Effect of Incentive Spirometry in Subjects with Snoring

Introduction

Snoring is the vibratory sound generated from the upper airway due to partial upper airway obstruction resulting from the narrowing that occurs during sleep.¹ Upper airway size also has a dependence on lung volume, with decreasing airway size as lung volume decreases.² The intensity of snoring depends on the velocity of the airflow, and its other sound characteristics on density, elasticity and size of the vibrating parts.

Snoring is favored by aging because of the increased flaccidity of oropharyngeal muscles and instability of breathing.³ Weight gain is a risk factor for snoring in all age groups.⁴

Evidence suggests that snoring may increase in severity over time, leading to obstructive sleep apnea (OSA) and its physiological abnormalities.⁵ OSA is the most common sleep disorder causing excessive daytime sleepiness, elevated risk of cardiovascular diseases and numerous other serious health consequences leading to reduced quality of life and increased medical cost.⁴ The physiological responses to OSA are triggered mainly by the reduction of PaO2 . The respiratory and autonomic changes that occur during each acute obstructive apnea episode are peripheral vasoconstriction, heart rate and blood pressure variability.⁶

Encouraging weight loss in those with a body mass index (BMI) > 25 kg/m2 is often effective in treating snoring patients.⁷ Nasal Continuous Positive Airway Pressure (NCPAP) is undoubtedly very effective, but the wellknown problems with it are compliance issues due to the discomfort of wearing the device and to some extent the noise of the machine.⁸

A Sustained Maximal Inspiration with incentive spirometry is functionally equivalent to performing a functional residual capacity to inspiratory capacity maneuver, followed by a breath hold.⁹ Air can be coaxed into poorly ventilated regions by interspersing every few deep breaths with breath-holds for a few seconds at full inspiration. This distributes air more evenly between lung segments and boosts collateral ventilation.¹⁰ Once inflated, alveoli stay open for about an hour at normal tidal breaths, so it is advisable to do at least 10 deep breaths every waking hour to maintain lung volume.¹¹

Deep breathing has shown benefits like increase in lung volume and ventilation, decrease in airways resistance and surfactant secretion, thereby improving lung compliance with increase in VA/Q matching, decrease in dead space ratio, increase in diffusion and oxygen saturation.¹¹

CPAP and incentive spirometry increases lung volume by increasing trans-pulmonary pressure gradient.⁹ Hence, the study was intended to incorporate incentive spirometry as a regular exercise in subjects with snoring, thereby decreasing the risk of OSA and cardiovascular diseases.

Materials and Methods

Source of Data: Self-reported snoring volunteers from Bangalore

Method of collection of data

• Population : Subjects with self-reported episodes of snoring

• Sampling : Convenience sampling

• Sample size : 30

• Type of Study : Experimental

• Duration of the study : 6 months

Inclusion Criteria

• Subjects with self-reported episodes of snoring

• Age group between 20-60 years

• Both the genders (Male/Female)

Exclusion Criteria

• Subjects with cardiovascular diseases (Arrhythmia, Ischemic heart disease, Hypertension, stroke)

• Subjects with respiratory diseases (Chronic obstructive pulmonary disease, pneumonia)

• Obese individuals

• Subjects on medication that induces sleep

• Subjects with alcohol abuse

• Subjects with thyroid disorder

Materials Required

• Incentive spirometry (tri flow)

• Pulse oximeter

• Paper

• Pen/pencil

• Google form

Procedure

• Phone numbers and email addresses were collected from known sources to communicate and find out if any of the contacts would volunteer for a post graduate research study. An online google form was created which consisted of self-administered questionnaire on snore outcome survey and sent to the above volunteers through email, phone number, messenger and WhatsApp at various locations in Bangalore. Participants who volunteered for the study were required to complete the google form and fulfill the inclusion criteria for the study.

• An appointment with the volunteers was fixed and the objectives of the study were explained.

• Informed consent was obtained from the subjects that met the inclusion and exclusion criteria for the study to be carried out.

• The test procedure was explained to the subjects once the approval was received.

• They were assigned to a single group based on convenient sampling.

• Pre-test values of overnight SPO2 and Snore Outcome Survey (SOS) questionnaire were recorded.

• Incentive spirometry training to the subjects was provided.

• Post-test values of overnight SPO2 and snore outcome survey questionnaire were recorded.

