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. 2021 Apr 22;2021(4):CD013170. doi: 10.1002/14651858.CD013170.pub2

Toussaint 2016.

Study characteristics
Methods Study design: prospective RCT comparing a single session of air (breath) stacking using a resuscitator bag (manual breathstacking) compared to a home ventilator (mechanical breathstacking).
Study grouping: parallel‐group
'Rescue' vs maintenance therapy: maintenance
Ethics: informed consent was obtained from patients before recruitment. Approval obtained from the Ethics committee at the institution (Inkendaal Rehabilitation Hospital).
Additional information: participants were randomly allocated to 1 of 2 interventions; there was no control group where participants received no intervention. This study was conducted over 2 years (January 2012 to December 2013).
Participants Baseline characteristics
Overall

  • sample size, n: 52

  • Age in years: ventilator and resuscitator bag groups were reported separately, but not as a whole (n = 52); mean (SD) was not provided

  • Body mass index in kg/m2, mean (SD): not provided

  • FVC in mL, mean (SD): not provided

  • FVC % predicted, mean (SD): not provided

  • MEP in cmH2O, mean (SD): not provided

  • PCF in L/min, mean (SD): not provided

  • Manually assisted PCF in L/min, mean (SD): not provided

  • NIV tidal volume in mL, mean: 720 (SD 90)

  • Mouthpiece intermittent positive pressure ventilation use, n: 35

  • Ventilator‐free time within a 24‐hour period, in hours, mean (SD): not provided

  • NIV duration in years, mean: 8.2 (SD 5.2)

  • Ventilator respiratory rate in cycles/min, mean: 22.2 (SD 4.2)


Mechanical breathstacking

  • Sample size, n: 27

  • Age in years, mean: 25.3 (SD 5.1)

  • Body mass index in kg/m2, mean: 17 (SD 6.5)

  • FVC in mL, mean: 809 (555)

  • FVC % predicted, mean: 17 (SD 10)

  • MEP in cmH2O, mean: 18.3 (SD 10.9)

  • Cough peak flow in L/min, mean: 132 (SD 55)

  • MAC peak flow in L/min, mean: 210 (SD 55)

  • NIV tidal volume in mL, mean: 716 (SD 88)

  • Mouthpiece intermittent positive pressure ventilation use, n: 19

  • Ventilation‐free time within a 24‐hour period in hours, mean: 7.2 (SD 6.3)

  • NIV duration in years, mean (SD): not provided

  • Ventilator RR in cycles/min, mean (SD): not provided


Manual breathstacking

  • Sample size, n: 25

  • Age in years, mean: 24.7 (SD 5.7)

  • Body mass index in kg/m2, mean: 17.1 (SD 6.6)

  • FVC in mL, mean: 807 (SD 495)

  • FVC % predicted, mean: 16 (SD 8)

  • MEP in cmH2O, mean: 17.7 (SD 7.5)

  • Cough peak flow in L/min, mean: 125 (SD 52)

  • MAC peak flow in L/min, mean: 205 (SD 52)

  • NIV tidal volume in mL, mean: 724 (SD 92)

  • Mouthpiece intermittent positive pressure ventilation use, n: 16

  • Ventilation‐free time within a 24‐hour period in hours, mean: 7 (SD 5.5)

  • NIV duration in years, mean (SD): not provided

  • Ventilator RR in cycles/min, mean (SD): not provided


Inclusion criteria

  • Adults with DMD aged > 18 years

  • Requiring NIV (all received volume cycle ventilation)

  • Followed up at the Neuromuscular Excellence Centre and Centre for Home Mechanical Ventilation, Inkendaal Rehabilitation Hospital in a 2‐year period.


Exclusion criteria

  • Inability to perform lung function tests

  • Tracheostomy in situ

  • Prior formal training in breathstacking

  • Respiratory instability (defined as acute respiratory failure)


Pretreatment: demographics, lung function values, and ventilation parameters were similar between the 2 groups (no statistically significant difference between groups, Table 1 of publication).
Interventions Intervention characteristics
Mechanical breathstacking

  • Participant position: sitting

  • Technique description: number of successive insufflations required for each participant to optimise their technique was individualised. Air stacking was performed using a volume‐cycled home mechanical ventilator and nasal mask interface, with parameters unchanged from those used for participant's nocturnal NIV. Instructions were tailored to the participant but an example of a provided explanation was, "Let your lungs fill with air from the ventilator/bag. Once this insufflation has finished, hold your breath and don't breathe out. Another insufflation will be delivered. Try to stack 2 or 3 of these successive insufflations. When your lungs feel like they're fully expanded, cough."

  • Measurement: after performing the breathstacking technique to maximal insufflation, participants coughed into a mask (held by therapist), without additional manual assistance or abdominal compression.


Manual breathstacking

  • Participant position: sitting

  • Technique description: number of successive insufflations required for each participant to optimise their technique was individualised. Air stacking was performed by an experienced physiotherapist, using a using a 2 L resuscitator bag (Resutator 2000, Drager, Lubeck, Germany) via a full face mask interface. Instructions were tailored to the participant as per 'mechanical breathstacking' above.

  • Measurement: after performing the breathstacking technique to maximal insufflation, participants coughed into a mask (held by therapist), without additional manual assistance or abdominal compression.
Outcomes Able to perform breath/airstacking

  • Outcome type: dichotomous (yes/no)


Number of insufflations to maximal insufflation capacity

  • Outcome type: continuous

  • Direction: higher was better


Breathstacking‐assisted PCF (primary outcome measure)

  • Outcome type: continuous

  • Unit of measure: L/min

  • Measurement technique: measured using a heated Fleisch No. 2 Pneumotachometer (Metabo, Lausanne, Switzerland), the best of 3 trials was recorded.

