    * Preparation:
    □ LIQUID FORM:
    - Dissolve 3gm. of EDTA. Salt in 100 ml. of 0.7% aqueous NaCl solution.
    - Use 0.5 ml. for each 9.5ml. of blood.
    □ DRAY SALTS:
    - Dissolve 10 gm. of EDTA. salts into 100ml. of distilled water.
    - Pipette 0.1 ml. of this solution into each container (vial) to be used for 5ml. of whole blood specimen collection.
    - Allow to dry at room temperature or into oven at low temperature , without cover, put cover after dry.
    2) HEPARIN:
    - Naturally producing by liver.
    - Neutralize thrombin which prevents the blood clotting mechanism.
    - Useful for red cell fragility test, electrolytes studies, L.E.cells.
    - Not useful in CBC, blood films.
    3) SODIUM CITRATE:
    - Sodium citrate combines with calcium to form insoluble calcium citrate.
    - 3.2% sodium citrate is the most commonly used for coagulation studies.(1volume of anticoagulant to 9volume of blood).
    - For ESR. (4volume of tri sodium citrate to 1volume of blood).
    4) ACID CITRATE DEXTROZE (ACD):
    - Commonly used in blood banking.
    - 63ml. of ACD. is sufficient for 450ml. of whole blood.
    5) OXALATE:
    - Sodium oxalate can be used in chemistry, haematocrite, coagulation tests.
    - Replaced by Sodium citrate.
    - Double oxalate is replaced by EDTA.
    PREPARATION OF BLOOD FILMS
    *THICK BLOOD FILM:
    - A large drop of blood is taken on the centre of a clean labeled slide ( a drop of finger puncture or from well mixed EDTA. tube of blood by capillary tube or pipette).
    - With an other slide corner spread the drop over 1/2 an inch square area (20 mm.) in diameter.
    - When dry the thickness should be such that printed litters can be seen through it.
    - Thick blood films used for detecting Malaria parasites and Microfilaria …..
    * THIN BLOOD FILM:
    Making of spreaders:
    - Select a slide with smooth edge ( a high quality polished side slides can be used).
    - Using a glass cutter, cut across a corner of the slide.
    - Break off the corner by holding the slide corner between a piece of cloth.
    Making a thin film:
    - Put one small drop of blood on a clean (grease-free) labeled slide.
    - Hold the spreader at 30-45degree angle against the surface of the slide.
    - Move the spreader back to touch the drop of blood and allow the blood to extend along the edge of the spreader.
    - Push the spreader with a steady hand across the slide.
    - Air dry the film.
    FIXING OF THIN BLOOD FILMS:
    * With absolute methanol, by immersing in a container of absolute methanol for 2 minutes.
    * When absolute methanol is no available absolute ethanol can be used.
    * Methanol containing water must not be used to fix blood films


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