Airway Resistance in Children with Obstructive Sleep Apnea Syndrome

Detection of Simulated Pediatric Breathing by CPAP/Noninvasive Ventilation Devices

BACKGROUND

Home CPAP and noninvasive ventilation (NIV) are increasingly used in children. An appropriate choice of the CPAP/NIV device, according to the manufacturer recommendations, should guarantee accurate data collection software. However, not all devices display accurate patient data. We hypothesized that the detection of patient breathing may be expressed as a minimal tidal volume (VTmin ) rather than a minimal weight. The aim of the study was to estimate the VTmin detected by home ventilators when set on CPAP.

METHODS

Twelve level I-III devices were analyzed using a bench test. Pediatric profiles were simulated with increasing VT values to determine the VTmin that the ventilator may detect. The duration of CPAP use and the presence/absence of waveform tracings on the built-in software were also gathered.

RESULTS

VTmin varied according to the device, ranging from 16-84 mL, independent of level category. The duration of CPAP use was underestimated in all level I devices, which were either not able to display any waveform or only intermittently, until VTmin was reached. The duration of CPAP use was overestimated for the level II and III devices, with the display of different waveforms according to the device as soon as the device was switched on.

CONCLUSIONS

Based on the VTmin detected, some level I and II devices may be suitable for infants. A careful testing of the device should be done at CPAP initiation, with a review of data generated from ventilator software.

Home Respiratory Polygraphy and Spirometry in Normal Weight and Children with Obesity Suspected for Obstructive Sleep Apnea Syndrome: Are There Any Associations?

Aim

It is known that children and adolescents with obesity are more prone to obstructive sleep apnea syndrome (OSAS) and that their lung function may show some disturbance. Literature is scarce about potential associations; therefore, we aimed to study the relationship between OSAS, lung function, and adiposity in a population of children suspected of OSAS. Material and Methods. We performed home respiratory polygraphy and spirometry in all subjects. The relationships between body mass index z-score (zBMI), polygraphy, and spirometry data were analyzed.

Results

We recruited 81 subjects aged between 5 and 16 years, 63% being obese. 43.2% of subjects were diagnosed with OSAS (32.1% mild, 4.9% moderate, and 6.2% severe). We found no correlation between respiratory polygraphy and the zBMI. The mean spirometric value FEV₁, FVC, and FEV₁/FVC ratio z's were normal in all subjects, whereas FVC z's and FEV₁/FVC ratio z's were significantly positively related for obesity and negatively for normal weight (p < 0.05). FEV₁ z's was inversely correlated to the percentage of analyzed time passed below 90% of SpO₂ (r = -0.224, p = 0.044). All subjects with FEV₁ (n = 8) and/or FVC (n = 9) z's below the lower limit for normal (LLN) had an AHI ≥ 1 (FEV₁: p = 0.001; FVC: p < 0.001), especially subjects with normal weight (FEV₁: p = 0.003; FVC: p = 0.010).

Conclusion

When comparing normal-weight children and adolescents with obesity, the prevalence of OSAS but not spirometric values was strongly related to BMI z-score, probably because obesity engenders advanced puberty and an accelerated growth spurt. FEV₁ was more frequently <LLN in normal-weight children, while obese subjects presented low FEV₁/FVC ratio z's and FEF_25-75% z's. Moreover, all subjects with abnormal spirometric values were suffering from at least mild OSAS, again more frequently in normal-weight subjects.

Critical to Know Pcrit: A Review on Pharyngeal Critical Closing Pressure in Obstructive Sleep Apnea

It is crucial to understand the underlying pathophysiology of obstructive sleep apnea (OSA). Upper airway collapsibility is an important pathophysiological factor that affects the upper airway in OSA. The aim of the current study was to review the existing body of knowledge on the pharyngeal collapsibility in OSA. After a thorough search through Medline, PubMed, Scopus, and Web of science, the relevant articles were found and used in this study. Critical closing pressure (Pcrit) is the gold standard measure for the degree of collapsibility of the pharyngeal airway. Various physiological factors and treatments affect upper airway collapsibility. Recently, it has been shown that the baseline value of Pcrit is helpful in the upfront selection of therapy options. The standard techniques to measure Pcrit are labor-intensive and time-consuming. Therefore, despite the importance of Pcrit, it is not routinely measured in clinical practice. New emerging surrogates, such as finite element (FE) modeling or the use of peak inspiratory flow measurements during a routine overnight polysomnography, may enable clinicians to have an estimate of the pharyngeal collapsibility. However, validation of these techniques is needed.

