State the maximum number of venipuncture which should be attempted and why this policy is set.

The information given here supplements that given in Chapter 2. Users of these guidelines should read Chapter 2 before reading the information given below. This chapter covers background information (Section 7.1), practical guidance (Section 7.2) and illustrations (Section 7.3) relevant to capillary sampling.

Capillary sampling from a finger, heel or (rarely) an ear lobe may be performed on patients of any age, for specific tests that require small quantities of blood. However, because the procedure is commonly used in paediatric patients, Sections 7.1.1 and 7.1.2 focus particularly on paediatric capillary sampling.

The finger is usually the preferred site for capillary testing in an adult patient. The sides of the heel are only used in paediatric and neonatal patients. Ear lobes are sometimes used in mass screening or research studies.

Selection of a site for capillary sampling in a paediatric patient is usually based on the age and weight of the patient. If the child is walking, the child's feet may have calluses that hinder adequate blood flow. Table 7.1 shows the conditions influencing the choice of heel or finger-prick.

Specimens requiring a skin puncture are best obtained after ensuring that a baby is warm, as discussed in Section 6.2.2.

A lancet slightly shorter than the estimated depth needed should be used because the pressure compresses the skin; thus, the puncture depth will be slightly deeper than the lancet length. In one study of 52 subjects, pain increased with penetration depth, and thicker lancets were slightly more painful than thin ones (67). However, blood volumes increased with the lancet penetration and depth.

Lengths vary by manufacturer (from 0.85 mm for neonates up to 2.2 mm). In a finger-prick, the depth should not go beyond 2.4 mm, so a 2.2 mm lancet is the longest length typically used.

In heel-pricks, the depth should not go beyond 2.4 mm. For premature neonates, a 0.85 mm lancet is available.

The distance for a 7 pound (3 kg) baby from outer skin surface to bone is:

• medial and lateral heel – 3.32 mm;

• posterior heel – 2.33 mm (this site should be avoided, to reduce the risk of hitting bone);

• toe – 2.19 mm.

The recommended depth for a finger-prick is:

• for a child over 6 months and below 8 years – 1.5 mm;

• for a child over 8 years – 2.4 mm.

Too much compression should be avoided, because this may cause a deeper puncture than is needed to get good flow.

With skin punctures, the haematology specimen is collected first, followed by the chemistry and blood bank specimens. This order of drawing is essential to minimize the effects of platelet clumping. The order used for skin punctures is the reverse of that used for venepuncture collection. If more than two specimens are needed, venepuncture may provide more accurate laboratory results.

Complications that can arise in capillary sampling include:

• collapse of veins if the tibial artery is lacerated from puncturing the medial aspect of the heel;

• osteomyelitis of the heel bone (calcaneus) (68);

• nerve damage if the fingers of neonates are punctured (69);

• haematoma and loss of access to the venous branch used;

• scarring;

• localized or generalized necrosis (a long-term effect);

• skin breakdown from repeated use of adhesive strips (particularly in very young or very elderly patients) – this can be avoided if sufficient pressure is applied and the puncture site is observed after the procedure.

7.2.1. Selection of site and lancet

• Using the guidance given in Section 7.1, decide whether to use a finger or heel-prick, and decide on an appropriate size of lancet.

• DO NOT use a surgical blade to perform a skin puncture.

• DO NOT puncture the skin more than once with the same lancet, or use a single puncture site more than once, because this can lead to bacterial contamination and infection.

Prepare the skin

• Apply alcohol to the entry site and allow to air dry (see Section 2.2.3).

• Puncture the skin with one quick, continuous and deliberate stroke, to achieve a good flow of blood and to prevent the need to repeat the puncture.

• Wipe away the first drop of blood because it may be contaminated with tissue fluid or debris (sloughing skin).

• Avoid squeezing the finger or heel too tightly because this dilutes the specimen with tissue fluid (plasma) and increases the probability of haemolysis (60).

• When the blood collection procedure is complete, apply firm pressure to the site to stop the bleeding.

