Research Article
Effects of Respiratory Exercise on Post-Stroke Cognition
Melody L. Sheldon, a, b Kenneth O. Simpson, a John McDonough, c
Purpose: The purpose of this investigation was to assess the effects of a self-administered respiratory exercise on cognition in individuals with chronic stroke. The questions investigated included the effects on working memory, sustained attention, executive functioning, forced vital capacity, and perceived health and emotional benefits.
Method: An AB single-subject design was used over an 11- to 12-week period beginning with the A phase. Baseline measurements were obtained over a three- to four-week period using the dependent variables (DV) digits backward, the Stroop Test, and verbal fluency, and forced vital capacity (FVC). During the intervention phase, the participants completed a respiratory exercise over an eight-week period.
Results: Post-stroke individuals showed improvements in working memory, executive functioning, and attention after implementing a self-administered respiratory exercise that was cost-effective, accessible, and motivating. There were no appreciable changes to respiratory capacity.
Conclusion: It is essential that providers address cognitive deficits in individuals with stroke given that cognitive impairments can interfere with the rehabilitation process and functional outcomes. When cognitive deficits are identified prior to treatment, intervention can improve outcomes. This investigation supports the use of respiratory exercise to improve cognition post stroke.
Key Words: attention, color word, executive dysfunction, forced vital capacity, respiratory capacity, spirometry
Cognition is the mental process of acquiring, interpreting, and using information (Korner-Bitensky et al., 2011). It is a multifaceted concept classified into the domains of attention, executive function, memory, and problem solving (Cumming et al., 2012; Nys, 2005). Any disruption in blood flow to the brain, such as a stroke, can potentially lead to impairments in cognition. Patel et al. (2002) reported that nearly half of all stroke survivors have cognitive deficits, substantially affecting the rehabilitative process and quality of life.
Cognitive Impairments
Attention deficits in stroke patients may include sustained attention (i.e., maintaining attention over time), selective attention (i.e., attending to a specific stimulus), divided attention (i.e., responding to two or more stimuli simultaneously), shifting attention (i.e., alternating attention between two or more tasks), or a combination thereof (Murray, 2012). In a compre-hensive assessment of cognitive decline in 299 stroke patients, Hochstenbach et al. (1998) found that greater than 70% showed significant slowness in information processing secondary to an attention deficit.
Memory is the ability to interpret information, simultaneously maintain and manipulate information (i.e., working memory), and store and retrieve information from immediate, short- or long-term storage. Memory deficits are prevalent following a stroke and evoke more complaints than any other domain (Lamb et al., 2013).
Diamond (2013) defined executive function as an interplay between inhibition and interference control, working memory, and cognitive flexibility. Executive skills include the ability to plan, initiate, sequence, monitor, and inhibit, all of which are particularly relevant to self-care and adherence to treatment recommendations (Miyake & Friedman, 2012). Unfortunately, it is estimated that 75% of post-stroke patients experience executive deficits (Chung et al., 2013), decreasing the ability to benefit from the rehabilitative process (Cummings et al., 2012).
