Snoring

Mandibular Advancement vs Combined Airway and Positional Therapy for Snoring: A Randomized Clinical Trial

Importance

Approximately 150 million individuals in the US snore in the absence of obstructive sleep apnea (primary snoring), but few studies have examined the efficacy of treatments for snoring or evaluated the effect of snoring in sleeping partners.

Objective

To evaluate the efficacy of 2 treatments for primary snoring.

Design, Setting, and Participants

This pilot randomized clinical trial that included a convenience sample of people who snore without sleep apnea and their sleeping partner who underwent 4 weeks of snoring treatment was conducted at an academic medical center between October 3, 2022, and July 3, 2023.

Interventions

Fifty couples were randomized to either use a mandibular advancement device (MAD) or receive combined airway and positional therapy (CAPT; external nasal dilator, nasal saline lavage with mometasone, mouth taping, and lateral positional therapy).

Main Outcome and Measure

Percentage of sleeping partners who reported that their partner's snoring was either very much improved or much improved (responder) on the Clinical Global Impression of Improvement scale.

Results

A total of 42 dyads completed the study; 23 (55%) were randomized to MAD and 19 (45%) to CAPT. Among people who snore, 26 (62%) were female, and the mean (SD) age was 48 (14) years. Of 23 dyads randomized to MAD, 21 people who snore (91%) were rated by the sleeping partner as a responder, while 11 of the 19 dyads (58%) randomized to CAPT were rated by the sleeping partner as responder, resulting in a difference of 33 percentage points (95% CI, 8-58) and a number needed to treat of 3. Of the 10 participants who were withdrawn, 4 were withdrawn due to adverse effects of the treatment that were evenly distributed between the MAD (n = 2) and CAPT (n = 2) groups.

Conclusion and Relevance

The results of this randomized clinical trial showed that the MAD may be more effective than CAPT for treating primary snoring, while both treatment options were found to reduce primary snoring. Physicians should have a patient-centered discussion to determine which treatment is best for individual patients with primary snoring, weighing convenience, adverse effects, and cost as factors.

Trial Registration

ClinicalTrials.gov Identifier: NCT05756647.

Automatic snoring detection using a hybrid 1D-2D convolutional neural network

Snoring, as a prevalent symptom, seriously interferes with life quality of patients with sleep disordered breathing only (simple snorers), patients with obstructive sleep apnea (OSA) and their bed partners. Researches have shown that snoring could be used for screening and diagnosis of OSA. Therefore, accurate detection of snoring sounds from sleep respiratory audio at night has been one of the most important parts. Considered that the snoring is somewhat dangerously overlooked around the world, an automatic and high-precision snoring detection algorithm is required. In this work, we designed a non-contact data acquire equipment to record nocturnal sleep respiratory audio of subjects in their private bedrooms, and proposed a hybrid convolutional neural network (CNN) model for the automatic snore detection. This model consists of a one-dimensional (1D) CNN processing the original signal and a two-dimensional (2D) CNN representing images mapped by the visibility graph method. In our experiment, our algorithm achieves an average classification accuracy of 89.3%, an average sensitivity of 89.7%, an average specificity of 88.5%, and an average AUC of 0.947, which surpasses some state-of-the-art models trained on our data. In conclusion, our results indicate that the proposed method in this study could be effective and significance for massive screening of OSA patients in daily life. And our work provides an alternative framework for time series analysis.

Smart Devices Are Poised to Revolutionize the Usefulness of Respiratory Sounds

The association between breathing sounds and respiratory health or disease has been exceptionally useful in the practice of medicine since the advent of the stethoscope. Remote patient monitoring technology and artificial intelligence offer the potential to develop practical means of assessing respiratory function or dysfunction through continuous assessment of breathing sounds when patients are at home, at work, or even asleep. Automated reports such as cough counts or the percentage of the breathing cycles containing wheezes can be delivered to a practitioner via secure electronic means or returned to the clinical office at the first opportunity. This has not previously been possible. The four respiratory sounds that most lend themselves to this technology are wheezes, to detect breakthrough asthma at night and even occupational asthma when a patient is at work; snoring as an indicator of OSA or adequacy of CPAP settings; cough in which long-term recording can objectively assess treatment adequacy; and crackles, which, although subtle and often overlooked, can contain important clinical information when appearing in a home recording. In recent years, a flurry of publications in the engineering literature described construction, usage, and testing outcomes of such devices. Little of this has appeared in the medical literature. The potential value of this technology for pulmonary medicine is compelling. We expect that these tiny, smart devices soon will allow us to address clinical questions that occur away from the clinic.

Reliability of parental reporting of child snoring in children referred for obstructive sleep apnea

Despite the high number of studies based on subjective reports of snoring, self-reported snoring has hardly been validated at all. As there is no "gold-standard" for objective snoring measurements, studies must evaluate whether the presence of snoring based on parental judgement is linked to objective measurements of nasal and/or pharyngeal obstruction in children referred for obstructive sleep apnea. A total of 146 children (median age 11 years) underwent polysomnography (with snoring recording using nasal cannula signal), acoustic rhinometry and pharyngometry, while their parents filled out the Spruyt-Gozal questionnaire assessing both frequency and loudness of subjective snoring. Three categories were further differentiated (null, low and high) for both frequency and loudness. The apnea-hypopnea index was significantly different in the three groups for both frequency (p = 0.04) and loudness (p = 0.01) of subjective snoring. Children in the low or high groups (frequency or loudness), compared with those in the null group, experienced a decline in both pharyngeal (sitting and supine positions) and nasopharyngeal (supine position) volumes (frequency, pharynx sitting: p = 0.03; supine: 0.005 and nasopharynx: p = 0.002; loudness, p = 0.03; p = 0.007 and p = 0.03; three group comparisons). Objective snoring frequency during the night obtained with cannula was weakly related to loudness of subjective snoring but not to subjective snoring frequency during the week, and was biased by nasal obstruction. In conclusion, our study showed that parental assessment of snoring is related to a reduction in both pharyngeal and nasopharyngeal volumes in snorers, arguing for the adequacy of their evaluation of both snoring frequency and loudness.

Efficacy of pillar implants to reduce snoring and daytime sleepiness

OBJECTIVE

To measure the efficacy of pillar implants in reducing snoring.

MATERIALS AND METHODS

A total of 30 adult patients who underwent pillar implants were assessed preoperatively and at 1, 3, 6 and 12 months after the implantation. Improvement was measured using snoring frequency, visual analog scale for snoring loudness, and Epworth sleepiness scale for daytime sleepiness.

