The researchers note that the administration of intravenous (IV) fluids is counterintuitive for patients with heart failure (HF) treated with diuretics; guidelines generally recommend fluid restriction and do not generally recommend IV fluids in these patients. IV fluids are however routinely administered to hospitalised patients.
In this retrospective cohort study, data from a national sample of hospitals in the US were analysed to determine how commonly IV fluids are prescribed for adults with HF receiving loop diuretics within the first two days of hospital admission. The final cohort consisted of 131,430 hospitalisations among patients with HF receiving loop diuretics (mainly furosemide); 11% of these were prescribed IV fluids (mainly normal saline). There was a large variation among hospitals, suggesting that factors beyond differences in patient populations influence co-administration of fluids and diuretics.
The researchers also examined the association between the early administration of IV fluids and in-hospital events in these patents, and noted increased rates of subsequent critical care admission (5.7% vs. 3.8%; p<0.0001), late intubation (1.4% vs. 1.0%; p=0.0012), renal replacement therapy (0.6% vs. 0.3%; p<0.0001), and in-hospital mortality (3.3% vs. 1.8%; p<0.0001). A causal association between IV fluid therapy and these outcomes cannot however be established due to the limitations of this study. Although it is possible that inadvertent use of fluids may lead to worse outcomes, there are other potential explanations that cannot be eliminated.
The authors comment that the administration of IV fluids in addition to loop diuretic therapy is “an unanticipated observation”. They suggest some possible reasons for this (haemodynamic instability; acute decompensated right ventricular failure; to counter the detrimental effects of excessive loop diuretic therapy) but note that these would be unlikely to account for many patients, due to the exclusion criteria.
Due to the use of administrative data for this study, the reasons for use of IV fluids in each of the patients in the cohort are unknown. Other limitations include lack of information on markers of renal function, left ventricular function indices and haemodynamic parameters; inability to distinguish between types of HF; and the use of billing to determine fluid administration rather than direct observation.
The authors conclude that until further data are available, decisions about the use of IV fluids in patients with decompensated HF should be made on a case-by-case basis with consideration of factors such as HF status and renal function. Hospitals should ideally implement strategies that would help minimise the possibility of inadvertent IV fluid therapy.