Abstract
Objective:
The extant pediatric biofeedback literature has several shortcomings, including small sample sizes, inconsistent methodology, and variable means to determine outcomes. The purpose of the current study was to build upon the existing literature and examine the feasibility of a brief, semi-structured, biofeedback intervention with a larger outpatient pediatric sample.
Methods:
Via chart review, we explored 2 years of referrals (N = 79) to our biofeedback program. We examined feasibility in terms of recruitment, program completion, and patient/caregiver satisfaction. Secondary aims included examination of changes in physiological and self-report data.
Results:
Seventy-three percent of referrals to the biofeedback program attended a first session, with 67% of those that attended a first session completing the program. The majority of patients who completed the program (N = 39, Mage = 13.4 years, 69% female) were referred for anxiety as their presenting problem. Both patients and parents were found to be highly satisfied with the program. By the end of treatment, almost all youth were able to demonstrate a lower respiration rate, accompanied by both improvements in heart rate variability (HRV) indices and self-reported somatic symptoms. The majority of patients, however, did not achieve the goal of a respiration rate lower than 8.0 breaths per minute.
Conclusions:
The current study demonstrated that a brief, semi-structured biofeedback protocol was feasible in terms of recruitment, retention, and satisfaction with an outpatient pediatric sample. Moreover, youth who completed the program demonstrated improvements as evidenced by physiological and self-report indices.
Implications for Impact Statement
This work holds important implications for pediatric psychology care, including that a brief psychology trainee-delivered, semi-structured biofeedback program was found to be feasible and acceptable to patients and families delivered in an outpatient setting. The program was found to be acceptable by participants with diverse diagnoses (e.g., anxiety and pain-related disorders). The current study contributes to the pediatric biofeedback literature by providing further direction around both implementation and outcome measurement in pediatric biofeedback.
While there are variations on the definition of biofeedback, the cornerstone of biofeedback involves instruction in self-regulation, and the use of sensors, instrumentation, and biofeedback software to provide information about physiological functioning in real time to the individual. Over time, the individual can develop mastery of the self-regulation strategy, self-regulate without use of the equipment, and with the accompanying reduction in sympathetic nervous system activity, the individual may experience mental and physical health benefits (Peper et al., 2008). The incorporation of biofeedback into pediatric health care has great potential, especially with significant developments in biofeedback technology that include availability, intuitive ease of use, and engaging software. In fact, in their survey of mental health providers, Benore & Banez (2013) found that three quarters of respondents were using biofeedback in various forms with pediatric populations. However, among those using biofeedback clinically, 59% reported only sometimes or rarely/never using a specific protocol, and 39% noted they either never or were unsure if they were following evidence-based practice.
The findings of the survey highlight the need for further study into the current state of clinical biofeedback research in pediatrics, as well as the existence of supported protocols available to practitioners working with youth. In adults, biofeedback has been shown to be an effective and efficacious treatment for many specific disorders including anxiety, hypertension, headache, and irritable bowel syndrome (Tan et al., 2016). A recent meta-analysis of existing biofeedback treatment studies in pediatrics found that biofeedback has a large and positive effect for a wide variety of pediatric conditions (Darling et al., 2019). Even so, several challenges were identified in the studies examined, including small sample sizes and wide variation in the protocols, modalities, and outcome measures employed. Additionally, many studies relied on self-report outcome measures with little examination of any physiological changes that may occur during the protocol. Taken together, it is not surprising that a majority of providers in the aforementioned survey were not following evidence-based protocols in their application of biofeedback to pediatric populations.