RESULTS

The mean snoring frequency, loudness and Epworth score were reduced from 6.9, 9.2 and 7.4 at the baseline to 5, 5.9 and 5.6, respectively, at 12 months postoperatively (all p < 0.03). The partial implant extrusion rate was 6.7%.

CONCLUSION

We suggest that a pillar implant procedure should be considered before proceeding to more morbid surgeries in patients with snoring and daytime sleepiness.

Audio-based snore detection using deep neural networks

BACKGROUND AND OBJECTIVE

Snoring is a prevalent phenomenon. It may be benign, but can also be a symptom of obstructive sleep apnea (OSA) a prevalent sleep disorder. Accurate detection of snoring may help with screening and diagnosis of OSA.

METHODS

We introduce a snore detection algorithm based on the combination of a convolutional neural network (CNN) and a recurrent neural network (RNN). We obtained audio recordings of 38 subjects referred to a clinical center for a sleep study. All subjects were recorded by a total of 5 microphones placed at strategic positions around the bed. The CNN was used to extract features from the sound spectrogram, while the RNN was used to process the sequential CNN output and to classify the audio events to snore and non-snore events. We also addressed the impact of microphone placement on the performance of the algorithm.

RESULTS

The algorithm achieved an accuracy of 95.3 ± 0.5%, a sensitivity of 92.2 ± 0.9%, and a specificity of 97.7 ± 0.4% over all microphones in snore detection on our data set including 18412 sound events. The best accuracy (95.9%) was observed from the microphone placed about 70 cm above the subject's head and the worst (94.4%) was observed from the microphone placed about 130 cm above the subject's head.

CONCLUSION

Our results suggest that our method detects snore events from audio recordings with high accuracy and that microphone placement does not have a major impact on detection performance.

A New Feature with the Potential to Detect the Severity of Obstructive Sleep Apnoea via Snoring Sound Analysis

The severity of obstructive sleep apnoea (OSA) is diagnosed with polysomnography (PSG), during which patients are monitored by over 20 physiological sensors overnight. These sensors often bother patients and may affect patients’ sleep and OSA. This study aimed to investigate a method for analyzing patient snore sounds to detect the severity of OSA. Using a microphone placed at the patient’s bedside, the snoring and breathing sounds of 22 participants were recorded while they simultaneously underwent PSG. We examined some features from the snoring and breathing sounds and examined the correlation between these features and the snore-specific apnoea-hypopnea index (ssAHI), defined as the number of apnoea and hypopnea events during the hour before a snore episode. Statistical analyses revealed that the ssAHI was positively correlated with the Mel frequency cepstral coefficients (MFCC) and volume information (VI). Based on clustering results, mild snore sound episodes and snore sound episodes from mild OSA patients were mainly classified into cluster 1. The results of clustering severe snore sound episodes and snore sound episodes from severe OSA patients were mainly classified into cluster 2. The features of snoring sounds that we identified have the potential to detect the severity of OSA.

The Presence of Snoring as Well as its Intensity Is Underreported by Women

STUDY OBJECTIVES

Women are underrepresented and thus sleep conditions are underdiagnosed at sleep clinics that evaluate sleep-disordered breathing. The most common sign of obstructive sleep apnea (OSA) is snoring; therefore, it is one of the main red flags for suspected OSA. The aim of this study is to determine whether self-reported snoring and snoring intensity by women and men correlates with snoring volume measured objectively during sleep laboratory study.

METHODS

Consecutive patients who were referred to a polysomnography (PSG) study in a university hospital over a 2-year period had their snoring volume quantified by means of a calibrated digital sound survey meter. Participants were given a questionnaire in which they were asked to rate the severity of their snoring. The correlation between objective snoring intensity as measured during PSG and the self-reported snoring intensity was evaluated.

RESULTS

A total of 1,913 patients were enrolled in the study. A positive correlation was found between objectively measured snoring intensity and the intensity listed by each participant in the questionnaire. Measurement of the volume of snoring revealed that women snored as loudly as men; however, 28% of the females (189/675) considered themselves to be nonsnorers compared to only 6.9% of men (P < .05). Furthermore, 36.5% of women (69/189) who reported themselves as nonsnorers turned out to have severe or very severe snoring intensity, whereas, in contrast, only 11.7% of men (10/85) of men had this discrepancy. These findings are in concordance with the finding that fewer women quantified their snoring as very severe or severe (38.4%), significantly less than men of whom 61.5% reported their snoring to be severe or very severe.

CONCLUSIONS

In a population of individuals referred to a PSG study, although no difference in snoring intensity was found between sexes, women tend to underreport the fact that they snore and to underestimate the loudness of their snoring. Improved awareness of this discrepancy may increase women's access to sleep laboratories, and improve diagnostic rates of sleep apnea in females.

Smoking and Improvement after Nasal Surgery in Snoring Men

Background

The aim of this study was to compare subgroups of smokers and nonsmokers undergoing nasal surgery and to evaluate improvement of nasal stuffiness, snoring, and symptoms related to sleep-disordered breathing after nasal surgery.

Methods

A cross-sectional prospective study was performed. The study population included 40 consecutive snoring men scheduled for surgical treatment of nasal obstruction. The patients completed nasal and sleep questionnaires, an Epworth sleepiness scale, and a visual analog scale of snoring intensity. They underwent polysomnography, anterior rhinomanometry, acoustic rhinometry, and cephalometric analysis.

Results

The smokers were younger, they snored longer and louder, and they had higher nasal resistance with decongestion and longer soft palates than the nonsmokers. Nasal stuffiness improved well after surgery, but a decrease of nasal resistance was not related to improvement of subjective snoring.

Conclusion

Smoking was associated with increased snoring, nasal obstruction, and pharyngeal soft tissue volume. Expectations of patients may influence subjective assessment of snoring after nasal surgery.

Sleep positions and nocturnal body movements based on free-living accelerometer recordings: association with demographics, lifestyle, and insomnia symptoms

BACKGROUND

In order to establish normative values for body positions and movements during sleep, the objective of this study was to explore the distribution of sleep positions and extent of nocturnal body moments and the association with sex, age, body-mass index (BMI), smoking, alcohol consumption, and insomnia symptoms.

MATERIALS AND METHODS

This cross-sectional study comprised data on a working population (363 men and 301 women) who participated in the Danish Physical Activity Cohort with Objective Measurements (DPHACTO). Measures of body position and movements were obtained from actigraph accelerometers on the thigh, upper back, and upper arm. Linear regression was used to estimate adjusted mean differences in movements among categories of demographic and lifestyle characteristics.

