LEC PMLS

• Second-site blood cultures


  More useful when drawn 30 minutes apart
• Blood volume for infants and younger children

  1% to 4% of the patient's total blood volume
• Blood culture volumes for adults or people weighing more than 80 pounds


  20 to 30 mL per culture with a minimum of 10 mL per draw
• Blood culture specimens


  Collected in special bottles containing nutrient broth (referred to as medium) that encourages the growth of microorganisms
• Blood culture specimen sets


  • One aerobic (with air)
  • One anaerobic (without air)
• Collecting blood culture specimens with a syringe

  Anaerobic bottle is filled first
• Collecting blood culture specimens with a butterfly

  Aerobic bottle is filled first
• Skin antisepsis


  • The destruction of microorganisms on the skin, is a critical part of the blood culture collection procedure
  • Failure to carefully disinfect the venipuncture site can introduce skin-surface bacteria into the blood culture bottles and interfere with interpretation of results
• Contaminating organism


  If misinterpreted as pathogenic, it could result in inappropriate treatment
• Antiseptic or sterile technique for blood culture collection

  Requires a 30- to 60-second friction scrub to get to the bacteria beneath the dead skin cells onto the surface of the arm
• Effective antiseptics


  • Tincture of iodine
  • Chlorhexidine gluconate
  • Povidone/70% ethyl alcohol combination
• Using a povidone–iodine or chlorhexidine gluconate ampule swab


  1. The swab should be placed at the site of needle insertion and moved outward in concentric circles without going over any area more than once

  2. The area covered should be 3 to 4 in. in diameter
• Chlorhexidine gluconate/isopropyl alcohol antiseptic preparations


  Have a one-step application and are effective with a 30-second scrub
• Chlorhexidine gluconate is the recommended blood culture site disinfectant for infants 2 months and older and patients with iodine sensitivity
• Inoculation of media methods


  • Directly into the bottle during specimen collection
  • After collection as when blood has been collected in a syringe
  • Using an intermediate collection tube to collect the sample for inoculation in the laboratory and not at the bedside
• Blood culture specimens are always collected first in the order of draw to prevent contamination from other tubes
• Direct inoculation of blood culture medium


  1. Use a butterfly and specially designed holder

  2. Connect the special holder to the Luer connector of the butterfly collection set

  3. Fill the aerobic vial first, because the butterfly tubing has air in it

  4. Avoid backflow by keeping the culture bottle or tube lower than the collection site and preventing the culture medium from contacting the stopper or needle during blood collection

  5. Mix each container after removing it from the needle holder

  6. After filling both containers and collecting blood for any other tests, remove the needle from the patient's arm, activate the safety device, and hold pressure over the site
• Syringe inoculation of blood culture bottles


  1. The blood must be transferred to the bottles after the draw is completed

  2. Use a safety transfer device for this procedure

  3. Activate the needle's safety device as soon as the needle is removed from the vein

  4. Remove the needle and attach a safety transfer device to the syringe

  5. Push the culture bottle into the device until the needle inside it penetrates the bottle stopper

  6. Allow the blood to be drawn from the syringe by the vacuum in the container

  7. Never push the plunger to expel the blood into the vial. This can hemolyze the specimen and cause aerosol formation when the needle is removed
• Never hold the culture bottle in your hand during the inoculation process. Place it on a solid surface or in a rack. When delivering blood to the bottles, direct the flow along the side of the container.
• Intermediate collection tube


  A yellow-top sodium polyanethol sulfonate (SPS) tube is acceptable for this purpose
• Use of an intermediate tube is discouraged because SPS in the collection tube when added to the blood culture bottle increases the final concentration of SPS, transfer of blood from the intermediate tube to the blood culture bottles presents another opportunity for contamination, and transfer of blood to the culture bottles presents an exposure risk to laboratory staff
• Fastidious antimicrobial neutralization (FAN) bottles


  Contain activated charcoal, which neutralizes the antibiotic
• Antimicrobial removal device (ARD) bottles


  Contain a resin that removes antimicrobials from the blood
• ARDs and FANs should be delivered to the lab for processing as soon as possible
• A clear tube is not necessary when collecting for a PT or PTT, but is required for all other coagulation tests (e.g., factor VIII)
• Sodium citrate tubes for coagulation studies

  Must be filled until the vacuum is exhausted to obtain a 9:1 ratio of blood to anticoagulant
• CTAD tube


  In addition to sodium citrate, contains theophylline, adenosine and dipyridamole to inhibit thrombocyte activation between collection of the blood and performance of the test
• All anticoagulant tubes must be gently inverted three or four times immediately after collection to avoid microclots, which can invalidate test results
• Cooling on ice during transport may be required for some test specimens to protect the coagulation factors, and if the tests cannot be performed in a timely manner, the specimen must be centrifuged and the plasma frozen
• If a coagulation specimen must be drawn from an indwelling catheter, the CLSI recommends drawing and discarding 5 mL of blood or six times the dead-space volume of the catheter before collecting the specimen, and if heparin has been introduced into the line, it should be flushed with 5 mL of saline before drawing the discard blood and collecting the specimen
• 1. Xylose


  A simple sugar, namely pentose, that is not normally found in blood or urine unless food containing it are eaten
• 1. Xylose absorption test


  1. The patient must not eat foods containing D-Xylose for 3 days before the test, to fast after midnight the day of the test, and to remain fasting until the test is completed 5 hours later

  2. The patient must void and discard urine prior testing

  3. An adult patient is given a drink containing 25g D-Xylose dissolved in 500mL water, and timing for the test is started as soon as patient finishes it

  4. All urine voided by the patient is collected, pooled, and refrigerated for the duration of the test

  5. A blood specimen is collected 1 hour after the start of the procedure and tested for D-Xylose

  6. A final urine specimen is collected at the end of the 5 hours and added to the pooled specimen, which is then tested for D-Xylose
• Normal D-Xylose absorption test


  1. Xylose present in blood and urine
• Abnormal D-Xylose absorption test


  Low concentrations of D-Xylose in blood and urine
• Postprandial (PP)


  After a meal
• 1. hour postprandial glucose test


  An excellent screening test for diabetes and other metabolic problems, also used to monitor insulin therapy

  
• 1. hour postprandial glucose test


  The patient is placed on a high-carbohydrate diet for 2 to 3 days prior to the test, the patient fasts prior to the test, a fasting glucose specimen may be collected before the start of the test, the patient is instructed to eat a special breakfast (typically one containing the equivalent of 100 grams of glucose) or given a measured dose of glucose beverage on the day of the test, a blood glucose specimen is collected 2 hours after the patient finishes eating

  
• Glucose tolerance test (GTT)


  Also called the oral glucose test (OGTT), used to diagnose problems of carbohydrate metabolism
• Glucose


  The major carbohydrate in the blood and the body's source of energy
• Early or late specimen collection


  • May be falsely elevated or decreased, respectively, leading to misinterpretation of results