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Does amethocaine gel influence blood results obtained from capillary sampling?
Noelle Llewellyn1, Andrew Liley, Jayne Cropper
1Acute Pain Service, Birmingham Children's Hospital NHS Trust.
Insights
Topical amethocaine gel (Ametop) significantly alters sodium and potassium levels in capillary blood samples. This topical anesthetic is not recommended for pain relief before capillary blood collection due to sample interference.
Area of Science:
- Pediatric Pain Management
- Clinical Chemistry
- Anesthesiology
Background:
- Capillary blood sampling in children often causes significant pain and distress.
- Topical anesthetics are considered for pain reduction during these procedures.
- Potential impact of anesthetics on sample integrity requires investigation.
Purpose of the Study:
- To assess the effect of a topical local anesthetic on biochemical test values from capillary blood samples.
- To determine if amethocaine gel (Ametop) interferes with common blood test results.
Main Methods:
- A preliminary study involving 22 healthy adult volunteers.
- Amethocaine gel (Ametop) applied to one digit, with the contralateral digit serving as control.
- Capillary blood samples analyzed for sodium, potassium, glucose, urea, ALP, AST, ALT, and bilirubin.
Main Results:
- Significantly higher sodium and potassium levels observed in samples from Ametop-treated digits.
- Significantly lower alkaline phosphatase (ALP) levels in samples from Ametop-treated digits.
- No significant changes noted for glucose, urea, AST, ALT, or bilirubin.
Conclusions:
- Amethocaine gel (Ametop) significantly affects sodium and potassium concentrations in capillary blood.
- The use of Ametop prior to capillary sampling is not recommended due to interference with test results.
- Further research may be needed to identify suitable topical anesthetics for capillary sampling.
Unlabelled:
In many children routine blood samples are obtained by capillary sampling, a technique that appears to cause high levels of pain and distress in the child. Topical anaesthesia might alleviate the pain associated with capillary blood sampling but would it affect the blood sample?
Aim:
a preliminary study to determine whether topical local anaesthetic would affect the values of commonly performed biochemical tests
Method:
22 healthy adult volunteers were recruited; each volunteer acted as his or her own control. Ametop was applied to a socially clean digit and covered with an occlusive dressing. After 30 minutes the dressing was taken off and excess gel was removed using a cotton wool ball. Two capillary samples were obtained from each volunteer, one from the Ametop treated digit and one from a digit on the opposing hand. The samples were analysed for sodium, potassium, glucose, urea, alkaline phosphatase (ALP), aspartate aminotransferase (AST), alinine aminotransferase (ALT) and bilirubin using a Vitros Chemistry analyser. Statistical analysis was performed on the blood results using Student's paired t-test.
Results:
Sodium and potassium levels were significantly higher in the samples from digits with Ametop applied, and alkaline phosphatase was significantly lower.
Conclusion:
The use of amethocaine gel (Ametop) appears to affect the results of both sodium and potassium in capillary blood samples and therefore it cannot be recommended as a suitable agent for topical anaesthesia prior to this procedure.
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