Improving detection of obstructive sleep apnoea by overnight oximetry in children using pulse rate parameters

Diagnostic accuracy of portable sleep monitors in pediatric sleep apnea: A systematic review

In recent years, a plethora of new type III and IV portable sleep monitors (PSM) have been developed, although evidence regarding their diagnostic accuracy for use in children remains heterogeneous. This study systematically reviews the literature addressing the diagnostic accuracies of type III and IV PSM for pediatric sleep apnea. Publications indexed in Medline, Embase, or Web of Science were reviewed using the PRISMA framework. Of 1054 studies, 62 fulfilled the inclusion criteria. Of the studies evaluating oximetry-based type IV PSM, one (6.25 %) demonstrated a balanced set of high (≥80 %) sensitivities and specificities for the diagnosis of any pediatric sleep apnea, while five studies (27.8 %) showed similar accuracies for moderate-to-severe sleep apnea. For non-oximetry-based type IV PSM, two studies (40 %) reported a balanced set of high diagnostic accuracies for moderate-to-severe sleep apnea. Type III PSM repeatedly demonstrated higher diagnostic accuracies, with six studies (66.7 %) reporting a balanced set of high diagnostic accuracies for moderate-to-severe sleep apnea. This review highlights the potential of type III PSM to detect moderate-to-severe pediatric sleep apnea, although current evidence is limited to support the stand-alone use of type IV PSM for the diagnosis of sleep apnea in most children.

Incidence / predictors of pediatric obstructive sleep apnea with normal oximetry

BACKGROUND

The polysomnogram (PSG) is the "gold standard" for diagnosing obstructive sleep apnea (OSA). However, nocturnal oximetry is a practical screening tool for children with adenotonsillar hypertrophy (ATH). This study aimed to investigate the incidence of, and predictive factors for, OSA in children with ATH and normal / inconclusive overnight oximetry.

METHODS

The prospective study enrolled children aged 3-15 years with ATH and normal / inconclusive overnight oximetry. All participants underwent full-night PSG. To evaluate the predictors of OSA, we used logistic regression analysis, including sex, history of allergic rhinitis, body mass index z-score, neck circumference-height ratio, and polysomnographic parameters (obstructive apnea-hypopnea index (OAHI), nadir oxygen saturation (SpO2), peak end-tidal CO₂ , and arousal index).

RESULTS

The participants were 189 children; 167 (88%) were diagnosed with OSA by PSG. A history of allergic rhinitis (P = 0.033), and the PSG findings for nadir SpO₂ (P = 0.027) and arousal index (P = <0.001) predicted the diagnosis of OSA. We divided patients with OSA into two groups (mild versus moderate to severe OSA). Patients with OAHI ≥5/h were defined as having moderate-to-severe OSA. No clinical factors significantly predicted OAHI ≥5. Of the 189 participants, 58 children (31%) were diagnosed with severe OSA (OAHI ≥10). The only PSG factor that predicted severe OSA was the arousal index (P < 0.001).

CONCLUSIONS

The observed incidence of OSA in children aged 3-15 years with ATH and normal/inconclusive overnight oximetry was very high. A history of allergic rhinitis may help to triage the patients. The arousal index was a predictor of pediatric OSA.

Diagnostic accuracy of level IV portable sleep monitors versus polysomnography for pediatric obstructive sleep apnea: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is one of the common sleep-related breathing disorders in children. However, polysomnography (PSG) is an expensive and labor-intensive diagnostic modality that may not always be feasible, especially in low-income countries or in non-tertiary hospitals. Portable monitors (PMs), a new approach for OSA diagnosis, have become more widely used with lower intolerance and cost in recent years. We aimed to analyze the diagnostic performance of Level IV PMs compared with PSG for the diagnosis of pediatric OSA.

METHODS

PubMed and Embase databases were searched for studies published in English up to December 31, 2020 evaluating the diagnostic accuracy of Level IV PMs against the apnea-hypopnea index (AHI) measured using overnight in-laboratory polysomnography (PSG) in children and adolescents. A random-effects bivariate model was used to estimate the summary sensitivity and specificity of oximetry-based statistical classifiers. A qualitative evaluation of studies was performed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) rating.

RESULTS

In total, 20 studies involving 7062 participants were included in this systematic review. Among these articles, seven studies (oximetry based on new mathematical classifiers) involving 5098 individuals satisfied the criteria for quantitative synthesis. Compared with AHI evaluation measured by PSG, different PM systems achieved diagnostic accuracy with variable degrees of success. A meta-analysis showed a pooled sensitivity of 74% (95% confidence interval [CI]: 66-80%) and pooled specificity of 90% (95% CI: 85-94%). The area under the summary receiver operating characteristic (SROC) curve was 0.89 (95% CI: 0.86-0.92).