Cognitive Rehabilitation
Several studies have stressed the importance of addressing cognitive issues in stroke patients as part of the rehabilitation process. First, cognitive deficits can interfere with the recovery process and the potential benefits of therapy. Stroke patients experiencing cognitive deficits, for example, may have greater difficulty participating in the rehabilitative process secondary to attention deficits, memory, and problems implementing self-management behaviors (e.g., medical adherence, exercise regime, and dietary control). Zinn et al. (2004) investigated the effect of post-stroke cognitive impairment on the rehabilitative process in a prospective analysis of 272 stroke patients. While the quality of rehabilitative services for stroke patients with and without cognitive issues was the same, patients with cognitive impairments fared worse at six months post infarct. The researchers surmised that a diagnosis of cognitive deficits might have alleviated the disparity between the two groups prior to intervention with implementing a remediation plan. Zinn et al. suggested that functional gains accrue status post discharge, and those patients who are inhibited due to cognitive deficits experience an expanding effect over time. Second, cognitive deficits are a predictor of the functional recovery process (Donovan et al., 2008). An investigation of the effects of cognitive dysfunction on subacute stroke patients’ functional status revealed that an awareness that cognitive impairments can serve as a predictive factor in determining functional prognosis and help with future planning (Paker et al., 2010). Skidmore et al. (2010) found that executive function in stroke patients correlated with the degree of rehabilitation participation. The investigators recommended developing markers to predict outcomes. With identification, they suggested that modifications during the intervention might lead to improved outcomes. Identification prior to an intervention is particularly important in stroke patients as impaired cognitive functioning is linked with a greater risk of being institutionalized (Pasquini et al., 2007), an increased rate of mortality (Patel et al., 2002), and diminished quality of life (Hochstenbach et al., 1998). Finally, cognitive deficits are often obscured by the physical impact of a stroke and frequently overlooked during the rehabilitative process (Kalaria et al., 2016). In a large cohort of lacunar stroke patients (n=1626), Jacova et al. (2012) found that cognitive deficits were as common as sensory and motor impairments but masked by the patient’s physical deficits. Identification of cognitive dysfunction and intervention following a stroke would appear to be an appropriate option for decreasing the effects in stroke survivors.
Direct Intervention. Cognitive rehabilitation can be classified as a direct or indirect therapeutic activity that addresses deficits associated with cognitive impairments. Traditionally, remediation involves a direct approach: a strategy (e.g., using a memory book) or structured activity (e.g., practicing word recall). While there are many different approaches, direct intervention targets restoring, compensating, or adapting to the functional loss of cognitive skills. Cummings et al. (2012) suggested that direct compensatory approaches have not been highly effective in remediating acquired memory impairments post stroke. Chung et al. (2013) completed a systematic review of randomized trials of executive function interventions that included 13 studies and a meta-analysis of 660 participants with traumatic and acquired brain injuries and stroke. Evidence suggested that traditional approaches showed limited improvements in specific cognitive functions after a stroke; these functions included memory, multi-tasking, problem-solving, goal management, and planning.
Indirect Intervention. Indirect intervention is defined as a treatment approach that focuses on the physical, social, or environment of stroke survivors (e.g., caregiver training). The goal of the rehabilitative process in general and cognitive therapy specifically is to regain function and improve independence and quality of life. Exercise has been suggested as an indirect treatment for remediation of cognitive dysfunction (Baker et al., 2010; Borror, 2017; Cummings et al., 2012; Duchesne et al., 2015; Quaney et al., 2009).
Indirect Intervention Theories. In a meta-analysis of 14 randomized controlled trials, Oberlin et al. (2017) reported that physical activity significantly improved attention and processing speed in patients with post-stroke cognitive impairments. Oberlin et al. also found that when trials combined interventions, such as strength and balance training, the effects nearly doubled.
Improved Blood Flow. There are several theories linking exercise to improvements in cognitive skills. In a pilot randomized controlled trial, Moore et al. (2015) showed a correlation between improved blood flow in temporal lobe tissue with exercise and cognitive functioning in stroke patients. The authors investigated metabolic factors via magnetic resonance imaging to see if structured exercise versus a home stretching program would improve glucose and the blood flow to the brain. Imaging showed exercise-related changes to cerebral blood flow in the therapy group. Secondary effects included positive changes to blood pressure, cholesterol, and cognition. However, the exclusion criteria required participants to complete a Six-Minute Walk test and score >24 on the Mini-Mental State Examination (MMSE) (1997), which reduces this study’s generalizability by excluding stroke patients with moderate physical and cognitive limitations. Another theory linking exercise to cognitive improvements suggests that exercise induces improved cerebral blood flow triggering an increase in brain-derived neurotrophic factor (BDNF), the protein linked to the ability of the brain to reorganize and repair itself (Borror, 2017). El-Tamawy et al. (2014) found that aerobic exercise resulted in a change in BDNF in post-stroke patients when exposed to rigorous exercise during 60-minute sessions, three times per week, for eight weeks compared to the control group. A limitation was the exclusion criteria, which prohibited patients with multiple strokes, a history of previous cognitive issues, neurological problems, and cardiac diseases, reducing generalizability to patients with moderate physical impairments and cognitive dysfunction.
