12. Nelson DL, Hable KA, Matsen JM. Proteus mirabilis osteomyelitis in two neonates following needle puncture. Successful treatment with ampicillin. Am J Dis Child. 1973;125:109.

13. Pape KE, Armstrong DL, Fitzhardinge PM. Peripheral median

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J Pediatr. 1978;93:852.

14. Skogland RR, Giles EJ. The false cortical thumb. Am J Dis Child.

1986;140:375.

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2003;88:F152.

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Laura A. Folk

16 Capillary Blood Sampling

A. Purpose

To obtain capillary blood samples that provide accurate

laboratory results with minimal discomfort and potential for

injury/infection

B. Background

Capillary heel blood sampling is an easily mastered, minimally invasive technique that, when performed with proper

technique and equipment, provides laboratory results

within acceptable tolerances compared with samples from

arterial catheters (1). The advantage of capillary sampling is

that repeated testing may be carried out, and peripheral

veins may be saved for IV access.

C. Indications

1. Capillary blood gas sampling

2. Routine laboratory analysis (standard hematology,

chemistries, toxicology/drug levels) requiring a limited

amount of blood in which minimal cell lysis does not

alter results

3. Newborn metabolic screen

D. Contraindications

1. Edema, because interstitial fluid dilutes the sample and

gives inaccurate results

2. Injury or anomalies that preclude putting pressure on

the foot

3. Areas that are bruised or injured by multiple previous

heelsticks

4. Poor perfusion

5. Local infection

E. Limitations

1. Venous or arterial blood rather than capillary samples

should be used for

a. Blood cultures, which require sterile technique

b. Tests in which even a minimal amount of hemolysis

will compromise results

c. Special tests such as coagulation studies (newer

coagulation tests that require only a few drops of

blood are still not widely available)

d. Laboratory tests that require more than 1.5 mL of

blood

F. Equipment

1. Gloves

2. Heel-warming device or a warm towel (see G)

3. Antiseptic (Betadine/saline or alcohol swab)

4. Pad or other means of protecting bed linens

5. Heel-lancing device (see G). Use appropriate size for

infant (Table 16.1).

6. Specimen collector as appropriate

a. Serum separators

b. Hematology tubes

c. Capillary blood gas tube

d. Newborn metabolic screen filter paper

7. Capillary tubes for blood transfer to lab tubes if appropriate

8. Small adhesive bandage or gauze wrap

G. Heel-Lancing Devices and

Heel Warmers

1. Automated heel-lancing device: Encased, springloaded, retractable blade that provides a controlled and

consistent width and depth of incision for blood testing

a. Incision depths range from 0.65 to 2 mm for micropreemies through toddlers (Tenderfoot, International

Technidyne Corporation, Edison, New Jersey) and

from 0.85 to 1 mm for preemies and newborns (BD

Quickheel Lancet, BD Vacutainer Systems, Franklin

Lakes, New Jersey) (Table 16.1).

b. The controlled depths avoid damage to the calcaneus (2,3) while providing greater yield with less

pain, hemolysis, and laboratory-value error (4–7).

The shallower devices can be used to obtain small