Specimen Collection Pt. II Flashcards
(70 cards)
1
Q
what to do after cleaning the puncture site?
A
Reapply tourniquet
- perform puncture
- DO NOT TOUCH SITE WITH UNCLEAN FINGERS
- ask patient to remake fist
- instruct not to pump/continuously clench fist (to prevent hemoconcentration)
2
Q
after anchoring the vein, insert the needle smoothly & swiftly at _________
A
15-30 degree angle; bevel up
- brace fingers against arm to prevent movement of needle when changing tubes
3
Q
T/F:
once blood flow is observed, release the tourniquet & ask patient to open fist
A
TRUE
4
Q
T/F:
for ETS, the prints on the tubes should face up when filling them with blood
A
FALSE
- prints should face down to allow blood flow to be seen
- once full, remove the tube gently, invert & fill the next tube (according to the order of draw)
5
Q
once the tubes are all filled, cover the puncture site, remove the needle swiftly & smoothly, and ______________
A
Ask patient to apply pressure
- arm should be straight or raised
- for 2-5 minutes
6
Q
T/F:
it is okay to leave the patient right away after collection
A
FALSE
- verify info for labelling
- examine puncture site for bleeding or hematoma
7
Q
specimens should be transported to the lab within ________
A
45 minutes - 2 hours
- do not forget to thank the patient, clean the area, and perform hand hygiene before transport
8
Q
sites that may be used when collecting venous blood in infants
A
- dorsal hand veins
- cord blood
- external jugular vein
- DOCTORS ONLY
9
Q
veins in the antecubital fossa are the best choice for _____________
A
children > 2 years old
10
Q
dorsal hand veins
A
- those used for IV therapy
- can be used for children < 2 years old
- PROS:
- sample is collected from superficial hand veins directly into microcontainers
- more blood is collected than heelstick
- there is less chance of hemolysis & contamination with tissue fluids
- CONS:
- requires additional training
- an institutional decision (saving veins for IV therapy may be preferred)
11
Q
sample obtained only at the time of delivery
A
Cord blood
- placental segment is allowed to drain into a test tube, OR
- umbilical vein is aspirated with needle & syringe
- admixture of cord jelly must be avoided
12
Q
cord jelly
A
“Wharton’s jelly”
13
Q
procedure in which only the doctors are allowed to perform
A
External jugular vein
- infant is wrapped in sheet (to immobilize infant)
- infant is placed on his/her back on the table with the head hanging over the edge (head should be supported)
- infant is turned to the side
- when child cries, EJV becomes visible
- running the angle of the mandible to midclavicular area
14
Q
method of choice for collecting blood from infants & children younger than 2 years old
A
Skin (dermal) puncture
- locating large, superficial veins are difficult
- available veins may be reserved for IV therapy
15
Q
total blood volume of a 2-pound infant
A
approx. 150mL
- drawing excessive amounts can rapidly cause anemia
16
Q
complications that may arise from using deep veins in infants
A
- cardiac arrest
- venous thrombosis
- hemorrhage
- damage to surrounding tissues & organs
- infection
- reflex arteriospasm –> resulting gangrene
- injury to the child (restraining)
17
Q
certain tests that require capillary blood from newborn & infants
A
- newborn screening tests
- neonatal bilirubin
- capillary blood gases
- POCT
18
Q
conditions where dermal puncture may be preferred over venipuncture in adults
A
- burned/scarred patients
- patients receiving chemotherapy
- patients with thrombotic tendencies
- geriatric patients; those with very fragile veins
- patients with inaccessible veins
- obese patients
- apprehensive patients
- patients requiring home glucose monitoring
- POCT
19
Q
why is dermal puncture preferred in patients receiving chemotherapy?
