Biofeedback is a technique used to improve the ability to modify involuntary processes consciously. It is frequently used for symptom management in chronic illness and as part of physical therapy for patients with motor dysfunction. The general strategy to biofeedback starts with utilizing non-invasive equipment to take measurements of a chosen physical parameter. The measured parameter is then either displayed directly or transformed into a visual, auditory, or tactile feedback signal. The patient will then practice controlling the feedback signal by consciously adjusting the physical parameter. Because the technique provides another form of feedback in addition to the body’s intrinsic sensory nervous system, it is sometimes called augmented feedback or extrinsic feedback.
Biofeedback divides into two major groups, biomechanical and physiologic, based on the parameter of interest. Biomechanical techniques measure body activity and movement using simple inertial sensors or more complex video motion sensors. Several different modalities serve to measure physiologic activity. Muscle activity measured by electromyography is one of the most common, but other options are cardiac activity measured by heart rate and heart rate variability, breathing activity measured by respiratory rate and depth, and electrodermal activity measured by skin conductance. Forms of biofeedback have been in use in physical therapy for more than 50 years, where it is beneficial in the management of neuromuscular disorders. Biofeedback techniques have shown benefit when used as part of a physical therapy program for people with motor weakness or dysfunction after stroke, after orthopedic surgery, or due to other neuromuscular diseases. These methods are getting better at training for complex task-oriented activities like walking and grasping objects as technology continues to advance.
Aside from neuromuscular retraining, the most common use for biofeedback is to help with chronic symptom management due to anxiety, pain, and urinary and fecal incontinence. These techniques focus on managing the overactive sympathetic response and coordinating muscle activity in gastrointestinal and genitourinary tracts.
Biofeedback techniques are generally regarded as safe and free of side effects. For this reason, they are incorporated into treatment plans despite lacking strong evidence to support their benefits.
Clinicians may use biofeedback to control global physiologic reactions or specific muscle actions. Frequently targeted muscle groups are in the upper and lower limbs and the muscles used in gait. Muscles controlled by the autonomic nervous system, such as digestion, defecation, and urination, are also commonly selected . For urinary incontinence, pelvic floor muscles are the target, while in fecal incontinence, it focuses on the external anal sphincter. Biofeedback also has non-musculoskeletal targets such as anxiety and stress reduction. Biofeedback has also seen use in controlling the vasculature to reduce vasoconstriction, as well.
CLinicians can incorporate biofeedback techniques into the overall treatment plan for a wide variety of conditions. It is frequently used to manage stress and anxiety, either if they are the primary illness or due to another cause. There is specific evidence that exists to support the use of biofeedback for specific ailments, including the following:
Biofeedback does not have any absolute contraindications. It may be used for any age population and has general acceptance as a safe procedure.
The patient must be able to play an active participatory role, so it may not be an apt procedure if the patient cannot comprehend and follow commands. It is also not suitable in cases of complete paralysis. Biofeedback may not be used as the sole treatment for severe hypertension and should be used with caution in acute psychiatric patients .
Biofeedback techniques can divide into two main groups based on the type of action they aim to control – physiologic or biomechanical. Each type requires specific equipment to measure the sensory parameter, transform to feedback, and display the results.
Physiologic biofeedback uses electromyography to measure muscle activity. The autonomic activity can be monitored through measurements of heart rate, respiratory rate and depth, and electrodermal activity. Electroencephalography is possible but less frequently used.
Biomechanical feedback parameters describe movement and spatial orientation. They are measured with inertial motion detectors (e.g., accelerometer or gyroscope), force plate sensors, and real-time ultrasound. Endoscopy has been used successfully used but is not a common strategy.
The information from the sensors is processed and transformed into the returned feedback, which may be visual (changing graphics display or pattern), auditory (varying tone or music volume), or haptic (vibrating wearable device).
Virtual reality uses wearable motion detector sensors and more extensive processing and display equipment. Virtual reality can help create interactive games that incorporate rehabilitation mechanics, which is especially beneficial for pediatric patients. This technology can be used to increase patient engagement (especially in the pediatric population), motivation, and improve overall outcomes.
Skilled physical therapists are vital to the proper use of biofeedback therapies. Experienced technicians are also necessary for several other modalities, including EEG, skin conductance, and ultrasound. Biofeedback technicians and clinical certificants are providers that have been certified by the Association for Applied Psychophysiology and Biofeedback (AAPB) to use biofeedback therapy. Finally, the patient's supervising physician is instrumental in determining the overall progress of the patient and coordinating the other therapies that the patient is receiving to maximize their progress.
