Portuguese Version

Year:  2002  Vol. 68   Ed. 3 - (3º)

Artigo Original

Pages: 308 to 311

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Polysomnographic evaluation of obstructive sleep apnea syndrome in children, before and after adenotonsillectomy

Author(s): Melissa A.G. Avelino(1),
Fabiana C. Pereira(1),
Daniela Carlini(2),
Gustavo A. Moreira(3),
Reginaldo Fujita(4),
Luc L.M. Weckx(5)

Keywords: sleep apnea, polysomnographic, adenotonsillar hypertrophy

Abstract:
Introduction: In the last years the Obstructive Sleep Apnea/Hypopnea Syndrome (OSAHS) has much interested because it has not been completed established. Many criteria defined for OSAS in adults and children are different. We know that patient's clinical story is not sufficient for the diagnosis of OSAHS. In childhood, the most common cause of OSAHS is adenotonsillar hypertrophy, clinically characterised by snoring, apnea episodes, restless sleep, mouth breathing and daytime somnolence. Aim: This study has the purpose of comprovating, by objective way, the OSAS improving in children who underwent adenotonsillectomy. Study design: Clinical prospective. Material and method: For that, 23 children, among 2 and 13 years old, with adenotonsillar hypertrophy, were analysed. After endoscopy and polysomnography, they were submitted to adenotonsillectomy. Results: The polysomnography was repeated 2 months after surgery. The polysomnographic findings were compared through statistic study. Conclusion: All the patients had an important improve after adenotonsillectomy. Only two children (8.69%) persisted with light OSAHS, but they had moderate and important OSAHS before. We concluded that OSAHS is a precise indication for adenotonsillectomy in children.

INTRODUCTION

Obstructive Sleep Apnea/hypopnea Syndrome has raised interest for the past years because it is an incompletely defined condition28. Guilleminault11, in 1976, defined apnea as the cessation of airflow through the mouth and nose for more than 10 seconds and obstructive sleep apnea/hypopnea syndrome (OSAHS) as the presence of 30 or more episodes of apnea during 7 hours of night sleep detected by polysomnography. There are minor modifications to these definitions, but they are basically similar19, 25.

The criteria used to define OSAHS in adults and children are different3. If assessed by the same parameters, we would not define severe obstructive problems in children26. According to the consensus of the American Thoracic Society, held in July 1995, pediatric normal polysomnographic criteria are: apnea/hypopnea index (AHI) below 1 respiratory event/hour, minimal duration of apnea of 2 respiratory cycles (approximately 5 seconds), oxy-hemoglobin saturation higher than 90%,carbonic gas at final expiration below 10% of the total sleep time. The polysomnographic study enables classification of snoring children who have primary snoring (absence of apnea episodes) and those who have mild, moderate or severe obstructive sleep apnea syndrome.

Apnea associated with snoring was described for the first time by Broadbent2 in 1877. Mackenzie18, in 1880, described the relation between upper airway obstruction and adenotonsillar hypertrophy. Only in 1960, the real interest in these children was raised, owing to the association with cor pulmonale 14, 15, 16, 20.

In children, the most common cause of OSAHS is adenotonsillar hypertrophy, normally characterized by the presence of night snoring, apnea episodes, agitated sleep, mouth breathing and diurnal sleepiness3, 17, 19, 24, 29. Clinical history, unfortunately, is limited to diagnosis because of lack of information available and the frequency of symptoms in normal children5, 6, 7, 29. In an unpublished study conducted in our center, we observed that many children with obstructive adenotonsillectomy and clinical history suggestive of OSAHS did not present apnea manifested in the polysomnography, whereas others with non-obstructive adenotonsillar hypertrophy presented polysomnography abnormalities. The symptoms of children with OSAS and primary snoring are similar. Thus, up to present, it is not possible to determine when adenotonsillectomy may benefit mild OSAHS and normal and symptomatic children. OSAHS is a precise indication for adenotonsillectomy in children, because it improves upper airway obstruction8, 9, 10, 13, 27.

There are a number of causes of upper airway obstructions and consequently, of OSAHS, such as nasal obstruction, micrognatia, laryngeal disorders, cranial-facial anomalies, and neuromuscular problems.

OBJECTIVE

The present study intended to objectively record the diagnosis of OSAHS, using polysomnography, in children who had adenotonsillar hypertrophy and improvement after adenotonsillectomy.

MATERIAL AND METHOD

We assessed 23 children aged between 2 and 13 years, who presented history of nasal obstruction, mouth breathing, night snoring followed by apnea episodes and adenotonsillar hypertrophy at the physical examination, carried out in the Ambulatory of Pediatric Otorhinolaryngology (1999-2001). The children were submitted to nasofibroscopy using 3.2 flexible optic fiber endoscopy to assess the size of the adenoids and tonsils. We performed then polysomnography: we assessed electrophysiological and cardio-respiratory parameters, recorded in a computed system - electrocardiogram, submentonial and tibial electromyography, right and left electrooculogram, oronasal airflow, thorax and abdomen movement, microphone (snoring), oxy-hemoglobin saturation (SaO2) and bed position. To analyze the results, we used Respiratory Disorder Indexes (IDR - No. of apnea/hypopnea episodes/hour), mean SaO2 during REM and NREM sleep, retention of CO2 and minimum oxy-hemoglobin desaturation (SaO2 Nadir).

