Acid-base changes after fluid bolus: sodium chloride vs. sodium octanoate.
OBJECTIVE
This study aims to test the hypothesis that fluid loading with sodium chloride (150 mmol Na and 150 mmol Cl) or sodium octanoate (150 mmol Na, 100 mmol Cl, and 50 mmol octanoate) would lead to different acid-base changes.


METHODS
We performed a double-blind crossover experimental study.


METHODS
The study was done at a University Physiology Laboratory.


METHODS
Eight Merino ewes were used as subjects.


RESULTS
We randomly assigned animals to a rapid intravenous infusion (1 L over 30 min) of either normal saline (NS) or sodium octanoate solution (OS). We collected blood samples at 0.5, 1, 2, 4, and 6 h after the start of the infusion for blood gas analyses and biochemistry. We calculated strong ion difference apparent (SIDa), effective strong ion difference, and strong ion gap (SIG). Animals in the NS group developed metabolic acidification immediately after fluid administration (pH 7.49 to 7.42, base excess 3.0 to -1.6 mEq/L), while the OS group did not (pH 7.47 to 7.51, base excess 1.1 to 1.4 mEq/L; P < 0.001). Additionally, the OS group had higher SIDa (36.2 vs. 33.2 mEq/L) and SIG (7.4 vs. 6.2 mEq/L) at the end of the infusion.


CONCLUSIONS
Our findings provide further evidence that acidification induced by intravenous fluid loading is dependent on fluid composition and challenges the paradigm of the so-called dilutional acidosis.
Howard Florey Institute, University of Melbourne, Parkville, Melbourne, Victoria, 3052, Australia, kkb9832@gmail.com.
Lu
L
Ke
Paolo
P
Calzavacca
Michael
M
Bailey
Wei-Qin
WQ
Li
Rinaldo
R
Bellomo
Clive N
CN
May