Mechanically assisted breathing improved autonomic nervous system functions, according to a study of a small group of fibromyalgia (FM) patients.
The study, “The effects of slow-paced versus mechanically assisted breathing on autonomic function in fibromyalgia patients,” was published in the Journal of Pain Research.
FM often is associated with other symptoms beyond chronic pain, such as fatigue, sleep disorders and depression. Even though there is no treatment for FM, medicines such as analgesics, and activities such as exercise, can help in pain management and improving patients’ quality of life.
Previous studies suggested that breathing at a slower pace improved pain and other FM-associated symptoms. A pilot study of 12 FM patients indicated that a slower breathing rate coupled with heart rate variability (HRV) biofeedback — an activity by which patients are aware of the physiological parameters being measured, in this case HRV, and can train to control them — reduced pain severity and depression and improved overall functioning.
In the new study, researchers wanted to understand how controlled breathing techniques can induce alterations on the autonomic nervous system of FM patients, and relieve symptoms associated with chronic pain.
The autonomic nervous system controls the involuntary activity of internal organs such as heart rate, respiratory rate, digestion and sexual arousal. The parasympathetic nervous system is a branch of the autonomic system known as the “rest-and-digest,” responsible for conserving the body’s energy and resources at rest, whereas another branch, the sympathetic nervous system, controls a ”fight-or-flight” response, mobilized in times of stress or arousal.
Decreases in the sympathetic and increases in parasympathetic nervous system activity have been associated with the slow breathing-relieving effects over symptoms such as fear and anxiety that often are present in chronic pain syndromes. Besides, increased sympathetic nervous system activity has been correlated in some studies with pain intensity in FM patients.
To elucidate the role of respiratory rate on autonomic nervous system activity, the effects of normal, slow-paced and mechanically assisted breathing over HRV and spontaneous baroreceptor sensitivity (sBRS; a cardiac index) were assessed in FM patients. These parameters were chosen as non-invasive surrogates of autonomic nervous system functioning, in particular of the parasympathetic nervous system.
The study was based on a single visit assessment of 20 FM patients (mean age of 46.2 years) and 14 healthy subjects. Participants were examined by electrocardiogram (ECG), and their blood pressure and respiratory rate were measured in three breathing conditions — normal conditions, slow-paced breathing, and mechanically assisted breathing.
After being asked to breathe normally for 15 minutes, participants started the slow-paced breathing protocol, in which they had to breathe with the help of a visual metronome that indicated an inhalation period of five seconds and an exhalation period of equal duration, for a total of 15 minutes.
Next, patients underwent a mechanically assisted breathing protocol using a continuous positive airway pressure (C-PAP) machine set for the same respiration rate (six breaths per minute) as the slow-paced.
At the beginning, FM patients already had higher heart rates, but lower HRV and sBRS, compared with healthy participants, which could be interpreted as an increased sympathetic and a lower parasympathetic nervous system activity.
When subject to mechanical assisted breathing, FM patients had significantly lower heart rate swith higher HRV and sBRS, compared with slow-paced breathing, which reflected an increased activity of the parasympathetic nervous system and, potentially, a decrease in sympathetic nervous system activity.
Taken together, these results indicate that “mechanically assisted breathing provided a greater benefit in autonomic function than paced breathing in untrained FM patients,” the researchers wrote.
In healthy participants, these parameters were not affected between the different breathing conditions.
The reasons behind the different effects of slow-paced and mechanically assisted breathing cannot be related with differences in respiratory rate, which was kept the same for both techniques. The team speculated that slow-paced and mechanically assisted breathing activate distinct brain routes — cortical and hypothalamic, respectively — and that it is likely patients trained for slow-breathing also could activate the same pathways as mechanically assisted breathing.
“By understanding the mechanisms behind the therapeutic effects of slow-paced breathing, treatments can be refined and applied to other chronic pain conditions.” the researchers wrote, highlighting the study’s relevance. But they added that future research “will be needed to elucidate the central pathways involved in these autonomic changes and whether training in paced breathing can eventually replicate the results seen in mechanically assisted patients.”
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