Phlebotomy Ch 9 Pre-Examination Flashcards
What does the pre-Examination / Pre-Analytical phase of testing include?
Begins when test is ordered and ends when testing begins.
Includes the ability technical ability to perform the draw and the ability to recognize factors prior to the draw that can compromise specimen quality, jeopardize the health and safety of the patient or increase the cost of care.
What are reference ranges?
- Tests confirm health or screen, diagnose, & monitor disease
- Test results are compared with specimens of healthy people
- Consist of range of values with high & low limits. Most often based on healthy, fasting people.
Some tests have age specific ranges (e.g. Diabetes).
What is the basal state?
Definition: Resting state of body early in the morning after fasting 12 hours
Why is the basal state specimens ideal for reference ranges on inpatients?
Effects of diet, exercise, etc. on test result are minimized
What factors influence basal state?
Age
Gender
Conditions of body
What is diurnal or circadian variation? Name some examples of body substances affect by these?
Diurnal daily variation or circadian 24 hour cycle – Diurnal is factors like posture, activity, eating and daylight.
Examples:
a) Melatonin effected by light increase at night when dark and decrease during day).
b) TSH thyroid stimulation hormone also have variation and levels occur in predawn hours of the morning.
What is hemoconcentration and what blood components does it affect when it is caused by dehydration?
Hemoconcentration is blood components that can not easily leave the bloodstream.
Therefore they become concentrated in the smaller plasma volume – RBC, enzymes, iron, calcium, Na and K along with coagulation factors.
What physiological variables affect hemoconcentration?
Dehydration, Environmental Factors.
How does age, dehydration, diet, diurnal, sex, and jaundice affect blood testing?
Age - RBC and WBC are normally higher in newborns than adults, Creatinine Clearance is directly related to age – due to decrease of kidney function as people age and needs to be factored.
Dehydration - hemoconcentration, RBC, enzymes, Fe, CA, Na and coagulation factors.
Diet - blood specimens collected soon after a meal or snack are typically unsuitable for lab tests. Typical fasting time is 8-12 hrs (dangerous to got past 12).
Diurnal - TSH, cortisol, and Fe affected.
Sex - RBC, Hgb, and Hct are all higher for males than females.
Jaundice - yellow colour interferes.
What is jaundice caused by? How does it affect sample integrity?
Jaundice also called icterus caused by increase bilirubin in the blood. Bilirubin is yellow bile pigment that is the product of destruction of RBCs and the breakdown of the hemoglobin they contain.
- High levels of bilirubin result in deposits of the pigment in the skin, mucous membrane and sclerae (eye seen here)
- Icteric is used to describe serum, plasma, or urine specimens that have deep yellow/brown colour due to high bili
SAMPLE INTEGRETY – This colour in the sample can interfere with chemistry tests based on colour reactions
What problems can burns, scars and tattoos cause for vascular vein puncture?
Veins are difficult to palpate here May have impaired circulation New burns are painful Tattoos may be more susceptible to infection; dyes may interfere Damaged Veins: - Occluded (obstructed) - Sclerosed: Hardened - Thrombosed: Clotted --> Difficult to puncture & can yield erroneous results
What is edema and how does it impact venipuncture?
- Swelling caused by abnormal accumulation of fluid in tissues. Results when fluid from IV infiltrates surrounding tissues
- a) Contaminates blood with tissue fluid
b) Veins are harder to locate, & tissue is fragile
What is a hematoma and how does it affect venipuncture?
- Hematoma: A swelling or mass of blood.
Caused by blood leaking from vessel during venipuncture. - Can be painful, contaminate blood sample, obstruct blood flow.
What effect can taking blood samples from edematous areas have on the lab results?
Can yield inaccurate test results as they are contaminated with tissue fluid or altered blood composition.
How does a patient’s mastectomy affect venipuncture?
- Mastectomy is surgical breast removal
- a) Lymph flow is obstructed with removal of lymph nodes
b) Swelling & infection may be present
c) Applying tourniquet here can cause injury
d) Can change blood composition
Where do you perform venipuncture in the case of mastectomy?
