Sodium Restriction vs Hypertonic Saline for CHF
Salt, or more specifically sodium, is central to this truly Hamlet of a match up! One has to really take a deep breath and relax before tackling this heavyweight battle. "To be or not to be," he said. Or, more fittingly for this bout: "to give or not to give!"
Hypertonic Saline in Acute CHF
For many decades, sodium restriction has been central in the management of HF over the long term. However, in recent years, high concentrations of saline have been used with high-dose loop diuretics for the treatment of acute decompensated failure.
The use of hypertonic fluids has been described as far back as 1919 when Penfield and colleagues described their use in the resuscitation of experimental animals. More recently, a number of small trials in the last decade or so have highlighted the potential benefit of using a low volume of hypertonic saline with furosemide for the treatment of acute decompensated HF. Experiments have shown that hypertonic saline can increase regional blood flow to the coronary and renal circulations and can increase cardiac contractility.
A recent meta-analysis looked at 10 randomized but small studies that compared hypertonic saline solution (HSS) and furosemide with furosemide alone. The interventions in each trial varied in terms of the volume of hypertonic saline or normal saline given and the dose of IV furosemide given. The HSS concentrations varied from 1.4% saline to 7.5% saline and the IV furosemide doses ranged from 40 mg daily to 1000 mg twice daily. Furthermore, some trials varied the tonicity of the hypertonic saline depending on baseline serum sodium using a higher percentage sodium solution in people with lower baseline serum sodium.
The largest study (Paterna 2011) compared:
• furosemide 250 mg IV with 150 mL of hypertonic saline twice a day
• moderate sodium restriction (~ 2.7 g/d) with
• furosemide 250 mg IV without hypertonic saline
• low sodium intake (~1.8 g/d).
The hypertonic saline group had an increase in diuresis and serum sodium levels, reduction in hospitalization time (3.5 vs 5.5 days), lower rate in readmissions (~19% vs ~34%) and lower mortality (~13% vs ~24%). This study also reported a survival benefit for the groups that received the hypertonic saline.
The aforementioned meta-analysis also concluded that hypertonic saline improves weight loss, preserved renal function, and decreased length of hospitalization, mortality, and HF rehospitalization. Of note, the Paterna 2011 study was by far the largest trial and may have driven much of the meta-analysis results. Furthermore, sodium restriction (included in the Paterna 2011 study) is a separate intervention. It is therefore hard to say a short course of hypertonic saline alone leads to improved long-term survival.
Overall, hypertonic saline for the treatment of acute decompensated HF is very promising. A large well-conducted randomized clinical trial needs to be performed to assess the long-term benefits of hypertonic saline treatment.
Sodium Restriction for CHF
The US Department of Agriculture and the Department of Health and Human Services recommend a 2300 mg daily intake of sodium for the general population (2010). Sodium restriction has been the mainstay of treatment for those with hypertension, CKD, and HF.
Although there are now many pharmacological and device therapies with proven benefit in HF patients, there is inconsistent evidence supporting the use of sodium restriction in HF management. An Institute of Medicine assessment of the evidence in JAMA Internal Medicine last year (2014) states there is evidence for potential harm in restricting sodium intake to less than 2.3 g/d in patients with congestive HF. Guidelines for sodium restriction are largely based on expert opinion and the available data is likely flawed by patient non-adherence to restrictive diets and inconsistent self-reporting of sodium intake.
The 2013 AHA/ACC guidelines for HF management suggest a sodium restriction of less than 3 g/d for heart failure stages C+D. This is based on opinion due to the fact that sodium consumption in the general population in the US is over 4 g/d.
Lennie et al showed sodium intake of less than 3 g/d was associated with better outcomes in HF class 3+4. This was an observational study that also reported sodium restriction to below 3 g/d in HF class 1+2 was associated increase hospital visits and mortality. This is contrary to the observational study by Arcand et al that showed sodium intake greater than 2.3 g/d in HF class 1+2 patients was associated with more hospitalizations compared to lower intake.
There are more examples in the literature of contradictory findings with regard to sodium intake and outcomes in HF patients. Most studies include other interventions such as water restriction and various pharmacological treatments. Not all patients enrolled in older trials received current standard to care such as ACE inhibition or beta blockade. Another flaw in this literature is predominance of white patients making it hard to generalize these findings to the total US HF population. Furthermore, there has been no large study investigating the effects of sodium restriction on patients with heart failure and preserved ejection fraction.
In summary, it seems that the medical community has little to no evidence to guide the short- or long-term management of sodium balance in heart failure patients. Both the administration of HSS and sodium restriction are cheap interventions with the potential to impact the many millions of patients with heart failure in all parts of the world.
NKF © 2015
The National Kidney Foundation
Cite this: Andrew House, Andrew Malone, Matthew Sparks. NephMadness 2015: Cardio-Nephrology Region - Medscape - Mar 02, 2015.