Background: Reduced respiratory muscle strength leads to reduced pulmonary function, chest wall movements in the affected side, and increased chest infections, which thereby reduces oxygenation and ventilation. Respiratory muscle training can be used in acute stroke subjects to increase their pulmonary function. Purpose: To compare the short-term effects of diaphragmatic breathing exercise, flow, and volume-oriented incentive spirometry on respiratory function following stroke. Methods: A non-randomized hospital-based study was conducted at Kasturba Medical College Hospitals, Mangalore, India. Forty-two sub-acute subjects of either gender, with the first episode of stroke within six months, were assigned to three groups by the consultant, i.e., diaphragmatic breathing group (DBE), Flow oriented-incentive spirometry group (FIS), and volume oriented-incentive spirometry group (VIS; N = 14) each. All subjects received intervention thrice daily, along with conventional stroke rehabilitation protocols throughout the study period. Pre- and post-intervention values were taken on alternate days until day 5 for all the three groups. Results: The pulmonary function and maximal respiratory pressures were found to be significantly increased by the end of intervention in all three groups, but FIS and DBE groups had better results than VIS (FVC = FIS group, 13.71%; VIS group, 14.89%; DBE group, 21.27%, FEV = FIS group, 25.97%; VIS group, 22.52%; DBE group, 19.38%, PEFR = FIS group, 38.76%; VIS group,9.75%; DBE group, 33.16%, MIP = FIS group, 28.23%; VIS group, 19.36%; DBE group, 52.14%, MEP = FIS group, 43.00%; VIS group, 22.80%; DBE group, 28.68%). Conclusion: Even though all interventions had positive outcomes in all variables, flow incentive spirometry had better results across all outcomes (pulmonary function and maximal respiratory pressures) when compared to the other two interventions making it a valuable tool for stroke rehabilitation. Keywords Volume and flow incentive spirometry, Diaphragmatic breathing exercise, Acute stroke, Pulmonary function, Maximal respiratory pressures Introduction 1 Department of Physiotherapy, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Karnataka, India Department of Physiotherapy, College of Health Sciences, University of Stroke is one of the prominent causes of death globally and the Sharjah, Sharjah, United Arab Emirates primary cause of long-term disability worldwide. Annually, Department of Physiotherapy, College of Health Sciences, Gulf Medical about 11 million people suffer stroke worldwide, and India is University, Ajman, United Arab Emirates 2,3 projected to have over 1 million strokes per year. Department of Neurology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Karnataka, India Stroke interferes with various respiratory processes Corresponding author: depending on the size and severity of the neurological Stephen Rajan Samuel, Department of Physiotherapy, Kasturba Medical damage. Muscular weakness is a prominent deficit in College, Mangalore, Manipal Academy of Higher Education, Karnataka, individuals with stroke, which is also seen in respiratory 575001, India muscles, like the diaphragm, which is the primary muscle of E-mail: firstname.lastname@example.org Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution- NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-Commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https:// us.sagepub.com/en-us/nam/open-access-at-sage). Shetty et al. 233 inspiration. Stroke survivors have been reported to have reduced diaphragmatic breathing exercises, flow, and volume-oriented diaphragmatic excursion with a higher position of the affected incentive spirometry on pulmonary function and maximum respiratory pressures in acute stroke subjects. diaphragm, and they showed a reduction in both maximal 5,6 inspiratory pressure and maximal expiratory pressure. The central weakness of the respiratory muscles can Methods adversely affect cough function, which is linked with low thorax expansion and postural trunk defect/malfunction. Design, Setting and Study Population This abnormality is paired with altered chest wall kinematics, A nonrandomized study was conducted after