A modified method of measuring plasma volume with indocyanine green: reducing the frequency of blood sampling while maintaining accuracy

• Published in: Journal of clinical monitoring and computing Vol. 35; no. 4; pp. 779 - 785
• Main Authors: Kim, Kyung Mi, Park, Do-Yang, Kang, Eun-Hwa, Kim, Myojung, Choi, Byung-Moon, Noh, Gyu-Jeong, Lee, Eun-Kyung
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2021; Springer Nature B.V
• Subjects: Anesthesiology; Blood; Critical Care Medicine; Dilution; Health Sciences; Intensive; Measurement methods; Medicine; Medicine & Public Health; Original Research; Plasma; Sampling; Statistics for Life Sciences; Volume measurement; Measurement; Plasma volume; Accuracy; Indocyanine green
• ISSN: 1387-1307; 1573-2614
• DOI: 10.1007/s10877-020-00536-5

Among various methods for measuring the plasma volume (PV), the indocyanine green (ICG) dilution technique is a relatively less invasive method. However, the ICG method is rather cumbersome because 10 blood samples need to be obtained within a short time after ICG administration. Thus, reducing the frequency of blood sampling while maintaining the accuracy would facilitate plasma volume measurement in clinical situations. We here developed a modified method to measure plasma volume using 2260 ICG plasma concentration data from 115 surgical patients. The mean relative error (MRE) and the percentage of cases with relative error (RE) greater than 5% in total (PRE) were used to quantify the difference between plasma volumes obtained by the original and modified methods. RE was determined as follows. RE(%) = (PV obtained by original method (
PV
origin
al
)—PV obtained by modified method (
PV
modified
))/
PV
origin
al
 × 100.
PV
modified
was assumed to be equal to
PV
original
when the RE was < 5%. When the number of samples selected for the plasma volume estimation was 4 or less, the PRE was mostly 10% or more. Five out of the 10 blood samples (order: 1st, 2nd, 3rd, 9th, and 10th) showed similar accuracies with the plasma volume obtained by the original method (original: 2.72 ± 0.64 l, modified: 2.72 ± 0.65 l). This modified method may be able to aptly replace the original method and lead to a wider clinical application of the ICG dilution technique. Further validation is needed to determine if the results of this study may be applied in other populations.