Successful biofeedback training requires a great deal of motivation and participation. The individual must be able to communicate and to comprehend and follow through with instructions. The proper modality must be chosen for the correct indication. For example, electromyography biofeedback is more commonly used for musculoskeletal conditions, while real-time ultrasound biofeedback can be used for pelvic floor dysfunction. For headaches, blood volume pulse feedback has been shown to have the most evidence for reducing headache severity and frequency. For each modality, sensors will be attached to the patient in different areas depending on the indication.
This process is essentially a form of operant conditioning with positive feedback for performing the desired action or behavior and negative feedback for not doing so. The first step is to choose the best modality and establish the baseline parameter. The next step is to learn to control the parameter and to practice until the action has become embedded into memory. An example of this is the use of biofeedback for hypertension. In thermal biofeedback, a temperature probe is attached to a patient's finger or toe and is instructed to increase or decrease the temperature in response to the feedback. Warming a digit involves decreasing sympathetic vasoconstrictive tone to that digit and thus increasing blood flow. The overall goal is that this training can help systemically to decrease neural-mediated vasoconstriction and thus decrease the total peripheral resistance leading to a decrease in blood pressure. Another common use of biofeedback is for urinary incontinence and enuresis in children. Electrodes get placed near the anus and on the leg, and a urotherapist teaches the child pelvic floor exercises. A video game incorporates these exercises where the child plays as a caterpillar and is instructed to contract their pelvic floor muscles to avoid obstacles. The child is also then taught to continue these exercises at home, with the hope of improving pelvic floor strength and decreasing urinary incontinence.
Biofeedback is a very safe and well-tolerated procedure that has minimal complications. If biofeedback is used at all times during therapy, there may be a drop in the performance following its discontinuation. It is, therefore, beneficial to practice the same techniques without the biofeedback equipment as part of the overall treatment for sustained improvement. If the patient does not practice the techniques often, then the treatment can have less than intended results over time and may require retraining.
Biofeedback techniques can potentially provide symptom relief and improve quality of life while also being safe and free of significant side effects. The methods allow patients to have some control over their disease, which is valuable in maintaining patient self-efficacy and overall well-being. With enough training sessions, patients can make changes that will last without the use of these instruments. Biofeedback can potentially also reduce the amount of medication a patient is taking, which can help patients avoid the problem of polypharmacy and limit side effects from other drugs.
Biofeedback techniques are suggested for symptom management for chronic pain, fatigue, and insomnia, but they are best as one part of a more extensive rehabilitation plan. Benefits vary between individuals, and results occur more often seen if used with some combination of cognitive-behavioral therapy, physical therapy, and other relaxation techniques. There have been several smaller studies and systemic reviews on biofeedback measures, but results are conflicting and likely subject to publication bias. Some of the studies had poor randomization or compared to a control of no treatment rather than standard physical therapy. More long-term studies are necessary to see if the positive outcomes are maintainable over time. An interprofessional team, including primary care providers, pain specialists, neurologists, physical therapists, and specialty-trained psychiatric health nurses who can assist the clinician and track results, can maximize the benefits of these procedures. Nurses and therapists educate patients, monitor response to biofeedback, and inform the team about patient progress. There must also be open avenues of communication between the multiple potential clinicians on a case. A functioning interprofessional team will lead to better outcomes with biofeedback. [Level 5]
Symptoms of anxiety or abnormalities in gait are often first notified by nurses. It can be very beneficial for them to know when biofeedback is beneficial and when it may be offered as a supplemental treatment. There are many indications where biofeedback can help in the care of a patient, so nurses should be aware of presenting symptoms and consider its use. In some states, certain providers such as psychologists may not be able to physically touch their patients to apply sensors and may require a health care provider such as a nurse to act as a chaperone or apply the sensors. Nurses can also provide education to patients about their current medical condition. For instance, a patient with urinary incontinence may receive information from nurses about reducing accidents by having scheduled voiding times.
During ongoing biofeedback therapy, primary monitoring is for fatigue, which can be exacerbated by ongoing treatment. Depending on the modality, nurses check for discomfort that some patients may experience, such as in some forms of fecal incontinence where probes and balloons are inserted into the rectum to stimulate defecation. Nurses also observe for complications such as reactions to sensor tape.
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