Protective effect of bronchial challenge with hypertonic saline on nocturnal asthma

Abstract

Inhalation of hypertonic saline (HS) causes bronchoconstriction in asthmatic subjects. Repeated inhalation of HS leads to substantially reduced bronchoconstriction, known as the refractory period. Refractoriness due to different stimuli has also been described (cross-refractoriness). Nocturnal asthma is defined as an increase in symptoms, need for medication, airway responsiveness, and/or worsening of lung function that usually occurs from 4 to 6 am. Our objective was to determine the effect of refractoriness on nocturnal asthma. The challenge test consisted of inhalations of 4.5% saline with increasing durations until a reduction of 20% in forced expiratory volume in 1 s (FEV 1 ) (PD 20 HS) or total time of 15.5 min. Twelve subjects with nocturnal asthma were challenged with HS at 16:00 and 18:00 h and FEV 1 was measured at 4:00 h. One to 2 weeks later, FEV 1 was determined at 16:00 and 4:00 h. LogPD 20 HS at 18:00 h was significantly greater than logPD 20 HS at 16:00 h, 0.51 ± 0.50 and 0.69 ± 0.60 mg, respectively (P = 0.0033). When subjects underwent two HS challenges in the afternoon, mean (± SD) FEV 1 reduction was 206 ± 414 mL or 9.81 ± 17.42%. On the control day (without challenge in the afternoon) FEV 1 reduction was 523 ± 308 mL or 22.75 ± 15.40% (P = 0.021). Baseline FEV 1 values did not differ significantly between the control and study days, 2.48 ± 0.62 and 2.36 ± 0.46 L, respectively. The refractory period following HS challenges reduces the nocturnal worsening of asthma. This new concept may provide beneficial applications to asthmatic patients.

Childhood asthma treatment based on indirect hyperresponsiveness test: Randomized controlled trial

“…It's worth pointing out that only in 5 cases out of about 400 tests performed in 2019 in our center, there was a mild, short‐term, reversible decrease in saturation (SpO 2 values 92%–93%) during bronchospasm. The safety of hypertonic saline inhalation is confirmed by its wide therapeutic use in patients with bronchiectasis, as well as in the AHR test, also in children with asthma 34,35 . The time needed for the AHR challenges is similar in both methods 21 …”

“…The safety of hypertonic saline inhalation is confirmed by its wide therapeutic use in patients with bronchiectasis, as well as in the AHR test, also in children with asthma. 34,35 The time needed for the AHR challenges is similar in both methods. 21 AHR is a promising tool for the treatment monitoring of mild-tomoderate asthma.…”

Halotherapy—An Ancient Natural Ally in the Management of Asthma: A Comprehensive Review

“…Refractoriness following HS challenges efficiently prevents nocturnal worsening of asthma. The authors speculate that the duration of the refractory period following HS challenges is at least 10 h [71]. However, no scientific evidence to date demonstrated its duration.…”

“…Although the inhalation of HS causes bronchoconstriction in asthmatic subjects, the repeated challenge of the airways with HS results in loss of airway responsiveness, known as the refractory period [71]. The existence of the refractory period paves the way for the use of HT in the prevention of asthma exacerbations.…”

“…The impact of refractoriness was evaluated on patients with nocturnal asthma (defined by an increase in symptoms, need for medication, airway responsiveness, and/or worsening of lung function, usually occurring from 4 to 6 a.m.) [71]. The mean overnight reduction of FEV 1 was significantly higher (523 ± 308 mL or 22.75 ± 15.40%) in the control day (with no challenge in the afternoon) compared to 206 ± 414 mL or 9.81 ± 17.42% on the study day (with two HS challenges in the afternoon), during the refractory period (p = 0.021).…”