receiving which leads to a decline in cardiovascular function and affects approval from the Institutional Ethics Committee, Kasturba oxygen delivery, thereby reducing exercise capacity for Medical College, Mangalore, Manipal Academy of Higher 4–9 activities of daily living. Education (IEC KMC MLR 11-18/414), and registered with Stroke survivors demonstrate altered breathing clinical trials registry of India (CTRI/2018/12/016651). The mechanisms and reduction in respiratory efficiency depending inclusion criteria were as follows: male and female subjects on chest wall asymmetry, degree of loss in the chest wall of the age group 18 to 80 years, diagnosed with the first 10,11 movement, and the extent of muscular paralysis. Abnormal episode of stroke (within last six months), National Institutes breathing patterns have been reported in 18% to 88% of of Health Stroke Scale score 5 to 25 with motor impairment, patients with stroke, particularly ones with more severe preserved cognition according to the mini-mental state neurological impairment and depressed consciousness. This 26,27 examination (score >22) and able to follow researcher’s is presumed to be because of increased muscle tone and verbal commands. The exclusion criteria were as follows: spasticity of the chest wall muscles caused by hemiplegia on subjects with BP >180/100 mmHg more than twice in 24 h, the affected side restricting the chest wall. Thus they history of unstable angina, myocardial infarction, or acute classically present with a restrictive pattern in which there is heart failures within past one month or neurological conditions a reduction in forced expiratory volume in 1 s (FEV ), forced other than stroke present before or after their admission to 12,13 vital capacity (FVC), and total lung capacity (TLC). ICU, presence of neurosurgical intervention in the past one Specifically, expiratory muscle weakness leads to the month, non-cooperative subjects and pre-existing postural impairment of cough capacity and expectoration, further and musculoskeletal deformities affecting lung volumes. leading to the retention of copious secretions resulting in Diagnosed stroke subjects, referred by a neurologist to the several respiratory complications including aspiration Department of Physiotherapy, were approached from pneumonia and dysphagia that are essential triggers of December 2018 to March 2020. The aim of the study was 14,15 nonvascular fatality after stroke. explained to the subjects, and those volunteering to participate Stroke patients receive respiratory care that involves use were recruited after signing a written informed consent. of numerous chest physiotherapy techniques like Demographic details and baseline data like pulmonary diaphragmatic breathing exercises, mechanical breathing assessment, including pulmonary function and maximum devices such as volume and flow-oriented incentive respiratory pressure values, were taken before the start of any spirometry, and use of inspiratory muscle training clinically intervention. The consultant allocated eligible subjects to as part of routine preventive and therapeutic regimen. three groups, i.e., diaphragmatic breathing exercise (DBE) Diaphragmatic breathing exercise helps in the diaphragmatic group, flow-oriented incentive spirometry (FIS) group descent during inspiration and its ascent during expiration. (respirometer), and volume-oriented incentive spirometry The benefits include decreased work of breathing, improved (VIS) group (Coach 2 device). All the subjects received oxygenation, ventilation, inflation of the alveoli, the reversal treatment thrice daily which included three sets of 15 breaths 16,17 of hypoxemia, and an increase in the diaphragm excursion. 