Objectives: To evaluate regional lung ventilation distribution in patients suffering from chronic heart failure (CHF) after completing inspiratory muscle training (IMT) and correlate it with functional capacity and quality of life among these individuals. Methods and Results: Nineteen CHF patients were randomly assigned to two groups: Control and IMT. Before and after muscle training, subjects were submitted to assessment protocol for respiratory muscles, digital spirometry, optoelectronic plethysmography (OEP), the six-minute walk test (6MWT) and a quality of life questionnaire (MLHFQ). There was no difference in lung function following the 12-week training period in either group. However, the IMT group showed an increase in actual and predicted MIP, higher MLFHQ score and greater distance walked in the 6MWT, as well as a reduction in the Borg scale after the 6 MWT in relation to the control. For the OEP, IMT group members exhibited higher values for total chest wall volume (Vcw), abdominal rib cage volume (Vrc,a) and abdominal volume (Vab) when compared to the control. Conclusions: For patients with CHF, IMT proved efficient in improving muscle strength, functional capacity and quality of life. The present study also analyzed the distribution behavior of lung volumes for the thoracoabdominal system in this population, showing that larger abdominal rib cage and abdomen volumes may result in more effective diaphragmatic contraction.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
19
All participants were instructed to use a Threshold® trainer for 30min a day, seven times a week over 12 consecutive weeks.10 Patients in the Control Group used a Threshold ® device without resistance, making them blind to the treatment. For the treatment group, inspiratory resistance of the Threshold® trainer was 30% of MIP, adjusted on a weekly basis to remain constant.
Patients from the control group were also assessed weekly to ensure homogenization of the learning effect for the manometer maneuver.
Departamento de Fisioterapia-Universidade Federal de pernambuco
Recife, Pernambuco, Brazil
Respiratory muscles
In order to evaluate inspiratory muscle strength, a digital manometer was used (MVD-300, Globalmed, Brazil) connected to a mouthpiece with a 2mm opening to reduce the influence of pressure caused by glottal closure. In a sitting position, each patient performed up to six maneuvers to obtain MIP, from residual volume (RV) to total functional capacity (TFC), considering the best of three maneuvers with \< 10% variation between them
Time frame: 3 months
Assessment of respiratory mechanics by Optoelectronic Plethysmography
The optoelectronic plethysmography system (OEP) of BTS Bioengineering (Italy) was employed in this study. To that end, a calibration instrument was used, containing three axes connected to reflective markers. This phase does not require participation by the individual to be examined. This creates a three-dimensional model, dividing the thoracoabdominal system into three parts: pulmonary rib cage (RCp), abdominal rib cage (RCa) and the abdomen (AB).
Time frame: 3 months
Evaluation of submaximal functional capacity
Functional capacity was assessed by the six-minute walk test (6MWT), according to the protocol published by the American Thoracic Society (ATS).
Time frame: 3 mounths
Quality of Life Questionnaire: Minnesota Living With Heart Failure Questionnaire (MLHFQ)
The MLHFQ is a questionnaire validated for the Brazilian population, consisting of 21 questions regarding limitations frequently associated with the extent to which heart failure has affected patient's lives in the previous month. Each question is attributed a value from 0 (zero) to 5 (five), with the highest score indicating worse quality of life. The total score is calculated by adding the 21 items, with a possible interval between 0 and 105.
Time frame: 3 months
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