Take laboratory samples in the correct order to minimize erroneous test results

• With skin punctures, collect the specimens in the order below, starting with haematology specimens:

  –

  haematology specimens;

  –

  chemistry specimens;

  –

  blood bank specimens.

Immobilize the child

• First immobilize the child by asking the parent to:

  –

  sit on the phlebotomy chair with the child on the parent's lap;

  –

  immobilize the child's lower extremities by positioning their legs around the child's in a cross-leg pattern;

  –

  extend an arm across the child's chest, and secure the child's free arm by firmly tucking it under their own;

  –

  grasp the child's elbow (i.e. the skin puncture arm), and hold it securely;

  –

  use his or her other arm to firmly grasp the child's wrist, holding it palm down.

Prepare the skin

• Prepare the skin as described above for adult patients.

• DO NOT use povidone iodine for a capillary skin puncture in paediatric and neonatal patients; instead, use alcohol, as stated in the instructions for adults.

Puncture the skin

• Puncture the skin as described above for adult patients.

• If necessary, take the following steps to improve the ease of obtaining blood by finger-prick in paediatric and neonatal patients:

  –

  ask the parent to rhythmically tighten and release the child's wrist, to ensure that there is sufficient flow of blood;

  –

  keep the child warm by removing as few clothes as possible, swaddling an infant in a blanket, and having a mother or caregiver hold an infant, leaving only the extremity of the site of capillary sampling exposed.

• Avoid excessive massaging or squeezing of fingers because this will cause haemolysis and impede blood flow (60).

Take laboratory samples in the order that prevent cross-contamination of sample tube additives

• As described above for adult patients, collect the capillary haematology specimen first, followed by the chemistry and blood bank specimens.

• Collect all equipment used in the procedure, being careful to remove all items from the patient's bed or cot; to avoid accidents, DO NOT leave anything behind.

There are two separate steps to patient follow-up care – data entry (i.e. completion of requisitions), and provision of comfort and reassurance.

Data entry or completion of requisitions

• Record relevant information about the blood collection on the requisition and specimen label; such information may include:

  –

  date of collection;

  –

  patient name;

  –

  patient identity number;

  –

  unit location (nursery or hospital room number);

  –

  test or tests requested;

  –

  amount of blood collected (number of tubes);

  –

  method of collection (venepuncture or skin puncture);

  –

  phlebotomist's initials.

Show the child that you care either verbally or physically. A simple gesture is all it takes to leave the child on a positive note; for example, give verbal praise, a handshake, a fun sticker or a simple pat on the back.

A small amount of sucrose (0.012–0.12 g) is safe and effective as an analgesic for newborns undergoing venepuncture or capillary heel-pricks (70).

Adhere strictly to a limit on the number of times a paediatric patient may be stuck. If no satisfactory sample has been collected after two attempts, seek a second opinion to decide whether to make a further attempt, or cancel the tests.

Collection Procedure:

LTD: Performing a Venipuncture  Version 5

PERFORMING A VENIPUNCTURE

Venipuncture Site Selection: The median cubital and cephalic veins are most

commonly used for venipuncture. See below. Alternative sites are the basilic

vein on the dorsum of the arm or dorsal hand veins. Due to its close proximity to

the brachial artery and median nerve, the basilic vein, which is located on the

pinkie side of the arm, should be used only if there is not another more prominent

arm vein. Veins in the foot and ankle should be utilized only as a last resort.

Veins on the underside of the wrist should be avoided. Certain other sites should

also be avoided. (See picture.)

Sites to avoid:

 Extensive scarring from burns or surgery

 The upper extremity on the side that a mastectomy was performed.

 Hematoma – A venipuncture should not be performed on a hematoma,

regardless of how small it may be. If there is not an alternate vein to draw,

the venipuncture should be performed distal to (below) the hematoma.

 Intravenous therapy/Blood Transfusions – If it is not possible to draw the

opposite arm, then blood should be drawn from BELOW (distal to) the IV.