26,28–30 each. Caretakers were instructed that the given exercise The volume and flow-oriented incentive spirometer aims to should be performed by the subject once every waking hour promote adequate alveoli ventilation and increase for the rest of the day. All the subjects underwent conventional transpulmonary pressure. The benefits include improved lung stroke rehabilitation for stroke motor impairments. Pulmonary 18–23 volumes and reduced pulmonary complications. These function and maximum respiratory pressure values will be techniques help in enhanced lung ventilation by increasing the taken on the first, third, and fifth day (Figure 1). expansion of chest wall, helping maintain or increase Methods to Perform Flow-Oriented and Volume- appropriate lung volumes and capacities, and eventually Oriented Incentive Spirometry reduce the incidence of pulmonary function loss and its Subjects were placed in a semi-recumbent position with eventual complications. Therefore, it aids in the preservation slight flexion of knees using pillows under them. They were 13,24 of airway patency by increasing muscle activity. then asked to take a deep inspiration, which is slow and Volume-oriented incentive spirometry was found to be sustained for a minimum 5 s and exhale passively. This is used effective in improving pulmonary function in acute stroke to avoid any forceful exhalation. The subject was asked to hold subjects. Therefore, the study aims to compare the effects of the device upright and then take a slow inspiration such that the 234 Annals of Neurosciences 27(3-4) Subjects meeting the inclusion criteria (N=42) Diaphragmatic Flow Oriented – Volume Oriented – Breathing Exercise Incentive Spirometry Incentive Spirometry Group Group Group Pre intervention data collection – Pulmonary Function Test (FVC, FEV1, PEFR) and Maximal Respiratory Pressures (MIP, MEP) Diaphragmatic Flow Oriented – Volume Oriented – Breathing Exercise Incentive Spirometry Incentive Spirometry Group Group Group rd th Post intervention values taken on3 and 5 (last) days of pulmonary function and maximal respiratory pressures Figure 1. Participants Recruitment Flowchart ball within the flow spirometer (respirometer–respiratory Method to Perform Diaphragmatic Breathing exerciser–Romsons; Figure 2) or the piston within the volume Exercise spirometer (Coach 2 device, Smiths Medical International Ltd, 31,32 The subjects were placed in semi-fowler’s position with head USA; Figure 3) is raised to the set target. All techniques and back fully supported, and the abdominal wall relaxed. were demonstrated by the therapist for a clear understanding of 17,21 the subject. The therapist administered the exercise thrice 26–33 daily of three sets with 15 repetitions in each session. Figure 3. Participant Using Volume-Oriented Incentive Figure 2. Participant Using Flow-Oriented Incentive Spirometry. Spirometry Shetty et al. 235 Maximum Respiratory Pressure Two maximum pressures were taken namely maximum inspiratory pressure (cmH O) where the participant made an inspiratory effort from residual volume to their total lung capacity. Maximum expiratory pressure (cmH O), was a reverse procedure. Each maneuver was maintained for at least 1 s, and three efforts were made. Only the best value was 35,36 entered in the datasheet. Data Analysis Data were entered and analyzed into a statistical package for the social sciences (SPSS) version 25. Demographic and baseline data were compared across groups using analysis of variance. p-value < .05 will be considered as statistically significant. Results Figure 4. Participant Performing Diaphragmatic Breathing Exercise This study included 42 acute stroke subjects that met the inclusion criteria. Table 1 describes the baseline They were asked to take a slow deep breath through their anthropometric values of all subjects such as age, gender, nose, i.e., from functional residual capacity to total lung height, weight, mini-mental state examination score, and capacity with a hold of a minimum of 3 s. They had to be National Institutes of Health Stroke Scale. Table 2 gives a relaxed so that they could appreciate the raised abdomen summary of forced vital capacity within the interventional during breathing. While exhaling, the subject should breathe groups before the intervention and the third day and last day out through his/her mouth (Figure 4). This movement of the for comparison of all groups. Table 3 gives a summary of abdomen during breathing in and out has to be felt by the forced expiratory volume in 1-s values of all interventional subject by placing his/her hand just below the anterior costal groups before and after intervention for comparison. Table 4 16,34 