To address some of these issues, Fahrenkamp and Benore (2019) investigated physiological changes in a small sample (N = 4) of adolescents (ages 15–17) in a 3-week pain rehabilitation program who completed a semi-structured biofeedback training protocol. The protocol was 4–5 sessions in length and comprised an initial physiological stress assessment, instruction in respiration training, accompanying heart rate variability (HRV) biofeedback training, and generalization of skills. The study resulted in several important findings. First, within a brief, semi-structured protocol of 4–5 sessions, adolescents were able to demonstrate a decrease in respiration rate from baseline (i.e., their initial physiological assessment) to various assessment points during their training. Second, accompanying this change in respiration was an anticipated increase in HRV, a proxy variable for autonomic nervous system functioning. The authors suggested that future research into biofeedback treatment protocols should involve assessment of both physiological changes (e.g., respiration, HRV) as well as treatment outcome measures (e.g., changes in symptoms, patient functioning) and that protocols should be examined with a larger sample to better understand the generalizability of their findings.
The current study aimed to expand upon the findings and recommendations by Fahrenkamp and Benore (2019) by examining the feasibility of a similar 4–5 session semi-structured HRV biofeedback protocol with a larger pediatric sample. Heart rate variability biofeedback examines the fluctuation in the time intervals between adjacent heartbeats as a proxy variable for autonomic nervous system functioning, with increases in HRV suggestive of activation of the vagal baroreceptor reflex (Shaffer & Ginsberg, 2017). This increase in HRV is thought to be related to a reduction in sympathetic nervous system arousal. Training in HRV biofeedback first involves training in respiration (Lehrer & Gevirtz, 2014), a common element in many biofeedback and general stress management protocols.
Hilliard et al. (2021) recently delineated the purpose of a feasibility study as determining acceptability and satisfaction with an intervention and potentially examining some outcomes of interest as a secondary aim. Following their recommendations, the current study utilized these benchmarks and described acceptability and satisfaction with the current intervention in terms of (a) recruitment, (b) program completion, and (c) patient and family satisfaction. As secondary aims, the study examined both physiological data and self-report of somatic complaints as initial indications of treatment efficacy.
Method
Procedures
The current study was a retrospective chart review of the electronic medical records (EMR) of all referrals to the biofeedback program over the course of two training years (August 2019–July 2021). The biofeedback program only accepts referrals from within our Psychology department, due to the small size of the program. Referrals included youth already involved in mental health treatment, as well as those who were seen only for an initial consultation by a mental health provider and then referred to the program as a targeted intervention for the presenting issue (i.e., no concurrent mental health treatment). Deidentified information obtained from the EMR included age, gender, insurance type, reason for referral, number of sessions completed, and physiological indices from training sessions, outlined below. Participants completed a measure of somatic symptom severity. At the end of Session 4, participants completed the same measure of somatic symptoms, and both the parent and the participant completed the satisfaction questionnaires. All of these scores were obtained from the chart review as well. This retrospective chart review was reviewed by the institutional review board and received an exempt determination based on the secondary use of existing data acquired through clinical activities. The IRB also granted a waiver of the requirement for obtaining consent, permission, and assent.
Biofeedback Program Overview
The biofeedback program was designed to provide a brief, semi-structured treatment with a focus on teaching self-regulation for children ages 9 and older with a wide array of presenting concerns. The current protocol only was used in children aged 10 and older due to the attentional capacity needed to take part in the current protocol, with sessions typically around 50 min long (Culbert et al., 1996). Program training objectives included the following: (a) understanding the connection between autonomic nervous system functioning and the presenting problem/symptoms, (b) learning effortless breathing (often referred to as diaphragmatic breathing) as a strategy by which to improve self-regulation, (c) utilizing biofeedback to train and reinforce the self-regulation skill, and (d) ultimately no longer requiring the feedback to achieve self-regulation. Biofeedback sessions were recommended to occur weekly, with flexibility offered as needed to accommodate each family's schedule. Each of the four training sessions (45–60 min) was conducted with a parent present to facilitate parent knowledge of the treatment approach and to encourage parent participation in treatment and home practice assignments.
Biofeedback training sessions were provided by psychology trainees under the supervision of a licensed psychologist who is board certified in biofeedback. As part of their training in the program, providers learned how to utilize three biofeedback systems, described below.