Immature control of breathing and apnea of prematurity: the known and unknown

This narrative review provides a broad perspective on immature control of breathing, which is universal in infants born premature. The degree of immaturity and severity of clinical symptoms are inversely correlated with gestational age. This immaturity presents as prolonged apneas with associated bradycardia or desaturation, or brief respiratory pauses, periodic breathing, and intermittent hypoxia. These manifestations are encompassed within the clinical diagnosis of apnea of prematurity, but there is no consensus on minimum criteria required for diagnosis. Common treatment strategies include caffeine and noninvasive respiratory support, but other therapies have also been advocated with varying effectiveness. There is considerable variability in when and how to initiate and discontinue treatment. There are significant knowledge gaps regarding effective strategies to quantify the severity of clinical manifestations of immature breathing, which prevent us from better understanding the long-term potential adverse outcomes, including neurodevelopment and sudden unexpected infant death.

Risk factors analysis and intervention of lung dysfunction in children with obstructive sleep apnea: A retrospective case series study

OBJECTIVES

To establish an optimized airway management process to improve preoperative lung dysfunction in obstructive sleep apnea (OSA).

METHODS

The study included 483 children (319 males and 164 females; 6y to14y years) with OSA who underwent an adenotonsillectomy from November 2017 to December 2018. Children with OSA and who had abnormal airway function were identified by lung function test, and the risk factors for abnormal lung function were assessed. Next, the children received individualized atomization intervention based on the severity of their abnormal lung function, and the improvement in lung function was evaluated.

RESULTS

Lung function tests revealed that 45 patients had obstructive ventilation dysfunction, and histories of chronic cough or asthma were identified as risk factors for perioperative abnormal lung function. The FEV1% pre exceeded 80% after 2 days of atomization intervention in 27 of 28 mild cases, 4 of 13 moderate cases, but in none of the 4 moderate-severe cases. After 4 days of atomization intervention, the FEV1%pre of the remaining 14 patients in the three groups all increased up to 80%. Other indicators of lung function (e.g., FEV1/FVC% pre, MEF50% pre, MEF25% pre, and MMEF% pre) were also greatly improved following the improvement of FEV1% pre. No perioperative airway complications occurred.

CONCLUSIONS

Prior to performing surgery on children with OSA and who have risk factors associated with abnormal lung function, it is potentially beneficial to establish an optimized airway management process to improve lung function before adenotonsillectomy.

The efficacy of adenotonsillectomy on oxidative stress evaluated by thiol / disulfide balance

BACKGROUND

Oxidative stress plays a role in the pathogenesis of many chronic diseases. Upper airway obstruction has been identified as a risk factor for increased oxidative stress-related disorders such as obstructive sleep apnea. The effect of adenotonsillar hypertrophy, which may result in a narrowing of the upper airways, on oxidative stress can be a valuable subject of research. This study aimed to investigate the efficacy of adenotonsillectomy on oxidative stress evaluated using the thiol / disulfide balance.

METHODS

Thirty children who underwent adenotonsillectomy and 30 healthy controls, all aged from 3 to 18 years, were included in the study. Blood samples were taken preoperatively and 3 months postoperatively in the study group; in the control group, baseline blood samples were taken and samples were again taken 3 months later. Thiol / disulfide homeostasis items were analyzed. Antioxidant markers were native thiol, total thiol, and native / total thiol. Oxidative stress markers were disulfide, disulfide / native thiol, and disulfide / total thiol.

RESULTS

At the preoperative period, oxidative stress parameters of thiol / disulfide homeostasis were higher in the study group than in the control group (P < 0.05) and antioxidant activity parameters were lower than in the control group (P < 0.05). Three months postoperatively, oxidative stress parameters were lower than in the control group (P < 0.05), and antioxidant parameters were no different from those in the control group (P > 0.05). In the adenotonsillectomy group considered separately, oxidative stress markers of disulfide and disulfide / native thiol decreased (P < 0.05) and antioxidant markers of native thiol and total thiol increased in the postoperative measurements (P < 0.05).

