The study was a quasi-experimental study conducted in Krupanidhi College of Physiotherapy, Bangalore, Karnataka, India. The study duration was from August 2017 to December 2018. Sampling was done by Block randomisation with 30 subjects divided in two groups. After taking the general cardio-pulmonary assessment, the subjects were divided into two groups. Group A were given AD technique and group B received ACBT. The eligible subjects included male and female aged between 30 to 50 years and clinically diagnosed with CB and with acute exacerbation of symptoms. Subjects with a recent history of angina, neurological deficits, uncontrolled hypertension and diabetes mellitus, haemodynamic instabilities, ventilator support, hernia and prolapsed uterus were excluded from the study. Ethical clearance was taken from the institute prior to the study. The institutional ethical clearance number is EC-FAC/17/PHY/011.

The materials used included PEF meter apparatus, copy of VAS for Breathlessness, measuring jar, chairs and cushions, treatment bed or couch.

Subjects clinically diagnosed with CB were considered for the study. An informed consent was taken from them. The subjects were then divided into two groups based on block randomisation. They were evaluated before the therapy and after 30 minutes of the therapy for:

PEFR: PEFR was measured using the Wright’s peak flow meter [15]. The Peak flow meter was set to zero. Subjects were to inhale completely, quickly place the peak flow meter into the mouth and to make a seal around the mouthpiece with the lips. The subjects then immediately exhaled completely with maximal force and the reading was taken as shown in the Peak flow meter. This measurement was repeated for two more times. The highest value obtained in PEFR was taken as the final reading [15,16].

VAS for breathlessness: VAS for breathlessness is a scale which gives the subjective measure of breathlessness [17]. In this, breathlessness was measured by a 100 mm scale ranging from No to greatest breathlessness. Subjects were asked to mark the point in the scale that they feel represents the perception of their current breathlessness. The distance of the mark in mm above the point of No breathlessness was recorded as the VAS Score for Breathlessness [18,19].

Expectorated sputum: The subject was asked to cough out the sputum before starting the treatment and the sputum was collected in a measuring jar (labeled ml scale). After the technique, the subject was asked to huff. The expectorated sputum was collected in another measuring jar (labeled mL scale).

After initial evaluation, the subjects received one of the two interventions. Group A received AD and Group B received ACBT.

Subjects were made to sit upright or supine (if subject prefers). The subjects were then asked to blow their nose and the throat was cleared. The technique involves three phases which are the unsticking phase, collecting phase and evacuating phase. The first stage involved subject to take a deep breath, then breathing out completely. After this the subjects had to take a small breath and breathe out completely. When the subject feels the movement of the secretions, the subject moved to the collecting phase in which the subject took a deeper breath, however the expiration didn’t go very deep into the expiratory reserve volume. Once the subjects felt the secretions moving to the more central airways, they were asked to take very deep breathes so as to reach the inspiratory reserve volume and enter the evacuating phase. As the subjects felt that the secretions have reached high in the central airways, they were asked to cough out the sputum. The subjects were asked to control the cough during cycle of breathing exercise [7]. The breathing cycle was repeated for 30 minutes.

ACBT: Subjects were positioned in upright sitting. ACBT involves three stages which are breathing control, deep breathing exercise and Forced Expiratory Techniques (FET). The cycle involved in a sequence breathing control in which subject was made to do quiet relaxed abdominal breathing, deep breathing exercise in which the subject took 3 or 4 deep breaths in order to expand the thoracic region. The first two stages were repeated for five to six times before reaching the third stage which is the FET in which the subject performed 1 or 2 huffs, from low lung volume followed by huff from high lung volume and relaxed abdominal breathing [7]. The entire technique was continued for 30 minutes.

Evaluation was done at the end of the session for both the groups within 30 minutes. The pre and post-therapy values of both the groups were statistically compared.

The statistical analysis was done using SPSS version 11.5 software. Paired t-test and Wilcoxon’s signed rank test was used to compare the pre and post-outcome measures within the group. Mann-Whitney U test was done to compare the outcome measures between the groups.

A significant increase was seen in PEF rate in both group A receiving AD and group B receiving ACBT [Table/Fig-1]. Analysis by the Mann Whitney test shows no significant difference on PEFR between the two groups [Table/Fig-2].

