DISCUSSION
Based on the findings, it can be suggested that the increase in
inspiratory muscle strength, through inspiratory muscle training, was
associated with decreased levels of cardiac anxiety in patients
undergoing myocardial revascularization.
Anxiety and depression are interdependent variables and several studies
have already shown a reduction in the intensity of these conditions in
patients undergoing cardiac surgery exposed to physical
exercise5,12,13. However, no studies were found to
determine the impact of inspiratory muscle training on cardiac anxiety
in this population.
A possible explanation for this result is the increase in levels of the
brain-derived neurotrophic factor (FNDC), mainly in the hippocampus
region14. The FNDC is of fundamental importance for
the learning and consolidation of memory, which in turn, are responsible
for the long-term effects of environmental stimuli as stressful life
events15. Broman-Fulks and collaborators demonstrated
a decrease in the self-reported feeling of fear or anxiety in patients
undergoing an aerobic exercise program16.
Based on the results found in our study, it can be associated that
inspiratory resistance training has the same effect on the FNDC protein,
providing a behavioral change in these patients.
Another possibility for reducing anxiety is the increase in cerebral
neurogenesis, which can be obtained through physical exercise. To
achieve this change in brain structure, some conditions are associated,
such as: increased endorphin B, vascular endothelial growth factor, FNDC
and serotonin14.
In addition, Bettencourt and collaborators report that the ability to
exercise has a direct influence on anxiety and
depression17. The greater the capacity to perform
activities, the lower the cardiac anxiety. Patients undergoing
cardiothoracic surgery tend to have reduced physical capacity in the
postoperative period8,9 and that IMT is a tool to
increase functional capacity. Thus, the reduction in anxiety found in
our study may have been influenced by the increase in functional
capacity secondary to muscle training.
Tamuleviciute-Prasciene et al.18 concluded in their
literature review that physical exercise enhances clinical and
functional outcomes such as increased strength and muscle mass,
mobility, cognition, activities of daily living and reduced anxiety.
Most of these studies address aerobic exercises as part of phase I
rehabilitation, in our study we increased the protocol with the IMT,
achieving encouraging results.
During IMT there is a reduction in the diaphragmatic metaborreflex,
generating a greater blood supply to appendicular muscles, thus
improving performance in activities13,19, increasing
the self-esteem of these patients, causing a reduction in cardiac
anxiety.
A study entitled EUROASPIRE III demonstrated that regular physical
exercise is associated with decreased levels of anxiety and depression
in patients with coronary artery disease20. A similar
result was found by Zheng and collaborators, but in patients after acute
myocardial infarction21.
Pain related to the presence of drains and surgical incision leading to
the avoidance of certain activities such as coughing, taking deep
breaths and physical activity22, can generate a
reduction in ventilatory muscle strength, thus increasing cardiac
anxiety.
Another form of anxiety control resides in the pre and postoperative
guidelines. It is based on the possibility of informing the patient what
will happen during the entire operative period that extends from
hospital admission to discharge home. These guidelines, in addition to
reducing anxiety, are linked to improved quality of life, self-report,
functional capacity and postoperative
complications6,7. Orienting and making the patient
aware of the need and benefits of inspiratory muscle training is of
fundamental importance. Orienting and making the patient aware of the
need and benefits of inspiratory muscle training is of fundamental
importance.
According to our knowledge, this is the first study that correlates the
direct impact of IMT on cardiac anxiety in patients undergoing CABG,
therefore, we cannot consider that training was the main contributor to
reducing the outcome variable.
Some limitations can be pointed out: (1) lack of sample calculation; (2)
non-stratification for risk factors such as age, surgical risk and
comorbidities; (3) not applying a pain scale, although all patients have
protocol-guided analgesia.