Spare the Chloride

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Fluid therapy is essential in ICUs and not surprisinglythere is still much controversy about which fluid to use, how much and when.Nephrologists often roll their eyes at other subspecialty's preferences, e.g.surgeon's preferences for Ringers, citing the risk of hyperkalemia in renalfailure patients given Ringers. I learned that normal saline is the preferredagent unless there is a special consideration such as acidemia necessitatingalternatives. Now chloride, the partner of sodium that gets considerablyless attention most of the time, enters the stage.Yunos et al in JAMA suggest that too much of chlorideincreases acute kidney injury (AKI) episodes in tertiary ICUs and increases theneed for renal replacement therapy (RRT) but does not affect mortality.The physiological rationale for the detrimental effect ofchloride on the kidney is described as vasoconstriction mediated by chloride in dog experiments and a possiblerole of tubuloglomerular feedback mediated vasoconstriction as well as decreasein GFR caused by increased distal chloride delivery. Furthermore they citethromboxane mediated vasoconstriction caused by chloride and enhancedresponsiveness to vasoconstrictor agents as possible physiological sequelae ofchloride administration.The authors of the JAMA article conducted a prospective, open-label sequentialpilot study of patients admitted consecutively to the ICU. Initially patientswere treated with chloride-rich IV fluids (0.9% saline, 4% succinylated gelatinsolution or 4% albumin solution) and after that initial control period achloride-restricted strategy was implemented with lactate (Hartmann solution),a balanced solution (Plasma-lyte 148) or chloride-poor 20% albumin as preferredagents.The results were a lower increase in serum creatinine levelsand fewer episodes of RRT in the chloride-restricted group but no differencesin mortality, hospital or ICU length of stay or need for RRT after discharge.How does this study affect our choice of ICU fluids?Certainly, these results are hypothesis generating and important but need to beviewed as preliminary given the design of the study. An accompanying editorialby Waikarmentions the Hawthorne effect as potential major concern. Clearly these important preliminary data need follow up in acontrolled prospective trial. Posted by Florian Toegel