We excluded children who had syndromes, craniofacial malformations, laryngeal abnormalities or other systemic diseases.

The studied children were then submitted to adenotonsillectomy, and assessed 60 days after surgery using polysomnography and nasofibroscopy. We used IDR and pre and post-operative O2 Nadir of these children to conduct the statistical analysis (Wilks' method), and to confirm post-surgical improvement.

RESULTS

All 23 studied children presented significant improvement of upper airway obstruction after adenotonsillectomy, confirmed by the polysomnography study. We assessed IDR (No. of apnea/hypopnea episodes/hour), O2 saturation during REM and NREM sleep, CO2 retention and SaO2 Nadir. Out of the total, 2 children (8.69%) persisted with mild OSAHS after the surgery, but they improved significantly when compared to preoperative polysomnography. Four children (17.39%) had suggestive history of OSAHS, but did not have it confirmed by the polysomnography, showing only primary snoring (see the Table below). Based on the calculation of mean pre and post-operative IDR, showing 7.46 events/hour and 0.64 events/hour, respectively, we used the statistical method of Wilks and the result was p = 0.0009 (significant p < 0.05). Mean preoperative nadir was 80.35 and the postoperative nadir was 92.48, and using this statistical method, the result was p = 0.002 (significant p < 0.05).

Table 1.

DISCUSSION

In children with upper airway obstruction, polysomnography may contribute to a more precise diagnosis and specific treatment8, 10. The routine use of polysomnography in children with suspicion of OSAHS that present large tonsils and/or adenoids is questioned3. Many authors suggested the use of polysomnography especially in cases that generate doubts. Approximately 10% of the children snore during sleep for part of the night, and most of the time it is primary snoring, which is defined as snoring during sleep without episodes of apnea, hypo-ventilation or hypoxia. Ali et al.1 (1993) observed that 50% of the children that presented snoring at the age of 4 years, as referred by the parents, had improved without treatment after a 2-year follow-up. Conversely, about 40% of these children with history of night snoring could present OSAHS 5, 6. According to Gilason et al.11, OSAS affects about 3% of the children.

The result of our study demonstrated that surgical treatment of OSAHS is effective, as reported by many authors in the literature4, 12, 13, 22, which was also confirmed by our study based on statistical analysis of pre and post-operative polysomnography in 23 children. Owing to the great number of data collected from the polysomnography, it was not statistically possible to compare the final results of polysomnography. We decided, therefore, to use two extremely important parameters, IDR and O2 Nadir. We compared IDR and O2 Nadir and although they were not the only parameters studied at polysomnography, their results were strong enough to provide statistical evidence of improvement comparing pre and post-operative status.

OSAHS may persist even after adenotonsillectomy, but the episodes are normally represented as central apnea and they are less frequent in number 26, data also confirmed by our study, in which 2 children (8.69%), even after surgery, maintained mild OSAHS, which was previously classified as moderate or severe.

We also observed, as reported by Weissbluth29, that in 4 children (17.39% of the cases), even though they had clinical history of sleep obstructive apnea, the polysomnography confirmed only primary snoring. In such children, we also noticed improvement of polysomnography pattern after surgery.

Symptomatic improvement of OSAHS with adenotonsillectomy has been documented by different authors [Brouillete et al., 1982 (n of children - 14); Butt et al., 1985 (n - 20); Eliaschar et al., 1980 (n - 9); Frank et al., 1983 (n - 14)3,4,8,10)].

Although there are a number of studies that confirmed the improvement of OSAHS after adenotonsillectomy, they were all based on symptomatic clinical criteria22, 24, 28, 29, 31, and no objective criteria were used to confirm improvement.

CONCLUSION

In our study, we concluded that improvement of OSAHS in children with adenotonsillar hypertrophy after adenotonsillar surgery is very significant and marked, which was objectively confirmed and did not rely on subjective parameters (symptomatic improvement).

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[1] Specialization studies under course, Discipline of Pediatric Otorhinolaryngology UNIFESP - EPM.
[2] Post-graduate studies under course, Discipline of Pediatric Otorhinolaryngology UNIFESP - EPM.
[3] Post-graduate studies under course, Discipline of Psychobiology, UNIFESP - EPM.
[4] Head of Clinic, Discipline of Pediatric Otorhinolaryngology UNIFESP - EPM.
[5] Head of the Discipline of Pediatric Otorhinolaryngology UNIFESP - EPM.

Discipline of Pediatric Otorhinolaryngology UNIFESP - EPM

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