margin on the rectus abdominis. gives a summary of peak expiratory flow rate values for comparison of all groups. Table 5 gives a brief of maximal Outcome Measures inspiratory pressure values for comparison of all groups. Table 6 summarizes maximal expiratory pressure values for Pulmonar y Function Test comparison of all groups. Table 7 summarizes the difference Pulmonary function test was done using a portable machine–a between baseline and fifth day between the three intervention spirometer by COSMED technologies, USA. Variables that groups of forced expiratory volume in 1 s, forced vital were used for this study included the following –forced vital capacity, peak expiratory flow rate. Table 8 summarizes the capacity (L), forced expiratory volume in the first second (L), difference between baseline and fifth day between the three peak expiratory flow rate (L/s), and three tests were taken. intervention groups of maximal inspiratory pressure and The best value was entered in the datasheet. maximal expiratory pressure. Table 1. Demographic Characteristics of Subjects Who Participated in the Study Diaphragmatic Breathing Exercise Flow-Incentive Volume-Incentive Variables (DBE) n = 14 Spirometry (FIS) n = 14 Spirometry (VIS) n = 14 p Value(p < .05) Age (years)(mean ± SD) 63.40 ± 7.83 56.07 ± 13.10 55.79 ± 13.79 .15 Gender (M:F) 11:3 8:6 9:5 .54 Height (m)(mean ± SD) 1.61 ± 0.13 1.64 ± 0.07 1.64 ± 0.07 .59 Weight (kg)(mean ± SD) 59.20 ± 9.05 67.00 ± 9.29 64.14 ± 6.11 .05 Lesion type 8:6 8:6 9:5 (ischemic:hemorrhagic) Paretic side (right:left) 6:8 8:6 7:7 (Table 1 Continued) 236 Annals of Neurosciences 27(3-4) (Table 1 Continued) Diaphragmatic Breathing Exercise Flow-Incentive Volume-Incentive Variables (DBE) n = 14 Spirometry (FIS) n = 14 Spirometry (VIS) n = 14 p Value(p < .05) Duration because 9.07 ± 9.53 5.28 ± 3.66 9.92 ± 14.57 stroke(days) MMSE 27.53 ± 1.64 27.36 ± 1.86 27.36 ± 2.31 .96 NIHSS 5.60 ± 0.91 5.21 ± 0.43 5.86 ± 0.86 .09 Abbreviations: MMSE, mini mental state examination; NIHSS, national institute of health stroke scale. Table 2. Comparison of Forced Vital Capacity Before and After Intervention in Post-stroke Subjects Forced Vital Capacity [Liters (L)] Baseline (Mean ± SD) Third Day (Mean ± SD) Fifth Day (Mean ± SD) Diaphragmatic breathing exercise 1.79 ± 0.63 1.95 ± 0.85 2.17 ± 0.90 group (n = 14) Flow incentive spirometry group 2.05 ± 0.80 2.17 ± 0.71 2.33 ± 0.70 (n = 15) Volume incentive spirometry group 1.95 ± 0.75 2.20 ± 0.71 2.24 ± 0.70 (n = 14) Mean Difference Between Baseline and Fifth Day Baseline to Third Day Third to Fifth Day Baseline to Fifth Day Diaphragmatic Breathing exercise -0.158.75% -0.2211.51% -0.3821.27% group p value 0.27 0.04* 0.01* Flow incentive spirometry group -0.115.81% -0.167.47% -0.2813.71% p value 0.77 0.17 0.03* Volume incentive spirometry group -0.2513.05% -0.031.62% -0.2914.89% p value 0.00** 1.00 0.04* Note: *p < .05 statistically significant; **highly significant. Table 3. Comparison of Forced Expiratory Volume in 1 s (FEV ) Before and After Intervention Forced Expiratory Volume in 1 s [Litres (L)] Baseline (Mean ± SD) Third Day (Mean ± SD) Fifth Day (Mean ± SD) Diaphragmatic breathing exer- 1.37 ± 0.51 1.47 ± 0.66 1.63 ± 0.61 cise group (n = 14) Flow incentive spirometry 1.56 ± 0.48 1.69 ± 0.57 1.97 ± 0.57 group(n = 14) Volume incentive spirometry 1.39 ± 0.75 1.64 ± 0.58 1.70 ± 0.68 group (n = 14) Mean Difference Between First and Fifth Day FEV1 Baseline to Third Day Third Day to Fifth Day Baseline to Fifth Day Diaphragmatic breathing exer- -0.107.81% -0.1510.73% -0.2619.38% cise group p value 1.00 0.29 0.18 Flow incentive spirometry -0.128.28% -0.2716.34% -0.4025.97% group p value 0.90 0.11 0.00** Volume incentive spirometry -0.2518.15% -0.063.70% -0.3122.52% group p value 0.23 1.00 0.17 Note: *p < .05 statistically significant; **highly significant. Shetty et al. 237 Table 4. Comparison of Peak Expiratory Flow Rate (PEFR) Before and After Intervention Peak Expiratory Flow Rate (PEFR)[Litres(L/s)] Baseline (Mean ± SD) Third Day (Mean ± SD) Fifth Day (Mean ± SD) Diaphragmatic breathing exer- 2.09 ± 0.97 2.36 ± 1.10 2.78 ± 1.43 cise group (n = 14) Flow incentive spirometry 2.06 ± 0.62 2.76 ± 1.30 2.85 ± 1.20 