Autogenic drainage: the technique, physiological basis and evidence

Sputum handling for rheology

The rheology of sputum is viewed as a powerful emerging biophysical marker for monitoring muco-obstructive pulmonary diseases such as cystic fibrosis (CF) and non-CF bronchiectasis (NCFB). However, there is no unified practice to process sputa from collection to analysis, which can lead to highly variable, and sometimes inconsistent results. The main objective of this study is to bring light into the handling of sputum samples to establish a standardised and robust protocol before rheological measurements. Sputum collected from 22 CF and 10 NCFB adults, was divided into control (vortexed and fresh: non-heated and non-frozen) and three treated conditions (either non-vortexed, heated or frozen). In addition, 6 CF expectorations were used to study the dynamics of ageing over 24 h. Sputum's mechanical properties were measured with a rotational rheometer to obtain their properties at rest, elastic ([Formula: see text]) and viscous moduli ([Formula: see text]), and at the onset of flow, critical deformation ([Formula: see text]) and critical stress ([Formula: see text]). We demonstrate that heating sputum is completely destructive while freezing sputa at [Formula: see text] has no discernible effect on their rheology. We also show that the variability of rheological measurements largely resulted from the sample's macroscopic heterogeneity, and can be greatly reduced by non-destructive vortex homogenisation. Finally, we observed contrasted ageing effects as a fonction of purulence: while the viscoelasticity of purulent samples reduced by half within 6 h after collection, semi-purulent samples did not evolve. These results guide towards a robust unified protocol for simple sputum handling in rheometry. We therefore suggest to vortex and snap freeze sputum samples immediately after collection when direct testing is not possible.

Autogenic drainage for airway clearance in cystic fibrosis

BACKGROUND

Autogenic drainage is an airway clearance technique that was developed by Jean Chevaillier in 1967. The technique is characterised by breathing control using expiratory airflow to mobilise secretions from smaller to larger airways. Secretions are cleared independently by adjusting the depth and speed of respiration in a sequence of controlled breathing techniques during exhalation. The technique requires training, concentration and effort from the individual but it has previously been shown to be an effective treatment option for those who are seeking techniques to support and promote independence.  However, at a time where the trajectory and demographics of the disease are changing, it is important to systematically review the evidence demonstrating that autogenic drainage is an effective intervention for people with cystic fibrosis.

OBJECTIVES

To compare the clinical effectiveness of autogenic drainage in people with cystic fibrosis with other physiotherapy airway clearance techniques.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews, as well as two ongoing trials registers (02 February 2021). Date of most recent search of the Cochrane Cystic Fibrosis Trials Register: 06 July 2021.

SELECTION CRITERIA

We identified randomised and quasi-randomised controlled studies comparing autogenic drainage to another airway clearance technique or no therapy in people with cystic fibrosis for at least two treatment sessions.

DATA COLLECTION AND ANALYSIS

Data extraction and assessments of risk of bias were independently performed by three authors. The authors assessed the quality of the evidence using the GRADE system. The authors contacted seven teams of investigators for further information pertinent to their published studies.

MAIN RESULTS

Searches retrieved 64 references to 37 individual studies, of which eight (n = 212) were eligible for inclusion. One study was of parallel design with the remaining seven being cross-over in design; participant numbers ranged from 4 to 75. The total study duration varied between four days and two years. The age of participants ranged between seven and 63 years with a wide range of disease severity reported. Six studies enrolled participants who were clinically stable, whilst participants in two studies received treatment whilst hospitalised with an infective exacerbation. All studies compared autogenic drainage to one (or more) other recognised airway clearance technique. Exercise is commonly used as an alternative therapy by people with cystic fibrosis; however, there were no studies identified comparing exercise with autogenic drainage. The certainty of the evidence was generally low or very low. The main reasons for downgrading the level of evidence were the frequent use of a cross-over design, outcome reporting bias and the inability to blind participants. The review's primary outcome, forced expiratory volume in one second, was the most common outcome measured and was reported by all eight studies; only three studies reported on quality of life (also a primary outcome of the review). One study reported on adverse events and described a decrease in oxygen saturation levels whilst performing active cycle of breathing techniques, but not with autogenic drainage. Seven of the eight included studies measured forced vital capacity and three of the studies used mid peak expiratory flow (per cent predicted) as an outcome. Six studies reported sputum weight. Less commonly used outcomes included oxygen saturation levels, personal preference, hospital admissions, intravenous antibiotics and pseudomonas gene expression. There were no statistically significant differences found between any of the techniques used with respect to the outcomes measured except when autogenic drainage was described as being the preferred technique of the participants in one study over postural drainage and percussion.