Increase in IGF-1 and Decrease in Homocysteine Levels. Resistance exercise (RE) has also been found to improve cognitive skills indirectly. The theory is that RE increases the insulin-like growth factor 1 (IGF-I) and decreases homocysteine levels in the central and peripheral nervous system. Liver-derived IGF-I is an anabolic hormone linked to improved concentration and overall neural function in older rats (Trejo et al., 2007). Increased levels of homocysteine, an amino acid known for forming disulfide bonds, have been correlated with cardiovascular disease and dementia (Kado et al., 2005). Nagamatsu et al. (2012) used the Stroop Color Word Test (SCWT) as an outcome measure to assess selective attention and conflict resolution. Nagamatsu et al. found that the resistance exercise (RE) group with mild cognitive impairments demonstrated significant improvements in selective attention (p=0.04) compared to the balance and tone control group. However, the RE program required trained staff to implement and safely engage the participants reducing the likelihood of stroke patients being able to use RE in the home unsupervised.
Pulmonary Function. Ferreira et al. (2015) linked pulmonary function with improvements in cognitive performance by investigating the influence of aerobic exercises and respiratory training on cognitive functioning in healthy individuals. Pulmonary function is the ability of the lungs to process oxygen and expel carbon dioxide. The authors hypothesized that specific respiratory exercises might yield results similar to studies that show improvements in cognitive functioning with aerobic exercise. Ferreira et al. randomized 102 middle-aged individuals into one of three groups: a control, breathing, or walking group. Outcome measures included several cognitive assessments, including digits backward (DB) from the Wechsler Adult Intelligence Scale (WAIS) (1979). The aerobic and respiratory exercise groups demonstrated improvements in pulmonary functions and attention and executive functions, whereas the control group showed no improvements. In a similar study, Kara et al. (2005) investigated the relationship between physical activity, cognitive functioning, and respiratory capacity in 45 healthy, older adult women in a community center based on the assumption that aerobic exercise improves cognitive abilities by increasing cerebral oxygen. Pulmonary functions were measured by assessing forced vital capacity (FVC), the maximum amount of air forcibly exhaled following a deep breath. Secondary measures included immediate verbal recall using the digit span test from the WAIS and processing speed using the SCWT. The four-month training program revealed significant improvements in the recall of digits and that improvements in short-term memory were strongly related to FVC.
Impact of Outpatient Therapy
A growing body of literature suggests improvements in cognition using such indirect interventions as an exercise with physically impaired post-stroke patients. However, leaving home to participate in treatment poses significant physical and financial hardships for the physically and cognitively impaired stroke patient.
Physical and Financial Hardships. Kluding et al. (2011) explored the effects of aerobic and resistance exercises on cognition in chronic stroke patients using DB from the WIAS as an outcome measurement of working memory. Using a 12-week program, the authors found significant improvements (p=0.05) in working memory in chronic stroke patients. The authors reported that the intensity of the intervention program and the requirement that the participants travel to an urban medical center were limiting factors and resulted in significant hardship for stroke patients. Baker et al. (2010) examined the effects of aerobic exercise on cognition in sedentary adults with mild cognitive issues using SCWT and Verbal Fluency (VF). The VF test is used to assess executive functioning by requiring the participant to name as many items as possible in one minute relevant to a specific topic. While Baker et al. reported that exercise improved cognitive skills, they cautioned that their aerobic intervention’s demands worked well for a controlled trial but might not be well-tolerated in less structured and less supervised settings.