Paired t-test shows that there is a significant decrease in VAS in both group A and group B [Table/Fig-3]. Mann-Whitney test shows that there is no significant difference on effect on VAS between the two groups [Table/Fig-4].

There was a significant increase found in sputum volume in both group A and group B [Table/Fig-5]. On comparison using Mann-Whitney test, no significant difference was seen between the two groups on the effect on sputum volume [Table/Fig-6].

The present study was designed to determine the immediate effect of AD over ACBT in airway clearance in subjects with CB.

In this study, both the techniques showed significant increase in PEFR. The mean increase in PEFR following AD is more compared to ACBT but this difference between the two techniques was not statistically significant. There was no significant difference in VAS between the two techniques of airway clearance. Both were equally effective. The mean change in expectorated sputum volume was more in AD than ACBT however this difference was not statistically significant.

Thus, the study results suggest that there was no overall difference between both the techniques of airway clearance. Both the techniques were effective in mucus clearance and reducing the level of dyspnea.

Comparison with the existing studies also supports that both the techniques are equally effective. Moiz JA et al., in his study indicates that similar effectiveness between ACBT and AD in patients with acute exacerbation of COPD [1].

Savci et al., in their study on comparison of ACBT and AD in patients with COPD have also found both the techniques to be effective in mucus clearance as well as to improve lung functions [20].

Melam GR et al., in their study on short term comparison of ACBT and AD in COPD found significant improvements in FEV1, FVC and PEFR following either of the techniques with no significant difference between both the treatments. Thus, suggesting both to be equally good [21].

Systemic review on ACBT by Lewis LK et al., supports the use of ACBT over other alternatives for short term improvements in airway clearance [22].

However, in a cochrane systemic review on AD in cystic fibrosis patients, AD was challenging technique requiring commitment from the patient. It was not found to be better than any other airway clearance techniques [23].

ACBT opens up the collateral airways by including deep breathing exercises with brief hold period in between the FET. Breathing control phase in ACBT is said to prevent bronchospasm thereby improving the ventilation. The deep breathing along with a hold period done during the second phase helps to open up collateral airways which further enhances the ventilation. An enhanced ventilation by itself helps in loosening the secretions. Performing FET or huffing along with deep breathing exercise also shifts the EPP lower in the respiratory tract. This shift of EPP results in secretion clearance [22].

AD may also help in opening up of collateral airways by breathing in different volumes with a brief hold period which would have resulted in a significant improvement in the dyspnea, PEFR and mucus clearance in the present study. Breathing in low lung volume, mid lung volume and high lung volume with breath hold may have developed collateral filling among the alveoli, enhanced ventilation and mobilised secretions which eventually reduced dyspnea, improved PEFR and mucus clearance [22].

ACBT involves active participation of the patients thus it can be used for airway clearance in conscious oriented patients suffering from various obstructive and restrictive lung disorders, and to prevent and treat various pulmonary complications post-lung and post-abdominal surgeries.

When compared to ACBT, AD is difficult to understand and learn. AD involves the patient to breathe actively in different lung volumes which makes AD difficult to be understood by patients easily. Once the patient follows the commands properly, AD becomes a very effective intervention for mucus clearance in conscious oriented patients suffering from various obstructive and restrictive lung disorders, and to prevent and treat various pulmonary complications post-lung and post-abdominal surgeries. It is especially beneficial in conditions affecting the lower respiratory airways as breathing in different lung volumes allows secretions to be targeted even in the lower airways.

Stated Preference (SP) methods using Survey and questionnaire can be used in this regard to understand patient preferences with both the techniques.

The study presented with few limitations. Generalisation to the population with CB cannot be made as the sample size was small. The study showed the immediate effect of both the techniques in airway clearance in CB. Thus, the long-term effects of these techniques could not be known. All the subjects were not able to perform the techniques for the prescribed duration which might have affected the results.

The study shows that there was significant improvement in mucus clearance and dyspnea in CB on giving ACBT as well as Autogenic Drainage. However, no significant difference exists in the effect of AD over ACBT on mucus clearance and level of dyspnea. Both therapies can be used for airway clearance in CB depending on patient and therapist preference.