A
they require frequent tests & their veins must be reserved for therapy
20
Q
blood collected by dermal puncture comes from ___________, ____________, __________
A
capillaries, arterioles, & venules
- a mixture of arterial & venous blood
- may contain small amounts of interstitial & intracellular fluids
21
Q
T/F:
because of arterial pressure, the composition of capillary blood more closely resembles arterial rather than venous blood
A
TRUE
- warming the site before collection increases blood flow by 7x –> producing a sample very close to arterial blood composition
22
Q
dermal puncture devices
A
- skin puncture devices (lancets)
- microcontainers
- glass slides
- heel warmer
23
Q
T/F:
to prevent contact with the bone, the depth of the puncture is critical
A
TRUE
- should not exceed 2mm (CLSI recommendation)
- length of lancet & spring release mechanisms control the puncture depth (automatic devices)
24
Q
major vascular area of the skin
A
Dermal subcutaneous junction
- newborn: 0.35-1.6mm below the skin
- adults: max. 3mm
25
sufficient blood flow should be obtained from incision widths __________
not greater than 2.5mm
- widths vary from needle stabs - 2.5mm
- number of severed capillaries depends on the incision width
26
the type of device selected depends on the following factors:
- age
- amount of blood sample required
- collection site
- puncture depth
27
lancets approved by the FDA for adults & children older than 5 years old
Laser lancets
- available for clinical & home use
- eliminates the risks of accidental punctures & the need for sharps containers
28
depth at which laser lancets penetrate the skn
1-2mm
- vaporizes water in the skin
- smaller wound is created
- pain & soreness associated with capillary puncture is reduced
- allows up to 100uL of blood to be collected
29
microcontainers
Microsample containers
- microcollection tubes
- capillary tubes
- micropipettes
30
frequently referred to as microhematocrit tubes
Capillary tubes
- used to collect approx. 30-75uL of blood
- primary purpose: for microhematocrit tests
- 2 types:
- - plain = blue band
- - heparinized = red band (ammonium heparin)
31
heel warmers
a. warm washcloths
- heating at 42C & applying for 3-5 minutes
- site should not be warmed for more than 10 minutes --> false results
- be careful not to burn the patient
b. commercial heel warmer
- sodium thiosulfate & glycerin
- produces heat when mixed together (gentle squeezing the packet)
32
puncture site for dermal puncture
- off center
- 3rd or 4th finger, palmar side (nondominant hand)
- perpendicular to the (ridges of the) fingerprint
33
position of puncture site
palmer surface facing up, finger pointing down
34
T/F:
| after puncturing, the first drop of blood is wiped away
TRUE
- to prevent contamination
- the first drop may contain alcohol residue & tissue fluid
35
sample should be collected within ________ to prevent clotting
2 minutes
36
number of inversions for microcontainers
5-10 times
- or as recommended by the manufacturer
- containers may be gently tapped to mix blood & anticoagulant
37
T/F:
| it is okay to apply bandage for children younger than 2 years old after puncture
FALSE
| - it can cause choking to the infant
38
T/F:
| punctures should never be made through previous puncture sites
TRUE
| - can easily introduce microorganisms into the puncture --> allowing them to reach the bone
39
where to collect blood when patient has had mastectomy?
Opposite to the side of the mastectomy
- inform health-care provider first
- aside from breast tissue, lymph nodes are also removed in mastectomy
- - there is greater chance of acquiring infections
40
site used for dermal punctures on infants younger than 1 year old
Heel puncture site
- contains more tissue than the fingers
- has not yet been calloused from walking
- acceptable areas: MEDIAL & LATERAL AREAS OF THE PLANTAR SURFACE (bottom) OF THE HEEL
- - distance between the skin & calcaneus (heel) bone is greatest
41
punctures performed in other areas aside from the acceptable areas may cause _____________
damage to nerves, tendons, cartilage
42
heel puncture vs. finger puncture
a. heel puncture
- medial & lateral areas of the plantar surface of the heel
- for children younger than 1 year old
b. finger puncture
- 3rd & 4th finger of the nondominant hand
- for adults & children over 1 year old
43
why should finger punctures be off center & perpendicular to the fingerprint?
- wound easily opens up
- collect more (rounded) blood
- tip & sides of the finger contain only about 1/2 tissue mass of the central area --> possibility of bone injury is increased
44
problems associated with the use of other fingers for puncture
a. thumb & index fingers
- possible calluses
b. index finger
- increased nerve endings
c. fifth finger
- decreased tissue
45
effect of puncturing a swollen site
increased tissue fluid --> contamination of blood sample
46
heel stick procedure
- same basic steps as venipuncture
- hold the foot with a firm grip
- - grasp the heel with the thumb placed below the site & index finger placed over the arch
- puncture at a 90 degree angle parallel to the heel
- use a quick continuous motion
47
when is warming the site required?