RESULTS

During their time in bed, participants spent 54.1% (SD 18.1%) in the side position, 37.5% (SD 18.2%) in the back position, and 7.3% (SD 12.3%) in the front position. Increasing age and BMI were associated with increased time in the side position and a proportional reduction in time in the back position. There were on average 1.6 (SD 0.7) position shifts per hour. Compared to males, females had fewer position shifts (-0.37, 95% CI -0.48 to -0.24) and fewer arm, thigh, and upper-back movements. Participants aged 20-34 years had more arm, thigh, and upper-back movements compared to participants ≥35 years. Obese participants had fewer shifts in body position (-0.15, 95% CI -0.27 to 0), but more arm, thigh, and upper-back movements compared to normal-weight participants. Smokers had fewer shifts in body position than nonsmokers (-0.27, 95% CI -0.4 to -0.13).

CONCLUSION

The predominant sleep position in adults is on the side. This preference increases with age and BMI. The extent of nocturnal body movements is associated with sex, age, BMI, and smoking.

Acoustic analysis of overnight consecutive snoring sounds by sound pressure levels

CONCLUSION

The sound pressure level (SPL) parameters, especially the A-weighted equivalent sound level (LAeq) and accumulative percentile sound level 10 (L10), were significantly different between simple snoring (SS) and obstructive sleep apnea-hypopnea syndrome (OSAHS). The apnea-hypopnea index (AHI) was the most significant factor to affect the SPLs of snoring sounds. LAeq and L10 were valuable acoustic characters of snoring which could reflect the severity of sleep disordered breathing in clinic.

OBJECTIVES

Due to the limitation of acoustic analysis of single snoring sound for snorers, this study analyzed characteristics of consecutive snoring sounds overnight by the SPLs in patients of SS and OSAHS.

METHOD

Ninety-four patients who underwent simultaneous SPL recording and polysomnography (PSG) were included in this study. Parameters of SPL such as LAeq, peak sound level (Lpeak), L10, L50, and L90 were analyzed. The correlation between these parameters and PSG results was also analyzed.

RESULTS

The LAeq and L10 in OSAHS patients were significantly different from patients with SS. The body mass index (BMI) was positively correlated to LAeq and L10. Among various factors of PSG data and demographic factors, the SPLs were mostly affected by the AHI and the lowest oxygen saturation (LSaO2).

Monitoring sound to quantify snoring and sleep apnea severity using a smartphone: proof of concept

STUDY OBJECTIVES

Habitual snoring is a prevalent condition that is not only a marker of obstructive sleep apnea (OSA) but can also lead to vascular risk. However, it is not easy to check snoring status at home. We attempted to develop a snoring sound monitor consisting of a smartphone alone, which is aimed to quantify snoring and OSA severity.

METHODS

The subjects included 50 patients who underwent diagnostic polysomnography (PSG), of which the data of 10 patients were used for developing the program and that of 40 patients were used for validating the program. A smartphone was attached to the anterior chest wall over the sternum. It acquired ambient sound from the built-in microphone and analyzed it using a fast Fourier transform on a real-time basis.

RESULTS

Snoring time measured by the smartphone highly correlated with snoring time measured by PSG (r = 0.93). The top 1 percentile value of sound pressure level (L1) determined by the smartphone correlated with the ambient sound L1 during sleep determined by PSG (r = 0.92). Moreover, the respiratory disturbance index estimated by the smartphone (smart-RDI) highly correlated with the apnea-hypopnea index (AHI) obtained by PSG (r = 0.94). The diagnostic sensitivity and specificity of the smart-RDI for diagnosing OSA (AHI ≥ 15) were 0.70 and 0.94, respectively.

CONCLUSIONS

A smartphone can be used for effectively monitoring snoring and OSA in a controlled laboratory setting. Use of this technology in a noisy home environment remains unproven, and further investigation is needed.

Effects of body mass index and adenotonsillar size on snoring sound intensity levels at highest power

OBJECTIVES

Snoring during sleep is a major clinical symptom of adenoid and tonsil hypertrophy in paediatric patients. The aim of this study was to determine the effects of adenoid and tonsil size on snoring sound frequency and intensity in children.

METHODS

Twenty-seven patients with adenotonsillar hypertrophy were included the study. Adenoid size was graded from 1+ to 4+ by rigid endoscopy. Patients were staged (I-III) according to body mass index (BMI) and tonsil and adenoid size. Snoring was recorded and analysed. The analysis focused on the highest power frequency (Fmax) and snoring sound intensity levels (SSILs).

RESULTS

SSIL and Fmax values for Stage III were significantly higher than those for Stages I and II. BMI for Stage III was higher than for Stages I and II, and that for Stage II was higher than for Stage I. The BMI, SSIL, and Fmax values increased at each stage and tonsil/adenoid grade.

CONCLUSIONS

SSIL seems to be related to Adenoid and Tonsils size and BMI. As stage increased, both Fmax and SSILs increased proportionally. Also, Fmax values shifted to higher frequencies. Physicians and parents should be aware of snoring, and be informed that a higher frequency and intensity may be related to obesity and/or adenotonsillar hypertrophy. Snoring analysis may be a useful tool for detecting cases of Adenoid and Tonsils hypertrophy and/or upper airway obstruction during sleep.

Automatic detection of whole night snoring events using non-contact microphone

Objective

Although awareness of sleep disorders is increasing, limited information is available on whole night detection of snoring. Our study aimed to develop and validate a robust, high performance, and sensitive whole-night snore detector based on non-contact technology.

Design

Sounds during polysomnography (PSG) were recorded using a directional condenser microphone placed 1 m above the bed. An AdaBoost classifier was trained and validated on manually labeled snoring and non-snoring acoustic events.

Patients

Sixty-seven subjects (age 52.5±13.5 years, BMI 30.8±4.7 kg/m², m/f 40/27) referred for PSG for obstructive sleep apnea diagnoses were prospectively and consecutively recruited. Twenty-five subjects were used for the design study; the validation study was blindly performed on the remaining forty-two subjects.

Measurements and Results

To train the proposed sound detector, >76,600 acoustic episodes collected in the design study were manually classified by three scorers into snore and non-snore episodes (e.g., bedding noise, coughing, environmental). A feature selection process was applied to select the most discriminative features extracted from time and spectral domains. The average snore/non-snore detection rate (accuracy) for the design group was 98.4% based on a ten-fold cross-validation technique. When tested on the validation group, the average detection rate was 98.2% with sensitivity of 98.0% (snore as a snore) and specificity of 98.3% (noise as noise).