AUTHORS' CONCLUSIONS

Autogenic drainage is a challenging technique that requires commitment from the individual. As such, this intervention merits systematic review to ensure its effectiveness for people with cystic fibrosis, particularly in an era where treatment options are changing rapidly. From the studies assessed, autogenic drainage was not found to be superior to any other form of airway clearance technique. Larger studies are required to better evaluate autogenic drainage in comparison to other airway clearance techniques in view of the relatively small number of participants in this review and the complex study designs. The studies recruited a range of participants and were not powered to assess non-inferiority. The varied length and design of the studies made the analysis of pooled data challenging.

Adding autogenic drainage to chest physiotherapy after upper abdominal surgery: effect on blood gases and pulmonary complications prevention. Randomized controlled trial

BACKGROUND

Hypoxemia and pulmonary complications are common after upper abdominal surgery (UAS).

OBJECTIVE

To examine whether inclusion of autogenic drainage (AD) in chest physiotherapy after UAS confers additional benefits in improving blood gases and reducing postoperative pulmonary complications (PPCs).

DESIGN AND SETTING

Randomized controlled study conducted at Kasr Al-Ainy teaching hospital, Egypt.

METHODS

A randomized controlled trial was conducted on 48 subjects undergoing elective UAS with high risk of developing PPCs. The study group received AD plus routine chest physiotherapy (deep diaphragmatic breathing, localized breathing and splinted coughing) and the control group received routine chest physiotherapy only. The outcomes included arterial blood gases measured at the first and seventh postoperative days, incidence of PPCs within the first seven days and length of hospital stay.

RESULTS

Baseline characteristics were similar between groups. In the AD group, SaO2, PaO2, PaCO2 and HCO3 significantly improved (P < 0.05) while in the physiotherapy group, only SaO2 and PaO2 significantly improved (P < 0.05). Nonetheless, significant differences in post-treatment SaO2 and PaO2 between the groups were observed. The overall incidence of PPCs was 16.66% (12.5% in the AD group and 20.8% in the physiotherapy group) (absolute risk reduction -8.3%; 95% confidence interval, CI, -13.5 to 29.6%), with no significant difference between the groups. The AD group had a significantly shorter hospital stay (P = 0.0001).

CONCLUSION

Adding AD to routine chest physiotherapy after UAS provided a favorable blood gas outcome and reduced the length of hospital stay. It tended to reduce the incidence of PPCs.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04446520.

Airway clearance therapy in acute paediatric respiratory illness: A state-of-the-art review

Background

Despite unclear evidence of effectiveness or safety, airway clearance therapy (ACT) is frequently performed in infants and children with acute pulmonary disease.

Objectives

The aim of this review was to critically synthesise published evidence, expert opinion and pathophysiological principles to describe the indications, effects, precautions and application of commonly used ACT modalities for managing infants and children with acute pulmonary disease.

Method

A comprehensive narrative review of published literature was conducted. Articles describing paediatric populations were prioritised, but adult and animal studies were also considered where appropriate.

Results

There is a dearth of high-level evidence supporting the use of ACT in acutely ill infants and children. Conversely, studies have highlighted the lack of effect of different modalities for a variety of conditions, and in some cases serious associated complications have been reported.Airway clearance therapy may be considered when there is retention of pulmonary secretions, and the consequential airway obstruction impacts either acutely on respiratory mechanics and gaseous exchange and/or has the potential for long-term adverse sequelae [a condition that is the consequence of a previous disease or injury]. However, it should not be considered a routine intervention.