Nexus-10 MKII Hardware/Biotrace+ Software (Mind Media, Herten, the Netherlands)
The Nexus-10 MKII is a comprehensive biofeedback system that allows for the measurement of several physiological signals simultaneously. In the current program, the physiological profile was conducted using sensors to measure respiration (via strain gauge), skin temperature (via temperature sensor), skin conductance (via skin conductance sensor and pregelled silver chloride monitoring electrodes), and heart rate (via blood volume pulse [BVP] sensor).
ProComp Infiniti System/BioGraph Infiniti Software, V. 6.7.1 (Thought Technology, Ltd, Montreal, Canada)
The ProComp Infiniti system also is a comprehensive system that measures the same physiological signals as the Nexus-10 MKII and uses the same sensor types and electrodes. In addition, both systems have similar protocolized physiological profiles and identical parameters for HRV frequencies (e.g., low frequency [LF] as 0.04–0.15 Hz).
Alive (Somatic Vision, Encinitas, CA, USA)
Alive utilizes two sensors—a BVP photoplethysmograph placed on the nondominant middle finger and two sensors to measure skin conductivity (each placed on the forefinger and ring finger of the same hand). Alive software was selected due to the user-friendly nature of the software and engaging games and graphics. In the biofeedback program, Alive was utilized for HRV training to demonstrate the connection between respiration and physiological change.
Session 1
During the first session, the participant's presenting concerns were reviewed and discussed in the context of autonomic nervous system functioning. Psychoeducation about biofeedback as a treatment modality was provided, and the goal of learning a self-regulation skill was reviewed. If the participant was involved in concurrent outpatient therapy, the connection was made between self-regulation and the participant's existing therapy goals. The participant then took part in a protocolized physiological profile utilizing one of the comprehensive biofeedback systems (i.e., Nexus-10 MKII or ProComp Infiniti). On both systems, the preprogrammed scripted physiological profile was 14 min in duration, with seven segments that included an initial 2-min baseline (Time 1), 2-min stressors (Stroop task, counting backward by 7's, talking about a stressful experience) separated by 2-min periods of recovery, and a final 2-min post-baseline.
Session 2
In Session 2, the provider reviewed the physiological profile data with the participant and parent and provided impressions about the participant's respiration rate and style, response to stressors across modalities (e.g., respiration rate, skin conductance), and ability to recover poststressor. Participants were then provided instruction in and practice of effortless respiration using one of the comprehensive biofeedback systems. The effortless breathing technique is an abdominally-focused, even breathing pattern, with brief 1-second “holds” upon both inhalation and exhalation. Respiration was trained at 8 breaths per minute (BPMs). While 6 BPM may be ideal in adults (Lehrer et al., 2000), clinical experience has shown this to be a challenging goal for youth, perhaps due to a somewhat higher natural respiration rate in children under 13 (Khazan, 2019). As such, part of the feasibility aspect of the current study included the determination of how participants trained at 8 BPM would fare regarding their ability to achieve this respiration goal. After learning effortless breathing and practicing with a respiration metronome, participants were instructed on the use of a home respiration metronome via apps recommended by providers (e.g., Calm) set to 8 BPM and were requested to practice respiration for a minimum of 3 min each day between sessions. Data on adherence to home practice were not collected.
Session 3
Session 3 involved a review of progress with home practice with discussion and problem-solving of barriers to practice as needed. This was followed by further respiration training and coaching utilizing either comprehensive biofeedback system, utilizing a strain gauge around the abdomen and visual feedback from the computer. Participants were provided with feedback and coaching regarding their respiration, including timing (e.g., breaths per minute) and form (e.g., abdominal vs. thoracic, including brief 1-second “holds” upon inhalation and exhalation).
Participants were then introduced to HRV biofeedback via the Alive software suite. Participants began their training on the “easy” level for initial instruction and then graduated to higher levels of difficulty based on progress. As the current protocol was not designed as a research study, no specific parameters were determined regarding when to move a participant to a more challenging level. Participants were asked to continue to practice respiration with their respiration app for a minimum of 3 min per day every day between sessions.
