Cardiopulmonary Exercise Testing Guided Physiotherapy During Pulmonary Rehabilitation in Patients With Dysfunctional Breathing, a Randomized Controlled Trial

Dysfunctional breathing (DB) is a common disorder affecting 9% of the general population and almost 1/3 of patients with underline pulmonary disease such as asthma or COPD. To date physiotherapy utilizing breathing retraining remains the mainstay treatment however, there is lack of evidence regarding the efficacy of these treatments or the superiority of one over the other in terms of symptom relief. Moreover, still there is no consensus on the diagnosis of DB patients and no gold standard diagnostic method exists.

R Boulding et. al. classified DB in to five categories incorporating the main characteristics of patients with DB which are hyperventilation and abnormal/irregular breathing patterns including periodic deep sighing, thoracic dominant breathing, forced abdominal expiration and thoraco-abdominal asynchrony. Patients may demonstrate one or more of the above breathing patterns which are also observed in diseases like asthma, COPD, heart failure, neuromuscular disease and panic/anxiety disorder. To date the main tools for diagnosing/ evaluating DB are expert physiotherapists examination, questionnaires and Cardiopulmonary exercise testing (CPET).

The Nijmegen questionnaire (NQ) has been widely used as a screening tool for DB2 with a cut-off score of ≥23 however, NQ was design for detecting hyperventilation syndrome which is frequent, yet not universal, in DB patients, common in various respiratory conditions and thus poorly agrees with expert respiratory physiotherapists evaluation in detecting DB. The NQ may miss other manifestations of DB like thoracoabdominal asynchrony or apical breathing. The Breathing Pattern Assessment Tool (BPAT) was specifically designed as a semiobjective screening tool for characterization and qualification of the key features of DB namely both hyperventilation and breathing pattern disorders. A cutoff score of ≥4 is highly sensitive (0.92) and specific (0.75) in diagnosing DB9. The Breathing Vigilance (V-Q) Questionnaire was developed to measure breathing vigilance which, if increased, may contribute to DB and could be a therapeutic target. A cut-off score of 16.5 has optimal sensitivity (0.718) and specificity (0.681) in differentiating between high and low DB risk.

CPET could be a valuable tool in diagnosing and assessing dysfunctional breathing. In contrast to questionnaires CPET can be used to objectively assess breathing pattern disorders and provide evidence for further investigations when an underlying disease is suspected. Moreover, as an objective measurement is more reliable in re-assessing DB patients after treatment since there is no "learning effect" from either the patient nor the therapist who both want the therapy to succeed. Assessing end-tidal PCO2 (PETCO2), air blood gases (ABGs) and ventilatory equivalent for VCO2 (VE/VCO2), could help diagnosing DB and ruling out concurrent pathology.

Since breathing retraining remains the main treatment of DB there is an urgent need for further treatment options. Pulmonary rehabilitation has been established as an essential and successful treatment in patients with diseases with high prevalence of DB such as Chronic Obstructive Pulmonary Disease (COPD) and asthma whereas the American Thoracic and European Respiratory Society urge for enhancing the implementation, usage, and Delivery of Pulmonary Rehabilitation in various diseases. We hypothesize that a rehabilitation program with integrated dynamic physiotherapy sessions guided by CPET will be more efficient in the treatment of DB patients than physiotherapy alone. The aim of the present study is to compare a rehabilitation program designed specifically for DB, utilizing CPET for diagnosis and treatment guidance, with breathing retraining alone.