- On the other arm if only one side affected.
2. Consult patient’s physician fi on both sides.
How does obesity affect venipuncture?
Obesity
Veins may be deep & hard to find
Use longer tourniquet & try median cubital or cephalic vein
Should you draw blood from a paralyzed arm? Why?
- Avoid drawing blood from paralyzed arm.
- Increased chance of thrombosis (blood flow stagnation)
- Difficulty detecting nerve injury
What are vascular access devices? How does that affect venipuncture?
- Used for patients who require frequent venous or arterial access.
- Administer medications, fluids, blood products and sometimes blood collection (by a nurse)
- A general rule venipuncture should not be performed on an extremity with a VAD
What is an intravenous (IV) line and how does it affect venipuncture?
Catheter inserted in peripheral vein
Avoid drawing blood from arm containing IV, if possible
What are the steps if one must perform venipuncture below an IV?
Ask patients nurse to turn off IV for at least 2 minutes
Apply tourniquet distal to the IV
Select a venipuncture site distal to the IV and tourniquet
Perform puncture in different vein that one with IV (if possible)
Ask nurse to restart IV
Document
What is an IC Catheter Lock and how does it affect venipuncture?
IC Catheter Lock:
1. Needleless connection device in the form of a stopcock or cap
2. Device is filled with saline, called Saline lock (to prevent clotting) or a Heparin lock (heplock).
Heparin adheres to the surface of the lock and it is difficult to flush out – a 5mL discard tube should be drawn first when blood specimens are collected from a heplock or a saline lock that has been flushed with heparin.
Drawing coagulation specimens from them is also not recommended as heparin or dilution of saline can effect results.
Trained personal (nurses, etc) should perform, phlebotomist assists.
What are the problems with previously active IV sites?
Potential source of testing error
Wait 24 to 48 hours after IV was discontinued before collecting a blood specimen.
What is an arterial line and how does it affect venipuncture?
Arterial Line: A catheter placed in an artery (usually radial). Provides accurate & continuous measurement of blood pressure
No tourniquet or venipuncture on an arm with an arterial line.
What are Arteriovenous Shunt or Fistula and how do they impact venipuncture?
Arteriovenous Shunt or Fistula: The permanent, surgical fusion of an artery and a vein. Created to provide access for dialysis. Located on back of arm above wrist.
This is a dialysis patients life line – venipuncture should never be performed from a fistula
What are the different types of arteriovenous shunt/fistulas?
AV Shunt –bypasses capillaries and forces arterial blood directly into a vein. Joins the radial artery and cephalic vein above the wrist on the underside of the arm
AV Fistula – Fusion of an artery and vein - Visible as a large bulging section of vein. This is most common type of fistula for dialysis.
AV Graft - Seen as a loop from the artery to the vein
When palpated a shunt has a buzzing sound called a ‘thrill’ from the pressure in the arterial blood flow
What is a blood sampling device?
Blood Sampling Device Connected to arterial or central venous catheter to collect blood Reduces chance of infection Prevents needlesticks Minimizes waste from line draws
What is an implanted port?
Implanted port
A small chamber attached to indwelling line
Surgically implanted under skin (upper chest or arm)
What are Central Vascular Access Devices (CVADs)? What are they used for?
Central Vascular Access Devices (CVADs)
- Known as indwelling lines. Consist of tubing inserted into a main vein or artery
- Used for:
a) Administering fluids & medications
b) Monitoring pressures
c) Drawing blood
What are the two types of CVADs (Central Vascular Access Devices)?
Types of CVADs
1. Central venous catheter or line (CVC)
Inserted into large vein (subclavian)
Advanced into superior vena cava. Requires surgical insertion.
2. Peripherally Inserted Central Catheter (PICC). Inserted in veins of extremities (e.g. arms) & threaded into central veins. Does not require surgical insertion. More common in MB hospitals.
What precautions are needed to be taken when drawing blood from a CVAD (Central Vascular Access Device)?