Treatment protocol

Incentive Spirometry:

• Flow oriented incentive spirometer (Tri-flow) was given to the subjects.

• Subjects were instructed to hold the spirometer in an upright position, exhale normally, and then place the lips tightly around the mouthpiece.

• The next step was a slow inhalation to raise the ball (flow-oriented) in the chamber to the set target.

• At maximum inhalation, the mouthpiece was removed, followed by a breath-hold and normal exhalation.

• Subjects were instructed to perform the incentive spirometry exercise four sessions a day, with a repetition of 10 deep breaths per session, with breath hold of 3-5 seconds for four weeks.

• Subjects were instructed to perform one session of exercise before going to bed.

• Subjects were instructed to perform incentive spirometry exercise at least one hour after the meal.

• Subjects were instructed to maintain a diary to record the daily session.

Data Analysis

The data was carefully collected on baseline characteristics and outcomes measures. The statistical software Statistical Package for the Social Sciences (SPSS) version 20.0 was used to analyze the data. The level of significance was set at 5% (i.e., α = 0.05).

The following statistical techniques were used:

• The frequency and percentage of the demographic data of the subjects were described

• The Unpaired t-test was used to describe the significant differences in age between the two genders among the subjects i.e. Male and Female

• The Unpaired t-test was used to describe the significant differences in BMI between the two genders among the subjects i.e. Male and Female

• The Paired t-test was used to describe the significant differences in the outcome measure i.e. overnight recording of SpO2 between the Pre-and Post-Test

• The Wilcoxon test was used to describe the significant differences in the outcome measure i.e. SOS between the Pre-and Post-Test

• The MS Word and MS Excel software was used to generate the tables and graphs

Results

A total 30 subjects were included in the study; 18 (60%) were male subjects and 12 (40%) were female subjects. The mean age of the subjects with standard deviation was 36.89±13.93 for males and 31.58±10.09 for females. The Unpaired t-test (t=3.467) was carried out to compare the means of the age of male and female subjects, which was found to be non-significant at 5% level (p>0.05) (Table 1). Seventeen subjects were in the age group of 20-30 years and six subjects were in the age group of 50-60 years.

Table 2 shows the mean and standard deviation of the BMI of the male and female subjects. Mean and standard deviation of the BMI of male subjects was 26.73±1.31 and female subjects was 25.06±2.78. The Unpaired t-test (t=1.88) was carried out to compare the means and standard deviations of BMI of male and female subjects, which was found to be non-significant at 5% level (p>0.05).

Table 3 shows the mean and standard deviation (SD) of the pre-test and post-test scores of the outcome measures (overnight recording of SPO2 and SOS) of the subjects. Number of the subjects at the start of the study were 30 and at the end of the study were 27, with three dropouts.

In pre-test, the mean and SD of the overnight recording of the SPO2 was 96.59±2.67 with the range of 85.36- 99.81. But in post-test, it increased to the range of 87.25- 99.69 with the mean and SD of 96.87±2.67. Paired t-test (t=1.425) was carried out to compare the mean and SDs of pre-test and post-test scores, which were found to be non-significant (p>0.05).

In pre-test, the mean and SD of the Snore Outcome Survey Questionnaire (SOS) was 14.80±4.85, with the range of 7-24. But in the post-test, it decreased to a range of 5-24 with the mean and SD of 12.69±5.13. The Wilcoxon test (z=4.065) was carried out to compare the mean and standard deviations of pre-test and posttest scores, which were found to be highly significant (p<0.001).

