OTORRHINOLARYNGOLOGY

CHRISTIANE RIBEIRO ANIAS, MD

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OBSTRUCTIVE SLEEP APNEA SYNDROME



Introduction

Although the sign and symptoms of the Obstructive Sleep Apnea Syndrom (OSAS) had been described a long time ago, this subject has received its importance only nowadays.

Apnea is caracterized by breath cessation for at least 10 seconds. Apnea is classified in central, obstructive and mixed. Central apnea occurs when the ventilatory effort is absent, and consequently all the respiratory muscles moviments are momentaneous abolished. Obstructive apnea occurs when the ventilatory effort persists throughout the apneic episod, but no airflow occurs because the transient obstruction of the upper airflow. Mixed apnea occurs when the absent ventilatory effort precedes upper airway obstruction during the apneic effort.

The OSAS affects 1-4% of people in middle age.

Fisiopatology

The collapse and obstruction of the upper airway is consequent of :

  • Anatomic alterations- tonsils hypertrophy and nasal obstruction are the main responsible of OSAS in children. Obesity related with retention of soft tissue in the pharynx is an important factor which worsen the narrowed of the airways.

  • Reduction of the ativity of the dilatations muscles of the pharynx- during the sleep time there is an hipotony of the muscles of the upper airway, and pharynx tends to collapse. Alcohol and sedatives used before sleeping usually precipate or worsen this condition due to its action in reducting the muscles activity.

  • Negative pression in the upper airway during the inspiration. - The anatomic and functional disturbance result in the narrowed of the upper airway and require geration of a bigger negative pression in order to maintain the ventilation. This negative pressure tends to collapse the pharynx and results in the OSAS.

    Clinical Manifestations

    When the symptoms start the patients have at least 10-15 episodes of apnea per hour of sleep. Patients complain of excessive day time somnolence, morning sluggishness and headaches, daytime fatigue, cognitive impairment. Bed partners usually report loud cyclical snoring , breath cessation, restlessness, and often thrashing moviments of extremities during sleep. Personality changes, work related problems, inability to concentrate may also be observed.

    Most patients with OSAS have cyclic desacceleration of the heart during apnea of 30-50 bpm followed by a taquicardia of 90-120 bpm during the ventilatory phase. A small number of patients have severe bradicardia with assystolia of 8-12seconds or danger taquicardia.

    About 10-15 % of patients have pulmonary hypertension, hipercapnia, cronic hipoxemia with erytrocytosis.

    Diagnostic

  • Anamnese- A very careful anamnese should be done including questions about snoring, day time somnolence...

  • Laboratory- It should always include exams of thyroid function to exclude hypothyroidism and red cell count to avaliate policetemia due to nocturnal hipoxemia.

  • Radiology- To avaliate adenoids hypertrophy.

  • Otolaryngologic exam- The oropharynx is frequently found to be narrowed by excessive soft tissuefolds, large tonsils, pendulous uvula or proeminent tongue. Nasal obstruction by a deviated nasal septum, poor nasal airflow may be observed.

  • Polysomnography- Exam which gives the definitive diagnostic. It,s a monitorization during the night, of many fisiologic variants such as electroencephalography, electrooculography, eletromyography, eletrocardiography, oximetry and measurement of respiratory effort and airflow.

    Treatment

    Weight loss and strict avoidance of alcohol and hypnotic medications are the first steps in management of OSAS. Patients should avoid to sleep in dorsal decubit which usually worsen the symptoms.

    Some drugs are used to reduce the symptoms such as Protriptyline (10-20 mg orally at bed time), but pharmacologic therapy is often disappoiting.

    Uvulopalatopharyngoplasty is a cirurgical procedure consisting of ressection of pharyngeal soft tissue and amputation of the free edge of the soft palate and uvula. It may be helpful only in selected patients

    Nasal continuous positive airway pressure (CPAP) is very helpful and is the elected treatment of OSAS. It,s a non-inasive method in which a positive pression from a flow gerator is aplayed in nose using a mask in face. The answer to this method is very good and quick, but some patients have difficult in adaptation with it.

    Acknowlogments to Cláudia Maria Valente, MD and Alexandra Torres Cordeiro Lopes de Souza, MD for their helpful review of this article.

    If you have suggestions or comments send an e-mail to Christiane Ribeiro Anias

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