- Only specially trained personnel should access CVADs to draw blood. Phlebotomist only assists.
- A discard tube must be drawn - 2x’s the dead space volume of the line and 6x’s for coagulation studies (about 5 ml), although it is not recommended to draw blood from a CVAD for coagulation tests.
What do you do if the patient has an adhesive allergy?
Adhesive allergy
Place gauze square over site; have patient remove in 15 minutes
Or, have patient apply pressure for more than 5 minutes instead of bandage
What do you do in the patient has an antiseptic allergy?
Use an alternate antiseptic.
How do you consider the potential for latex allergies and if there is one what do you do?
Latex allergy
Look for sign indicating latex allergy on patient’s door
Use nonlatex equipment (e.g., gloves, tourniquet, & bandages)
Note: Patients with known allergies often wear special armbands or have allergy-specific warning signs posted in their hospital rooms
What may cause excessive bleeding in a patient?
Patients on aspirin or anticoagulant may bleed longer
What do you do in the case of excessive bleeding?
- Maintain pressure until bleeding stops
If bleeding continues >5 minutes, notify appropriate personnel - Never apply a pressure bandage instead of maintaining pressure until bleeding has stopped
- Do not dismiss an outpatient or leave an inpatient until bleeding has stopped or the appropriate personnel have taken charge of the situation
What do you do in the case of patient fainting?
Have patients w. history of fainting lie down during venipuncture.
Note (recall): Fainting is a loss of consciousness and postural tone caused by insufficient blood flow to brain.
What are the steps to follow if a patient starts to faint?
- Release tourniquet and remove needle as quickly as possible
- Apply pressure to the site while having the patient lower the head and breath deeply
- Talk to the patient
- Physically support the patient
- Ask permission and explain what you are doing if it is necessary to loosen tight collar or tie.
- Apply a cold compress or wet cloth to forehead and back of neck
- Have someone stay with patient until recovery is complete
- Call for first aid personnel if patient does not respond
- Document incident
What is the most important first step when you see a patient start to faint?
Remove tourniquet and needle is most important first thing to do as this can cause lots of complications later if not done.
What you should ask while drawing blood, in particular if a person notes they are susceptible to fainting during the procedure?
- Also ask them how they are doing while you are drawing blood. I always do this with you all in lab – safety first !
Watch for paleness, perspiration, hyperventilation dizziness, light-headed, nausea, tunnel vision, sound fading - Fainting can occur without notice also so always be ready and never turn your back on a patient
What do you do if the patient has nausea and vomits?
Nausea and Vomiting
- Discontinue blood draw until feeling subsides
- Give patient emesis basin or wastebasket
- Apply cold, damp washcloth to forehead
How do you handle the possibility of pain for the patient during the procedure?
Pain:
- Warn patient before needle insertion, e.g. “1, 2, 3, poke”
- Avoid excessive, deep, blind, or lateral redirection of needle
- Extreme pain or numbness indicates nerve involvement; remove needle immediately, apply ice, document incident if pain persists
- Put patient at ease prior to the poke.
- Allow alcohol to dry completely before poke.
What are petechiae?
Petechiae are tiny non-raised red spots that appear on arm when tourniquet is applied.
Note:
a) These are minute drops of blood that escape the capillaries and come to the surface below the skin. Capillary wall defects or coagulation abnormalities – platelet defects and thrombocytopenia
b) This is not of any fault to phlebotomist – is a good indication that may bleed excessively
What do you in the rare case a patient starts having a seizure/convulsion during venipuncture?
Seizures/Convulsion:
- Untie tourniquet and withdraw needle immediately
- Hold pressure over site without restricting patient’s movement
- Call for help to ease the patient to the floor
- Turn patient on their side to keep the airway clear. Do not put anything in patient’s mouth
- Loosen clothing that could make breathing difficult and protect patient from self-injury.
- Notify first-aid personnel
What do we do if we notice a hematoma forming and/or bruising?