Discussion

The study aimed to evaluate the effect of incentive spirometry in subjects with snoring. Habitual snoring is common in the population, its overall prevalence increases with age and is higher in males (35–45%) than females (15–28%). ¹² In the present study, a total 30 subjects were included, among which 18 (60%) were males and 12 (40%) were females. Male subjects with self reported snoring were more compared to female subjects. This male predominance among snorers can probably be explained by gender differences in the upper airway anatomy and difference in hormonal affects. These results were in agreement with the studies conducted by Chuang et al., in Taiwan and Patel et al., in California.^13,14 Men have longer upper airways and this is believed to predispose them to pharyngeal collapse. Minal patel et al., conducted a study to assess the prevalence of snoring in 2200 college students. 30% of the participants reported snoring and the prevalence of snoring was higher among men than women (42% and 25%, respectively). In a survey by Pasha and Khan, out of 111 Pakistani medical students, it was found that 27% men and 12% women reported snoring.¹⁵ Wasan J AlAni, Mary Mohammed Sabri and Wafaa Hamad Saleh conducted a study to determine the prevalence of snoring in 300 subjects and to find the associative factors related to it, such as socio- demographic characteristics, smoking, alcohol, obesity, nasal problems, some chronic diseases, drugs and family history. They found a statistically significant association between snoring and male sex, obesity, smoking, heavy work, family history and nasal trauma.¹⁶ Roi Westreich et al., has a different opinion on male dominance over snoring. They conducted a study to determine whether self-reported snoring and snoring intensity by women and men correlates with snoring volume measured objectively during sleep laboratory study on 1,913 subjects. They reported no difference in snoring intensity between the genders and also observed that women tend to underreport the fact that they snore and underestimate the loudness of their snoring.¹⁷

In the present study, the age of the subjects ranged between 20-60 years. Six subjects were in the age group of 51-60 years, whose BMI, SOS scores was higher and SpO2 was lower than the younger age group. Studies showed that snoring rate increases with age and it was more frequent in the older age group of 51-60 years. Kara et al., in Turkey and Sogebi et al., in Nigeria also found that snoring increases with age and its prevalence is greatest in the fifth and sixth decades of life. Snoring is favored by aging because of the increased flaccidity of oropharyngeal muscles and instability of breathing.³ The American insurance industry categorizes snoring, absence of neurocognitive consequences, as a social nuisance and not a medical condition. However, habitual snoring causes major psychological effects to the patients.¹⁴ Chang Hu Lee et al., conducted a study to evaluate the incidence and characteristics of emotional and behavioral problems using outpatientbased psychological screening tools in the children with habitual snoring. Their findings suggested that the presence of habitual snoring in young children is associated with wide spectrum of behavioral problems and the level of psychological distress.¹⁸ In the present study, 17 out of 30 subjects were in the age group of 20-30 years, among which 11 were college students. In response to the question, “During the past 4 weeks, how much did your snoring interfere with your normal sleep and level of your energy?”, almost 60% of the subjects responded as “a little bit” and “moderately”. Sleep deprivation is common in this age group due to demanding study or work schedules, together with irregular sleeping patterns.¹⁹ Prolonged partial sleep deprivation may have effect on snoring time, apneic events and decrease in oxygen saturation.²⁰

Twenty-two out of 30 participants were overweight i.e. BMI (25-29.9) kg/m2 , mean and SD of the BMI was 26.73±1.31 in males and 25.06±2.78 in female subjects; there was no significant difference in BMI between the genders. Obesity is considered a risk factor for snoring. Interrelation between obesity and snoring was clarified as obesity-neck circumference-upper airway patency. Recently, there have been reports that neck circumference and/or body fat proportion are more important factors for snoring and sleep apnea than BMI itself.21 Although we did not assess the neck circumference, this study showed the relationship between higher BMI and severity of snoring. Fat deposition around the neck tends to compress the airway and compromise the lumen size which results in snoring. Subjects with BMI <25 kg/m2 had higher overnight recording of oximetry i.e. 97.42% pre-test and 97.94% post-test in comparison to subjects with BMI >25 kg/m2 i.e. 96.28% pre-test and 96.42% post-test. Similarly, the score of SOS questionnaire was higher in the subjects with higher BMI group i.e. BMI>25 kg/m2 . Catherine et al., found out that regular aerobic exercises improves symptoms of sleep-disordered breathing in overweight children, as has been shown in adults.²²

Our subjects did not have any kind of co-morbidities like cardiovascular diseases, respiratory diseases, and obesity. SDB and OSA have wide-ranging effects that can predispose individuals to coronary artery disease, hypertension, stroke, and metabolic diseases in addition to the significant adverse effects on Quality of Life (QOL) related to symptoms of chronic daytime fatigue and excessive somnolence. ²³ Subjects in our study never complained of these symptoms. Paired t- test (t=1.425) was carried out to compare the mean and SDs of pretest and post-test scores of overnight recording of SpO2 , which was found to be non-significant (p>0.05). Oxygen saturation levels below 90% were considered harmful. Usually, treatment is directed at correcting the apnea, which will in turn prevent hypoxemia.²⁴ Mean and SD of SpO2 pre-test was 96.59±2.88 and post-test was 96.87±2.67. The pre- test value of SpO2 was already at the normal range and change in the post test value of SpO2 was found negligible. Most of the subjects were young, healthy, without any respiratory and metabolic disorders. This may be a reason for good oxygen saturation. This is supported by a study conducted by J. Rogelio et al., on young, asymptomatic, healthy, light snorers in the age group of 25-34 years who found no changes in Sa02, HR, or breathing pattern during snoring.²⁵

