OPEN Research Support

Biomedical Laboratory Scientist Specialist
Ulla List Tønnesen
Department of Clinical Biochemistry and Immunology, Lillebaelt Hospital, University of Southern Denmark

Projekt styring
Projekt status    Closed
Data indsamlingsdatoer
Start 26.08.2020  
Slut 31.12.2021  

Comparison of three warm-up methods before capillary blood sampling - a randomized controlled study.

Short summary

Capillary blood sampling in the heel is often used in the treatment of infants admitted to neonatal intensive care (NICU). Some infants experience a difficult blood sampling which can lead to a blood sample of poor quality. To minimize the risk of that, the infant's heel is warmed up in advance. The purpose of this randomized controlled study is to investigate which of three warm-up methods ensures the best quality of the blood sample and provides the most gentle blood sampling for the infant.


At Kolding Hospital, the biomedical laboratory scientists perform some 5000 capillary heelstick blood samplings a year at the neonatal intensive care unit.

The infant's heel is warmed up before the procedure. The warming of the heel is believed to increase capillary blood flow and thereby reduce the risk of a difficult blood sampling.

Asking other neonatal intensive care units in Denmark, we experienced that different warm-up methods were in use. Going through national and international literature no consensus was found on which warm-up method is the most suitable.

Accordingly, the purpose of this research study was to investigate which warm-up method would ensure both the best quality of the blood sample and give the infant the most gentle experience.

The study was conducted as a blinded randomised controlled trial with three different groups of warm-up items: glove, blanket and gel pack. Randomisation was computer generated through OPEN Randomise. The study was approved by The Regional Ethics Committee before start of data collection.

Description of the cohort

Infants admitted to the neonatal intensive care unit at Kolding Hospital.

Applied Inclusion criteria:

gestational age of 28 or more weeks and scheduled to a capillary blood sampling performed by a biomedical laboratory scientist.

Applied Exclusion criteria:

Gestational age of 44 or more weeks, weight above 6 kilogram, severe illness or coagulation disorder.

Data and biological material

Biological material:

capillary blood.

Categories of data was measurements of time and temperature, analytical parameters as hematocrit and hemolysis of potassium, questionnaire data from biomedical laboratory scientist and nurse, observational data of pain assessment and heel appearance.

Collaborating researchers and departments

Department of Paediatrics and Adolescent Medicine, Lillebaelt Hospital, University Hospital of Southern Denmark

  • Betty Nørgaard, Quality Coordinator, MHSc, Ph.D.