Conclusion

Airway clearance therapy should not be performed routinely in children admitted to hospital with acute respiratory conditions. Patients should be clinically assessed and treatment planned according to individual presentation, in those with signs and symptoms that are potentially amenable to ACT.

Clinical implications

This review can serve as a guide for physiotherapists in the respiratory management of children with acute respiratory illness, as well as identifying areas for clinical research.

Feasibility of computerized adventitious respiratory sounds to assess the effects of airway clearance techniques in patients with bronchiectasis

Objective: To examine the feasibility of adventitious respiratory sound (ARS) as an outcome measure to assess the effects of airway clearance techniques (ACTs) in outpatients with bronchiectasis. Methods: ARS were registered pre/post four ACTs sessions. Clinical outcomes included: number of crackles (coarse and fine), number of wheezes (monophonic and polyphonic), wheezes occupation rate (%) and sputum quantity. Feasibility outcomes of ARS included: reasons for exclusion, suitability, safety, equipment and time required, magnitude of change after intervention and sample size estimation. Results: Seven patients (49.7 ± 20.5 years; FEV₁ 69.3 ± 15.8% predicted) were included. Recordings from four patients were excluded due to excessive environment noise. All ARS measurements were completed without any adverse events. An electronic stethoscope was acquired and the time spent to complete each assessment was 6 ± 3.5 min. The largest changes were observed for number of expiratory coarse crackles [effect size (95%CI) ES = 0.40 (0.01-0.79)], which correlated moderately with sputum quantity (r = 0.56), and inspiratory monophonic wheezes [ES = 0.61 (0.22-1.00)]. The estimated sample size for a full crossover trial was 46. Conclusions: ARS is feasible to assess the effects of ACTs in patients with bronchiectasis. Expiratory coarse crackles seem to be the most appropriate ARS parameter, but this finding needs to be confirmed in an adequately powered trial.

Impact of Hypertonic Saline Solutions on Sputum Expectoration and Their Safety Profile in Patients with Bronchiectasis: A Randomized Crossover Trial

BACKGROUND

The role of hyaluronic acid plus hypertonic saline (HA+HS) as a mucoactive treatment in patients with bronchiectasis is still unknown. This study evaluated whether HA+HS solution enhances similar sputum quantity with better safety profile than HS alone in patients with bronchiectasis.

METHODS

In this double-blind randomized crossover trial, three solutions (7% HS; 0.1% HA +7%HS; and 0.9% isotonic saline, IS) were compared in outpatients with bronchiectasis and chronic sputum expectoration. Participants inhaled each solution across four consecutive sessions. All sessions, except on session 3, also included 30 minutes of airway clearance technique. A 7-day washout period was applied. Sputum weight was collected during the sessions (primary outcome) as well as during a 24-hour follow-up. The Leicester Cough Questionnaire (LCQ) and lung function were measured before/after each treatment arm. Safety was assessed by the monitoring of adverse events (AEs).

RESULTS

Twenty-eight patients with bronchiectasis (mean age of 64.0 (17.9) and FEV₁% 60.9 (24.6) of predicted) were recruited. HS and HA+HS promoted similar expectoration during sessions, both being greater than IS [median difference HS vs. IS 3.7 g (95% CI 0.5-6.9); HA+HS vs. IS 3.2 g (95%CI 0.5-5.9)]. Sputum expectorated exclusively during the ACT period was similar across all treatment arms [HS vs. IS -0.3 g (95% CI -1.7 to 0.9); HA+HS vs. IS 0.0 g (95% CI -1.3 to 1.4); HS vs. HA+HS 0.0 g (95% CI -1.2 to 0.4)]. Sputum collected over the 24-hour follow-up tended to be lower for HS and HA+HS compared with IS [HS vs. IS -1.7 g (95% CI -4.2 to 0.0); HA+HS vs. IS -1.1 g (95%CI -3.6 to 0.7)]. No differences in LCQ or lung function were observed. Most severe AEs were reported using HS.

