Timing of hypertonic saline inhalation for cystic fibrosis

Timing of hypertonic saline inhalation for cystic fibrosis

BACKGROUND

Inhalation of hypertonic saline improves sputum rheology, accelerates mucociliary clearance and improves clinical outcomes of people with cystic fibrosis. This is an update of a previously published Cochrane Review.

OBJECTIVES

To determine whether the timing of hypertonic saline inhalation (in relation to airway clearance techniques or in relation to time of day) has an impact on its clinical efficacy in people with cystic fibrosis.

SEARCH METHODS

We identified relevant randomised and quasi-randomised controlled trials from the Cochrane Cystic Fibrosis Trials Register, the Physiotherapy Evidence Database (PEDro), and international cystic fibrosis conference proceedings. Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register: 28 February 2019.

SELECTION CRITERIA

Any trial of hypertonic saline in people with cystic fibrosis where timing of inhalation was the randomised element in the study protocol with either: inhalation up to six hours before airway clearance techniques compared to inhalation during airway clearance techniques compared to inhalation up to six hours after airway clearance techniques; or morning compared to evening inhalation with any definition provided by the author.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed the trials identified by the search for potential inclusion in the review. The certainty of the evidence was assessed using GRADE.

MAIN RESULTS

The searches identified 104 trial reports which represented 51 trials, of which three cross-over trials (providing data on 77 participants) met our inclusion criteria. We present three comparisons: inhalation before versus during airway clearance techniques; inhalation before versus after airway clearance techniques; and inhalation during versus after airway clearance techniques. One trial (50 participants), given its three-arm design, was eligible for all three comparisons. No trials compared morning versus evening inhalation of hypertonic saline. The evidence from the three trials was judged to be of low quality downgraded for limitations (high risk of bias due to blinding) and indirectness (all participants are adults, and therefore not applicable to children). Intervention periods ranged from one treatment to three treatments in one day. There were no clinically important differences between the timing regimens of inhaling hypertonic saline before, during or after airway clearance techniques in the mean amount of improvement in lung function or symptom scores (77 participants), with the between-group comparisons being non-significant (low-certainty evidence). While there may be little or no difference in the rating of satisfaction when hypertonic saline was inhaled before versus during the airway clearance techniques (64 participants) (with the 95% confidence interval including the possibility of both a higher and lower rating of satisfaction), satisfaction may be lower on a 100-mm scale when inhaled after the airway clearance techniques compared to before: mean difference (MD) 20.38 mm (95% confidence interval (CI) 12.10 to 28.66) and when compared to during the techniques, MD 14.80 mm (95% CI 5.70 to 23.90). Perceived effectiveness showed similar results: little or no difference for inhalation before versus during airway clearance techniques (64 participants); may be lower when inhaled after the airway clearance techniques compared to before, MD 10.62 (95% CI 2.54 to 18.70); and also when compared to during the techniques, MD 15.60 (95% CI 7.55 to 23.65). There were no quality of life or adverse events reported in any of the trials.

AUTHORS' CONCLUSIONS

Timing of hypertonic saline inhalation makes little or no difference to lung function (low-certainty evidence). However, inhaling hypertonic saline before or during airway clearance techniques may maximise perceived efficacy and satisfaction. The long-term efficacy of hypertonic saline has only been established for twice-daily inhalations; however, if only one dose per day is tolerated, the time of day at which it is inhaled could be based on convenience or tolerability until evidence comparing these regimens is available. The identified trials were all of very short intervention periods, so longer-term research could be conducted to establish the effects arising from regular use, which would incorporate the influence of changes in adherence with long-term use, as well as generating data on any adverse effects that occur with long-term use.

New insights into the mechanisms controlling the bronchial mucus balance

In this work, we aim to analyze and compare the mechanisms controlling the volume of mucus in the bronchial region of the lungs of a healthy human adult, at rest and in usual atmospheric conditions. This analysis is based on a balance equation for the mucus in an airway, completed by a computational tool aiming at characterizing the evaporation, during respiration, of the water contained in the bronchial mucus. An idealized representation of the lungs, based on Weibel’s morphometric model, is used. The results indicate that the mechanisms controlling the volume of mucus in an airway depend on the localization of the airway in the bronchial region of the lungs. In the proximal generations, the volume of mucus in an airway is mainly controlled by the evaporation of the water it contains and the replenishment, with water, of the mucus layer by epithelial cells or the submucosal glands. Nevertheless, cilia beating in this part of the bronchial region remains of fundamental importance to transport the mucus and hence to eliminate dust and pathogens trapped in it. On the other hand, in the distal generations of the bronchial region, the volume of mucus in an airway is mainly controlled by the mucociliary transport and by the absorption of liquid by the epithelium. This absorption is a consequence of the mucus displacement by the cilia along generations with an interface between the epithelium and the airway surface layer of decreasing area. The numerical results obtained are in good agreement with previously published experimental data, thus validating our approach. We also briefly discuss how our results can improve the understanding and, possibly, the treatment of pulmonary diseases.

Timing of hypertonic saline and airway clearance techniques in adults with cystic fibrosis during pulmonary exacerbation: pilot data from a randomised crossover study

Background

Streamlining the timing of treatments in cystic fibrosis (CF) is important to optimise adherence while ensuring efficacy. The optimal timing of treatment with hypertonic saline (HTS) and airway clearance techniques (ACT) is unknown.

