Polygraphic respiratory events during sleep in children treated with home continuous positive airway pressure: description and clinical consequences

Highlights

• Data are scarce on respiratory events during CPAP for children.

• The index of respiratory events during home CPAP treatment in children was low.

• Respiratory events may be associated with a desaturation or an autonomic arousal.

• No correlation was observed between nocturnal gas exchange and polygraphy results.

• A systematic sleep study seems justified for children treated with long-term CPAP.

Abstract

Objective

Data are scarce on respiratory events during sleep for children treated at home with continuous positive airway pressure (CPAP). The present study aimed to characterize the respiratory events with CPAP during sleep and to analyze their clinical consequences.

Patients/Methods

Consecutive polygraphies (PG) performed on stable children treated with CPAP were analyzed and scored using SomnoNIV Group definitions. For every respiratory event, the presence of a 3% oxygen desaturation and/or an autonomic arousal was systematically searched. Nocturnal gas exchange was assessed using summary data of oximetry and transcutaneous carbon dioxide pressure recordings.

Results

Twenty-nine consecutive polygraphies, performed on 26 children (mean age 7.8 ± 6.2 years, mean CPAP use 10.6 ± 14.4 months), were analyzed. The index of total respiratory events was low (median value 1.4/h, range 0–34). The mean number of different types of respiratory events per PG was 2 ± 1 (range 0–4), with always a predominant event. Partial or total upper airway obstruction without a decrease in ventilatory drive was the most frequent event and was the most frequently associated with an oxygen desaturation (in 30% of the events) and an autonomic arousal (in 55% of the events). Weak correlations were observed between nocturnal oximetry and PG results.

Conclusions

The index of respiratory events during CPAP treatment for stable children is low. As these events may be associated with an oxygen desaturation or an autonomic arousal, and as nocturnal gas exchange cannot predict PG results, a systematic sleep study seems justified for the routine follow-up of children treated with CPAP.

Introduction

Obstructive sleep apnea syndrome (OSAS) in children is a relatively common disease, with a reported prevalence that varies between 1 and 5% of the pediatric population [1]. Since adenotonsillar hypertrophy constitutes the most common cause of OSAS, adenotonsillectomy represents the first-line and most efficient treatment in children [1]. However, residual OSAS is common in children with underlying disorders such as Down syndrome, craniofacial abnormalities, or obesity. In these cases, continuous positive airway pressure (CPAP) represents an effective treatment [2], [3], [4], [5], [6], [7].

In children with OSAS, manual titration of CPAP during attended laboratory polysomnography (PSG) is recommended [8], but such a procedure is time consuming and not feasible in all pediatric centers. Therefore, CPAP is usually set up during the day, according to the clinician's experience and the patient's characteristics. The optimal CPAP level is then adjusted according to nocturnal tolerance to treatment, normalization of nocturnal gas exchange, and the disappearance of OSAS symptoms. However, once CPAP is successfully instituted, validated follow-up guidelines are lacking. Current guidelines recommend a periodic reassessment of CPAP pressure [9]; a large adult series has shown the need for an active re-evaluation of pressure therapy, even after accurate titration studies [10], [11]. This may be even more relevant for children whose condition may improve with age due to a physiological increase in upper airway caliber and patency, or worsen because of weight gain or upper respiratory infections or allergy. However, very few studies have assessed the need for pressure changes over time in children having CPAP, and little is known about the type and incidence of the different residual respiratory events [2], [12], [13]. Furthermore, the current definitions of respiratory events during noninvasive ventilation (NIV) and CPAP derive from those in spontaneous breathing and do not accurately take into account the complex interaction between the patient and the response or reaction of a ventilator [14].

Recently, the SomnoNIV Group proposed a systematic scoring analysis of respiratory events observed with polygraphy (PG) during NIV [15]. These criteria were originally set up for NIV, taking into account the events generated by the patient, the ventilator, or the patient–ventilator interaction. However, CPAP differs from NIV, as it delivers a positive pressure during the whole respiratory cycle without actively assisted inspiration [16]; therefore, it is not considered to be a ventilatory mode per se. However, except for patient–ventilator interaction, all of the other SomnoNIV respiratory events may occur during CPAP, such as: unintentional leaks, partial or total upper airway obstruction (UAO) without or with decrease in ventilatory drive (DVD), DVD, and mixed events.

The aim of the present study was to characterize respiratory events in infants and children having CPAP treatment at home, according to the SomnoNIV Group definitions, and to examine the clinical consequences of these events (ie, the occurrence of an oxygen desaturation or an autonomic arousal). Whether oximetry and transcutaneous carbon dioxide tension (PtcCO₂) were associated with the occurrence of respiratory events during CPAP therapy was also explored.