Conclusions

Audio-based features extracted from time and spectral domains can accurately discriminate between snore and non-snore acoustic events. This audio analysis approach enables detection and analysis of snoring sounds from a full night in order to produce quantified measures for objective follow-up of patients.

Mean tracheal sound energy during sleep is related to daytime blood pressure

STUDY OBJECTIVES

The pathological role of snoring independent of obstructive sleep apnea remains under debate. The authors hypothesized that snoring sound intensity, as assessed by mean tracheal sound energy (Leq) during sleep, is related to daytime blood pressure.

DESIGN

Retrospective analysis of clinical records and polysomnography data.

SETTING

Sleep laboratory at a national hospital in Japan.

PATIENTS

Consecutive patients who underwent diagnostic polysomnography with suspicion of sleep apnea between January 2005 and December 2009 (n = 1,118).

INTERVENTIONS

Not applicable.

MEASUREMENTS AND RESULTS

Leq was calculated from tracheal sound spectra recorded every 0.2 sec during polysomnography. Daytime high blood pressure (HBP) was defined as taking antihypertensive drugs or having a systolic blood pressure ≥ 140 mm Hg or a diastolic blood pressure ≥ 90 mmHg at the patient's first clinical visit. Patient age, sex, body mass index, apnea-hypopnea index, alcohol consumption, and smoking were considered as confounders. Leq during sleep was associated with HBP after adjusting for all confounding factors (n = 1,074, P = 0.00019). This association was demonstrated even in nonapneic nonobese patients (n = 232, P = 0.012).

CONCLUSIONS

The association between snoring intensity, as assessed by mean sound energy, and blood pressure suggests a pathological role for heavy snoring. Further study in a general population is warranted.

Evaluation of position dependency in non-apneic snorers

The aims of this study are to determine the prevalence of position dependency in non-apneic snorers, as defined by the American Academy of Sleep Medicine (AASM) guidelines, and to investigate the influence of various factors such as BMI, neck circumference, age, gender, and sleep efficiency on sleeping position. A cohort of consecutive patients was screened for complaints of excessive snoring or symptoms suspicious for sleep disordered breathing. Overnight polysomnographic data were collected and non-apneic snorers who met all the inclusion criteria were selected for statistical analysis. To assess position-dependent snoring, the snore index (total snores/h) was used. Supine-dependent patients were defined as having a supine snore index higher than their total non-supine snore index. 76 patients were eligible for statistical analysis. Prevalence of position dependency in non-apneic snorers was 65.8% (p < 0.008). A stepwise regression showed that only BMI had a significant effect (p < 0.003) on the supine snore index. This is the first study that uses the AASM guidelines to accurately define non-apneic snorers (AHI < 5) and provides scientific evidence that the majority of non-apneic snorers are supine dependent. Furthermore, these results show that non-apneic snorers with a higher BMI snore more frequently in supine position. The use of sleep position therapy therefore, has the potential to play a significant role in improving snoring and its associated physical and psychosocial health outcomes in this population.

The undervalued potential of positional therapy in position-dependent snoring and obstructive sleep apnea-a review of the literature

Purpose

Research during the past 10–20 years shows that positional therapy (PT) has a significant influence on the apnea–hypopnea index. These studies are predominantly performed as case series on a comparably small number of patients. Still, results have not found their way into the daily diagnostic and treatment routine. An average of 56 % of patients with obstructive sleep apnea (OSA) have position-dependent OSA (POSA), commonly defined as a difference of 50 % or more in apnea index between supine and non-supine positions. A great deal could be gained in treating patients with POSA with PT. The aim of this paper was to perform a thorough review of the literature on positional sleep apnea and its therapy.

Methods

A broad search strategy was run electronically in the MEDLINE and EMBASE databases using synonyms for position and sleep apnea.

Results

Sixteen studies were found which examined the effect of PT on OSA. In this literature review, we discuss the various techniques, results, and compliance rates.

Conclusion

Long-term compliance for PT remains an issue, and although remarkable results have been shown using innovative treatment concepts for PT, there is room for both technical improvement of the devices and for further research.

Four-year outcomes of palatal implants for primary snoring treatment: a prospective longitudinal study

OBJECTIVES/HYPOTHESIS

The objective of this study was to evaluate the long-term effectiveness of palatal implants as the treatment of primary snoring.

STUDY DESIGN

Prospective longitudinal cohort study.

METHODS

This study compared snoring outcomes before and after soft palate implantation for patients diagnosed with primary snoring (no sleep apnea). Snoring severity was obtained by the subjects' sleep partners on a 10-point Likert scale. A paired Student t test compared the mean scale values preoperatively at week 52 and at the current 4-year follow-up. Body mass index for each patient was also compared to evaluate for any significant confounders.

RESULTS

Data were obtained from 23 patients out of 26 who were followed for the full study term. The follow-up time was on average 4 years following palatal implantation. A statistically (P < .016) and clinically significant improvement in the snoring scale was noted when comparing snoring severity between the preoperative and 4-year period and between the 52-week and 4-year scores. Although statistically significant improvement was found between the preoperative period and 52 weeks, there was a clinical deterioration in snoring scale scores between 52 weeks and 4 years. The mean (standard deviation) preoperative score was 9.5 (0.5), mean week-52 score was 5.0 (1.6), and mean 4-year score was 7.0 (1.8). Body mass index did not change through the observation interval.

CONCLUSIONS

Soft palate implantation is a possible surgical technique with which to attempt to achieve subjective improvement of primary snoring severity. Subjective improvement, however, deteriorates significantly over time, and is only minimally sustained at 4 years postoperatively. This study provides new information on long-term palatal implant effectiveness.

Gender dependant snore sound based multi feature obstructive sleep apnea screening method

Obstructive Sleep Apnea (OSA) is a serious sleep disorder that occurs due to collapsing upper airways (UA). More than 80% of OSA sufferers remain undiagnosed and the situation demands simplified, convenient technology for community screening. Almost all OSA patients snore and snoring is the earliest nocturnal symptom of OSA. Snore signals (SS) are produced due to vibration of soft tissues in the narrowed parts of the UA. It is known that the UA properties are gender specific. In this paper, we work under the hypothesis that gender specific analysis of snore sounds should lead to a higher OSA detection performance. We propose a snore based multi-parametric OSA screening technique, which incorporates the gender differences in the algorithm. The multi feature vector was modeled using logistic regression based algorithms to classify subjects into OSA/non-OSA classes. The performance of the proposed method was evaluated by carrying out K-fold cross validation. This procedure was applied to male (n=51) and female (n=36) data sets recorded in a clinical sleep laboratory. Each data set consisted of sound recordings of 6-8 hr. duration. The performance of the method was evaluated against the standard laboratory method of diagnosis known as polysomongraphy. Our gender-specific technique resulted in a sensitivity of 93±9% with specificity 89±7% for females and sensitivity of 91±8% with specificity 89±12% for males. These results establish the possibility of developing cheap, convenient, non-contact and an unattended OSA screening technique.

