Accuracy and repeatability of blood volume measurement by pulse dye densitometry compared to the conventional method using 51Cr-labeled red blood cells.
OBJECTIVE
To determine the accuracy and repeatability of pulse dye densitometry (PDD) in measuring blood volume (BV) by comparing it with the conventional method using 51Cr-labeled red blood cells (RI method) and by assessing sequential measurements.


METHODS
Prospective clinical study.


METHODS
University hospital.


METHODS
Eleven adult ICU patients who received cardiac surgery (1st ICU day).


METHODS
None.


RESULTS
After injecting indocyanine green (10 or 20 mg) into the right atrium, its arterial concentration was continuously monitored at the nose and finger by PDD, and BV was calculated by back extrapolating the logarithmic dye concentration on the dye elimination curve between 2.5 and 5.5 min after mean transit time to each mean transit time with the least squares method. These measurements were repeated in eight patients and performed only once in the other three, and the BV was measured concurrently by the RI method one time. The Bland-Altman method was used for evaluating differences between methods and within methods. The (percentage) biases and standard deviations between the PDD and RI methods and between the successive measurements by PDD at the finger and nose were 0.26 +/- 0.491 (8.8 +/- 15.3%) and 0.004 +/- 0.251 (0.06 +/- 5.9%) with the probe on a nostril, and 0.16 +/- 0.561 (2.5 +/- 14.4%) and 0.19 +/- 0.311 (4.7 +/- 7.3%) using the finger probe. The bias between methods was less than 10%, and the repeatability of PDD was better.


CONCLUSIONS
As PDD can measure BV with good repeatability and with a small bias compared to the RI method, serial changes in BV can be evaluated at the bedside of critically ill patients noninvasively and repeatedly.
Imai
T
T
Department of Critical Care Medicine, Tokyo Medical and Dental University School of Medicine, Bunkyo District, Japan. taka.ikasika.ccm@med.tmd.ac.jp
Mitaka
C
C
Nosaka
T
T
Koike
A
A
Ohki
S
S
Isa
Y
Y
Kunimoto
F
F
D000368:Aged; D001811:Blood Volume Determination / Q000379:methods*; D006348:Cardiac Surgical Procedures; D002860:Chromium Radioisotopes; D004396:Coloring Agents; D003720:Densitometry / Q000379:methods; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D007208:Indocyanine Green; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results
D002860:Chromium Radioisotopes; D004396:Coloring Agents; D007208:Indocyanine Green