Daily intravenous chloride load and the acid-base and biochemical status of intensive care unit patients

Background: Studies have described the development of metabolic acidosis after the rapid intravenous administration of large amounts of chloride-rich solutions. There are little data on the effect of daily intravenous fluid therapy within the intensive care unit. Aim: To test the correlation between daily intravenous chloride load and the acid-base and biochemical status of intensive care unit patients. Method: Data were prospectively collected on the type and volume of intravenous fluids administered to intensive care unit patients over 24-hour cycles. Correlation was then tested between daily chloride load and the acid-base and biochemical variables obtained from the first morning measurement of arterial blood gases on the following day. Results: 49 patients were audited. 30 (61%) patients had hyperchloraemia on intensive care unit admission with a median serum chloride level of 108 mmol/L (range 87-123); 32 (65%) patients had a negative base excess above -2 mEq/L and 11 (23%) patients had a bicarbonate level below 22 mmol/L. The median daily amount of chloride administered was 88.5 mmol (range 0-732). There was a statistically significant negative correlation between total chloride intake and serum bicarbonate (p < 0.0002), base excess (p < 0.0002), pH (p < 0.006), sodium chloride difference (p < 0.0001) and a positive correlation with serum chloride concentration (p < 0.006). Conclusion: The daily chloride load significantly influenced the acid-base and biochemical status of intensive care unit patients. The higher the chloride load, patients are more likely to develop metabolic acidosis, hyperchloraemia and decreased sodium chloride difference.