Evaluation of the obstructive sleep apnea patient and management of snoring

This article provides a practical strategy for the systematic evaluation of the obstructive sleep apnea patient. The management of snoring is also discussed. The presented strategy is based upon review of the current literature, the principles set forth in the American Academy of Sleep Medicine clinical guideline publication, and the author's personal experience.

Analysis and modeling of snore source flow with its preliminary application to synthetic snore generation

With the emerging use of snore properties for clinical purposes, there is a need to understand the characteristics of snore source flow (SF)-the acoustic source in snore production. This paper attempts to analyze and model both SF and its derivative (SFD), along with its preliminary application to the generation of synthetic snores. SFs and SFDs were extracted from natural snores via an iterative adaptive inverse filtering approach, and subsequently parameterized into various time- and amplitude-based parameters to quantify the oscillatory maneuvers of snore excitation source (ES). The SF and SFD waveforms were also, respectively, modeled using the first and second derivatives of the Gaussian probability density function. Subjective and objective measures, including paired comparison score and sum-of-squared error, were assessed to appraise the performance of SFD model in producing natural-sounding snores. Results consistently show that: 1) the shapes of SF pulse are different among snores and can be associated with the dynamic biomechanical properties (e.g., compliance and elasticity) of ES; 2) changes to the SF or SFD pulse shape can affect the snore properties, both acoustically and perceptually; and 3) the proposed SFD model can generate close-to-natural sounding snores. Further research in this area can potentially yield valuable benefits to snore-oriented applications.

Investigation of obstructive sleep apnea using nonlinear mode interactions in nonstationary snore signals

Acoustic studies on snoring sounds have recently drawn attention as a potential alternative to polysomnography in the diagnosis of obstructive sleep apnea (OSA). This paper investigates the feasibility of using nonlinear coupling between frequency modes in snore signals via wavelet bicoherence (WBC) analysis for screening of OSA. Two novel markers (PF1 and PSF), which are frequency modes with high nonlinear coupling strength in their respective WBC spectrum, are proposed to differentiate between apneic and benign snores in same- or both-gender snorers. Snoring sounds were recorded from 40 subjects (30 apneic and 10 benign) by a hanging microphone, and subsequently preprocessed within a wavelet transform domain. Forty inspiratory snores (30 as training and 10 as test data) from each subject were examined. Results demonstrate that nonlinear mode interactions in apneic snores are less self-coupled and usually occupy higher and wider frequency ranges than that of benign snores. PF1 and PSF are indicative of apneic and benign snores (p < 0.0001), with optimal thresholds of PF1 = 285 Hz and PSF = 492 Hz (for both genders combined), as well as sensitivity and specificity values between 85.0 and 90.7%, respectively, outperforming the conventional diagnostic indicator (spectral peak frequency, PF = 243-275 Hz, sensitivity = 77.7-79.7%, specificity = 72.0-78.0%, p < 0.0001). Relationships between apnea-hypopnea index and the proposed markers could likely take the functional form of exponential or power. Perspectives on nonlinear dynamics analysis of snore signals are promising for further research and development of a reliable and inexpensive diagnostic tool for OSA.

[Smoking and sleep disorders]

Snoring and sleep apnea-hypopnea syndrome (SAHS) are two disorders of considerable relevance due to their high prevalence in the general population and their notable morbidity and mortality, particularly in association with their harmful effects on the cardiovascular system. As well as sex, age, weight, craniofacial malformations, alcohol consumption, and use of hypnotic drugs, it has been suggested that smoking may be a risk factor for developing sleep-disordered breathing. While there is solid evidence for the independent association between snoring and smoking in both children and adults, it is still unclear whether smoking constitutes an independent risk factor for developing SAHS, despite the many studies carried out to assess this link. This is probably because the association, if it exists, is very weak.

Ronco habitual e apnéia obstrutiva observada em adultos: estudo de base populacional, Pelotas, RS

OBJETIVO: Estimar a prevalência de ronco habitual e apnéia obstrutiva observada e fatores associados. MÉTODOS: Estudo transversal com amostra representativa de 3.136 adultos, com 20 anos ou mais, residentes em Pelotas, Rio Grande do Sul, em 2005. Informações sobre os desfechos e variáveis demográficas, socioeconômicas, comportamentais e antropométricas foram coletadas por meio de questionário. A análise estatística bruta e ajustada foi realizada utilizando-se teste exato de Fisher ou qui-quadrado de tendência linear e regressão de Poisson, respectivamente. RESULTADOS: A prevalência encontrada de ronco habitual foi de 50,5% (IC 95%: 48,1;52,8) e de apnéia obstrutiva de 9,9% (IC 95%: 8,7;11,2). Na análise ajustada, o relato de ronco foi maior nos homens (Razão de Prevalências - RP=1,25; IC 95%: 1,16;1,34), nos idosos (RP=1,62; IC 95%: 1,46;1,80), nos tabagistas (RP=1,15; IC 95%: 1,07;1,25), nos alcoolistas (RP=1,17; IC 95%: 1,03;1,31) e nos obesos (RP 1,71, IC95% 1,55;1,88). O relato de apnéia obstrutiva foi maior nos homens (RP=2,05; IC 95%: 1,67;2,52), nos idosos (RP=2,23; IC 95%: 1,64;3,03), nos tabagistas (RP=1,60; IC 95%: 1,25;2,05) e nos obesos (RP=2,61; IC 95%: 1,97;3,47). CONCLUSÕES: Ronco habitual e apnéia obstrutiva foram sintomas comuns na população estudada. Fatores de risco conhecidos como sexo masculino e idade entre quarta e quinta décadas de vida não são modificáveis. Entretanto, tabagismo, alcoolismo e obesidade também associados aos desfechos, devem ser identificados e tratados na população geral.