  • Direction: higher was better


Maximal insufflation capacity

  • Outcome type: continuous

  • Unit of measure: mL

  • Measurement technique: measured using a heated Fleisch No. 2 Pneumotachometer (Metabo, Lausanne, Switzerland), the best of 3 trials was recorded.

  • Direction: higher was better


MEP following breathstacking

  • Outcome type: continuous

  • Unit of measure: cmH2O

  • Measurement technique: recorded from total lung capacity

  • Direction: higher was better


Adverse events: not reported on
Identification Sponsorship source: not mentioned
Conflict of interest: no conflict‐of‐interest statement presented
Country: Belgium
Setting: Neuromuscular Excellency Centre and Centre for Home Mechanical Ventilation Inkendaal Rehabilitation Hospital
Comments: –
Author name: Michel Toussaint
Institution: Rehabilitation Hospital (Ziekenhuis), Inkendaal
Email: michel.toussaint@inkendaal.be
Address: Rehabilitation Hospital, InkendaalInkendaalstraat 1B‐1602 Vlezenbeek (Brussels), Belgium
Notes  
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Quote: "Participants were allocated by coin toss to a single session of either air stacking via home ventilator or air stacking via a resuscitator bag at a routine clinical visit."
Comment: randomisation to intervention was determined by coin toss (air stacking with ventilator or resuscitator bag), therefore, selection bias was low.
Allocation concealment (selection bias) Unclear risk Comment: no information provided regarding allocation concealment.
Blinding of participants and personnel (performance bias)
All outcomes High risk Comment: participants and therapists were not blinded to treatment. All participants were trained in both air stacking techniques, before randomisation was implemented. However, it was not possible to blind participants to the techniques that were used.
Blinding of outcome assessment (detection bias)
All outcomes High risk Comment: a blinded outcome assessor gathered baseline data prior to group allocation. However, the postintervention outcome assessment seemed to have been done by the attending therapist, who was not blinded to group allocation. The best of 3 values was recorded and standardised assessment guidelines were followed, but insufficient information was provided about who performed the assessments. As with blinding of participants and staff, it would have been difficult to blind the person assessing PCF, as they would have been aware of intervention allocation and air stacking technique. Other measures such as FVC and MEP were routinely assessed at the centre.
Incomplete outcome data (attrition bias)
All outcomes Low risk Comment: all participants allocated to a group were assessed in the group, with no loss to follow‐up/missing data. Eligibility criteria were clear. 6 participants could not perform breath stacking (as defined by the study) and the number was too small to make a comparison between the 46 that could perform the procedure and those that could not. There was full transparency of the research process and alignment with the protocol.
Selective reporting (reporting bias) Low risk Quote: "primary outcome measure was air stacking‐assisted cough peak flow."
Quote: "Lung volume was recorded from a maximal effort unassisted breath (FVC) and following an air stacking‐assisted breath (maximum insufflation capacity). Maximal expiratory pressure (P Emax) was recorded from total lung capacity as per American Thoracic Society/European Respiratory Society guidelines."
Quote: "no difference in air stacking‐assisted cough peak flow between groups."
Quote: "P.001). Similarly, there were comparable expired volumes between techniques, with maximum insufflation capacity values greater than spontaneous FVC in both groups (mean within group change: 672)."
Quote: "difference in maximum insufflation capacity between groups (Table 2)."
Quote: "Table 2. Comparison of Air Stacking via Ventilator Versus via Resuscitator Bag."
Comment: all outcome measures reported in the methods section were analysed and presented in the results section (Table 2 and in text). The study protocol was well described regarding study procedure, participants, and outcome measures (reproducible) and all the specified outcomes were reported in the prespecified way.
Other bias Low risk Quote: "Able to perform air stacking, n (%) 24/27 (89) 22/25 (88) NS [not significant]"
Comment: the following factors placed the study at low risk of other bias.

  • Groups well matched at baseline.

  • Number of participants unable to perform breathstacking was similar between groups.

ACBT: active cycle of breathing technique; ALS: amyotrophic lateral sclerosis; BiPAP: bilevel positive airway pressure; BMD: Becker muscular dystrophy; CEV: cough expiratory volume; CMD: congenital muscular dystrophy; CNS: central nervous system; CO2: carbon dioxide; DMD: Duchenne muscular dystrophy; FEV1: forced expiratory volume in one second; FVC: forced vital capacity; IBS: involuntary breathstacking; ICU: intensive care unit; IQR: interquartile range; IPPB: intermittent positive pressure breathing; LVR: lung volume recruitment; MAC: manually assisted cough; MD: mean difference; MEE: maximal expiration effort; MEP: maximal expiratory pressure; MI‐E: mechanical insufflation‐exsufflation; MIC: maximal inspiratory or insufflation capacity; MIP: maximum inspiratory pressure; min: minute; n: number of participants; MVV: maximal voluntary ventilation; N/A: not available; NIPPV: non‐invasive positive pressure ventilation; NIV: non‐invasive ventilation; NMD: neuromuscular disease; PCF: peak cough flow; PECF: peak expiratory cough flow; PEFR: peak expiratory flow rate; PETCO2: end‐tidal carbon dioxide tension; Pmo,w: maximal pressure within the mouth; PtcCO2: transcutaneous carbon dioxide tension; PVT: peak value time; RCT: randomised controlled trial; RR: risk ratio; s: second; SaO2: oxygen saturation in arterial blood; SD: standard deviation; SMA: spinal muscular atrophy; SNIP: sniff nasal inspiratory pressure; SpO2: peripheral capillary oxygen saturation; VAS: visual analogue scale; VC: vital capacity; VCM: volumetric cough mode; COPD: chronic obstructive pulmonary disease