CONCLUSIONS

Oxidative stress related to adenotonsillar hypertrophy decreased after adenotonsillectomy. The antioxidant parameters of the thiol homeostasis increased after adenotonsillectomy. We concluded that adenotonsillectomy operations should be planned and applied timeously to prevent the adverse effects of adenotonsillar hypertrophies on thiol homeostasis.

A contemporary review of obstructive sleep apnea

PURPOSE OF REVIEW

This review provides a contemporary review of sleep apnea with emphasis on definitions, epidemiology, and consequences.

RECENT FINDINGS

Amyloid β-42 is one of the main peptides forming amyloid plaques in the brains of Alzheimer patients. Poorer sleep quality and shorter sleep duration have been associated with a higher amyloid burden. Decreased sleep time in the elderly is a precipitating factor in amyloid retention. Studies have shown that the dysregulation of the homeostatic balance of the major inhibitory and excitatory amino acid neurotransmitter systems of gamma-aminobutyric acid (GABA) and glutamate play a role in sleep disordered breathing (SDB).

SUMMARY

Untreated sleep disordered breathing (obstructive sleep apnea and/or central sleep apnea) are an important cause of medical mortality and morbidity. OSA is characterized by recurrent episodes of partial or complete collapse of the upper airway during sleep followed by hypoxia and sympathetic activation. Apneic events are terminated by arousal, followed by increases in pulse and blood pressure, and re-oxygenation and the release of inflammatory factors. Individuals with OSA have an increased risk of developing atrial fibrillation. Hypoxemia and poor sleep quality because of OSA increase the risk of cognitive decline in the elderly.

[Etiopathogenesis of obstructive sleep apnoea and its consequences in the children]

The article presents the modern view of etiology of the obstructive sleep apnoea/hypopnoea syndrome (OAHSS) in the children taking into consideration the ontogenetic stage and the principal mechanisms of its formation including the short-term and long-term consequences of sleep apnoea with special reference to the pathogenetic commonness of OAHSS with endothelial dysfunction, metabolic syndrome, cardiac disorders, and systemic chronic inflammation. The role of ENT diseases in the children with obstructive sleep apnoea is discussed. The results of genetic studies of the processes influencing the formation of the risk of development of sleep apnoea/hypopnoea syndrome and its outcomes in the children are discussed.

Association between allergic and nonallergic rhinitis and obstructive sleep apnea

PURPOSE OF REVIEW

Allergic rhinitis and nonallergic rhinitis (NAR) are common disorders, which have been considered as potential risk factors for obstructive sleep apnea (OSA). This review summarizes the proposed underlying pathophysiological mechanisms to provide a better understanding of the relationship between these conditions.

RECENT FINDINGS

In adults, allergic rhinitis and NAR may be considered as symptoms potentiating, rather than risk potentiating factors in the pathophysiology of OSA, whereas in children, these are considered to be independent predictors for sleep-disordered breathing (SDB) and failure of adeno-tonsillectomy, the recommended first-line therapy for children with OSA. Current advances suggest IL-6 may be important in regulating the sleep-wake cycle, and serum soluble IL-6 receptor (sIL-6R) levels may reflect the severity of OSA. Elevated Th17/Treg ratio correlates positively with apnea-hypopnea index of OSA patients, and Th17 and Treg imbalances caused by allergic rhinitis and OSA, respectively, may possibly promote each other, leading to further imbalance. Moreover, obesity is a strong risk factor for OSA, and leptin plays an important role in ventilatory function and upper airway obstruction. The variant trigeminocardiac reflex and nasotrigeminal reflex may also be involved in the association between rhinitis and OSA.

SUMMARY

Allergic rhinitis/NAR and OSA are closely associated, and each condition can be detrimental to the other. Thus, clinicians should pay attention to the potential presence of allergic rhinitis/NAR in OSA patients and vice versa.

