Capillary Blood Sample

Question 1

1) Which of these contraindications to performing a capillary blood gas
a. Patient is less than 24 hours old
b. The patient respiratory rate and WOB has changed
c. To monitor the severity and progression of a documented disease process
d. To patient’s oxygen requirement have recently increased

Answer 1

a. Patient is less than 24 hours old

Question 2

2) According to Egan’s what is the temperature in Celsius to warm a sampling site
a. 37
b. 40
c. 42
d. 45

Answer 2

c. 42

Question 3

3) Approximately how much blood should be obtained according to Egan’s
a. 50-70 mcl
b. 75-100 mcl
c. 125-200 mcl
d. 200-250 mcl

Answer 3

b. 75-100 mcl

Question 4

4) What is the purpose of the metal flee being placed in the capillary tube
a. To mix oxygen and other gases in the sample
b. To break up RBC so the oxygen levels can be evaluated
c. To ensure that there is enough blood in the sample
d. To break up clots in the sample

Answer 4

d . To break up clots in the sample

Question 5

5) How much time is recommended before the sample should be analyzed (Egan’s)
a. 5 min
b. 10-15 min
c. 20 min
d. No time limit

Answer 5

b. 10-15 min

Question 6

6) How many punctures are you allowed to perform during a single collection according to AHS policy
a. 1
b. 2
c. 3
d. 4

Answer 6

b. 2

Question 7

7) What temperature does AHS suggest should be used for capillary sampling
a. 37
b. 40
c. 42
d. None of the above

Answer 7

d. None of the above

Question 8

8) The 1stdrop of blood should be captured in the capillary tube
a. True
b. False

Answer 8

b . False

Question 9

9) Squeezing the site should be avoided because it may dilute the sample
a. True
b. False

Answer 9

a. True

Question 10

10) Capillary blood samples are an effective method of monitoring and modifying oxygen therapy in the neonatal patient
a. True
b. False

Answer 10

b . False

Question 11

Egan’s Indications for Capillary Blood Sampling

Answer 11

ABG analysis is indicated but arterial access is available

Non-Invasive monitoring readings (ex. PtcCO2, PETCO2, Spo2) are abnormal

Assessment of initiation, administration, or change om therapy (ex. mechanical ventilation) is needed

A change in patient status is detected by history or physical assessment

Monitoring the severity and progression of documented disease progress

Question 12

A CBS should not be done When

Egan’s

Answer 12

The infant is less than 24 hours old as there will be poor peripheral perfusion still

When there is a need for a direct analysis of oxygenation

When there is a need for a direct analysis of arterial blood

Question 13

CBG should not be performed on the following areas

Egan’s

Answer 13

Should not be performed at the posterior curvature of the heel as t can puncture bone

The heel of a patient who has begun walking and has callus development

The fingers of neonates because it can cause nerve damage

Previous puncture sites

Swollen tissue

Cyanotic or poorly perfused tissues

Localized areas of infection

Peripheral arteries

Question 14

Egan’s Relative Contraindications of CBG

Answer 14

Peripheral vasoconstriction

Polycythemia caused by a shorter clotting time

Hypotension

Question 15

Egan’s Precautions and Possible Complications of the CBG

Answer 15

Contamination and infection which can include calcaneus osteomyelitis and cellulitis

Inappropriate patient management may result on reliance of capillary PO2 values

Inadvertent puncture

Tibial artery laceration -Puncture of the posterior sample of the medial aspect of the heel)

Burns

Hematoma

Bruising

Scaring

Bleeding

Question 16

The following should be monitored and documented in the chart as a part of capillary blood sampling

Answer 16

FIO2 and oxygen flow

Appearance of puncture site

Mechanical ventilator settings

Complications or adverse reactions to the sample

Ease or difficultly of the procedure

Results of the procedure

Patients vitals

Level of foot or finger use to obtain a sample

Date and time of sample

Non-invasive monitoring values

Question 17

CBG Procedure

Answer 17

• Procedure
• Check medical record
• Confirm steady state conditions
  
  • 20-30 minutes after changes
• Obtain and assemble all necessary equipment
• Wash hands and don PPE
• Select site
• Warm the site to 42oC for 10 minutes using a compress, heat lamp, or commercial hot pack
• Puncture the skin (<2.5mm) with lancet
• Wipe away the first drop of blood to get free flow
  
  • Do not squeeze
• Fill the sample tube from the middle of the blood drop until it is completely full (75-100 mcl)
• Place metal flea in capillary tube and then seal tube ends
• Tape sterile cotton or a bandage over puncture wound
• Mix sample by moving the magnet back and forth along capillary tube
• Sample should be immediately chilled or analyzed within 10-15 minutes if left at room temperature
• Dispose of waste arterial
• Document the procedure

Question 18

AHS CBG Purpose

Answer 18

Purpose: Safe and effective procedure for collecting blood in neonates

Question 19

AHS Policy of CBG

Answer 19

Policy: The maximum number of punctures that can be made per sample collection is 2 per heel, providing that the heel is in good condition. If the babies heels are in poor condition a judgement call will need to be made about the method of sampling.

Question 20

CBG in the Order of Collection

Answer 20

Order of Collection

1. Blood Gas
2. CBC
3. Neonatal Screen
4. Chemistry

Question 21

CBG Equitment

Answer 21

Gloves

Cleaning solution (betadine cannot be use)

Dry gauze

Microtainer lancet for weight of baby

micro collection tubes

Question 22

Capillary Blood Sampling

Answer 22

• CBG are used as an alternative to arterial access in infants and small children
• Can help give estimates for arterial pH and PaCO2, but little value with arterial oxygenation
• Is better than values gained from a finger sticks

Question 23

Capillary Blood Sampling Troubleshooting

Answer 23

• The most common technical errors in capillary sampling are an inadequate warming of the capillary blood and squeezing of the puncture site
  
  • Squeezing of the site can result in venous and lympathetic contamination of the sample
  • Both errors can invalidate test results
• Other preanalytical errors are the same as the ones for arterial puncture
• Because of the small sample volume, and collection tube size, the clinician must ensure an adequate sample collection while avoiding air contamination and clotting

Question 24

Capillary Blood Gas Sampling Analyzing

Answer 24

• The primary analytes or parameter of pH, PCO2, and PO2 in a blood sample are measured with a blood gas analyzer
• Analyzer use these measures to compute several secondary values, such as plasma bicarbonate level, base excess, and Hb saturation
  
  • If the actual measurement of total Hb saturation (oxyhemoglobin (HbO2), methemoglobin (metHb), and carboxyhemoglobin (HbCO) is required that sample should be analyzed separately using hemoximetry
• Some analyzers combine the blood gas and hemoximetry measurements which may require a larger sample size (usually 100 mcl)

Question 25

CBG and Arterilization

Answer 25

Capillary blood samples are only useful when the sample site is properly warmed (~42 Celcius) as it will cause dilation of the underlying blood vessels and increase capillary flow well above what the tissue needs

Blood gas values will resemble the values in the arterial circulation which is why a sample is known as arterialized blood