The lowest recorded SpO2 value was 85.36% in one female subject with the BMI of 29 kg/m2 . Her ODI (Oxygen Desaturation Index) was 60 events per hour; ODI ≥31 is considered as severe OSA. She was advised to take the CPAP as the treatment by her physician, but she opted to give a try on incentive spirometer as she did not feel comfortable with CPAP. Post-test recorded value was 87.25%, which was still below the normal range and her ODI was 56 events per hour, which was still above the normal range. Her high BMI could be a reason for severity. FRC (Functional Residual Capacity) is reduced in obese individual, lower FRC is associated with lower oxygen stores before a respiratory event. Low oxygen stores at the start of apnea and ventilationperfusion mismatch, both contribute to a more rapid and more severe drop in the SaO2 during apnea or reduced ventilation (hypopnea).²⁶ The rate of fall in the SaO2 is inversely proportional to the baseline SaO2 and to the lung volume (oxygen stores). The rate of fall is disproportionately higher at low lung volumes secondary to increases in ventilation-perfusion mismatch.

The incentive spirometry increases lung volume and maintains the saturation. Air can be coaxed into poorly ventilated regions by interspersing every few deep breaths with breath-holds for a few seconds at full inspiration. This distributes air more evenly between the lung segments and boosts collateral ventilation.10 Some studies supporting the beneficial effects of incentive spirometry are discussed here. Daehwan Moon, KyeHa Kim, Seogki Lee conducted a study to examine the effects of deep breathing with Incentive Spirometer on pulmonary function and O2 saturation by time process in patients with rib fracture. Pulmonary function and O2 saturation were measured by using micro spirometer and pulse oximeter at admission and at 1 day, 2 day, 3 day, 4 day, 5 day and 6 days after applying intervention. The level of pulmonary function and oxygen saturation after applying deep breathing with incentive spirometer were increased with time.²⁷ Hazem Mohamed Yasin Abbais, Samah Mahmoud Ismail, Emad Mohamed Ibrahim, Gomma Abdel-Razkahmed conducted a study to analyze the effect of incentive spirometer on oxygen saturation in patients in ICU. Forty male patients with renal failure grade II were selected from intensive care unit department. They were assigned to two groups (A and B) equal in number. Twenty patients in Group A received Incentive spirometer and traditional physiotherapy (circulatory ex, early mobilization and turning) and their routine medical treatment, while 20 patients in Group B received traditional physiotherapy and their routine medical treatment. It was found out that the effect of Incentive spirometer and early mobilization was better than the effect of early mobilization alone.²⁸

The Wilcoxon test (z=4.065) was carried out to compare the mean and standard deviations of pre-test and post-test scores of Snore Outcome Survey (SOS) questionnaire, which was found to be highly significant (p<0.001). Our results demonstrated clinically significant improvement in SOS scores. The mean and SD had decreased from 14.80±4.85 to 12.69±5.13 in the period of four weeks. SOS included a total of eight questions and the maximum score was 32. The SOS questionnaire score had improved i.e decreased after the four weeks practice of incentive spirometery.