group (n = 14) Volume incentive spirometry 2.10 ± 1.12 2.16 ± 0.81 2.31 ± 1.19 group (n = 14) Mean Difference Between First and Fifth Day Baseline to Third Day Third Day to Fifth Day Baseline to Fifth Day Diaphragmatic breathing exer- -0.2712.96% -0.4217.89% -0.6933.16% cise group p value 1.00 0.41 0.16 Flow incentive spirometry -0.7034.25% -0.093.36% -0.7938.76% group p value 0.04* 1.00 0.04* Volume incentive spirometry -0.052.58% -0.156.99% -0.209.75% group p value 1.00 1.00 1.00 Note: *p < .05 statistically significant. Table 5. Comparison of Maximal Inspiratory Pressure Before and After Intervention Maximal Inspiratory Pressure [cmH O] Baseline (Mean ± SD) Third Day (Mean ± SD) Fifth Day (Mean ± SD) Diaphragmatic breathing exercise 24.93 ± 14.51 32.20 ± 19.50 37.93 ± 19.81 group(n = 14) Flow incentive spirometry group 32.64 ± 15.39 39.14 ± 15.69 41.86 ± 11.64 (n = 14) Volume incentive spirometry 33.57 ± 14.01 37.21 ± 14.35 40.07 ± 13.06 group(n = 14) Mean Differences Compared on Fifth Day in Between Groups Maximal Inspiratory Pressure Baseline to Third Day Third Day to Fifth Day Baseline to Fifth Day Diaphragmatic breathing exercise -7.2629.14% -5.7317.81% -13.0052.14% group p value 0.00** 0.06 0.00** Flow incentive spirometry group -6.5019.91% -2.716.93% -9.2128.23% p value 0.00** 1.00 0.01* Volume incentive spirometry group -3.6410.85% -2.857.68% -6.5019.36% versus p value 0.04* 0.31 0.04* Note: *p < .05 statistically significant; **highly significant. Table 6. Comparison of Maximal Expiratory Pressure Before and After Intervention Maximal Expiratory Pressure [cmH O] Baseline (Mean ± SD) Third Day (Mean ± SD) Fifth Day (Mean ± SD) Diaphragmatic breathing exercise group (n = 14) 35.80 ± 17.10 41.73 ± 16.36 46.07 ± 17.46 Flow incentive spirometry group(n = 14) 36.71 ± 16.34 48.79 ± 19.18 52.50 ± 17.18 Volume incentive spirometry group(n = 14) 38.21 ± 13.46 43.79 ± 13.49 46.93 ± 13.91 (Table 6 Continued) 238 Annals of Neurosciences 27(3-4) (Table 6 Continued) Mean Differences MEP Baseline to Third Day Third Day to Fifth Day Baseline to Fifth Day Diaphragmatic breathing exercise group -5.9316.57% -4.3310.38% -10.2628.68% p value 0.03* 0.00* 0.01* Flow incentive spirometry group -12.0732.88% -3.717.61% -15.7843.00% p value 0.00* 0.41 0.00* Volume incentive spirometry group versus -5.5714.58% -3.147.18% -8.7122.80% p value 0.01* 0.26 0.00* Note: *p < .05 statistically significant; **highly significant. Table 7. Difference Between Baseline and Fifth Day Between the Three Intervention Groups of Forced Expiratory Volume in 1 s, Forced Vital Capacity, Peak Expiratory Flow Rate Baseline Minus Fifth Day Forced Vital Capacity Forced Expiratory Volume in 1 s Peak Expiratory Flow Rate (Mean Difference) [Liters (L)] [Liters (L)] [Liters/s (L/s)] Flow incentive spirometry 0.1 0.15 0.11 group versus diaphragmatic breathing exercise group p value 0.77 0.74 0.39 Flow incentive spirometry 0.00 0.1 0.59 group versus volume incentive spirometry group p value 0.77 0.74 0.39 Volume incentive spirometry 0.09 0.05 0.48 group versus diaphragmatic breathing exercise group p value 0.77 0.74 0.39 Note: *p < .05 statistically significant. Table 8. Difference Between Baseline and Fifth Day Between the Three Intervention Groups of Maximal Inspiratory Pressure and Maximal Expiratory Pressure Baseline Minus Fifth Day (Mean Difference) Maximal Inspiratory Pressure Maximal Expiratory Pressure Flow incentive spirometry group versus diaphragmatic 3.79 5.52 breathing exercise group p value 0.20 0.26 Flow incentive spirometry group versus volume incentive 2.71 7.08 spirometry group p value 0.20 0.26 Volume incentive spirometry group versus diaphragmatic 6.5 1.56 breathing exercise group p value 0.20 0.26 Note: *p < .05 statistically significant. three interventions were successful in enhancing the pulmonary Discussion function and maximal respiratory pressures when respiratory It is the first study to our knowledge that evaluates the effects of muscle training is given for five days in acute stroke subjects. diaphragmatic breathing exercises, volume and flow-oriented Pulmonary function tests such as forced expiratory volume incentive spirometry on pulmonary function and maximal in 1 s (L), forced vital capacity (L), and peaked expiratory flow respiratory pressures in patients with stroke compared to the rate (L/s) improved in all three interventions. However, flow- effects of the three interventions. The study revealed that all oriented incentive spirometry showed better improvement in Shetty et al. 239 forced vital capacity values when compared to others. One of even more elevated than the nonaffected side. It shows a the reasons could be the higher baseline value at the start of reduced diaphragmatic motion of the paretic side. Therefore, the intervention in this group. Although these interventions stroke patients are unable to generate negative pressure and showed clinical significance in pulmonary function of forced hence show reduced forced vital capacity and maximal vital capacity, higher statistical significance and percentage inspiratory pressure. Because the diaphragm is the primary change were observed in the diaphragmatic breathing exercise muscle and cannot be used for normal respiration because of group (21.27%) when compared to flow and volume-oriented the stroke, these patients find it easier to use accessory muscle incentive spirometry (13.71% and14.89%, respectively). for respiration, as promoted by this device. This group, Forced expiratory volume in 1 s also exhibited improvement hence, has shown better results than others. This might be the clinically in all the three groups by the end of this study. reason why our results do not reflect the findings from the However, statistically significant improvement was found in previous studies that have used these interventions in flow-oriented incentive spirometry (25.97%) when compared abdominal surgery patients where volume-oriented incentive to diaphragmatic (19.38%) and volume-oriented incentive spirometry was proven to be better. spirometry (22.52%). Although volume-oriented incentive spirometry provides Peaked expiratory flow rate values improved in flow- visual feedback, it was a little difficult to follow for our oriented incentive spirometry (38.76%) with statistical patients when compared to the flow-oriented incentive significance than in the other two groups. Even though peaked spirometry device. Possible reasons for its group showing expiratory flow rate values were not statistically significant, improvement from baseline might be that it produces more clinically, we noticed an improvement in the other two symmetrical expansion in the pulmonary rib cage during groups. The present study suggests that flow-oriented incentive spirometry, suggesting that it promotes an increase incentive spirometry has shown more improvement in in ventilator output on the paretic side, resulting in more pulmonary function overall than in the other two interventions, significant expansion. It also provides low-level resistance 24,43 though all interventions had shown an increase from baseline. training to the diaphragm and minimizes fatigue. Our study was in line with the results given by Joo et al. Diaphragmatic breathing exercise works on the principle who, in his study, showed a 27.89% increase in forced of increasing diaphragmatic descent during deep inspiration expiratory volume in 1 s and 26% increase in forced vital to increase collateral ventilation and diaphragmatic excursion, capacity value after administering game-based exercise as an leading to an increase in pulmonary capacities, but the intervention to stroke subjects for five weeks. A study done adherence to this technique is least because there is no visual by Jung et al. used inspiratory muscle training as an feedback, and therefore, patients do not practice it as often as intervention in stroke and found a 9.6% increase in forced required. expiratory volume in 1 s and 6.56% increase in forced vital Secondary outcome variables were maximal inspiratory capacity. Possible reasons for reduced pulmonary function in pressure and maximal expiratory pressure under maximal stroke are because of reduced activity of the rib cage muscles respiratory pressures. They help us assess and monitor the and diaphragm. The diaphragm of the affected side also tends weaknesses of inspiratory musculature. Maximal inspiratory to attain a higher