Feature extraction for snore sound via neural network processing

Snore sound (SS) is the earliest and the most common symptom of Obstructive Sleep Apnea (OSA) which is a serious disease caused by the collapse of upper airways during sleep. SS should carry vital information on the state of the upper airways and is simple to acquire and rich in features but their analysis is complicated. In this study we use neural network (NN) based method to model SS via a simple second order one-step predictor. We show that the some hidden information/feature of a SS can be conveniently captured in the connection-weight-space (CWS) of the NN, after a process of supervised training. The availability of the proposed method is investigated by performing independent component analysis (ICA) on CWS.

The effect of pharyngeal soft tissue components on snoring

OBJECTIVE

To determine the effect of oropharyngeal air column area, parapharyngeal fat pad thickness, pterygoid muscle thickness, and parapharyngeal wall thickness on snoring.

MATERIALS AND METHODS

Fifty-six individuals (35 men, 21 women) complaining of snoring in a questionnaire administered to patients attending the MR unit for cervical MR imaging were enrolled as the study group, and 39 (23 men, 16 women) individuals with no complaint of snoring were enrolled as the control group. Firstly, patients' body mass index (BMI) was determined. Then turbo spin echo T2-weighted MR imaging in the axial plane was performed, from the nasopharynx to the hyoid bone level, in both groups. From the MR images, oropharyngeal air column area, parapharyngeal fat pad thickness, pterygoid muscle thickness and parapharyngeal wall thickness measurements were made. Finally, the results were statistically analysed using SPSS (Statistical Package for Social Sciences) for Windows 10.0. Student's t-test was used as a complementary method in the analysis of the study data. The correlations between BMI and parapharyngeal wall thickness, and BMI and oropharyngeal air column area were determined by Pearson's correlation analysis.

RESULTS

No statistically significant difference was found between study and control groups in terms of mean age, pterygoid muscle thickness, or pharyngeal fat pad thickness (P>.05). Snorers' BMI levels (P<.01) and average parapharyngeal wall thicknesses (P<.05) were statistically significantly higher than those of the control subjects. Snorers' oropharyngeal air column area was significantly narrower than that of the control subjects, statistically (P<.01).

CONCLUSION

As a result of the study, it was concluded that only oropharyngeal air column area and parapharyngeal muscle thickness had an effect on snoring.

Effect of asthma on the risk of obstructive sleep apnea syndrome in atopic women

BACKGROUND

Obstructive sleep apnea syndrome is associated with significant morbidity and remains underdiagnosed in women. Identification of high-risk groups among women is important for early detection and treatment.

OBJECTIVE

To describe the prevalence of snoring in young women with atopy and to determine the risk factors for snoring in these individuals.

METHODS

The Cincinnati Childhood Allergy and Air Pollution Study is an ongoing prospective birth cohort study of infants with at least 1 atopic parent. Mothers of study participants were evaluated by questionnaire for snoring, respiratory symptoms, and smoking status. Women who snored were compared with those who did not snore. Logistic regression analysis was performed to determine risk factors for snoring.

RESULTS

Data were available on 677 women who had at least 1 live birth. Of these 677 women, 546 (81%) were white, 122 (18%) were African American, and 9 (1%) were biracial or Asian. The mean +/- SD age of the cohort at the time of evaluation for snoring was 29.6 +/- 5.6 years. Of the 677 women, 231 (34%) reported snoring at least 1 night per week, and snoring almost always (5-7 nights per week) was reported by 85 (13%). An almost 2-fold risk of snoring was associated with asthma (diagnosis and current symptoms) (odds ratio, 1.8; 95% confidence interval, 1.1-2.8) and African American race (odds ratio, 1.6; 95% confidence interval, 1.04-2.6) after controlling for income level and smoking status.

CONCLUSIONS

We found a high prevalence of snoring inyoung women with atopy and a significant association with asthma.

Oropharyngeal surgery for obstructive sleep apnoea in CPAP failures

Continuous positive airway pressure (CPAP) for moderate and severe obstructive sleep apnoea (OSA), albeit effective management, is poorly tolerated. This study looks at the role of laser assisted uvulopalatoplasty (LAUP) in patients with moderate and severe OSA who would not tolerate CPAP. All subjects underwent dynamic sleep nasendoscopy to determine the anatomical level of obstruction and their suitability for the procedure. Twenty subjects were included. Pre-procedure mean apnoea-hypopnea index (AHI) was 47.9 per hour (21.3-101) and mean Epworth sleepiness score 15.6 (4-23). Post operative polysomnography at >or=4 months showed a 73% reduction in AHI to a mean of 12.9 per hour. Two subjects still required CPAP post procedure but both at reduced pressure. Epworth sleepiness questionnaire scores were reduced by a mean of 7.9 points. There was no confounding weight loss. The finding that LAUP offers an effective instrument to reduce the severity of OSA in patients intolerant of CPAP results disagree with the conclusion of the recent Cochrane Collabration review of surgery for OSA. We believe this is due to the careful selection of patients for LAUP based on the anatomical level of obstruction as opposed to random selection.

Snoring is not relieved by nasal surgery despite improvement in nasal resistance

OBJECTIVES

In the present study, we evaluated the effect of nasal surgery on snoring time, snoring intensity, and sleep-disordered breathing. The role of abnormal cephalometry in treatment outcome was assessed.

DESIGN

A cross-sectional prospective study.

SETTING

University teaching hospital.

PATIENTS

Forty consecutive snoring men who were referred to ENT Hospital because of a snoring problem or suspicion of sleep apnea.

INTERVENTIONS

The patients underwent anterior rhinomanometry and polysomnography (PSG) with recording of snoring before and after operative treatment of nasal obstruction. Cephalometric radiographs were obtained before surgery.

RESULTS

Nasal resistance decreased significantly in the overall patient group. Snoring time, snoring intensity, nocturnal breathing, and sleep architecture did not change after nasal surgery. Cephalometry did not predict operative outcome in these patients. Snoring intensity was found to be significantly higher during non-rapid eye movement (NREM) sleep than during rapid eye movement sleep.

CONCLUSIONS

Operative treatment of mainly structural nasal obstruction did not seem to decrease snoring intensity, snoring time, or sleep-disordered breathing in an objective assessment by PSG performed after surgery. The effect of treating inflammatory nasal changes during nocturnal breathing, as well as the role of cephalometry in the prediction of treatment outcome will need further evaluation. Higher snoring intensity related to NREM sleep may add to the sleep disturbance of a bed partner in the evening.