Transference of Gains. There are also concerns regarding the transference of gains made during outpatient therapy into the home environment for long-term benefits, given motivation, and subsequent compliance issues with the cognitively impaired stroke patient. Dobkin (2005) reported that formal therapy is frequently discontinued after several weeks when the patient stops showing gains and reaches a plateau. However, the author stated that “a plateau in recovery does not necessarily imply a diminished capacity for further gains in physical speed or precision or in learning a new task” (p. 4). In a retrospective study of aerobic and resistance therapy training involving stroke patients, Jurkiewicz et al. (2011) found that patients were compliant during treatment, but adherence to the protocol declined following graduation from therapy. They reported that exercise improved function post stroke in an outpatient setting, yet when prescribed a home program, only a few patients participated, and for a short duration only.
Self-motivating Activities. Patient motivation is particularly important during the rehabilitation process as the patient’s active participation is crucial. In a retrospective study examining adherence to a home-based rehabilitation program for stroke patients, Jurkiewicz et al. reported that motivation was a common factor in preventing follow-up of the recommended protocol. Rapolienė et al. (2018) found a statistically significant (p<0.05) correlation (r=0.72) between patient motivation and independence following the rehabilitation process. Puhan et al. (2006) investigated the effects of playing the didgeridoo on daytime sleepiness in sleep apnea patients in a small randomized controlled trial. Puhan et al. provided the participants with 20 to 30-minute lessons weekly and required playing of the instrument five days a week for 20 minutes at home. Not only did the participants note a statistically significant (p = .03) improvement in daytime sleepiness, but they were also highly motivated, practicing on average 5.9 days versus the required five days a week. At present, there are very few self-motivating activities that physically impaired stroke patients can perform independently to improve cognition, especially in the home. Yet, patient motivation is imperative.
Research Purpose
The authors hypothesized that using a respiratory exercise capable of perfusing the brain with oxygen, which is both motivating and accessible to physically and cognitively impaired post-stroke patients, would significantly improve cognition. The purpose of this study was to examine the effects of a self-administered respiratory exercise that creates backpressure while maintaining an open glottis sufficient to perfuse the brain with oxygen for a total of 20 minutes five days a week, on cognitive functioning in three domains (attention, executive function, and memory) and respiratory capacity (forced vital capacity) compared with treatment as usual in post-stroke patients.
Method
Participants. Twelve subjects, between the ages of 60 and 85, were recruited using convenience sampling of the available population. Inclusion criteria consisted of a history of a cerebral vascular accident with time since a stroke three to eighteen months, a MMSE score greater >13, and digits backward score < four, both administered by the speech-language pathologist conducting the study. Exclusion criteria included a diagnosis of Alzheimer’s disease, disease with a limited life expectancy of six months or less, recent history of pneumothorax or unstable cardiovascular status, thoracic, abdominal, or cerebral aneurysms, recent eye surgery, color-blindness, and concurrent participation in some other rehabilitation program. Of the eight participants who met the criteria and agreed to participate, five participants withdrew from the study; three for health reasons unrelated to the investigation, one secondary to inconvenience, and one individual who expressed non-interest. Three participants completed the study. See participant demographics listed in Table 1.1.
Variables. This investigation was designed to measure the effects of a respiratory exercise (the independent variable) on cognitive skills (the dependent variables) as indicated by the scores on the outcome measurement tools, digits backward, the Stroop Test (ST) (Novak, 2016), a color word application, and verbal fluency (VF). Digits Backwards, like the Digit Span Backward subtest from the WAIS, was used to measure the number of digits backward retrieved from working memory. The ability to sustain attention when presented with interfering stimuli was measured using the Stroop Test, an iPad application created by Novak (2016). The screen displayed a color word to which participants selected the color of the word rather than the word itself. The application produced the total score of correctly identified color words identified in 30 seconds. Verbal fluency, like the Verbal Fluency Test (Lezak et al., 2012), measured neural functioning, a reflection of executive functioning, by measuring the number of words recalled in a given semantic category in one minute. To avoid a learning effect, a different semantic category was chosen during each session preventing the use of a formal assessment tool. In addition to improvements in cognitive skills, this investigation measured the effects of a respiratory exercise on forced vital capacity (FVC). The Contac spirometer was used to assess pulmonary functioning as it was expected that FVC, a reflection of the amount of air an individual can forcefully exhale (mL) over time (seconds), would improve with respiratory exercise post stroke. The longest of three trials collected at the end of each session was recorded. This investigation included four dependent variables, three of which focused on cognition and one on respiration. Of the four dependent variables, the most critical one for this investigation was digits backward, one of the cognitive domains most likely affected by stroke (McDonnell et al., 2011) and sensitive to intervention (Kluding et al., 2017; Quaney, 2009).
