Relationship of respiratory muscle strength, pulmonary function, and functional capacity with quality of life in patients with atrial fibrillation

Cut-off values of 6-min walk test and sit-to-stand test for determining symptom burden in atrial fibrillation

Background

Since symptomatology is a major predictor of quality of life and an endpoint for the management of atrial fibrillation (AF), practical approaches for objectively interpreting symptom burden and functional impairment are needed.

Aims

We aimed to provide cut-off values for two frequently used field tests to be able to objectively interpret symptom burden in atrial fibrillation.

Methods

One hundred twenty-five patients with AF were evaluated with European Heart Rhythm Association (EHRA) score, 6-min walk test (6MWT), 30 s sit-to-stand test (30 s-STST), Short-Form 36 (SF-36), International Physical Activity Questionnaire-Short Form (IPAQ-SF), and spirometry. Patients with EHRA 1 were classified as “asymptomatic”, and those with EHRA 2–4 as “symptomatic”. Cut-off values of 6MWT and 30 s-STST for discriminating between these patients were calculated.

Results

The optimal cut-off value was “450 m” for 6MWT (sensitivity: 0.71; specificity of 0.79) and “11 repetitions” for 30 s-STST (sensitivity 0.77; specificity of 0.70). Area under ROC curve was 0.75 for both tests (p < 0.001). Discriminative properties of the two tests were similar, and they were significantly correlated (r = 0.58; p < 0.001). Subgroup analysis revealed patients below cut-off values also had worse outcomes in SF-36, IPAQ-SF, and spirometry.

Conclusions

In patients with AF, walking < 450 m in 6MWT or performing < 11 repetitions in 30 s-STST indicates increased symptom burden, as well as impaired exercise capacity, quality of life, physical activity participation, and pulmonary function. These cut-off values may help identifying patients who may require adjustments in their routine treatment or who may benefit from additional rehabilitative approaches.

Mechanism of Dyspnea during Exercise in Children with Corrected Congenital Heart Disease

This study will evaluate cardiorespiratory and peripheral muscle function and their relationship with subjective dyspnea threshold after the surgical correction of congenital heart disease in children. Thirteen children with surgically repaired congenital heart disease were recruited. Each participant performed an incremental exercise test on a cycle ergometer until exhaustion. Gas exchanges were continuously sampled to measure the maximal aerobic parameters and ventilatory thresholds. The functional capacity of the subjects was assessed with a 6 min walk test. At the end of the exercise test, isokinetic Cybex Norm was used to evaluate the strength and endurance of the knee extensor muscle in the leg. Dyspnea was subjectively scored with a visual analog scale during the last 15 s of each exercise step. Oxygen consumption measured at the dyspnea score/VO₂ relationship located at the dyspnea threshold, at which dyspnea suddenly increased. Results: The maximal and submaximal values of the parameters describing the exercise and the peripheral muscular performances were: VO₂ Peak: 33.8 ± 8.9 mL·min^-1·kg^-1; HR: 174 ± 9 b·min^-1; VEmax: 65.68 ± 15.9 L·min^-1; P max: 117 ± 27 W; maximal voluntary isometric force MVIF: 120.8 ± 41.9 N/m; and time to exhaustion Tlim: 53 ± 21 s. Oxygen consumption measured at the dyspnea threshold was related to VO₂ Peak (R² = 0.74; p < 0.01), Tlim (R² = 0.78; p < 0.01), and the distance achieved during the 6MWT (R² = 0.57; p < 0.05). Compared to the theoretical maximal values for the power output, VO₂, and HR, the surgical correction did not repair the exercise performance. After the surgical correction of congenital heart disease, exercise performance was impeded by alterations of the cardiorespiratory function and peripheral local factors. A subjective evaluation of the dyspnea threshold is a reliable criterion that allows the prediction of exercise capacity in subjects suffering from congenital heart disease.

Influence of inspiratory muscle strength on exercise capacity before and after cardiac rehabilitation

Background/Aims

Coronary artery bypass grafting is a complex procedure that triggers a series of clinical and functional complications. The reduction of inspiratory muscle strength that persists during the late postoperative period has been suggested as an important determinant of functional capacity after coronary artery bypass grafting. The aim of this study was to investigate whether inspiratory muscle strength, functional capacity and quality of life are determinants of exercise capacity before and after a short-term phase II cardiac rehabilitation programme in patients who have had coronary artery bypass graft surgery.

Methods

A prospective quasi-experimental study was undertaken with 20 patients who had recevied coronary artery bypass surgery. All patients completed a short-term, moderate-to-high intensity inspiratory muscle training programme, followed by aerobic and resistance exercise, two times a week for 12 weeks, totalling 24 sessions, under the direct supervision of a physical therapist.

Results

Pre-intervention, peak oxygen consumption (peak VO2) was associated with maximum inspiratory pressure (β=0.037; 95% confidence interval 0.01–0.06; P=0.002). Post-intervention, peak VO2 was associated with maximum inspiratory pressure (β=0.03; 95% confidence interval 0.007–0.053; P=0.014) and the 6-Minute Walk Test (β=0.007; 95% confidence interval, 0.001–0.013; P=0.024).