Hematoma Formation & Bruising:
- Discontinue draw immediately and hold pressure over site 2 minutes
- Offer cold compress or ice pack if it is large & swollen
What do you do if the patient has Iatrogenic Anemia?
Iatrogenic Anemia (Anemia brought about by blood loss from blood draws):
- Life is threatened if >10% of blood volume is removed at once
- Collect only minimum required specimen volumes
What are signs of an inadvertent arterial puncture?
Inadvertent Arterial Puncture, Signs:
- Rapidly forming hematoma,
- blood filling tube quickly
How do you avoid infection of the patient during venipuncture?
- Avoid by using aseptic technique:
- Don’t open tape or bandages ahead of time
- Don’t preload needles onto tube holders ahead of time
- Don’t touch needle insertion site after sterilizing it
- Minimize time between needle cap removal & venipuncture
- Remind patient to keep bandage on at least 15 minutes
What is nerve injury caused by?
Caused by:
1. Improper site or vein selection
2. Inserting needle too deeply or quickly
3. Excessive lateral redirection of needle
4. Blind probing
Relatively rare – can be a serious problem that can result in permanent damage to arm or hand, e.g. claw hand by ulnar nerve injury.
What is reflux of additive and how do you prevent it?
Reflux of Additive
- Blood flows back into vein from collection tube
- Tube additives (e.g., EDTA) may cause adverse reaction
- Keep arm in downward position and tube below venipuncture site
TIPS: a) To avoid reflux in a phlebotomy chair get patient to sit or lean forward and extend arm downward over the arm of the chair
b) Raising the head of the bed for a inpatient and extending the arm over the edge of the bed or utilize a towel or pillow
How do you avoid vein damage?
Vein Damage
- Avoid numerous venipunctures in the same area over time
- Avoid blind probing & improper technique
What is hemoconcentration?
Hemoconcentration
A decrease in fluid content of blood
An increase in nonfilterable large molecules
Caused by stagnation of normal venous flow due to tourniquet
What is hemolysis and its impact on the specimen?
Hemolysis
Damage to or destruction of RBCs
Hemoglobin escapes into fluid part of specimen
What is the problem with partially filled tubes (short draw)?
Partially Filled Tubes (short draw)
Blood-to-additive ratio may be incorrect
Usually result from a difficult draw situation
Which short draw may be acceptable and what are some specific issues with additives you have learned?
OK: Red top tubes SST generally acceptable
NOT OK:
- EDTA short draw – shrink RBCs erroneously low blood cell count and morphological examination on blood smear
- Heparin short draw tubes can affect some chemistry analytes
- Sodium Fluoride short draw- results in hemolysis of blood
- Coagulation Na citrate – 9:1 ratio must be adhered to
Should you ever use a wrong or expired collection tube?
No never!
What are some sources of specimen contamination?
Allowing alcohol residue, fingerprints, glove powder, baby powder, urine on newborn screening samples
Getting glove powder on blood films or capillary specimens
Dripping perspiration into capillary specimens
Following improper antiseptic procedure
Using wrong antiseptic
What are things to troubleshoot for failed venipuncture in regards to needle position?
Needle not inserted far enough Bevel partially out of skin Bevel partially into vein Bevel partially through vein Bevel completely through vein Bevel against vein wall Bevel in valve Needle beside vein Undetermined position
What are things to troubleshoot for failed venipuncture in regards to tube position?
Tube Position
- Improper seating
- Needle fails to penetrate stopper
What are three words to remember when troubleshooting failed venipuncture?
STOP, ASSESS & CORRECT.
What is a collapsed vein and what is it caused by?
Collapsed Vein
- Vein walls draw together temporarily, shutting off blood flow
- Caused by:
a) Vacuum of tube or plunger pressure is too strong for vein
b) Tourniquet is too tight or too close to site
c) Tourniquet is removed during draw (esp. w. elderly)
What causes a loss of tube vacuum?
Loss of Tube Vacuum causes:
- Loss of vacuum due to bevel partially out of skin
- Loss of vacuum due to damage of tube