- for patients with very cold (cyanotic) fingers
- for heel sticks to collect multiple samples
- for collection of capillary blood gases
- - BVs are dilated --> arterial blood flow is increased
48
_____________ may also increase blood flow to the area
Massaging the puncture area
| - do not squeeze when collecting sample
49
presence of air bubbles in the sample
Interferes with blood gas determinations
| - bubbles limit the amount of blood that can be collected
50
how to prevent air bubbles?
hold capillary tubes horizontally while being filled (capillary action)
- do not remove the tube while collecting
51
what to do when tubes are filled?
Seal
- sealant clay
- designated plastic caps
- place the end of the tube (with no band) into the clay
- - remove with a slight twisting action
- - be careful not to break the tube
52
effect of using adhesives as bandage
- skin irritation
| - tear sensitive skin (part. fragile skin)
53
how to label microcollection tubes
The same info required for venipuncture samples
- wrap around a number of microcollection tubes
- place in a large tube for transport
- - the outside of the capillary pipettes may be contaminated with blood
- - prevents breakage
54
order of draw for dermal puncture
1. blood gas (?)
2. blood smear
3. EDTA tubes
- pink/lavender
- HEMA tubes
4. heparin tubes
- light/dark green
- tests requiring plasma
- K, Glu, chem tests
5. red/gold tubes
- tests requiring serum
- K, Na, bilirubin, chem tests, blood bank
55
veins in antecubital fossa used for venipuncture
1. Median cubital
- most well-anchored
- largest, superficial
- most preferred
2. Cephalic
- well-anchored
3. Basilic
- least well-anchored
- surrounded by nerves
- least preferred
56
sources of error for skin puncture
a. hemolysis
- most common
- infants' RBCs are more fragile than adults'
b. failure to dry site completely
c. failure to wipe away 1st drop of blood
d. vigorous massaging/milking
e. accidental capturing of air bubbles into tubes
*"skin puncture" should be noted in requisition slip - lab values may differ
57
coagulation of blood can be prevented by:
a. removing (chelating) calcium
- oxalates
- citrates
- EDTA
b. inactivating thrombin & thromboplastin
- heparin
c. removing fibrin
58
too little anticoagulant
partial clotting; interferes with:
- - WBC, RBC, platelet cts.
- - ESR, etc.
59
interferes with K assay
potassium salts of EDTA
60
interferes with BUN determinations
ammonium oxalate
61
affects white cell morphology
oxalates
| - affects peripheral blood smear
62
diluted blood samples interfere with ____________
quantitative determinations
63
sodium citrate
- used for many coagulation studies
- anticoagulant of choice for PT, PTT
- - factor V is relatively stable
64
concentration of sodium citrate for coagulation studies
3. 8%
- light blue top tube
- 3.8g sodium citrate to 100mL dist. H2O
65
black top tube sodium citrate concentration
3. 2%
| - used for ESR (Westergren)
66
potassium salt of EDTA
- preparation of choice
- commercial name: Sequester Solution
- used as anticoagulant for platelet counts, function tests & most hematological tests
67
optimal concentration of EDTA
1. 5mg EDTA/mL blood
- does not cause cell distortion if read within 2 hours
- excessive amounts induce red cell shrinkage --> decreased Hct, ESR values
68
heparin
- powerful anticoagulant: anti-thrombic & anti-thromboplastic
- NOT USED FOR COAGULATION STUDIES
- anticoagulant of choice for osmotic fragility test (unless defibrinated blood is used)
69
appearance of blood & bone marrow smears prepared from heparinized blood
- light bluish background (Wright-Giemsa stain)
- causes morphologic distortions of platelets, WBCs
- causes errors in automated cell counting
70
effect of oxalates when used alone
a. potassium oxalate
- shrinks RBC
- "potaSHRINK oxalate"
- 0.8g
b. ammonium oxalate
- causes swelling of cells
- "ammonium oxSWELLate"
- 1.2g
*when combined, they do not affect cell shape --> Hct not affected
