From the Guidelines
For the treatment of bronchiolitis, 3% hypertonic saline nebs are recommended over 9% due to their established safety and efficacy in improving symptoms and reducing hospital length of stay in settings where the average length of stay exceeds 3 days. The evidence from a 2013 Cochrane review 1 and subsequent randomized trials suggests that 3% saline is effective at improving symptoms of mild to moderate bronchiolitis after 24 hours of use. The typical dosage is 4mL of 3% solution administered via nebulizer over 10-15 minutes, usually 2-4 times daily.
Some key points to consider when using hypertonic saline nebs include:
- The preponderance of the evidence suggests that 3% saline is safe and effective at improving symptoms of mild to moderate bronchiolitis after 24 hours of use and reducing hospital LOS in settings in which the average LOS is more than 3 days 1.
- It has not been shown to be effective at reducing hospitalization in emergency settings or in areas where the length of usage is brief 1.
- Most studies have used a 3% saline concentration, and most have combined it with bronchodilators with each dose; however, there is retrospective evidence that the rate of adverse events is similar without bronchodilators 1.
- Patients should be monitored for adverse effects including cough, throat irritation, and bronchospasm, particularly during initial treatments.
The therapeutic effect of hypertonic saline comes from its osmotic properties, which draw water into the airway lumen, hydrating mucus secretions and improving mucociliary clearance 1. This helps thin secretions, making them easier to expectorate and improving airway patency.
In terms of comparison, there is limited evidence directly comparing 3% and 9% hypertonic saline nebs, but the available data suggest that 3% is a safer and more effective option for most clinical situations requiring hypertonic saline 1. The 9% solution is generally reserved for more severe cases or when 3% proves insufficient, as it carries a higher risk of bronchospasm and respiratory irritation.
From the Research
Comparison of 3% and 9% Hypertonic Saline Nebulizers
- There is limited direct evidence comparing 3% and 9% hypertonic saline nebs, as most studies have focused on comparing 3% to 7% hypertonic saline solutions to placebo or other treatments 2, 3, 4.
- One study compared hypertonic saline 7% versus hypertonic saline 3%, but found very low-certainty evidence for an improvement in FEV1 % predicted after treatment with 7% hypertonic saline compared with 3% 3.
- The majority of the evidence suggests that hypertonic saline, regardless of concentration, enhances mucociliary clearance and may lessen the destructive inflammatory process in the airways 2, 3, 4.
- However, the certainty of the evidence for the use of hypertonic saline in cystic fibrosis ranges from very low to low at best, according to the GRADE criteria 2, 3.
Tolerability and Safety
- Hypertonic saline solutions can cause adverse effects such as cough, dyspnea, throat irritation, or salty taste after inhalation 5, 6.
- The addition of hyaluronic acid may increase the tolerability of hypertonic saline solutions, both in patients with cystic fibrosis and in bronchiectasis of other etiologies 5, 6.
- There is no evidence to suggest that 9% hypertonic saline nebs are more effective or safer than 3% hypertonic saline nebs, and the use of higher concentrations may increase the risk of adverse effects.
Clinical Implications
- The use of hypertonic saline nebs, regardless of concentration, may be beneficial in patients with cystic fibrosis and bronchiectasis, but the evidence is limited and the certainty of the evidence is low 2, 3, 4.
- Clinicians should consider the potential benefits and risks of hypertonic saline nebs, including the risk of adverse effects, and individualize treatment decisions based on patient needs and preferences.