Session 4
In Session 4, respiration and HRV training via Alive continued with gradual withdrawal of supports such as the respiration metronome. The use of this new self-regulation skill was discussed as it relates to both real-life situations and ongoing therapy goals (as appropriate). Two posttreatment physiological measurements were then obtained utilizing either the Nexus-10 MKII or ProComp Infiniti. The measurements included 2 min of “normal” breathing (Time 2) followed by 2 min of the participant demonstrating their new respiration skill, with no metronome support or feedback (Time 3). The two distinct posttreatment measurements were collected with a specific rationale in mind. Time 2 or “normal” breathing was measured to determine if any changes had occurred to the individual's “normal” baseline respiration over the course of treatment. Time 3 (“new respiration skill”) was measured to determine the degree of success in achieving the desired respiration rate, as well as any associated physiological changes (via HRV).
Participants completed the measure of somatic symptoms once again at the end of the session. In addition, both the participant and parent completed a brief measure of satisfaction with the biofeedback program. One or two follow-up or booster sessions were offered to families, with the purpose being further practice opportunities to develop the participant's respiration/self-regulation skill.
Measures
Physiological Data
Respiration Rate
Respiration rate was monitored by use of a strain gauge around the abdomen and reported in mean BPMs. Participants were trained to breathe at a rate of 8 BPM. As described earlier, biofeedback research with adults has determined that a respiration rate (also referred to as the “resonant frequency” or “RF” rate) between 4.5 and 7 BPM is ideal in increasing HRV. However, the same has not been determined for pediatric populations, with some suggestions that the RF respiration rate may be somewhat higher (Khazan, 2019). As training youth to breathe slowly can be a challenge clinically, our program selected 8.0 BPM as a training goal so that we could explore success with training at this rate, but also examine accompanying physiological change.
Heart Rate Variability
HRV was monitored via a BVP photoplethysmograph placed on the middle finger of either hand. Initially, our program collected a 5-min sample of respiration and HRV at three measurement time points—in Session 1 immediately preceding the physiological profile, and twice at the end of Session 4. However, in clinical practice, these baselines were perceived as quite long and challenging for youth to complete, especially when immediately followed by the 14-min preprogrammed physiological profile (which begins with another 2-min baseline). Due to this, our program changed from 5-min samples to 2-min samples. In addition, at Time 1, rather than collecting a separate 2-min baseline followed immediately by another 2-min baseline as part of the physiological profile protocol, we decided to utilize the 2-min baseline data from the physiological protocol itself. Shaffer and Ginsberg (2017) indicated there likely is little meaningful difference between 5-min and 2-min “ultra-short-term” samples. To verify this in our sample, we compared the 5-min baseline data (i.e., mean respiration rate and HRV data) to the 2-min baseline data pulled from the physiological profile for the same patient. The two baselines were found to correlate highly and to a statistically significant degree, with respiration data correlating at 0.66 (p < .005) and HRV data at 0.59 (p < .05). While perhaps not ideal, we felt confident combining this data for analyses, with 21 participants completing 2-min samples and 18 completing 5-min samples.
At each of the three time points, two physiological indices were captured–the participant's mean respiration rate and an index of HRV (low-frequency percentage or LF%). There is little agreement among pediatric biofeedback researchers or providers as to the best metrics with which to examine changes in HRV (Shaffer & Ginsberg, 2017). One manner of describing HRV data is by examining frequency domain measurements from the HRV signal. LF reflects the sympathetic and parasympathetic influences on cardiac functioning, with increases in the LF signal suggestive of an increase in parasympathetic activity. Low-frequency percentage (LF%) refers to the percentage of LF signal during the specific sample (e.g., 2 min). In addition to considering the theoretical underpinnings of these indices (i.e., respiration rate and LF%) the current metrics were selected due to their demonstrated utility in other studies (e.g., Feldman et al., 2016; Fahrenkamp & Benore, 2019).