CONCLUSION

HS and HA+HS were more effective on sputum expectoration than IS in patients with bronchiectasis, reporting HA+HS better safety profile than HS.

Intrapulmonary percussive ventilation improves lung function in cystic fibrosis patients chronically colonized with Pseudomonas aeruginosa: a pilot cross-over study

High levels of shear stress can prevent and disrupt Pseudomonas aeruginosa biofilm formation in vitro. Intrapulmonary percussive ventilation (IPV) could be used to introduce shear stress into the lungs of cystic fibrosis (CF) patients to disrupt biofilms in vivo. We performed a first-of-its-kind pilot clinical study to evaluate short-term IPV therapy at medium (200 bursts per minute, bpm) and high frequency (400 bpm) as compared to autogenic drainage (AD) on lung function and the behavior of P. aeruginosa in the CF lung in four patients who are chronically colonized by P. aeruginosa. A significant difference between the three treatment groups was observed for both the forced expiratory volume in 1 s (FEV1) and the forced vital capacity (FVC) (p < 0.05). More specifically, IPV at high frequency significantly increased FEV1 and FVC compared to AD (p < 0.05) and IPV at medium frequency (p < 0.001). IPV at high frequency enhanced the expression levels of P. aeruginosa planktonic marker genes, which was less pronounced with IPV at medium frequency or AD. In conclusion, IPV at high frequency could potentially alter the behavior of P. aeruginosa in the CF lung and improve lung function.

TRIAL REGISTRATION

The trail was retrospectively registered at the ISRCTN registry on 6 June 2013, under trial registration number ISRCTN75391385.

Autogenic drainage for airway clearance in cystic fibrosis

BACKGROUND

Autogenic drainage is an airway clearance technique that was developed by Jean Chevaillier in 1967. The technique is characterised by breathing control using expiratory airflow to mobilise secretions from smaller to larger airways. Secretions are cleared independently by adjusting the depth and speed of respiration in a sequence of controlled breathing techniques during exhalation. The technique requires training, concentration and effort from the individual. It is important to systematically review the evidence demonstrating that autogenic drainage is an effective intervention for people with cystic fibrosis.

OBJECTIVES

To compare the clinical effectiveness of autogenic drainage in people with cystic fibrosis with other physiotherapy airway clearance techniques.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews, as well as two trials registers (31 August 2017).Dtae of most recent search of the Cochrane Cystic Fibrosis Trials Register: 25 September 2017.

SELECTION CRITERIA

We identified randomised and quasi-randomised controlled studies comparing autogenic drainage to another airway clearance technique or no therapy in people with cystic fibrosis for at least two treatment sessions.

DATA COLLECTION AND ANALYSIS

Data extraction and assessments of risk of bias were independently performed by two authors. The authors assessed the quality of the evidence using the GRADE system. The authors contacted two investigators for further information pertinent to their published studies.

MAIN RESULTS

Searches retrieved 35 references to 21 individual studies, of which seven (n = 208) were eligible for inclusion. One study was of parallel design with the remaining six being cross-over in design; participant numbers ranged from 17 to 75. The total study duration varied between four days and two years. The age of participants ranged between seven and 63 years with a wide range of disease severity reported. Six studies enrolled participants who were clinically stable, whilst participants in one study had been hospitalised with an infective exacerbation. All studies compared autogenic drainage to one (or more) other recognised airway clearance technique. Exercise is commonly used as an alternative therapy by people with cystic fibrosis; however, there were no studies identified comparing exercise with autogenic drainage.The quality of the evidence was generally low or very low. The main reasons for downgrading the level of evidence were the frequent use of a cross-over design, outcome reporting bias and the inability to blind participants.The review's primary outcome, forced expiratory volume in one second, was the most common outcome measured and was reported by all seven studies; only three studies reported on quality of life (also a primary outcome of the review). One study reported on adverse events and described a decrease in oxygen saturation levels whilst performing active cycle of breathing techniques, but not with autogenic drainage. Six of the seven included studies measured forced vital capacity and three of the studies used mid peak expiratory flow (per cent predicted) as an outcome. Six studies reported sputum weight. Less commonly used outcomes included oxygen saturation levels, personal preference, hospital admissions or intravenous antibiotics. There were no statistically significant differences found between any of the techniques used with respect to the outcomes measured except when autogenic drainage was described as being the preferred technique of the participants in one study over postural drainage and percussion.