Sleep-Disordered Breathing in Children with Recurrent Wheeze/Asthma: A Single Centre Study

The relationship between asthma and sleep-disordered breathing is bidirectional due to common risk factors that promote airway inflammation. Obstructive sleep-disordered breathing and recurrent wheeze/asthma are conditions that involve the upper and the lower respiratory system, respectively. The aim of the present study was to investigate the sleep disordered breathing in children with recurrent wheeze/asthma. This was a retrospective study concerning children older than 2 years who underwent—between January 2014 and November 2016—an in-laboratory overnight polygraphic study. We match the children between those who do or do not have recurrent wheeze/asthma disease. We examined the clinical records of 137 children. We excluded eight patients because of neurological and genetic conditions. Children with recurrent wheeze/asthma (N = 28) were younger (p = 0.002) and leaner (p = 0.013) compared to non-affected children (N = 98). Children with wheeze/asthma and unaffected ones had a similar obstructive apnea-hypopnea index (p = 0.733) and oxygen desaturation index (p = 0.535). The logistic regression analysis, in which the condition of wheeze/asthma (yes/no) was a dependent variable, while demographic (age, sex, body mass index (BMI) Z-score) and polygraphic results during sleep (obstructive apnea-hypopnea index, central apnea index, peripheral oxygen saturation (SpO₂), and snoring) were covariates, showed that children with wheeze/asthma had higher central apnea index (Exp(B) = 2.212; Wald 6.845; p = 0.009). In conclusion, children with recurrent wheeze/asthma showed an increased number of central sleep apneas than unaffected children. This finding may suggest a dysfunction of the breathing control in the central nervous system during sleep. Systemic or central inflammation could be the cause.

Persistent respiratory effort after adenotonsillectomy in children with sleep-disordered breathing

OBJECTIVES

Adenotonsillectomy (AT) markedly improves but does not necessarily normalize polysomnographic findings in children with adenotonsillar hypertrophy and related sleep-disordered breathing (SDB). Adenotonsillectomy efficacy should be evaluated by follow-up polysomnography (PSG), but this method may underestimate persistent respiratory effort (RE). Mandibular movement (MMas) monitoring is an innovative measurement that readily identifies RE during upper airway obstruction. We hypothesized that MMas indices would decrease in parallel of PSG indices and that children with persistent RE more reliably could be identified with MMas.

METHODS

Twenty-five children (3-12 years of age) with SDB were enrolled in this individual prospective-cohort study. Polysomnography was supplemented with a midsagittal movement magnetic sensor that measured MMas during each respiratory cycle before and > 3 months after AT.

RESULTS

Adenotonsillectomy significantly improved PSG indices, except for RE-related arousals (RERA). Mandibular movement index changes after AT significantly were correlated with corresponding decreases in sleep apnea-hypopnea index (AHI) and O₂ desaturation index (ODI) (Spearman's rho = 0.978 and 0.922, respectively), whereas changes in MMas duration significantly were associated with both RERA duration (rho = 0.475, P = 0.017) and index (rho = 0.564, P = 0.003). Conditional multivariate analysis showed that both AHI and RERA significantly contributed to the variance of MMas index after AT (P = 0.0003 and 0.0005, respectively), whereas MMas duration consistently was related to the duration of RERA regardless of AT.

CONCLUSION

Adenotonsillectomy significantly reduced AHI. However, persistent RERA were apparent in a significant proportion of children, and this was reflected by the remaining abnormal MMas pattern. Follow-up of children after AT can be recommended and readily achieved by monitoring MMas to identify persistent RE.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:1230-1237, 2018.

Effect of Obstructive Sleep Apnea Treatment on Lipids in Obese Children

Obesity in children is associated with several co-morbidities including dyslipidemia. Obstructive sleep apnea (OSA) is commonly seen in obese children. In adults, diagnosis of OSA independent of obesity is associated with cardiometabolic risk factors including dyslipidemia. There is limited data on the impact of treatment of OSA on lipids in children. The objective of the study was to examine the impact of treatment of OSA on lipids in 24 obese children. Methods: Seventeen children were treated with continuous positive airway pressure (CPAP) and five underwent adenotonsillectomy. Mean apnea hypopnea index prior to treatment was 13.0 + 12.1 and mean body mass index (BMI) was 38.0 + 10.6 kg/m². Results: Treatment of OSA was associated with improvement in total cholesterol (mean change = -11 mg/dL, p < 0.001), and low-density lipoprotein cholesterol (mean change = -8.8 mg/dL, p = 0.021). Conclusion: Obese children should be routinely screened for OSA, as treatment of OSA favorably influences lipids and therefore decreases their cardiovascular risk.