Parent and Participant Satisfaction
The Biofeedback Program Satisfaction Questionnaire (BPSQ) was developed specifically by the authors of this study to obtain data on the most relevant aspects of satisfaction with the current program. The four questions inquired about the following domains (a) global satisfaction with the biofeedback program, (b) to what degree the program helped with the main presenting issue (written in for the respondent), (c) level of confidence that the self-regulation skill would be used, and (d) if the respondent would refer others with similar presenting problems. Participants responded via a 4-point Likert scale format which read “1 = No, definitely not, 2 = No, not really, 3 = Yes, generally, and 4 = Yes, definitely.” Higher scores were suggestive of higher positivity and satisfaction in that domain.
The questionnaire was given to both the participant and one parent at the end of the final session at the conclusion of the program (i.e., session 4, 5, or 6). Families were informed that the questionnaires were confidential, and that information would not be reviewed by their provider. Questionnaires were marked with an identification number, and once completed, were placed in a sealed envelope and delivered to the program director. Participants and parents were asked to wait to complete the questionnaire until after the provider had left the room to promote honest feedback from families.
Somatic Symptoms
The Children's Somatic Symptoms Inventory—24 (CSSI-24; Walker et al., 2009) is a 24-item self-report of somatic complaints. Each item is accompanied by a 5-item Likert scale response, describing the intensity of each symptom over the past 2 weeks, ranging from 0 (Not at all) to 4 (A Whole Lot), with total raw scores ranging from 0 to 96. The CSSI-24 possesses strong internal consistency and validity (Lavigne et al., 2012). Stone et al. (2019) demonstrated clinically useful cut-off scores for the total score, with 0–18 suggestive symptoms that are low, 19–31 as moderate, and ≥32 as high. This measure was completed by participants at the start of Session 1 and after the completion of Session 4.
Statistical Analyses
Descriptive data analyses were performed with SPSS Statistics, Version 27. Regarding secondary aims, several analyses were conducted. First, the percentage of participants who were able to demonstrate a respiration rate of 8.0 BPM or less with no feedback (Time 3) was calculated. Paired t-tests were used to evaluate changes in mean respiration rate and accompanying changes in physiological functioning. Comparisons were made between pretreatment baseline (Time 1) physiological data and posttreatment (Time 2 and Time 3) physiological data (i.e., mean respiration rate and LF%). Paired t-tests were used to examine changes in somatic symptoms pre- and posttreatment.
Results
Primary Aims: Acceptability and Satisfaction
Participant Recruitment
An initial review captured all referrals to the biofeedback program over the course of two training years. There were 79 referrals to the biofeedback program over the 2-year period. Twenty-one of these referrals (27%) did not schedule a first session. Fifty-eight referrals came to at least one session, resulting in a recruitment rate of 73%. Nineteen attended at least one session but did not complete the program (i.e., attend four or five sessions), resulting in a drop-out rate of 33%. Independent samples t-tests were used to compare referrals who did not attend a first session with those who completed the program. No differences were identified for age, race, ethnicity, gender, or insurance type (e.g., private, public) between the samples, p > .05. Independent samples t-tests were used to compare participants who were referred and attended at least one session and those who completed the program. These samples also did not differ on any of the sociodemographic variables listed above, p > .05.
Program Completion
Demographic Information for Participants Who Completed the Biofeedback Program
Program Satisfaction
Program Satisfaction as Reported by Participants and Their Parents on the Biofeedback Program Satisfaction Questionnaire (BPSQ)
Note. Response range is 1–4 for each question.
Secondary Aims: Psychophysiological Data and Somatic Complaints
Measure Scores and Psychophysiological Outcomes
Note. CSSI-24 scores range from 0 to 96 with higher scores indicating greater somatic complaints. Time 1 refers to data collected at the preintervention session. Time 2 refers to data collected at the postintervention session when participants were recorded without instruction. Time 3 refers to data collected at the postintervention session when participants were instructed to use effortless breathing skills learned during the biofeedback program.