Conclusions

Inspiratory muscle strength influences exercise capacity before and after a short-term cardiac rehabilitation programme in patients who have had coronary artery bypass graft surgery.

Anxiety and Depression Symptomatology Related to Inspiratory Muscle Strength and Functional Capacity in Preoperative Cardiac Surgery Patients: A Preliminary Cross-sectional Study

BACKGROUND

Poor psychological health and cardiorespiratory fitness prior to open heart surgery (OHS) might be predictors of postoperative pulmonary complications that lead to morbidity and mortality. Assessment of physical and psychological conditions should be considered for patients receiving OHS, to possibly prevent these complications. This study investigates how inspiratory muscle strength (IMS) and functional capacity (FC) relate to the psychological health of preoperative cardiac surgery patients.

METHOD

A cross-sectional study was designed before OHS; the 6-minute walk test and IMS were performed on patients who were admitted for OHS. All participants were requested to complete Hospital Anxiety and Depression Scale. Pearson correlation and hierarchal regression analysis were performed to determine the relationships between IMS and FC and psychological conditions (anxiety and depression).

RESULTS

Overall, 36 males and 28 females aged 56.89±10.23 years were recruited. Significant relationships were observed between IMS and anxiety and depression symptoms (r = -0.33 and r = -0.27, respectively). Anxiety was negatively related to FC (r = -0.25). These relationships remained significant after adjustment for age, sex, and body mass index (BMI) (∆R 2 = 0.11 and ∆R 2 = 0.09). In addition, anxiety was also related to FC after controlling for age, sex, and BMI (∆R 2 = 0.09).

CONCLUSION

Among patients undergoing OHS, those with a higher level of depression or anxiety had a lower cardiorespiratory fitness than those with a low level of depression or anxiety.

Maximal inspiratory pressure is associated with health-related quality of life and is a reliable method for evaluation of patients on hemodialysis

OBJECTIVE

To evaluate the association between Maximal Inspiratory Pressure (MIP) and health-related quality of life (HRQoL) and to verify the reliability of the MIP in patients on hemodialysis.

METHODS

In a repeated-measures design, patients on hemodialysis performed MIP and specific HRQoL questionnaire (trial 1). The MIP was repeated after 6 to 8 weeks (trial 2) and reliability was assessed using Intra-class Correlation Coefficient. Standard Error of Measurement and Minimal Detectable Change scores were calculated.

RESULTS

Sixty-one individuals (68.9% men) were evaluated in trial 1. MIP was associated with specific domains "Symptoms" (r = 0.45; R² adjusted = 0.192) and the kidney disease component summary (r = 0.38; R² adjusted = 0.138). Regarding generic domains, the MIP was associated with "Physical Functioning" (r = 0.57; R² adjusted = 0.375) and Physical component summary (r = 0.47; R² adjusted = 0.258). Thirty-three patients were randomly selected to perform a second MIP test (trial 2). The Intra-class Correlation Coefficient was 0.94 (95%CI 0.88-0.97). By Bland-Altman analysis, the bias was 3.2 cmH2O, which represents a difference of 3.7%. The Standard Error of Measurement and Minimal Detectable Change for MIP were 5.9 cmH2O and 13.8 cmH2O, respectively.

CONCLUSION

The MIP is a reliable test, associated with physical domains of HRQoL in patients on hemodialysis. Thus, it is a useful method for respiratory evaluation in this population.

Relationships between respiratory muscle strength, chest wall expansion, and functional capacity in healthy nonsmokers

Chest wall expansion determines lung volume and functional capacity. Factors determining chest wall expansion include respiratory muscle strength. Accordingly, there may be association among respiratory muscle strength, chest wall expansion, and functional capacity. Thusly, this cross-sectional study identified the relationship between respirato-ry muscle strength, chest wall expansion, and functional capacity. Seventy-six healthy male and female participants aged between 20 to 59 years exhibiting a body mass index of 18.5 to 22.9 kg/m² were enrolled. Inspiratory and expiratory muscle strength were evaluated via maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP), respectively. Chest wall expansion was measured through thoracic circumferences at three different levels; upper, middle, and lower levels with diaphragmatic movement also measured utilizing the circumference of the lower edge of the 10th rib. Functional capacity was evaluated through distance obtained from a 6-min walk test. Results showed that both MIP and MEP were significantly correlated with chest wall expansion at the middle (P=0.005 and P=0.006) and lower (P=0.012 and P=0.020) thoracic levels as well as diaphragmatic movement (both P<0.001). Moreover, both MIP and MEP were significantly related amid the 6-min walk distance (P=0.025 and P<0.001). In conclusion, respiratory muscle strength is positively associated with chest wall expansion, diaphragmatic movement, and functional capacity in healthy participants.