Using the first drop of blood for monitoring blood glucose values in critically ill patients: An observational study.

CONTEXT: Using the first drop or second drop of blood while measuring blood glucose (BG) values.

OBJECTIVE: The study was planned to compare the BG values from the first and second drops of blood.

RESEARCH SETTINGS: The study was conducted at the Main Intensive Care Unit, PGIMER, Chandigarh, India.

RESEARCH DESIGN: This study was a comparative study.

MATERIALS AND METHODS: Ninety patients aged 2-93 years were enrolled in this study. BG values from the first and second drops of blood were taken and compared.

STATISTICAL ANALYSIS USED: Agreement between two drops was assessed using Bland-Altman analysis. A bias of <10 mg/dl was considered clinically acceptable. Linear regression of the mean difference (bias) with the BG readings was performed.

RESULTS: One thousand four hundred and seven pairs of BG readings were taken from the enrolled patients. BG values had a bias of 3.9 ± 14.9 mg/dl. Nearly 96.7% of BG readings were within the limits of agreement. The absolute difference between first and second drops of blood was calculated; nearly 75.4% of the readings had fallen between 0 and 10 mg/dl, i.e. clinically acceptable range.

CONCLUSION: There is no compete concordance of values of blood glucose between the first and the second drops of blood; any of the drops can be used for measuring BG values as the difference is not statistically significant. However, if hands are visibly clean and to decrease the blood loss in the critically ill patients where the BG values are measured frequently, using the first drop of blood is advised.