In SOS questionnaire, as the response for the question, “In the past 4 weeks, when you have been asleep, to the best of your knowledge do you snore?”, 40%, 20%, 36% had responded as “most of the time”, “all the time” and “a little of bit” respectively. This shows the subjects were mixed in terms of frequency in snoring in pre-test. Post-test response was 40%, 7%, 48% as “most of the time” , “all the time” and “a little of bit” respectively. The frequency of snoring had decreased in the post-test results. The response for the next question “How would your spouse/bed partner describe your snoring?”, 33%, 30%, 23% had reponded as “very loud”, “somewhat loud” and “soft or quite” in pre-test and 18%, 14%, 52% in post-test respectively. Spouse/bed partner’s response to the intensity of snoring over the period of four weeks had changed. “Does your snoring annoy or bother your spouse/bed partner?” and in response to this question, 30%, 23%, 16%, 7% had responded as “moderately”, “a little bit”, “quite a bit” and “extremely (sleeps in the other room)” in pre-test and 22%, 30%, 15%, 4% in post-test respectively. Bed partners/spouse of the subjects were disturbed by the sound of their snoring moderately. This shows that the partners were also at the risk of developing some health hazards. Women living with snorers are more likely to report daytime sleepiness, morning headache, and fatigue than women living with non-snorer.²⁹ Virkkula et al., illustrated that 55% of bed partners were regularly disturbed by snoring. Of the affected bed partners, 40% slept in separate bedrooms at least once a week, and 26% used aids like sleeping pills, ear plugs, or both. Relationship problems caused by the bed partner’s snoring were reported by 35% of the sample.³⁰ Another study revealed a significant improvement in the quality of life of the patients as well as in that of their bed partners after successful treatment for snoring.³¹ In this study, severity of annoyance had decreased in the course of treatment sessions, which inturn improved the quality of life of the subjects and their spouse/bed partner as described in the earlier studies. 

In response to one of the question, “please describe when you snore”, 33%, 36%, 13% had responded as “I snore most of the time”, “I snore only in certain positions”, “I snore very rarely” in pre-test and 33%, 40%, 26% in post-test respectively. Response for “I snore very rarely” had increased, but for “I snore only in certain positions” had increased post-test. We failed to ask about the sleeping positions of the subjects, although it is one of the predisposing factors for snoring. Many studies stated that positions during the sleep play vital role in occurance and absence of snoring. The major causes of upper airway obstruction are the tongue and the soft palate falling backwards due to gravity, the mouth being open, and muscle relaxation.²⁹ Braver et al., described a combined group of 20 apneic and non-apneic snorers for whom it was not a change in sleep position, but rather weight reduction that had a positive effect on their snoring.³² Nakano et al., found out that most non apneic snorers snore less in a lateral position than in a supine one, whereas OSA patients snore to the same extent regardless of their position.³³ Koutsourelakis et al., also observed in a group made up of 77 apneic and 27 non apneic snorers, that both snoring intensity and snoring frequency were higher in the supine position when compared to lateral one.³⁴

Alisa Yamasaki, Patricia A Levesque and Robin W Lindsay conducted a study to characterize longitudinal snoring symptoms and nasal obstruction after functional nasal surgery for patients with SDB, stratified by history of snoring or obstructive sleep apnea (OSA). This study supports the use of SOS as a cost-effective method for monitoring postoperative snoring-related QOL for patients with SDB and provides QOL outcomes data to assist with perioperative counseling.²³ In SOS questionnaire, higher the score, higher the severity and lower the score, lower the severity. Although there are limitations for patient reported outcome measure, selfreported snoring is a practical way to determine patients’ own perceptions of their snoring and, most importantly, to probe the Quality of Life (QOL) impact of their snoring symptoms.

During the follow up for the post experimental recordings, three of the subjects did not participate in the study. Two of the participants did not respond to the phone call and one of the participants was out of the town.

Limitations

In this study, the short-term effects of the intervention could be assessed. However, due to limited time duration of dissertation, the long-term effects could not be further identified. The variables like neck circumference, upper airway examination and sleeping posture were not recorded in our study.

Recommendations

Subjects with more severity should have been included in the study. Future studies can be performed in the specific age group i.e. only old age/young age group to see the age specific effects. Although we had included some questions related to subject’s partner response to their snoring, direct participation of the subject’s partner would have helped to gain information from their aspect. The study can be performed in larger population to further validate the generalization of study result.

Conclusion

The study was aimed to evaluate the effect of Incentive spirometry in the subjects with snoring. This study concluded that the effect of incentive spirometry in subjects with snoring was not statistically significant but clinically significant. The practice of incentive spirometry exercise four sessions a day, with repetition of 10 deep breaths per session, with breath hold of 3-5 seconds for four weeks, in subjects with self-reported snoring with less severity did not show much effects on the overnight oxygen saturation. However, the patient reported outcome measure i.e. SOS questionnaire showed significant improvement after the practice of incentive spirometer exercise for four weeks in terms of quality of life.

Conflict of Interests

Declared.