Special Laboratory Tests PDF

NB 3172 SPECIAL TECHNIQUE: SPECIFIC LABORATORY TESTS Dr Noor Hazfalinda Hamzah 1. Blood gases 2. Blood cultures old people - Glucose Tolerance Test (GTT) pregnant mone 3....

NB 3172 SPECIAL TECHNIQUE: SPECIFIC LABORATORY TESTS Dr Noor Hazfalinda Hamzah 1. Blood gases 2. Blood cultures old people - Glucose Tolerance Test (GTT) pregnant mone 3. - 4. Therapeutic Drug Monitoring (TDM) 1. Blood gases - diagnosis and management of respiratory disease blood) - adult : wrist Carterial Capillary blood gases -baby : capillary used in place of samples from arterial punctures or indwelling arterial catheters to estimate acid-base balance (pH) and adequacy of ventilation (PaCO2)usually for babies Capillary PO2 measurements are of little value in estimating arterial oxygenation A puncture or small incision is made with a lancet or similar device into the cutaneous layer of the skin at a highly vascularized area (heel, finger, toe) To accelerate blood flow and reduce the difference between the arterial and venous gas pressures, the area is warmed prior to the puncture. As the blood flows freely from the puncture site, the sample is collected in a heparinized glass capillary tube  Arterial blood gases (ABGs) Radial artery is artery of choice, located on the thumb side of the wrist. Disadvantage is small size, requires considerable skill Femoral artery Selah is largest kangkang artery for arterial puncture; located superficially in groin; this puncture performed by physicians Other sites include scalp and umbilical arteries in infants Because of higher arterial pressure, a hematoma is more likely to occur, especially elderly patients and patients on anticoagulants contraction of artery Possibility of arteriospasm, a reflex condition of the artery in response to pain or to anxiety 2. Blood cultures - Indicated for patients with Fever of Unknown Origin (FUO) Cleansing of venipuncture site is the most critical step; most facilities use chlorhexidine gluconate. disinfectant/antiseptic ~ for skin Must cleanse tops of blood culture bottles according to manufacturer’s directions and allow to air dry. Many manufactures recommend 70% Isopropyl alcohol. L disinfect Draw 1 aerobic and 1 anaerobic Chlorhexidine gluconate 3. Glucose Tolerance Test (OGTT) - screen for gestational diabetes/ DM 2 his after ~ Tube color : gray - drink 759 Fasting blood and 2 hrs post prandial of glucose Draw fasting blood Have patient drink glucose load which usually contains 75g of glucose; watch for signs of nausea hourspost /2 prandial After 2 hours then draw 2hpp blood 4. Therapeutic Drug Monitoring (TDM) Used to evaluate the concentration of certain drugs for various reasons Drugs that are highly toxic When over or under dosing can have serious consequences If the use of multiple drugs may alter the action of the drug being measured When different patients metabolize drugs at different rates If the drug’s effectiveness is questionable  Time is more critical for drugs with short half life such as carrica arrythmias & gentamicin, tobramycin, procainamide than those with antibiotics longer half life such as phenobarbital or digoxin Specimen should not be collected immediately after dose is given; usually 30 minutes after a dose for peak, 15 minutes before next dose for trough peal 30: after mins trough 15 : hefre Trough – lowest level; Peak – highest level ming next doge TDMs collected in plain red tops; no additives or serum separators (gel) ~ no anticoagulant Keep specimens upright, away from stopper which may release interfering substances