Objectives

This study hypothesised that HTS before ACT would be more effective than HTS during ACT as measured by Lung Clearance Index (LCI).

Methods

Adults with CF providing written informed consent were randomised to a crossover trial of HTS before ACT or HTS during ACT on consecutive days. ACT treatment consisted of Acapella Duet. Patients completed LCI and spirometry at baseline and 90 min post treatment. Mean difference (MD) and 95% CIs were reported.

Results

13 subjects completed the study (mean (SD) age 33 (12) years, forced expiratory volume in 1second % (FEV₁%) predicted 51% (22), LCI (no. turnovers) 14 (4)). Comparing the two treatments (HTS before ACT vs HTS during ACT), the change from baseline to 90 min post treatment in LCI (MD (95% CI) −0.02 (−0.63 to 0.59)) and FEV₁% predicted (MD (95% CI) −0.25 (−2.50 to 1.99)) was not significant. There was no difference in sputum weight (MD (95% CI) −3.0 (−14.9 to 8.9)), patient perceived ease of clearance (MD (95% CI) 0.4 (−0.6 to 1.3) or satisfaction (MD (95% CI) 0.4 (−0.6 to 1.5)). The time taken for HTS during ACT was significantly shorter (MD (95% CI) 14.7 (9.8 to 19.6)).

Conclusions

In this pilot study, HTS before ACT was no more effective than HTS during ACT as measured by LCI.

Trial registration number

NCT01753869; Pre-results.

Timing of hypertonic saline inhalation for cystic fibrosis

BACKGROUND

Inhalation of hypertonic saline improves sputum rheology, accelerates mucociliary clearance and improves clinical outcomes of people with cystic fibrosis.

OBJECTIVES

To determine whether the timing of hypertonic saline inhalation (in relation to airway clearance techniques or in relation to time of day) has an impact on its clinical efficacy in people with cystic fibrosis.

SEARCH METHODS

We identified relevant randomised and quasi-randomised controlled trials from the Cochrane Cystic Fibrosis Trials Register, the Physiotherapy Evidence Database (PEDro), and international cystic fibrosis conference proceedings.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register: 19 December 2016.

SELECTION CRITERIA

Any trial of hypertonic saline in people with cystic fibrosis where timing of inhalation was the randomised element in the study protocol with either: inhalation up to six hours before airway clearance techniques compared to inhalation during airway clearance techniques compared to inhalation up to six hours after airway clearance techniques; or morning compared to evening inhalation with any definition provided by the author.

DATA COLLECTION AND ANALYSIS

Both authors independently assessed the trials identified by the search for potential inclusion in the review.

MAIN RESULTS

The searches identified 97 trial reports which represented 46 studies, of which two studies (providing data on 63 participants) met our inclusion criteria. Both studies used a cross-over design. Both studies had low risk of all types of bias except the participants and the therapists who applied the treatments were not blinded. Intervention periods ranged from one treatment to three treatments in one day. The effects of the various regimens on lung function were non-significant. Satisfaction was rated significantly lower on a 100-mm scale when hypertonic saline was inhaled after the airway clearance techniques: mean differences 20.38 mm (95% confidence interval 12.10 to 28.66) compared to before airway clearance techniques and 14.80 mm (95% confidence interval 5.70 to 23.90) compared to during the techniques. Perceived effectiveness showed similar significant results. Other outcomes were unaffected by the timing regimen used. No trials compared morning versus evening inhalation of hypertonic saline.

AUTHORS' CONCLUSIONS

People with cystic fibrosis could be encouraged to inhale hypertonic saline before or during airway clearance techniques to maximise perceived efficacy and satisfaction, even though these timing regimens may not have any better effect on lung function than inhalation after airway clearance techniques. Given the long-term efficacy of hypertonic saline has only been established for twice-daily inhalations, clinicians should advise patients to inhale hypertonic saline twice daily. However, if only one dose per day is tolerated, the time of day at which it is inhaled could be based on convenience or tolerability until evidence comparing these regimens is available.

Inhaled therapy in cystic fibrosis: agents, devices and regimens

Key points

Summary

The recognised mainstay daily treatments for cystic fibrosis (CF) focus on inhaled and oral medications, airway clearance and optimised nutrition. This review discusses recent advances in inhaled therapies for the management of CF, including devices such as intelligent nebulisers, drug formulations and supporting evidence for inhaled antibiotics (for the management of chronic Pseudomonas aeruginosa) and muco-active drugs. We include practical advice for clinicians regarding the optimisation of inhalation technique and education. The influence of adherence on the use of inhaled therapies in CF is also reviewed.

Educational aims

Structure and function of the mucus clearance system of the lung

In cystic fibrosis (CF), a defect in ion transport results in thick and dehydrated airway mucus, which is difficult to clear, making such patients prone to chronic inflammation and bacterial infections. Physiotherapy using a variety of airway clearance techniques (ACTs) represents a key treatment regime by helping clear the airways of thickened, adhered, mucus and, thus, reducing the impact of lung infections and improving lung function. This article aims to bridge the gap between our understanding of the physiological effects of mechanical stresses elicited by ACTs on airway epithelia and the reported effectiveness of ACTs in CF patients. In the first part of this review, the effects of mechanical stress on airway epithelia are discussed in relation to changes in ion transport and stimulation in airway surface layer hydration. The second half is devoted to detailing the most commonly used ACTs to stimulate the removal of mucus from the airways of patients with CF.