AUTHORS' CONCLUSIONS

Autogenic drainage is a challenging technique that requires commitment from the individual. As such, this intervention merits systematic review to ensure its effectiveness for people with cystic fibrosis. From the studies assessed, autogenic drainage was not found to be superior to any other form of airway clearance technique. Larger studies are required to better evaluate autogenic drainage in comparison to other airway clearance techniques in view of the relatively small number of participants in this review and the complex study designs. The studies recruited a range of participants and were not powered to assess non-inferiority. The varied length and design of the studies made the analysis of pooled data challenging.

Assisted autogenic drainage in infants and young children hospitalized with uncomplicated pneumonia, a pilot study

BACKGROUND AND PURPOSE

Pneumonia is the most important respiratory problem in low-to-middle income countries. Airway clearance therapy continues to be used in children with pneumonia and secretion retention; however, there is lack of evidence to support or reject this treatment. This study aimed to investigate the feasibility of a randomized controlled trial (RCT) on the efficacy and safety of assisted autogenic drainage (AAD) compared to standard nursing care in children hospitalized with uncomplicated pneumonia.

METHODS

A single-blinded pilot RCT was conducted on 29 children (median age 3.5 months, IQR 1.5-9.4) hospitalized with uncomplicated pneumonia. The intervention group received standard nursing care with additional bi-daily AAD, for 10 to 30 min. The control group only received standard nursing care, unless otherwise deemed necessary by the physician or physiotherapist. The primary outcome measure was duration of hospitalization. The secondary outcome measures included days of fever and supplemental oxygen support; respiratory rate (RR) and heart rate adjusted for age; RR and oxygen saturation pre-, post-, and 1-hr post-treatment; oxygen saturation; adverse events; and mortality.

RESULTS

No difference was found for duration of hospitalization (median 7.5 and 7.0 days for the control and intervention groups, respectively); however, Kaplan-Meier analysis revealed a strong tendency towards a shorter time to discharge in the intervention group (p = .06). No significant differences were found for the other outcome measures at time of discharge. No adverse events were reported. Within the intervention group, a significant reduction in RR adjusted for age was found.

DISCUSSION

As no adverse events were reported, and AAD did not prolong hospitalization; AAD might be considered as safe and effective in young children with uncomplicated pneumonia. However, a larger multicentred RCT is warranted to determine the efficacy of AAD compared to standard nursing care.

Effects of Autogenic Drainage on Sputum Recovery and Pulmonary Function in People with Cystic Fibrosis: A Systematic Review

PURPOSE

To determine the effects of short- and long-term use of autogenic drainage (AD) on pulmonary function and sputum recovery in people with cystic fibrosis (CF).

METHODS

The authors conducted a systematic review of randomized and quasi-randomized clinical trials in which participants were people with CF who use AD as their sole airway clearance technique.

RESULTS

Searches in 4 databases and secondary sources using 5 key terms yielded 735 articles, of which 58 contained the terms autogenic drainage and cystic fibrosis. Ultimately, 4 studies, 2 of which were long term, were included. All measured forced expiratory volume in 1 second (FEV1) and found no change. The long-term studies were underpowered to detect change in FEV1; however, the short-term studies found a clinically significant sputum yield (≥4 g).

CONCLUSION

AD has been shown to produce clinically significant sputum yields in a limited number of investigations. The effect of AD on the function of the pulmonary system remains uncertain, and questions have emerged regarding the appropriateness of FEV1 as a valid measure of airway clearance from peripheral lung regions. Further consideration should be given to the use of FEV1 as a primary measure of the effect of AD.