Secondary Outcomes Analysis of Psychophysiological Data and Reported Somatic Complaints
Discussion
Evaluation of the application of biofeedback in the pediatric literature has revealed several challenges, including small sample sizes, few protocolized interventions with empirical support, and reliance upon self-report data of symptom improvement. The current study sought to determine the feasibility of a brief, semi-structured protocolized biofeedback intervention to be used with an outpatient pediatric population. In addition to investigating acceptability and satisfaction with the protocol, the study examined initial indicators of treatment efficacy such as physiological data and self-report of somatic complaints.
Results suggest that the current protocol is feasible in several ways. Regarding recruitment, a majority of participants (73%) referred to the biofeedback program attended a first visit. Of the 58 participants who attended a first visit, 39 (67%) completed the program by attending four or more visits. Across parents and participants who completed the treatment, satisfaction ratings were strong. Ratings indicated that both parents and participants found the skills taught to be beneficial in improving their presenting issue, felt confident that they would be able to use the skills outside of the therapy milieu, and would recommend the program to others with similar challenges.
Secondary aims of the current study sought to determine if physiological changes (e.g., slower respiration, increases in LF%) or changes in self-report of somatic symptoms were observable, as would be anticipated. Participants were trained to a respiration rate of 8 breaths per minute. This rate was practiced during biofeedback training sessions and recommended for daily home practice utilizing a respiration app on a personal device. In the fourth session, with no pacer or feedback provided (Time 3), results showed that participants were able to adjust and reduce their respiration rate successfully. Unfortunately, closer examination of the data indicated that only 31% of our sample demonstrated the target 8 BPM or slower.
An examination of HRV indices found that along with changes in respiration rate, participants showed improvement in HRV (as measured by LF%). Changes were in the anticipated direction, suggesting that with training and modification of respiration, participants experienced an increase in HRV. Finally, participants reported a significant decrease in overall somatic complaints, with the sample moving from the “moderate” range of symptoms to the “mild” range. In all, results suggested physiological and self-report improvements associated with the intervention.
The results of the current study expand and build upon the outcomes of prior pediatric biofeedback studies. These findings are consistent with other studies that have utilized brief biofeedback protocols in pediatrics. Similar to other studies, our participants demonstrated improvements in physiological functioning (Fahrenkamp & Benore, 2019) and improvements in somatic symptoms such as pain and migraine with brief biofeedback protocols (Scharff et al., 2002; Schurman et al., 2010). In addition, the current findings also are consistent with studies that have demonstrated both physiological changes in addition to a reduction in somatic symptoms with biofeedback training (McKenna et al., 2019; Myrvik et al., 2012).
Implications for Clinical Practice, Limitations, and Future Directions
The current study demonstrates that a brief semi-structured biofeedback training protocol, with a focus on training a self-regulation skill, is feasible in the pediatric health care setting. The brief intervention was found to be acceptable to families and allowed for both physiological and clinical improvements. In addition, the protocol was successfully administered by psychology trainee providers. While the findings support the ongoing use of the current protocol, they also lead to several questions for future research.
As we consider the strong recruitment rate, we also acknowledge that referrals for the biofeedback program came only from mental health providers within our Psychology department. It may be the case that mental health providers discussed biofeedback treatment in a manner that allowed for a better understanding of the treatment and rationale for the referral. Additionally, these providers may have had a stronger understanding of when biofeedback would be a useful and effective intervention, and therefore “stronger” referrals were made. Also, the majority of patients who completed the program were involved in concurrent outpatient therapy. This, too, may have contributed to the involvement and commitment to completing all four sessions, with likely ongoing encouragement from their primary mental health provider to continue with biofeedback to support existing treatment goals. The role of the referring provider in recruitment and retention should be examined further.