The tourniquet should be applied between the IV site and the venipuncture

site. If drawing above the IV site is the only option, then the IV infusion

must be turned off for at least 2 minutes before performing the

venipuncture. As there is still a risk that the sample could be

contaminated, you must document that the specimen was drawn above

(proximal to) an IV site and how many minutes the IV was turned off

before the draw occurred. The lab may reject the specimen as

contaminated based on the test results.

 Cannula, Fistula or Vascular Graft – Blood should only be drawn from an

arm with a cannula, fistula or vascular graft with the provider’s prior

approval.

 Edematous extremities – tissue fluid accumulation can alter test results.

 Sites with noticeable skin conditions, such as eczema or infection.

Palpate and trace the path of the vein with the index finger. Arteries pulsate, are

more elastic and have a thicker wall than a vein. Thrombosed veins lack

resilience, feel cord-like and roll easily. If you are using a tourniquet for

preliminary vein selection, it should be released after one minute, left off for two

minutes and then reapplied before performing the venipuncture.

Procedure and Performance of a Venipuncture:

 Select the proper size needle and attach it to the syringe or Vacutainer

hub.

 When using a syringe, make sure that you pull the plunger in and out to

assure free motion.

 Position the draw site for best visualization and/or palpation. Apply the

tourniquet 3-4 inches above the selected puncture site. Do not place

tightly or leave on for more than 1 minute. Instruct the patient to make a

fist and hold it; do not have them pump their hand. Select the

venipuncture site by palpating with the gloved index finger.

 Prepare the patient’s arm using a Chlorhexadine wipe. Allow to air dry.

Do not dry the site with gauze and do not blow on the area to dry as this

will contaminate the site. After cleansing the area, if it is accidentally

touched before performing the venipuncture, it should be cleansed again.

 Grasp the patient’s arm firmly using your thumb to draw the skin taut and

anchor the vein; do not use the index finger to pull the skin upward as this

increases the risk of sticking yourself. Swiftly insert the needle through

the skin, bevel side up, at a 15 – 30 degree angle with the skin, into the

lumen of the vein. (See diagram.)

 If the patient complains of “shooting, electric-like pain, or tingling or

numbness proximal or distal to the puncture site,” the needle should be

removed immediately. It is possible that a nerve has been punctured

and possibly damaged. The venipuncture should be repeated in a

different site. A Supervisor or Manager should be notified and the incident

should be documented.

 If an arterial puncture is suspected, as indicated by a bright red, quick,

pulsing flow, with or without rapid development of a hematoma, the needle

should be removed immediately. Forceful, direct pressure should be

applied to the site for a minimum of five minutes or until the bleeding has

stopped. The nursing staff should be notified, and they in turn must notify

the physician. A laboratory Supervisor or Manager should also be notified

and the incident should be documented.

 If the blood does not begin to flow, reposition the needle by gently moving

the needle either backwards for forwards in the arm. If the blood is flowing

slowly, gently adjust the angle to see if the needle is sitting up against the

wall of the vein. Loosen the tourniquet, as it may be obstructing blood

flow. If you are vacutaining, try another tube – there may be no vacuum in

the tube.

 After you have attempted to reposition the needle and are still not

successful, remove the tourniquet, remove the needle and begin the

process with a new site. In the case of a difficult venipuncture, an

individual may make a maximum of two attempts before having

someone else try. A third stick is allowable if a partial sample has been

obtained and you as the drawer feel reasonably confident that you can

obtain the specimen on the next try.

 When the collection is complete, remove the tourniquet and place gauze

over the venipuncture site. While the needle is still in the vein, activate the

safety button with the tip of the index finger; the needle will automatically

retract from the vein and the safety device will cover the needle.

 Apply adequate pressure to the puncture site to stop the bleeding and

avoid formation of a hematoma. If you used a needle and syringe, ask

your patient or a parent to apply pressure to the site so that you can fill

your tubes. Do not have the patient bend his/her arm; this may cause the

arm to start bleeding when the arm is straightened out.

 If blood was drawn with a syringe, attach the blood transfer device to the

syringe and fill tubes according to the ‘Order of Draw for a Venipuncture’

(see picture).