CONCLUSION

This study showed the potential of Level IV PMs for screening pediatric OSA patients. Oximetry based on new mathematical classifiers may provide a simple and effective alternative to PSG in the diagnosis of pediatric OSA especially in the context of appropriate clinical evaluation.

Continuous oximetry recordings on the first post-operative night after pediatric adenotonsillectomy-a case-control study

BACKGROUND

Children with obstructive sleep apnea (OSA) with recurrent dips in oxygen saturation (SpO₂) during sleep are known to be at increased risk of post-operative airway compromise after adenotonsillectomy (AT). We aimed to determine the extent of desaturation on the first post-operative night in children known to have recurrent desaturation pre-operatively and to compare the extent of desaturation in that group with results in children known to have normal oximetry recordings pre-operatively.

METHODS

Prospective sequential recruitment of 57 children who had overnight oximetry performed on the first night after adenotonsillectomy was undertaken, including 28 with a McGill Oximetry Score (MOS) of 2-4 pre-operatively (high risk group) and 29 with a normal/inconclusive pre-operative MOS (low risk group). Oximetry parameters (mean SpO₂, SpO₂ nadir, and rates of SpO₂ dips below 90% and dips of ≥4%) were compared to the pre-operative oximetry result. Demographic and clinical factors, and the occurrence of post-operative complications, were derived from the medical record.

RESULTS

In the high risk group, the MOS improved in 23/28 children, but remained abnormal in 82%. Conversely, in the low risk group 26/29 (90%) had a normal post-operative oximetry. The remaining 3, all of whom had severe OSA on pre-operative polysomnography, had a lowered baseline SpO₂ post-operatively. Mean SpO₂ was slightly lower post-operatively in both groups. In the high risk group, all other SpO₂ measures improved post-operatively. Respiratory adverse events were more common in the high risk group as expected (39% compared to 3% in the low risk group, p = 0.001). An adverse event requiring clinical intervention was significantly more likely if the post-operative oximetry was abnormal (result unknown to the treating team), occurring in 73% of children with an abnormal compared with 32% of children with a normal post-operative oximetry (p = 0.002).

CONCLUSION

Most children with an abnormal oximetry pre-operatively continued to have an abnormal oximetry on the first night after AT, albeit somewhat improved. While adverse events were more frequent in children with an abnormal post-operative oximetry, half (54%) did not suffer a clinical respiratory adverse event despite having repetitive desaturations on downloadable oximetry. These findings support close clinical observation of children at high risk of complications post-operatively, especially those with abnormal oximetry pre-operatively, rather than focusing on recurrent dips in SpO₂ on post-operative oximetry downloads in the absence of clinically evident complications.

Automated analysis of nocturnal oximetry as screening tool for childhood obstructive sleep apnea-hypopnea syndrome

Childhood obstructive sleep apnea-hypopnea syndrome (OSAHS) is a highly prevalent condition that negatively affects health, performance and quality of life of infants and young children. Early detection and treatment improves neuropsychological and cognitive deficits linked with the disease. The aim of this study was to assess the performance of automated analysis of blood oxygen saturation (SpO2) recordings as a screening tool for OSAHS. As an initial step, statistical, spectral and nonlinear features were estimated to compose an initial feature set. Then, fast correlation-based filter (FCBF) was applied to search for the optimum subset. Finally, the discrimination power (OSAHS negative vs. OSAHS positive) of three pattern recognition algorithms was assessed: linear discriminant analysis (LDA), quadratic discriminant analysis (QDA) and logistic regression (LR). Three clinical cutoff points commonly used in the literature for positive diagnosis of the disease were applied: apnea-hypopnea index (AHI) of 1, 3 and 5 events per hour (e/h). Our methodology reached 88.6% accuracy (71.4% sensitivity and 100.0% specificity, 100.0% positive predictive value, and 84.0% negative predictive value) in an independent test set using QDA for a clinical cut-off point of 5 e/h. These results suggest that SpO2 nocturnal recordings may be used to develop a reliable and efficient screening tool for childhood OSAHS.

Assessment of oximetry-based statistical classifiers as simplified screening tools in the management of childhood obstructive sleep apnea

PURPOSE

A variety of statistical models based on overnight oximetry has been proposed to simplify the detection of children with suspected obstructive sleep apnea syndrome (OSAS). Despite the usefulness reported, additional thorough comparative analyses are required. This study was aimed at assessing common binary classification models from oximetry for the detection of childhood OSAS.

