Chapters 9, 11, 10 Flashcards
If small amounts of blood are acceptable for lab tests, skin punctures are used when the following conditions occur in adult patients:
- Fragile or difficult-to-access veins
- When veins are being saved for therapy (e.g. cancer)
- Patient already had multiple unsuccessful venipunctures and tests require small amounts of blood
- Home testing
- Point-of-care testing (POCT)
- Severe burns or scarring on common venipuncture sites
- Obese patients
- Thrombotic tendencies
- Patient receiving IV therapy in both arms
- Patient needs only one test that can be done on a small sample volume
Capillary blood is more of a mixture, composed of blood from:
- arterioles
- venules
- capillaries
- intracellular & interstitial fluid
What is the preferred site of puncture for fingersticks?
The fleshy, central palmar surface of the distal phalanx of the third (middle) finger or fourth (ring) finger of the nondominant hand is the preferred site for puncture.
How should the skin be prepped prior to a fingerstick?
The skin puncture site should be cleaned with a 70% aqueous solution of isopropyl alcohol and allowed to thoroughly dry before being punctured.
Explain why blood cultures are drawn and their clinical significance.
Blood cultures are often collected from patients who have fevers of unknown origin. Sometimes during the course of a bacterial infection in one location of the body, bacteremia (presence of bacteria in the blood) or septicemia (presence of pathogens in the circulating bloodstream, sometimes called blood poisoning) may result and become the dominant clinical feature. Septicemia is a major cause of death in the United States.
Important differences in blood culture procedure relate to the following:
- the healthcare worker must explain the procedure in greater detail to the patient.
- puncture site must be sterilized
- collection tubes must contain culture media that enables bacteria to grow under lab conditions
- timing and # of blood cultures must be clearly indicated, as well as location of venipuncture.
What important collection procedure is required for a urine culture and sensitivity (C&S) test?
Clean catch midstream urine collection
List examples of point-of-care testing
glucose, hemoglobin A1c, Hemoglobin, influenza A & B, cholesterol
Describe the procedure for disinfecting the skin for blood cultures.
Cleanse the site with alcohol for 60 seconds and with Betadine (iodine tincture) for 30 seconds. Cleanse in outward-moving concentric circles to a diameter of approximately 2.5 inches.
Describe ways that you can encourage parental involvement in pediatric phlebotomy.
Explain how parent can assist by holding, distracting, and soothing during the procedure. Maintaining eye contact with the child can reduce stress.
List the typical psychological response to needles and pain for children 1-2 years old.
May react extremely to painless procedures, such as taking their temperature.
List the typical psychological response to needles and pain for children 3-5 years old.
Perceive pain as punishment for bad behavior and may react aggressively.
List the typical psychological response to needles and pain for children 6-12 years old.
Relate pain to past experiences; may perceive shots and needles hurt more than anything else that has ever happened to them.
List the typical psychological response to needles and pain for children 13-17 years old.
More independent and may be embarrassed to show fear. Need privacy. May act hostile to mask fear.
Describe the use of EMLA as a topical anesthetic to decrease needlestick pain in children.
EMLA is eutetic mixture of local anesthetics. It is rubbed on the skin and doesn’t require a needle. It is applied as a patch or cream, covered with a transparent adhesive dressing. Optimal anesthesia occurs after 45 to 60 minutes and may last 2 to 3 hours. Drawbacks are cost, need to apply 60 minutes before procedure, and having to know in advance the location of the vein to be used. Don’t use if the child is allergic to local anesthetics.
Describe why only the smallest amounts of blood are collected from babies and children.
To minimize the effects of reductions in blood volume. Over-collecting during phlebotomy may require packed-blood-cell transfusions in an infant.
What is the most desirable site for skin puncture on an infant or neonate?
The most medial or lateral section of the plantar surface of the heel. Do not use the central area of the heel.
List physical problems that are common in older individuals and the implications related to phlebotomy.
- hearing loss may cause embarrassment and frustration.
- impaired verbal communication due to stroke, Parkinson’s. Alzheimer’s, etc.
- Failing eyesight; guide patient to seat or bathroom for urine collections
- Loss of taste, smell, feeling: lack of appetite leading to malnutrition and dehydration; may drop things or be unable to make a fist due to weakness
- memory loss may affect patient taking meds or remembering when they ate, which may interfere with lab results.
- skin is thinner, making venipuncture difficult. Hold skin taut to the vein doesn’t roll. Don’t slap arm, because this causes bruising. Instead, use a warm compress.
- Increased susceptibility to hypothermia may require warming of puncture site
- increased sensitivities and allergies
- anxiety related to becoming older and less capable
Under which circumstances are fingerstick procedures NOT recommended?
- Lab tests require large amounts of blood (blood cultures, erythrocyte sedimentation rates)
- Patient has swollen fingers; the interstitial fluid may dilute the sample
- Patient is dehydrated
- Poor peripheral circulation
- Coagulation studies (because of dilution by interstitial fluid)
Which lab tests are commonly performed using capillary blood?
- Blood smears for WBC differentials
- CBC, hemoglobin, hematocrit
- electrolytes
- neonatal blood gasses
- neonatal bilirubin
- neonatal screening using filter paper
- point-of-care testing or home testing
What complications can occur when performing venipuncture in children?
- anemia
- cardiac arrest
- hemorrhage
- venous thrombosis
- damage to surrounding tissues or organs
- infections
- injuries from restraining the child during the procedure
Describe the special qualities of capillary blood.
- generally has slightly more arterial than venous blood because the arterial pressure in capillaries is stronger than venous pressure.
- Lab values of glucose, potassium, total protein, and calcium differ in capillary versus serum or plasma
- in all cases EXCEPT GLUCOSE, the values are lower in skin puncture blood.
Why should plastic capillary tubes be used instead of glass?
Glass tubes break easily and can cause injury.
Why is the nondominant hand preferred for fingersticks?
It is often less callused so the puncture is more effective
Which sites are NOT recommended for routine skin puncture?
- earlobe due to interference with piercings and proximity to eyes, and anxiety due to patient jerking their head.
- central arch of infant’s heel and posterior curve of heel due to risk of injuring nerves, tendons, cartilage, or bone
- fingers of newborn or infants less than 1 year due to risk of hitting bone and infections
- 5th finger/pinky because it is more sensitive and likely to be callused
- thumb because it has a pulse
- index finger because it is sensitive and more likely to be callused
- swollen, infected, callused, burned, cut, scarred sites due to chance of contamination and bruising and pain
- fingers on the side of a mastectomy because of lymphedema
What are some considerations concerning alcohol on the skin puncture site?
- if alcohol drips or pools at the site, it can cause hemolysis and contaminate testing for glucose determinations
- alcohol will prevent formation of well-rounded drops of blood which are best for making blood smears
