Echocardiographic screening in children with very severe obstructive sleep apnea

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Abstract

Objective

(i) To determine the prevalence of echocardiographic abnormalities in children with very severe OSA defined by an apnea hypopnea index (AHI) ≥ 30 events/hour. (ii) To test the hypothesis that polysomnographic parameters predict echocardiographic variables in this population.

Methods

Children aged 1–17 years presenting with polysomnography demonstrating an AHI ≥30 and referred for pre-operative echocardiography performed within the 6 months prior to tonsillectomy and adenoidectomy (T&A), over a two-year period (January 1, 2016 to December 31, 2018) were evaluated. The exclusion criteria were the presence of (i) unrepaired congenital cardiac disease, (ii) tracheostomy, (iii) poorly controlled asthma, or (iv) neuromuscular disorder. The prevalence of echocardiographic abnormalities was determined for the study population. The impact of the severity of OSA on echocardiographic parameters was evaluated using Student's t-test. The relationships between polysomnographic variables and biventricular function as well as pulmonary hemodynamics were measured. A penalized regression model was used to identify the contributions of polysomnographic variables to each echocardiographic parameter by mitigating inter-variable relationships. P < .05 was considered significant.

Results

Eighty-nine children were screened, of whom 47 were included for analysis. The mean age was 68.8 months [95% confidence interval, 56.0 to 81.6]. Thirty-three (70.2%) were boys. Twenty (42.6%) were obese. All children had normal echocardiograms. The differences in echocardiographic variables between children grouped by the severity of OSA were not statistically significant (P: 0.18-0.98). Polysomnographic variables predicted only 4 out of 13 studied echocardiographic parameters.

Conclusions

Pre-operative echocardiography did not identify significant abnormalities in children with very severe OSA. Majority of the echocardiographic variables were not predicted by polysomnographic parameters. This study demonstrates the limited benefit associated with routine echocardiographic screening of children with very severe OSA solely based on polysomnographic indices.

Introduction

Obstructive sleep apnea (OSA) in children is characterized by intermittent partial or complete airway obstruction resulting in a cycle of hypoxemia and arousal [1]. Pediatric OSA has an estimated prevalence of 5% in the United States [2]. The gold standard for the diagnosis and stratification of OSA is overnight, laboratory-based polysomnography. Untreated OSA has been shown to have detrimental effects on behavior, metabolism, and growth and development [1]. The first line treatment for pediatric OSA is tonsillectomy and adenoidectomy (T&A), which results in significant improvement or resolution of the condition in the majority of children [3].

Polysomnographic severity of OSA is an established risk factor for perioperative adverse events associated with T&A [4]. A relationship between adenotonsillar hypertrophy and cor pulmonale has been described, and complications related to cardiac dysfunction in these children have been associated with unexplained mortality following T&A [5]. Therefore, preoperative screening for cardiac abnormalities in children with chronic upper airway obstruction is recommended due to the potential for perioperative adverse events [6]. However, universal echocardiographic screening of 300,000 children undergoing T&A each year is impractical due to significant financial implications [7].

Descriptions of the detrimental effects of episodic upper airway obstruction have been mostly described in adults with OSA. Specifically, obstructive apneas result in increased intrathoracic pressures, causing changes in left ventricular relaxation, filling, and afterload [8]. At the end of an apnea, venous return to the right heart increases causing distension of the right ventricle, reduced left ventricular compliance by displacement of the interventricular septum, and therefore reduced left-ventricular end-diastolic filling and reduced left-ventricular stroke volume [9]. During the apnea, the sympathetic system is activated leading to vasoconstriction with sustained increased vasomotor tone and subsequent remodeling [10,11]. Together, these changes result in alterations in left ventricular mass and wall thickness, end diastolic dimensions, and interventricular septal thickness [9,11]. In addition, cyclic obstructive apneas may result in alveolar hypoventilation leading to hypoxemic pulmonary vasoconstriction and subsequent right ventricular dysfunction in the setting of pulmonary hypertension [11,12].

Most studies examining the prevalence of OSA-related cardiac dysfunction have focused on children with relatively mild OSA as defined by AHI. For example, Amin et al. prospectively evaluated 63 children in whom the majority (60%) had an AHI less than 5 [13]. Similarly, 73% of the 101 children enrolled in a community-based study examining cardiac dysfunction in children with OSA also had an AHI less than 5 [14]. However, there is a paucity of studies focusing on children with a greater severity of OSA who are likely to have more significant cardiovascular functional impairments, based on evidence suggesting this association [13].

We aimed to evaluate the prevalence of echocardiographic abnormalities in children screened for cardiovascular dysfunction due to a diagnosis of very severe OSA, defined as an AHI greater than or equal to 30 [15,16]. We hypothesized that this population was likely to have a greater prevalence of abnormal echocardiographic measurements based on the severity of upper airway obstruction. We also sought to identify the potential polysomnographic determinants of echocardiographic parameters in children with very severe OSA.

Section snippets

Study design and population

Medical records of children aged 1–17 years with very severe OSA diagnosed by polysomnography, defined as AHI ≥30 [15] undergoing T&A from January 1, 2016 to December 31, 2018 were reviewed. Children were included in the study if they underwent echocardiographic evaluation within six months prior to the procedure. The studies were ordered by the pediatric otolaryngologists as part of the institutional protocol at University of Maryland Medical Center. The exclusion criteria were the presence of

Demographics and chart review

Of 89 eligible children, 47 met inclusion criteria. The rest were excluded based on non-availability of data or the length of time elapsed between the echocardiography and the surgery date. The demographic and clinical characteristics are summarized in Table 1. The majority of the children were male (33/47, 70.2%). Thirty (63.8%) were African American. Twenty (42.6%) were obese with BMI percentile ≥ 95%. The mean AHI was 61.8 [54.5 to 69.0]. One child (2.1%) was documented to have hypertension

Discussion

In this case series of children who underwent echocardiographic screening prior to surgical management of very severe OSA, no significant functional or structural cardiac abnormalities were identified. Moreover, the majority of the echocardiographic parameters were predicted by non-polysomnographic parameters such as age. Apnea hypopnea index, which is used to stratify the severity of upper airway obstruction, was not identified as a predictor for any of the echocardiographic outcome variables.

Conclusions

In children with very severe OSA undergoing T&A, preoperative echocardiographic screening did not identify any abnormalities. The majority of the echocardiographic parameters were predicted by non-polysomnographic variables. Routine echocardiographic screening solely based on polysomnographic parameters is unlikely to yield relevant clinical information, could reduce cost-efficiency and delay treatment. Prospective studies are required to identify reliable markers of cardiovascular morbidity in

Disclosures

Amal Isaiah receives patent-related royalties from the University of Maryland, Baltimore. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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