Snoring-related energy transmission to the carotid artery in rabbits

Epidemiological studies link habitual snoring and stroke, but mechanisms involved are poorly understood. One previously advanced hypothesis is that transmitted snoring vibration energy may promote carotid atheromatous plaque formation or rupture. To test whether vibration energy is present in carotid artery walls during snoring we developed an animal model in which we examined induced snoring (IS)-associated tissue energy levels. In six male, supine, anesthetized, spontaneously breathing New Zealand White rabbits, we surgically inserted pressure transducer-tipped catheters (Millar) to monitor tissue pressure at the carotid artery bifurcation (PCT) and within the carotid sinus lumen (PCS; artery ligated). Snoring was induced via external compression (sandbag) over the pharyngeal region. Data were analyzed using power spectral analysis for frequency bands above and below 50 Hz. For frequencies below 50 Hz, PCT energy was 2.2 (1.1-12.3) cmH2O2 [median (interquartile range)] during tidal breathing (TB) increasing to 39.0 (2.5-95.0) cmH2O2 during IS (P = 0.05, Wilcoxon's signed-rank test). For frequencies > 50 Hz, PCT energy increased from 9.2 (8.3-10.4) x 10(-4) cmH2O2 during TB to 172.0 (118.0-569.0) x 10(-4) cmH2O2 during IS (P = 0.03). Concurrently, PCS energy was 13.4 (8.5-18.0) x 10(-4) cmH2O2 during TB and 151.0 (78.2-278.8) x 10(-4) cmH2O2 during IS (P < 0.03). The PCS energy was greater than PCT energy for the 100-275 Hz bandwidth. In conclusion, during IS there is increased energy around and within the carotid artery, including lower frequency amplification for PCS. These findings may have implications for carotid atherogenesis and/or plaque rupture.

Surgery for obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea/hypopnoea syndrome(OSAHS) is the periodic reduction or cessation of airflow during sleep. The syndrome is associated with loud snoring, disrupted sleep and observed apnoeas. Surgery for obstructive sleep apnoea/hypopnoea syndrome aims to alleviate symptoms of daytime sleepiness, improve quality of life, and reduce the signs of sleep apnoea recorded by polysomnography.

OBJECTIVES

The objective of this review was to assess the effects of any type of surgery for the treatment of the symptoms of obstructive sleep apnoea/hypopnoea syndrome in adults.

SEARCH STRATEGY

We searched the Cochrane Airways Group Specialised Register and reference lists of articles. We contacted experts in the field, research dissemination bodies and other Cochrane Review Groups. Searches were current as of July 2005.

SELECTION CRITERIA

Randomised trials comparing any surgical intervention for obstructive sleep apnoea/hypopnoea syndrome with other surgical or non-surgical interventions or no intervention.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed electronic literature search results for possibly relevant studies. Characteristics and data from studies meeting the inclusion criteria were extracted and entered into RevMan 4.2.

MAIN RESULTS

In the 2005 update for this review eight studies (412 participants) of mixed quality met the inclusion criteria. Data from seven studies were eligible for assessment in the review. No data could be pooled. Uvulopalatopharyngoplasty (UPPP) versus conservative management (one trial): An un validated symptom score showed intermittent significant differences over a 12-month follow-up period. No differences in Polysomnography (PSG) outcomes were reported. Laser-assisted uvulopalatoplasty (LAUP) versus conservative management/placebo (two trials): One study recruited mixed a population, and separate data could not be obtained for this trial. In the other study no significant differences in Epworth scores or quality of life reported. A significant difference in favour of LAUP was reported in terms of apnoea hypopnoea index (AHI) and frequency and intensity of snoring. UPPP versus oral appliance (OA) (one trial): AHI was significantly lower with OA therapy than with UPPP. No significant differences were observed in quality of life. UPPP versus lateral pharyngoplasty (lateral PP) (one trial): No significant difference in Epworth scores, but a greater reduction in AHI with lateral PP was reported. Tongue advancement (mandibular osteotomy) + PPP versus tongue suspension + PPP (one trial): There was a significant reduction in symptoms in both groups, but no significant difference between the two surgery types. Complications reported with all surgical techniques included nasal regurgitation, pain and bleeding. These did not persist in the long term. An additional study assessed the effects of four different techniques. No data were available on between group comparisons. Multilevel temperature-controlled radiofrequency tissue ablation (TCRFTA) versus sham placebo and CPAP (one trial): There was an improvement in primary and secondary outcomes of TCRFTA over sham placebo and but no difference in symptomatic improvement when compared with CPAP.

AUTHORS' CONCLUSIONS

There are now a small number of trials assessing different surgical techniques with inactive and active control treatments. The studies assembled in the review do not provide evidence to support the use of surgery in sleep apnoea/hypopnoea syndrome, as overall significant benefit has not been demonstrated. The participants recruited to the studies had mixed levels of AHI, but tended to suffer from moderate daytime sleepiness where this was measured. Short-term outcomes are unlikely to consistently identify suitable candidates for surgery. Long-term follow-up of patients who undergo surgical correction of upper airway obstruction is required. This would help to determine whether surgery is a curative intervention, or whether there is a tendency for the signs and symptoms of sleep apnoea to re-assert themselves, prompting patients to seek further treatment for sleep apnoea.

The management of simple snoring

Simple snoring is a very common problem that presents a number of different challenges. The initial difficulty is in confirming the presence of snoring, next one must exclude any other nocturnal respiratory pathology and finally a decision as to an appropriate treatment must be made. There are many different ways of achieving these objectives, but no one-way has a clear advantage in terms of both accuracy and cost effectiveness. In this review the authors do not intend to give a didactic method for the management of simple snoring but to discuss the pros and cons of various different options in order to help physicians make a choice based on local priorities.

Palatal implants: a new method for the treatment of snoring

OBJECTIVE

To evaluate the safety, feasibility and effectiveness of a treatment for snoring using permanent palatal implants.

MATERIAL AND METHODS

This was a prospective, non-randomized study involving 35 healthy patients (26 males, 9 females) referred for treatment of habitual snoring. A baseline medical examination, an evaluation of snoring-related subjective symptoms and an overnight sleep analysis were performed. Three PET implants were placed in the palate of each patient using a new delivery device under local anaesthesia. The patients were followed by means of office visits at 2-3, 14, 30 and 90 days postoperatively, at which discomfort, pain, adverse events and changes in snoring-related parameters were recorded.

RESULTS

The average time required for the procedure was 8 min; 23% of the patients required no postoperative analgesia; the average consumption of analgesic was 125 mg of diclofenac and the average duration of analgesia was 1.5 days after the procedure. No bleeding, haematoma or infection were observed. Two of the implants were extruded; both of these patients experienced a satisfactory reduction in snoring intensity and no replacements were necessary. The mean reduction in snoring intensity was 51%, with the visual analogue scale score evaluated by the bed partner falling from 7.3 to 3.6 (p<0.001). The Epworth Sleepiness Score dropped from 9.3 to 4.6 (p<0.001). In total, 86% of the bed partners and 89% of the patients recommended the procedure.

