Capillary Blood Sample Flashcards
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
a. Patient is less than 24 hours old
2) According to Egan’s what is the temperature in Celsius to warm a sampling site
a. 37
b. 40
c. 42
d. 45
c. 42
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
b. 75-100 mcl
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
d . To break up clots in the sample
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
b. 10-15 min
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
b. 2
7) What temperature does AHS suggest should be used for capillary sampling
a. 37
b. 40
c. 42
d. None of the above
d. None of the above
8) The 1stdrop of blood should be captured in the capillary tube
a. True
b. False
b . False
9) Squeezing the site should be avoided because it may dilute the sample
a. True
b. False
a. True
10) Capillary blood samples are an effective method of monitoring and modifying oxygen therapy in the neonatal patient
a. True
b. False
b . False
Egan’s Indications for Capillary Blood Sampling
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
A CBS should not be done When
Egan’s
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
CBG should not be performed on the following areas
Egan’s
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
Egan’s Relative Contraindications of CBG
Peripheral vasoconstriction
Polycythemia caused by a shorter clotting time
Hypotension
Egan’s Precautions and Possible Complications of the CBG
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
The following should be monitored and documented in the chart as a part of capillary blood sampling
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
CBG Procedure
- 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
AHS CBG Purpose
Purpose: Safe and effective procedure for collecting blood in neonates
AHS Policy of CBG
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.
CBG in the Order of Collection
Order of Collection
- Blood Gas
- CBC
- Neonatal Screen
- Chemistry
CBG Equitment
Gloves
Cleaning solution (betadine cannot be use)
Dry gauze
Microtainer lancet for weight of baby
micro collection tubes
Capillary Blood Sampling
- 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
Capillary Blood Sampling Troubleshooting
- 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
Capillary Blood Gas Sampling Analyzing
- 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)
CBG and Arterilization
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