In our sample, presenting issues were varied and often not well-defined (e.g., patients referred for and categorized as “anxiety” may have had a significant somatic symptom or panic component). Moreover, our measurement of general somatic symptom improvement did not allow for a more fine-tuned examination of whether there was an improvement in the presenting issue. Future research should determine if the current protocol allows for differential improvement based on the presenting issue. In addition, providers should consider tracking these changes between sessions. Such information would be important in understanding treatment improvement and an optimal number of sessions and may be useful for the family as part of the feedback they receive in treatment.
Satisfaction was measured from the perspective of the participant and the parent, but not on the part of the referring provider. Most providers who refer their patients to the biofeedback program anticipate that their patients will learn a skill that will be useful in their overall treatment. Future research should examine progress after discharge from the biofeedback program. This may include whether the primary provider continues to support the use of the self-regulation skill in their therapy if the patient continues to be successful utilizing the skill, and if the primary provider found the biofeedback training to be a successful adjunctive component to their own treatment. While the current sample size is larger than many other samples in the pediatric biofeedback literature, a much larger sample would be required to examine these relationships with increased statistical power.
There are several considerations specific to the use of physiological measurement in the current study that should be addressed in future research. First, investigators should continue to evaluate the clinical value of specific HRV indices. For example, few normative values are available for youth, and little is known about how much change or improvement in HRV is clinically relevant, or how the degree of these physiological changes relates to clinical change. Furthermore, it should be noted that the variables captured here (e.g., mean respiration rate and HRV) are but two aspects of a wealth of data that can be explored with biofeedback. For example, with a similar protocol and equipment, future researchers can examine other variables related to self-regulation such as arousal and recovery time after stressors.
Second, while patients are instructed to practice their respiration at home, the current protocol does not require any documentation or reporting of quantity or quality of practice in the natural setting. Without such data, an understanding of the role of adherence to daily practice remains unclear. Future research should consider not only the number and duration of training sessions but provide measurement of work at home to better estimate the “dose” of respiration work and its relationship to clinical change. In addition, future research should assist in determining if a respiration rate lower than 8.0 BPM provides any additional physiological or clinical benefit.
Third, there are limitations to our own data that suggest caution in interpretation. As the current study was not specifically designed as a proper research study before data collection, there are aspects that are not as well-controlled as would have otherwise been desired. As described earlier, we combined 2-min and 5-min samples. While they were highly related to one another, this certainly remains a limitation as the 5-min sample could be somewhat “richer” and not quite as comparable to the 2-min sample captured from other participants in the study. Another limitation is related to the timing of when samples were retrieved. For the first 2-min sample (Time 1), the participant is naïve to biofeedback and is utilizing the novel equipment for the first time. At Times 2 and 3, the participant had just completed an entire session of self-regulation which may have resulted in the participant being in a generally more regulated state when demonstrating their skill. In the future, consideration should be made about the timing of physiological data collection and the situational variables that may impact the data obtained. Finally, there likely was deviation within the session and between providers with regard to how skills were taught and when decisions were made (such as increasing a difficulty level in HRV training). Having greater control over treatment implementation and data collection would allow for even greater certainty around the interpretation of our data.
Finally, it has not gone unnoticed that our sample is predominantly White. As our group has discussed the lack of patient racial and ethnic diversity in our program, we have considered that our program itself has inherent limitations. These include the requirements to receive services in-person and travel to one location. Future development of our program will consider the expansion of services to multiple locations, and telehealth adaptations to the protocol (Schaefer et al., 2021).
The findings of the current study suggest that a four-session biofeedback training protocol is feasible for youth in a pediatric outpatient setting as delivered by psychology trainees. Not only was the brief semi-structured intervention found to be accepted by patients and families, patients successfully learned a respiration skill and demonstrated improvements in physiological indices of self-regulation and self-report of somatic symptoms. Future research will assist in determining the benefit of the protocol with specific presenting issues, the utility of HRV indices, the relationship between HRV indices and clinical change in youth, and how best to make these interventions available to a wider population.