CONCLUSION

The new palatal implant system is safe and is associated with low morbidity. It is a fast, simple and effective treatment for snoring.

Does the oropharyngeal fat tissue influence the oropharyngeal airway in snorers? Dynamic CT study

Objective

The aim of this study was to determine if snorers have a narrower oropharyngeal airway area because of fat infiltration, and an elevated body mass index.

Materials and Methods

Ten control subjects and 19 patients that snored were evaluated. We obtained 2-mm-thick axial CT scan images every 0.6 seconds during expiration and inspiration at the same level of the oropharynx. We selected the largest and the smallest oropharyngeal airway areas and found the differences. From the slice that had the smallest oropharyngeal airway area, the thickness of the parapharyngeal and subcutaneous fat was measured. The measurements from the left and right side were added together and single values for parapharyngeal and subcutaneous fat tissue thickness were then found.

Results

The conventional measure of body mass index was significantly higher in the snorers (p < 0.05). The difference in the smallest oropharyngeal airway area between snorers and the controls was statistically significant (p < 0.01). The average difference between the largest and the smallest oropharyngeal area in the control group and the snorer group was statistically significant (p < 0.05). There was no significant difference in the largest oropharyngeal airway area, the total subcutaneous fat width and the total parapharyngeal fat width between snorers and control subjects (p > 0.05).

Conclusion

We concluded that the oropharyngeal fat deposition in snorers is not an important factor, and it does not predispose a person to the upper airway narrowing.

Assessment and management of patients with pulmonary disease

OBJECTIVE

Often, the critically ill are not optimized in terms of their chronic diseases and are with little physiologic reserves.

DATA SOURCES

This article contains a review of the pathophysiology of the major preexisting and chronic pulmonary disease encountered in the critically ill, such as asthma, emphysematous disease, and chronic bronchitis. It also includes a summary of other significant disease processes such as acute respiratory disease syndrome, cigarette smoking, and pulmonary alveolar proteinosis and the implications of obesity and obstructive sleep apnea. When confronted with critical illness, the morbidity is magnified. Close observation of patients for evidence that the underlying disease may complicate their pulmonary status, and vice versa, creates an environment where the whole patient can heal and recover from illness.

CONCLUSION

The aim of the intensive care unit team should be recognition of the patient at risk, use of necessary therapies (i.e., bronchodilators) as early as feasible, and treatment titrated to realistic endpoints as the acute illness progresses and subsequently resolves.

Patient discomfort in polysomnography with esophageal pressure measurements

The reference method for measuring respiratory effort and for differentiating between obstructive and central apneas in the diagnosis of sleep-related breathing disorders is overnight monitoring of esophageal pressure. Despite this being the reference method, it is not widely used because it is considered invasive and uncomfortable for the patients. The aim of this study was to assess patient discomfort and insertion difficulty when using an esophageal catheter during polysomnography. We have performed a prospective questionnaire-based clinical study in 799 consecutive patients where polysomnography with an esophageal catheter was routinely performed in the diagnosis of sleep-related breathing disorders. The main outcome measures were the catheter-related discomfort experienced by the patient and difficulty of catheter insertion reported by the sleep technician. Ninety-six percent of the patients accepted the insertion of the catheter, and most of the patients considered it acceptable to sleep with the catheter. Correspondingly, in most of the patients, the catheter was easily inserted, and there were difficulties in only a few patients. Specifically, no complications or side effects were reported when using the catheter. To optimize the diagnosis of sleep-related breathing disorders, an esophageal sensor catheter can be used during polysomnography, without causing major patient discomfort.

Prevalence and correlates of habitual snoring in high school students

STUDY OBJECTIVES

To examine the prevalence and correlates of habitual snoring in senior high school students in Korea.

DESIGN

A cross-sectional survey.

SETTING

Ten high schools in the southern part of Seoul, Korea.

PARTICIPANTS

A total of 3,871 high school students (2,703 male students and 1,168 female students; age range, 15 to 18 years; mean age: male students, 16.8 years; female students, 16.9 years) who were attending the 11th grade.

MEASUREMENTS AND RESULTS

Data were collected on sociodemographic characteristics, school performance, and patterns of sleep and sleep-related disturbances. The overall prevalence of habitual snoring was 11.2% (boys, 12.4%; girls, 8.5%). The mean total sleep time was similar in habitual snorers vs nonsnorers (6.4 and 6.3 h per day, respectively). Frequency of snoring increased significantly with body mass index (BMI) [p < 0.001], cigarette smoking (p < 0.01), prevalence of witnessed apnea (p < 0.001), and Epworth sleepiness scale score (p < 0.001). The frequency of snoring increased with a decline in school performance (p < 0.001). For those whose school performance was low, there was a 35% excess in the odds of habitual snoring vs those whose school performance was high (odds ratio, 1.35; 95% confidence interval, 1.01 to 1.78).

CONCLUSIONS

These findings suggest that chronic habitual snoring is associated with multiple factors in adolescents. Whether interventions to modify BMI and smoking can alter snoring habits and related clinical problems warrants further study, particularly as it also may improve academic performance in high school students.

Pulse transit time as a measure of inspiratory effort in children

STUDY OBJECTIVES

The current criterion standard for measuring inspiratory effort, esophageal manometry, is an invasive procedure that young patients find intolerable. Inspiratory effort can also be assessed noninvasively by measuring the pulse transit time (PTT). PTT is the time the pulse wave (PW) takes to travel between two arterial sites (normally heart to finger). The speed at which the PW travels is directly proportional to arterial BP. When BP rises, PTT shortens. Conversely, when BP falls, PTT lengthens. In this study, we investigated PTT as a measure for evaluating inspiratory effort in children.

PARTICIPANTS

We studied 15 healthy children (age range, 5 to 12 years; mean age [+/- SD], 8.3 +/- 2.74; 9 male children) selected from patients referred to our pediatric center for routine assessment.

MEASUREMENTS AND RESULTS

We assessed changes in the PTT during breathing against known resistances in awake children. Resistance was applied to the nose and mouth with a modified, two-way, nonrebreathing facemask. Our data show a good correlation between the induced inspiratory effort and the amplitude of PTT variations.

CONCLUSIONS

PTT should be a useful method for quantifying changes in inspiratory effort due to augmented upper airway resistance in awake children.