 Dispose of the contaminated materials and needle in the appropriate

waste containers.

 Mix and label all appropriate tubes at the patient’s bedside. Return to your

patient and assess the site of the puncture. Apply a band-aid or CoFlex to

the site. (See “Use of Band-Aids in the Post-Phlebotomy Policy)

Additional Considerations When Performing a Venipuncture: The following

considerations should be taken into account:

 Preventing a Hematoma: puncture only the uppermost wall of the vein.

Remove the tourniquet before removing the needle. Make sure the

needle fully penetrates the upper-most wall of the vein; partial penetration

may allow blood to leak into the tissue surrounding the vein. Adequate

pressure should be applied to stop the bleeding once the phlebotomy is

complete. A hematoma can cause a post-phlebotomy compression injury

to a nerve.

 Preventing Hemolysis: Mix tubes gently, by inversion, 5-10 times – do not

shake them. Avoid drawing blood from a hematoma. If using a needle

and syringe, avoid drawing the plunger back too forcefully. Make sure the

venipuncture site is dry. Avoid probing for the vein. If using a blood

transfer device to fill vacutainer tubes, allow the vacuum to pull the blood

into the tubes; do not use the plunger on the syringe to force the blood into

the tubes more quickly.

 Preventing Hemoconcentration: An increased concentration of larger

molecules and formed elements in the blood may be due to several

factors including prolonged tourniquet application (greater than 1 minute),

massaging, flicking, squeezing or probing the site, long-term IV therapy,

and sclerosed or occluded veins.

 Preventing injury to a nerve, tendon, or muscle: Use careful palpitation

and appropriate angle of entry. Excessive probing (uncalculated side-to-side

movement) with the needle should be avoided.

 Preventing dizziness or fainting and potential follow-up injuries due to a

fall: Be sure patient is seated in an appropriate draw chair and or lying in

a bed. Have appropriate back up staff as available.

 Preventing of infection: Follow proper infection control policies.

 Preventing injury from improper immobilization – Immobilize the patient

with care. If there is any concern regarding injury, contact nursing for

Inpatients and follow the Policy for Proper Handling of an Uncooperative

Patient.

Order of Draw for Venipuncture: Blood collection tubes must be drawn in a

specific order to avoid cross-contamination of additives between tubes. Follow

the order of draw listed here for both syringes (utilizing the blood transfer device)

and vacutainers:

1. Blood Cultures

2. Na Citrate Coagulation tubes – light blue top tube

3. Non-additive tube – red top tube

4. SST red or gold top – this tube contains a gel separator and clot

activators.

5. Sodium Heparin – green top tube

6. Lithium Heparin – green top tube

7. EDTA – lavender top tube

8. ACDA or ACDB – light yellow top tube

9. Oxalate/fluoride – light gray top tube

If Gases (venous – no O2 reported) are drawn with a needle and syringe, the

blood must be put into the Lithium Heparin tube using a blood transfer device; do

not pop the top of the tube open to fill the tube. Tubes with additives or clot

activators must be thoroughly mixed by gentle inversion, 5-10 times. Shaking

and vigorous mixing should be avoided.

References

Ernst, Dennis J. “Pediatric Pointers.” Center for Phlebotomy Education, Inc.

2004-2008, edited for accuracy 1/08.

Ernst, Dennis J. and Catherine Ernst. “Mastering Pediatric Phlebotomy.” Center

for Phlebotomy Education, Inc. Adapted from Phlebotomy for Nurses and

Nursing Personnel. HealthStar Press, Inc. 2001, updated 1/08.

Kiechle, Frederick L. So You’re Going to Collect a Blood Specimen: An

Introduction to Phlebotomy, 11th Edition. Northfield, IL: College of American

Pathologists, 2005.

NCCLS. Procedures for the Collection of Diagnostic Blood Specimens by

Venipuncture; Approved Standard—Sixth Edition. CLSI document H3-A6.

Wayne, PA: Clinical and Laboratory Standards Institute; 2007.

Proper Handling of an Uncooperative Patient in an Outpatient Setting – Akron

Children’s Hospital