During the baseline phase of this investigation, a minimum of three data points were established. 80% of the data points for digits backward, the primary dependent variable, fell on or within 25% of the median suggesting that the data was stable without trend per the recommendations of Gast and Ledford (2014). This investigation had one primary dependent variable, Digits Backward, which was used to determine the baseline duration for all the secondary dependent variables regardless of the stability of those secondary dependent variables.
The independent variable (IV), a respiratory exercise, was playing the didgeridoo for a total of 20 minutes four days a week in the home and one day a week either in an outpatient setting or in the patient’s home with the first author present as this frequency was shown in the investigation by Puhan et al. (2006) to be enough time to demonstrate changes in behavior. Playing the didgeridoo was defined as placing the mouth on the open mouthpiece and blowing while trilling the lips with enough force to produce a droning sound characteristic of a didgeridoo. Each participant was provided a curved, acrylic didgeridoo manufactured by Tribal Sun, as acrylic is easier to learn to use versus a wooden instrument (Puhan et al., 2006). The didgeridoos were 127 cm long with a 12-14 cm diameter and a width of 9-10 cm at the mouth. During the first and second lessons, participants learned to sustain an unvoiced lip trill. Emphasis was placed on blowing as soft as possible yet sufficient to create the droning sound. The participants were encouraged to sit upright as much as possible, sustaining an expanded ribcage. Emphasis was also placed on puffing out the cheeks. The concept of circular breathing was introduced during the third week. This technique required inhalation of air through the nose while trillling by way of the lips using the cheeks as bellows. The remaining sessions focused on respiratory efficiency and optimization resulting in the transmission of vibrations produced by the trilling of the lips to the lower airway (Tarnopolsky et al., 2005) and making corrections in technique, as necessary.
Data Analysis. Slope, the two standard deviation band method, and percent non-overlapping data (PND) were used to examine the effects of playing the didgeridoo on the primary dependent variable digits backward and secondary dependent variables the Stroop Test, verbal fluency, and forced vital capacity. A journal form was filled out by the participants four days a week indicating the time spent playing the didgeridoo and perceived health and emotional benefits.
Table 1.1
Participant Demographics
| Participant | MV | VR | MM |
| Age | 61 | 85 | 67 |
| Gender | M | M | F |
| Time post- onset | 6 months | 6 months | 10 months |
| Number of Strokes | 1 | 1 | 1
|
| Type of Stroke(s) | unknown | unknown | unknown |
| Location of Stroke | unknown | unknown | Brainstem |
| Education | High School | Some
College |
Some College |
| Language | English | English | English |
| MMSE (score) | 24 | 27 | 27 |
Results
The primary dependent variable digits backwards demonstrated a stable baseline with an accelerating trend during the intervention phase for each participant (Figure 1.1). The mean average for the group at baseline was 3.45 + .99 and during intervention 4.96 + .64 with a mean difference of 1.51 digits. The two standard deviation band for DB demonstrated at least two consecutive data points above the upper band for each participant. The average PND for the three participants was 50%, 100%, and 42%.