METHODS

Overnight oximetry recordings from 176 children referred for clinical suspicion of OSAS were acquired during in-lab polysomnography. Several training and test datasets were randomly composed by means of bootstrapping for model optimization and independent validation. For every child, blood oxygen saturation (SpO₂) was parameterized by means of 17 features. Fast correlation-based filter (FCBF) was applied to search for the optimum features. The discriminatory power of three statistical pattern recognition algorithms was assessed: linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), and logistic regression (LR). The performance of each automated model was evaluated for the three common diagnostic polysomnographic cutoffs in pediatric OSAS: 1, 3, and 5 events/h.

RESULTS

Best screening performances emerged using the 1 event/h cutoff for mild-to-severe childhood OSAS. LR achieved 84.3% accuracy (95% CI 76.8-91.5%) and 0.89 AUC (95% CI 0.83-0.94), while QDA reached 96.5% PPV (95% CI 90.3-100%) and 0.91 AUC (95% CI 0.85-0.96%). Moreover, LR and QDA reached diagnostic accuracies of 82.7% (95% CI 75.0-89.6%) and 82.1% (95% CI 73.8-89.5%) for a cutoff of 5 events/h, respectively.

CONCLUSIONS

Automated analysis of overnight oximetry may be used to develop reliable as well as accurate screening tools for childhood OSAS.

Nocturnal Oximetry-based Evaluation of Habitually Snoring Children

RATIONALE

The vast majority of children around the world undergoing adenotonsillectomy for obstructive sleep apnea-hypopnea syndrome (OSA) are not objectively diagnosed by nocturnal polysomnography because of access availability and cost issues. Automated analysis of nocturnal oximetry (nSp_O2), which is readily and globally available, could potentially provide a reliable and convenient diagnostic approach for pediatric OSA.

METHODS

Deidentified nSp_O2 recordings from a total of 4,191 children originating from 13 pediatric sleep laboratories around the world were prospectively evaluated after developing and validating an automated neural network algorithm using an initial set of single-channel nSp_O2 recordings from 589 patients referred for suspected OSA.

MEASUREMENTS AND MAIN RESULTS

The automatically estimated apnea-hypopnea index (AHI) showed high agreement with AHI from conventional polysomnography (intraclass correlation coefficient, 0.785) when tested in 3,602 additional subjects. Further assessment on the widely used AHI cutoff points of 1, 5, and 10 events/h revealed an incremental diagnostic ability (75.2, 81.7, and 90.2% accuracy; 0.788, 0.854, and 0.913 area under the receiver operating characteristic curve, respectively).

CONCLUSIONS

Neural network-based automated analyses of nSp_O2 recordings provide accurate identification of OSA severity among habitually snoring children with a high pretest probability of OSA. Thus, nocturnal oximetry may enable a simple and effective diagnostic alternative to nocturnal polysomnography, leading to more timely interventions and potentially improved outcomes.

Design of an ultrasonic physiotherapy system with pulse wave feedback control

BACKGROUND

Due to different physical and biological mechanisms behind ultrasound hyperthermia and phonophoresis, the requirement for ultrasound power, frequency and control modes varies.

OBJECTIVE

This paper introduces an adaptive ultrasonic physiotherapy system based on real-time surveillance over physiological characteristics of the patients, which in turn assists the individual treatment and dose limitation in auxiliary rehabilitation.

METHODS

The method essentially takes advantage of distinctive characteristics of two different phases (systole and diastole) of the human cardiac cycle as a medium for modulation. The abundance of blood flow during systole enables energy exchange for hyperthermia while blood flow insufficiency caused by diastole assists in drug penetration. Said method could improve the adjuvant therapy as it provides partial drug penetration and therapeutic dosage control.

RESULTS

By adjusting time window and intensity of multi-frequency ultrasound, it is possible to reduce the irradiation dosage to around 22% of that during continuous irradiation at 1 MHz. The method shows high potential in clinical practice.

CONCLUSION

Frequency-tuning ultrasound therapy would be more efficient regarding drug penetration and improve the therapeutic efficacy of hyperthermia.

Automated Screening of Children With Obstructive Sleep Apnea Using Nocturnal Oximetry: An Alternative to Respiratory Polygraphy in Unattended Settings

STUDY OBJECTIVES

Nocturnal oximetry has become known as a simple, readily available, and potentially useful diagnostic tool of childhood obstructive sleep apnea (OSA). However, at-home respiratory polygraphy (HRP) remains the preferred alternative to polysomnography (PSG) in unattended settings. The aim of this study was twofold: (1) to design and assess a novel methodology for pediatric OSA screening based on automated analysis of at-home oxyhemoglobin saturation (SpO₂), and (2) to compare its diagnostic performance with HRP.