position, thereby reducing the pulmonary pressure has shown an increasing trend with statistical capacity of that side. Similar interventions were given to significance in all three groups. However, the diaphragmatic patients with open abdominal surgery by Kumar et al. and a breathing exercise group has shown high statistical significant increase in forced expiratory volume in 1 s and significance with a higher percentage change of 52.14% in forced vital capacity (18% to 25%) was found. maximal inspiratory pressure when compared with flow- In the overall pulmonary function, the flow-oriented oriented incentive spirometry (28.23%) and volume-oriented incentive spirometry group has shown better improvement incentive spirometry (19.36%). On the other hand, flow- than volume-oriented incentive spirometry. Possible reasons oriented incentive spirometry has shown 43% of change with for flow-oriented incentive spirometry showing better higher statistical significance in maximal expiratory pressure improvement are as follows: (a) there is visual feedback with when compared to diaphragmatic breathing exercise and this device, and it is easy to follow, which motivates the volume-oriented incentive spirometry. patient and thereby increases the adherence to this device. Our study is in agreement with Britto et al., where they Earlier studies have already highlighted that the flow- found a 50.7% increase in maximal inspiratory pressure after oriented incentive spirometry device does not facilitate the eight weeks of inspiratory muscle training in chronic stroke. diaphragm but causes increased use of accessory muscles of A similar study that gave inspiratory training to one group of the rib-cage. It also imposes more significant work of stroke patients and expiratory muscle training to another 39,40 breathing in this device. We postulate that the mechanism group found 55% and 38% improvement from baseline, by which it was useful primarily in the stroke population is respectively, in maximal inspiratory pressure values and 47% that as there is the weakness of the abdominal muscle and and 32% improvement in maximal expiratory pressure after respiratory muscles, the affected side of hemi diaphragm is four weeks of training. A study that provided high-intensity 240 Annals of Neurosciences 27(3-4) home-based respiratory muscle training also found 62% Ethical Statement improvement in inspiratory muscle strength and 68% in that This study was conducted after receiving approval from the of expiratory muscles. Institutional Ethics Committee, Kasturba Medical College Stroke not only involves upper and lower extremities but Mangalore, Manipal Academy of Higher Education (IEC KMC MLR also affects the trunk and pulmonary musculature. The 11-18/414), and registered with Clinical Trials Registry of India abdominal muscles contribute to diaphragmatic action and play (CTRI/2018/12/016651). an essential role during inspiration, for maintaining abdominal wall tonus. Abdominal muscles help diaphragm function in a Funding more favorable position on its length-tension curve. Stroke The authors received no financial support for the research, leads to weakness of the abdominal muscles, which may affect authorship, and/or publication of this article. this synergy by weakening the capacity of the diaphragm to generate negative force. The decline of maximal inspiratory ORCID iDs pressure in stroke according to a previous study includes Stephen Rajan Samuel https://orcid.org/0000-0002-4744-0180 weakness of the expiratory muscles and may influence the effectiveness of coughing and the airway clearance reduction Sampath Kumar Amaravadi https://orcid.org/0000-0002-4744-0180 thus increasing the risk of aspiration. We recommend further studies that may evaluate the molecular and genetic mechanisms References behind the changes elicited in our study. 1. Mozaffarian D, Benjamin EJ, Go AS, et al. Executive summary: Heart disease and stroke statistics-2016 update: A report from the American Heart Association. Circulation 2016; 133: 447– Conclusion 2. Jandt SR, da Sil Caballero RM, Junior LA, et al. 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Annals of Neurosciences – SAGE
Published: Jul 1, 2020