The secondary dependent variable, the Stroop Test (Figure 1.2) revealed an accelerating trend at baseline for MM and MV, with a flat trend during the intervention phase. VR demonstrated a decelerating trend at baseline and an accelerating trend during the intervention phase with a slope of y=0.18x. The two standard deviation band method and PND did not reveal a treatment effect for MV and MM. Participant VR demonstrated a PND of 100% and all data points were above the upper two standard deviation band.
Verbal fluency, another secondary dependent variable, showed a positive trend for all participants during the intervention phase. Items named in a given category in one minute on average changed from 13.91 ± 3.15 during baseline to 20.91 ± 5.61 with an average mean difference of 6.28 words (Table 1.3) The two standard deviation band method revealed at least two consecutive data points above the upper band for all participants. The intervention was very effective for MM with a PND of 100%, somewhat effective for VR with a PND of 67.5%, and not as effective for MV with a PND of 37%.
Forced Vital Capacity (FVC) (Figure 1.4) showed no linear trend for the participants across baseline and intervention phases. The two standard deviation band method and PND revealed no appreciable improvements in FVC following the intervention for VR and MM. Participant MV demonstrated three consecutive data points above the two standard deviation band, four in total with a PND of 62%.
Table 2.1
| Outcome Measures
|
|||||
| Didgeridoo Group n=3 | Baseline | Intervention | |||
| M (SD) | M (SD) | ||||
| Digits Backward | 3.45 ± .99 | 4.96 ± 0.64 | |||
| Stroop Test | 8.27 ± 3.99 | 9.48 ± 2.73 | |||
| Verbal Fluency | 13.91 ± 3.15 | 20.91 ± 5.61 | |||
| Forced Vital Cap | 2.08 ± 0.24 | 2.08± 0.19 | |||
Figure 1.1
Slope of Digits Backward: MV, VR, and MM
Figure 1.2
Slope of the Stroop Test: MV, VR, and MM
Figure 1.3
Slope of Verbal Fluency: MV, VR, and MM
Figure 1.4
Slope of Forced Vital Capacity: MV, VR, and MM
Discussion
Visual and statistical analyses revealed that playing the didgeridoo improved working memory, as measured using digits backward, the primary outcome measurement tool used during this investigation. The digit span task is a common component of such standardized assessment tools as the WAIS. In this investigation, digits backward was used in isolation as an informal assessment tool. The results revealed a mean average difference of 1.51 digits between baseline and intervention phases. To gage the significance of improvements, the results of this investigation were compared to the data of Kluding et al. (2012) which revealed a mean average change of .56 digits across their 12-week intervention phase using aerobic fitness with chronic stroke.
On average, significant improvement in sustained attention using the Stroop test across participants was not observed. The lack of overall improvement may have been due to health issues. MV expressed difficulty differentiating the colors red and yellow and blue and green and MM reported difficulty seeing out of her right eye, which may have interfered with the participants’ performance.
To gage the significance of improvements in executive functioning as measured by verbal fluency, the results of this investigation were compared to stratified normative data published by Tombaugh et al. (1999). The mean average for the age group 60-79 with 9-12 years of education was 16.4 + 4.3. This placed MV and VR close to the 10th percentile with a mean baseline score of 11.6 and 12.75 at baseline, respectively. Following the intervention phase MV and VR moved to the 50th and 75th percentile respectively with a mean score of 17 and 19. MM was slightly below the 50%ile at baseline with an average score of 16 and scored well above the 90%ile with an average score of 28 during the intervention phase. Caution must be taken when interpreting the results from this study using normative data from Tombaugh’s study as their participants (n=1300) were Italian and in good health. In addition, norms were based on only one category (animals).