METHODS

SpO₂ recordings were parameterized by means of time, frequency, and conventional oximetric measures. Logistic regression models were optimized using genetic algorithms (GAs) for three cutoffs for OSA: 1, 3, and 5 events/h. The diagnostic performance of logistic regression models, manual obstructive apnea-hypopnea index (OAHI) from HRP, and the conventional oxygen desaturation index ≥ 3% (ODI3) were assessed.

RESULTS

For a cutoff of 1 event/h, the optimal logistic regression model significantly outperformed both conventional HRP-derived ODI3 and OAHI: 85.5% accuracy (HRP 74.6%; ODI3 65.9%) and 0.97 area under the receiver operating characteristics curve (AUC) (HRP 0.78; ODI3 0.75) were reached. For a cutoff of 3 events/h, the logistic regression model achieved 83.4% accuracy (HRP 85.0%; ODI3 74.5%) and 0.96 AUC (HRP 0.93; ODI3 0.85) whereas using a cutoff of 5 events/h, oximetry reached 82.8% accuracy (HRP 85.1%; ODI3 76.7) and 0.97 AUC (HRP 0.95; ODI3 0.84).

CONCLUSIONS

Automated analysis of at-home SpO₂ recordings provide accurate detection of children with high pretest probability of OSA. Thus, unsupervised nocturnal oximetry may enable a simple and effective alternative to HRP and PSG in unattended settings.

Oximetry for suspected obstructive sleep apnea-Does removal of awake data affect the result?

Frequency of dips below 90% on overnight oximetry can be used to estimate severity of obstructive sleep apnea (OSA) in children. Movement can result in artifact on oximetry recordings. Clinicians may therefore be tempted to remove periods of wakefulness from the recording to improve accuracy, but removal of such periods of potential artifact is time consuming. The aim of this study was to determine whether removing periods of wakefulness had a significant impact on analysis of overnight oximetry. Children aged 2-18 years (N = 108) with suspected OSA underwent overnight simultaneous oximetry and actigraphy at home on a single night. Actigraphy defined awake periods were "trimmed" from the oximetry data and oximetry variables compared between full and trimmed analysis. There was a statistically but not clinically significant difference between the full and trimmed data for mean SpO₂ , minimum SpO₂ , 4% desaturation index, and 3% desaturation index (all P < 0.05). There was no difference between the two analyses for median SpO₂ or the frequency of dips below 90%, 85%, or 80%. In conclusion, removal of periods of wakefulness at the start and end of overnight oximetry recordings does not affect the result in the context of testing for suspected OSA in children. Pediatr Pulmonol. 2016;51:1409-1413. © 2016 Wiley Periodicals, Inc.

Pediatric Home Sleep Apnea Testing: Slowly Getting There!

Pediatric OSA can result in significant neurocognitive, behavioral, cardiovascular, and metabolic morbidities. Prompt diagnosis and treatment are, therefore, of paramount importance. The current gold standard for diagnosis of OSA in children is in-laboratory polysomnography (PSG). Home sleep apnea testing has been considered as an alternative as it is potentially more cost effective, convenient, and accessible. This review concentrates mainly on the use of type 2 and 3 portable monitoring devices. The current evidence on the feasibility and diagnostic accuracy of home testing in the diagnosis of pediatric OSA was examined. Overall, the evidence in children is limited. Feasibility studies that have been performed have on the whole shown good results, with several reporting > 90% of their home recordings as meeting predetermined quality criteria regarding signal artifact and minimum recording time. The limited data comparing type 2 studies with in-laboratory PSG have shown no significant differences in respiratory parameters. The results pertaining to diagnostic accuracy of type 3 home sleep apnea testing devices are conflicting. Although more research is needed, home testing with at least a type 3 portable monitor offers a viable alternative in the diagnosis of otherwise healthy children with moderate to severe OSA, particularly in settings where access to polysomnography is scarce or unavailable. Of note, since most studies have been performed in habitually snoring healthy children, home sleep apnea testing may not be applicable to children with other comorbid conditions. In particular, CO2 monitoring is important in children in whom there is concern regarding nocturnal hypoventilation, such as children with neuromuscular disease, underlying lung disease, or obesity hypoventilation, and most home testing devices do not include a transcutaneous or end-tidal CO2 channel.