Domiciliary humidification improves lung mucociliary clearance in patients with bronchiectasis

Abstract

Inspired air humidification has been reported to show some benefit in bronchiectatic patients. We have investigated the possibility that one effect might be to enhance mucociliary clearance. Such enhancement might, if it occurs, help to lessen the risks of recurrent infective episodes. Using a radioaerosol technique, we measured lung mucociliary clearance before and after 7 days of domiciliary humidification. Patients inhaled high flow saturated air at 37 degrees C via a patient-operated humidification nasal inhalation system for 3 h per day. We assessed tracheobronchial mucociliary clearance from the retention of (99m)Tc-labelled polystyrene tracer particles monitored for 6 h, with a follow-up 24-h reading. Ten out of 14 initially recruited patients (age 37-75 years; seven females) completed the study (two withdrew after their initial screening and two prior to the initial clearance test). Seven patients studied were non-smokers; three were ex-smokers (1-9 pack-years). Initial tracer radioaerosol distribution was closely similar between pre- and post-treatment. Following humidification, lung mucociliary clearance significantly improved, the area under the tracheobronchial retention curve decreased from 319 +/- 50 to 271 +/- 46%h (p < 0.07). Warm air humidification treatment improved lung mucociliary clearance in our bronchiectatic patients. Given this finding plus increasing laboratory and clinical interest in humidification mechanisms and effects, we believe further clinical trials of humidification therapy are desirable, coupled with analysis of humidification effects on mucus properties and transport.

The Effects of Flow on Airway Pressure During Nasal High-Flow Oxygen Therapy

“…8,9 In addition to a low-level pressure effect, other proposed mechanisms of action may include the ability to more accurately control the patient's F IO 2 , 4,10 flushing of anatomical dead space, 11 and better mucociliary clearance. 12 The extent to which each mechanism affects physiological outcomes and therapy efficacy remains to be determined.…”

A Preliminary Randomized Controlled Trial to Assess Effectiveness of Nasal High-Flow Oxygen in Intensive Care Patients

“…5 NHF provides body-temperature-and-pressure-saturated gas (37°C, 44 mg H 2 O/L), which is important for patient comfort 16 and improves mucociliary clearance. 21 Longterm humidity therapy with NHF in patients with chronic respiratory disease improved lung function and reduced exacerbation days. 22 Rea and colleagues proposed that these improved clinical outcomes may be the result of enhanced lung mucociliary clearance.…”

Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device

“…By this mechanism, mucociliary function and secretion clearance is improved [15], as shown in patients with idiopathic bronchiectasis from the reduced percentage of retention of an inhaled tracer before and after receiving warm and humidified air through NHF [16]. Furthermore, the required metabolic cost of warming and increasing the relative humidity of inspired gas is reduced, especially in patients with increased minute ventilation [17].…”

“…Stable chronic obstructive pulmonary disease (COPD) patients with chronic respiratory failure could benefit from NHF application through a reduction of anatomical dead space [85,86], improvement in mucociliary clearance in conducting airways [16,87] and passive elevation in end-expiratory pressure [6,7,9,85]. These mechanisms lead to improved exercise performance with fewer symptoms and better gas exchange [85,88,89], improved lung mechanics [90] with less respiratory muscle load [91] and less work of breathing [86].…”