This investigation revealed minimal change in pulmonary functioning across participants over the course of eight weeks of playing the didgeridoo an average of 20 minutes a day, five days a week. MV was able to circular breathe towards the end of this investigation. VR learned to consistently produce a droning sound but was unable to circular breathe. MM had significant difficulty maintaining the droning sound typical of the didgeridoo. VR and MM demonstrated no change between FVC scores at baseline and intervention phases. MV showed some improvement with three consecutive data points above the two standard deviation band and a PND of 62%. It is possible that circular breathing must be obtained before realizing the respiratory benefits of playing the didgeridoo. The degree of physical effects derived from playing the didgeridoo differs from taking a breath via the mouth with each lip trilling effort to circular breathing, which ranges from an average from 8 to 12 breaths when playing slowly up to 48 to 60 per minute when playing quickly. Conversely, it may be that playing the didgeridoo was not a respiratory exercise per se, but rather, one that strengthened the pharyngeal wall and muscles of the upper airway as suggested by Puhan et al. (2006).
A journal form was used to record the participant’s reaction to playing the didgeridoo. Uniformly, the participants did not report improvements in breathing or respiratory health. Playing the didgeridoo appeared to be motivating as participants played on average 119 minutes per week when only 80 minutes were required. All participants played the device independently, even VR who had a dense left-sided paresis. All but one participant indicated that they would continue to play the instrument following the investigation. MM indicated that playing the didgeridoo gave her energy and she thought that it might be helping with memory.
Study Limitations. Only three individuals post-stroke completed the investigation limiting replication and generalization of the results to other populations.
Non-standardized tools were used to assess the effects of respiratory exercise on working memory, attention, and executive function.
Participants were not screened for vision impairments to rule out color blindness and hemianopsia.
The use of FVC to assess improvements in respiratory muscle strength secondary to playing the didgeridoo may not be sensitive to changes in the capacity of the inspiratory muscles to generate pressure. One of the limitations of using FVC includes patient effort according to Kacmared et al. (2020). Using the didgeridoo creates backpressure increasing oxygen diffusion across the alveolar membrane. One of the expected changes in respiration includes an increase in residual volume, that is, the volume of air that cannot be expelled. And that can only be measured with body plethysmography.
The qualitative component of this investigation used a journal form whereby participant entered comments. Uniformly, the participant’s comments were limited, “no change” or “breathing the same.”
Future Research and Clinical Implications. A larger and varied population is needed to confirm the findings of this investigation.
Future research should include standardized assessment protocols to facilitate interpretation of the degree of improvement per participant.
If the Stroop Test is used to assess attention, it is recommended that screening for vision impairments be implemented.
A pulmonary function assessment is recommended at baseline and following the intervention phase to assess for changes in respiration. Replacement of FVC with Forced Expiratory Volume in one second (FEV1) should be considered as FEV1 may demonstrate improvement from increasing the work of the diaphragm caused by playing the didgeridoo.
It is recommended that future research include a visual analog scale that can be used by the participant and caregiver rating sleep quality, alertness, memory, and endurance. Drawing from the field of respiratory therapy, examining the perspectives and experiences of the patient’s caregiver is important in gaining a complete understanding of both the drawbacks and benefits of a respiratory exercise.
Conclusions
Service providers need to address cognitive deficits in individuals with stroke because cognitive impairments can interfere with the rehabilitation process and functional outcomes. When cognitive deficits are identified prior to treatment, intervention can improve outcomes. This investigation supports the use of the didgeridoo as a respiratory exercise to improve cognition.
Findings revealed that participants were able to easily access the didgeridoo. They were motivated to perform the exercise. More importantly, all participants demonstrated improvement in working memory as measured by digits backward, executive functioning as measured by verbal fluency, and one participant, without visual impairment, showed improvement in attention as measured by the Stroop Test. The actual respiratory benefits were limited, with the exception of some measurable improvements for MV who demonstrated circular breathing.
Acknowledgments
This research is a portion of an investigation by Melody L. Sheldon and could not have been completed without support from Dr. Kenneth Simpson, director of the Department of Speech-Language Pathology, Rocky Mountain University of Health Professions, Provo, Utah and John McDonough, content expert, retired director of Respiratory Therapy at Mercy Medical Center, Roseburg, Oregon.
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