Blood sampling, neonatal capillary

It can be used to monitor:

• blood sugar levels
• drug levels
• blood gases
• full blood counts
• urea and electrolytes
• newborn bloodspot screening tests

The procedure is not without risk. The main problems are:

• increased pain (McIntosh et al 1993)
• local trauma (Blumenfield et al 1979; Moxley 1989)
• damage to nerves, blood vessels and bones (Blumenfield et al 1979; Moxley 1989)
• excessive blood loss (Moxley 1989)
• infection (Blumenfield et al 1979; Moxley 1989)

These problems can be avoided by using a good technique (Moxley 1989).

Blood sampling: neonatal capillary

Preparation

Gather the following equipment (Rationale 1):

• gloves (Rationale 2)
• cotton wool or gauze
• capillary tube and/or blood bottle
• tenderfoot or other appropriate device (Rationale 3)
• clean tray to hold equipment
• sharps disposal box (Rationale 4)

Soft paraffin solutions such as Vaseline^® should not be used for heel punctures (Rationales 5, 6, 7 and 8).

The appropriate sized automated lancet devised for use on infants should be selected (Rationale 9). Skin puncture must be no deeper than 2.0mm. A penetrative depth of no more than 1.0mm is recommended for preterm infants. Manual lancets should not be used (Cavanagh and Coppinger 2009).

Comfort measures and analgesia are recommended to reduce the pain caused to the infant during blood sampling (Rationale 15) (Frank and Gilbert 2003). An assessment of the baby's ability to tolerate handling must be made prior to obtaining the sample.

A clinical hand wash should be performed prior to starting the procedure (Rationale 10).

Select an appropriate site for blood sampling (see appendix).

The site chosen for sampling should continually be rotated and be free from previous injury (Rationales 11 and 12).

Obtaining the sample

Gloves should be worn (Rationale 13).

Equipment should be placed in a convenient position (Rationale 14).

To obtain the sample:

• Ensure baby is lying in a safe and secure position (Rationale 15).
• Ensure the heel is warm but additional pre-warming if the foot is not required (Rationale 14, 15, 16, 17).
• Hold the baby's heel with the non-dominant hand (Rationale 18).
• Hold the ankle with index and middle finger (Rationale 19).
• Use other fingers to steady the baby’s leg.
• Partly encircle the baby’s heel with thumb.
• Clean the proposed puncture site with warm water and gauze (Rationale 20).
• Alcohol impregnated wipes should not be used (Rationale 21, 22, 23, 24, 25).
• Allow the area to dry (Rationale 26).
• Gently compress the heel and hold the skin under tension (Rationale 16).
• Puncture the skin in a steady and intentional manner (Rationale 27).
• Relax tension and wipe away initial blood flow with cotton wool or gauze (Rationale 28).
• Whilst maintaining grip hold the heel so that blood is allowed to hang (Rationale 17).
• Gently but firmly compress the baby’s heel to form a large droplet of blood (Rationale 29).
• Do not squeeze (Rationale 30).
• Hold the capillary tube or blood bottle to the blood droplet and touch (Rationale 31).
• Momentarily release pressure to collect subsequent blood then reapply pressure, allowing the blood to flow.
• Continue until sufficient blood has been obtained (Rationale 32).

Completing the procedure

Once the sample has been obtained:

• Apply pressure to the site with gauze (Rationale 33).
• Maintain pressure until bleeding has stopped (Rationale 34).

Use hypoallergenic tape. Do not use Elastoplast^® (Rationale 35).

The baby should be left comfortable.

Equipment should be disposed of according to the hospital Waste Policy (Rationale 36).

The person performing the skin puncture should wash their hands (Rationale 37).

The sample should be sent for analysis as soon as possible (Rationale 38).

Appendix

Recommended sites for neonatal capillary blood sampling (PDF)

Rationale

Rationale 1: To be prepared for the procedure.
Rationale 2: To protect the person obtaining sample.
Rationale 3: To minimise pain by using correct device.
Rationale 4: To safely dispose of lancet device.
Rationale 5: It increases the risk of infection.
Rationale 6: It can alter the blood results.
Rationale 7: It can clog the equipment.
Rationale 8: To reduce costs.
Rationale 9: To reduce the risk of calcaneal puncture and therefore prevent osteomyelitis.
Rationale 10: To prevent cross infection.
Rationale 11: To minimise the risk of further trauma.
Rationale 12: To minimise the risk of infection.
Rationale 13: To meet universal precautions.
Rationale 14: To enable the procedure to be performed with ease.
Rationale 15: To assist procedure and promote comfort.
Rationale 16: To increase blood flow to the area.
Rationale 17: To aid collection.
Rationale 18: To keep the dominant hand free for the procedure.
Rationale 19: To produce a steady grip and minimise movement.
Rationale 20: To minimise the risk of infection.
Rationale 21: Alcohol is absorbed by and is drying to the skin. It has been associated with chemical burns in premature infants (Association of Women's Health, Obstetric and Neonatal Nurses and the National Association of Neonatal Nurses 2001).
Rationale 22: Alcohol containing products can cause injury to delicate or healing tissue (Association of Women's Health 2001).
Rationale 23: Minimising unnecessary chemical exposure in the newborn period may reduce the risk of toxicity and later contact irritant sensitisation (Association of Women's Health, Obstetric and Neonatal Nurses and the National Association of Neonatal Nurses 2001).
Rationale 24: Test results may be affected if the skin is not allowed to dry properly.
Rationale 25: Rubbing alcohol over a previous puncture site can cause pain.
Rationale 26: To ensure effectiveness of cleaning.
Rationale 27: To produce blood flow.
Rationale 28: To reduce haemolysis as blood and alcohol mix.
Rationale 29: Steady compression aids collection.
Rationale 30: Squeezing causes haemolysis and potentially inaccurate results, plus bruising.
Rationale 31: To obtain adequate blood sample.
Rationale 32: To ensure viable sample.
Rationale 33: To stop bleeding.
Rationale 34: To prevent bruising.
Rationale 35: Certain adhesive tape can damage fragile skin and cause infection.
Rationale 36: To ensure safe disposal.
Rationale 37: To minimise the risk of cross infection.
Rationale 38: To promote effectiveness of testing.

References

Reference 1:
McIntosh N, Van Veen L, Brameyer H (1993) The pain of heel prick and its measurement in preterm infants. Pain 52 (1): 71-4.

Reference 2:
Blumenfeld TA, Turi GK, Blanc WA (1979) Recommended site and depth of newborn heel skin punctures based on anatomical measurements and histopathology. Lancet 1 (8110): 230-3.

Reference 3:
Moxley S (1989) Neonatal heel puncture. Canadian Nurse 85 (1): 25-7.

Reference 4:
The Association of Women's Health, Obstetric and Neonatal Nurses and the National Association of Neonatal Nurses (2001) Evidence-based clinical practice guideline: neonatal skin care. Viewed on: 23/08/2006

Reference 5:
Cavanagh C, Coppinger C (2009) Newborn blood spot sampling. Infant 5(3): 83-86.

Reference 6:
Frank L, Gilbert R (2003) Reducing the pain during blood sampling in infants. Clinical Evidence 9: 419-435.

Document control information

Lead author(s)
Annabel Linger, Sister, Neonatal Intensive Care Unit (NICU)

Document owner
Annabel Linger, Sister, Neonatal Intensive Care Unit (NICU)

Approved by
Clinical Practice Committee

First introduced: 1 December 1998
Date approved: 5 October 2011
Review schedule: Two years
Next review: 7 October 2013
Document version: 3.0
Replaces version: 2.0