INTRODUCTION

The localization of obstruction of upper airways in patients who have Obstructive Sleep Apnea-Hypopnea Syndrome has been evaluated through several methods. Some of such methods are the physical and otorhinolaryngological exams (ORL), endoscopy with Muller Maneuver (MM) and image exams with cephalometry and magnetic resonance image (MRI) (1, 2). However, physical exam and UA endoscopy are not considered objective measures during sleep and their predictive values are still controversial to define the levels of collapsibility and snoring during sleep (3, 4).

In 1991, Croft and Pringle described a new diagnosis technique for patients with OSAHS based on direct and dynamic evaluation, under endoscopic view, of UA during sleep. Through the method which is known as Somnoendoscopy or Nasoendoscopy under sedation, examiner may observe the anatomic area which is liable to produce noise and the area where UA is narrowed and obstructed in conditions which resemble physiological sleep (5, 6). Since its introduction, the aforementioned authors have developed a classification scheme, according to the findings of nasoendoscopy under sedation, selecting patients to indicate uvulopalatopharyngoplasty (7, 8).

Many surgeons, mainly in England, recommend such technique and consider it "the best currently available method to directly evaluate pharynx during induced sleep" (6).

Different sedative agents and different infusion techniques have been used in Somnoendoscopy. Choosing the drug, dose and mainly, the infusion technique of the hypnotic agent is crucial to obtain an ideal sedation plan which allows proper muscle relaxation to reproduce snoring, without breathing depression (1, 9).

This study aims at developing and introducing such methodology in Brazil and objectively presenting the obstruction areas in OSAHS physiopathology.


MATERIAL AND METHOD

This study was approved by the Research Ethics Committee of the Centro Universitário São Camilo under research registration number 185/04 according to requirements of Resolution CNS-MS 196/96.

Two groups of patients underwent somnoendoscopy. The first group was made of 10 patients (6 men and 4 women) aging from 18 to 52 years (mean age 33.6 years). This group underwent to the analysis in surgical environment, with previous general anesthesia, to have otorhinolaryngologic surgery not related to OSAHS. Such patients did not present clinical symptoms related to snoring and sleep apnea, a fact which was confirmed by their partners.

The second group was made of 30 patients, 21 (70%) men and 9 (30%) women, aging from 24 to 59 years (mean age 34.5 years). This group was selected to this study because it presented clinical diagnosis of OSAHS. Such patients underwent an accurate clinical history and to a questionnaire concerning sleep, general and otorhinolaryngologic physical examination, which includes calculation of body mass index (BMI) and measure of cervical perimeter, and UA endoscopic exam with MM watching. Polissonography was requested after that. Somnoendoscopy was performed in the sleep laboratory of Hospital e Maternidade São Camilo - Pompéia and of Otorhinolaryngology and Head and Neck Surgery Center of São Paulo, before night polissonography.

Patients were placed in horizontal dorsal decumbent (Picture 1). Topic anesthesia of nasal fossa is done with 2% Neututocaine before hypnotic induction. The agent which was used was 1% Propofol through slow and gradual manual infusion. The average dose of the agent was of up to 2mg/kg (varying from 1.5 to 2.5 mg/kg). The following items were used for the procedure: video endoscopy devices, a 2.7-mm nasofibroscope, and materials which give ventilation support to patients, such as wrist oximeter, network oxygen system, Ambu mask, Guedel tubes, orotracheal intubation probes, secretion aspirator and cardioversion device (Picture 2).

Picture 1 - Somnoendoscopy.


Picture 2 - Procedure room.

The exam starts when patients start snoring and/or when the examiner detects their hypo responsiveness to verbal and touch stimuli with the device in nasal vestibule.

In addition to nasal exam, direct inspection of all pharynxes is performed. It starts through retropalatal space, then retrolingual space and finally supraglottis. We evaluated the collapsibility degree of pharynx in its different levels, the kind of closing of pharyngeal walls (round, lateral or antero-posterior), the areas of vibration and snoring generation, position of soft palate and of uvula in relation to oropharynx walls, position of tongue base, of lateral walls of pharynx, of epiglottis and aryepiglottic ligaments in relation to laryngeal vestibules, mean and minimum oxygen saturations and also snoring intensity and tone.

During such procedure, it is important to observe chest and abdomen movements of patients to check non-occurrence of central apnea. Meanwhile, anesthesiologist should control oxygen saturation levels through clinical signs and wrist oximetry. During the evaluation of supraglottis, it is also possible to observe the slight movements of arytenoid cartilage which follow breathing movements, showing the non occurrence of breathing depression.

The pharynx collapsibility results obtained in both groups were finally compared. It is important to point out that the first phase of the study involving group 1 represented the first contact of our team with such new technique. Collapsibility of upper pharynx or the retropalatal one and of lower pharynx or the retrolingual one evaluated in both exams was classified in five degrees: degree zero - absence of closing; degree 1 - up to 25% of pharyngeal lumen; degree 2 - until 50%; degree 3 - until 75% and degree 4 - higher than 75%. Only one patient of group one presented obstruction in supraglottis level (see results).


RESULTS

The patients were divided in two groups.

The first group was made of 10 patients (6 men and 4 women) aging from 18 to 52 years (mean age 33.6 years). This group underwent to the analysis in surgical environment, with previous general anesthesia, to have otorhinolaryngologic surgery not related to OSAHS. This first group provided examiners and anesthesiologists with first contact with this new technique, mainly concerning sedation plan to be reached, without breathing depression, in addition to risks, side effects and main cares to be taken during such exam. Through this initial group, it was tried to standardize the technique of manual infusion of propofol - dose and infusion velocity. Table 1 shows main results obtained in this phase of the study (Table 1). Only one patient presented degree three collapse in supraglottis level. Concerning snoring and breathing depression (hypopnea/apnea) clinically defined as the absence of chest and abdomen movements and/or drop of oxi-hemoglobin saturation, 5 patients presented snoring (50%) and 3 patients presented clinical signs of apnea/hypopnea (30%).

The second group was made of 30 patients, 21 (70%) men and 9 (30%) women, aging from 24 to 59 years (mean age 34.5 years). Such patients were selected for the second phase of the study once they presented clinical diagnosis of OSAHS. Table 2 shows main results obtained in group 2 (Table 2). Concerning occurrence of snoring and apnea/hypopnea during examination, (80%) presented snoring and 6 patients (20%) did not. Nine patients (30%) presented apnea or hypopnea during exam. One patient of group 2 which was not mentioned in our caustics presented significant breathing depression and oxi-hemoglobin desaturation during the procedure, thus needing ventilation support through oxygen mask with Ambu. There was no need of orotracheal intubation.

DISCUSSION

Localization and kind of UA obstruction in patients with OSAHS represent one of main elements to diagnose such patients, besides defining disease's severity and their co-morbidities (3).

Before the introduction of Somnoendoscopy by Croft and Pringle (1991), different diagnostic methods such as MM endoscopy, UA manometry and radiological exams have been used to try to preview the areas of partial or total obstruction of UA, however none of them is able to provide objective measures during sleep (1,4,9). Somnoendoscopy, in turn, provides a direct and dynamic inspection, under endoscopic view, of pharynx, which allows the identification of the obstruction area and of snoring generation during physiological sleep. Once it is a dynamic, non-invasive, cheap evaluation of pharynx with conditions which resemble sleep, such method is very attractive to diagnose patients with snoring and apnea (4, 5).

However, Somnoendoscopy has been criticized because it does not produce a physiological sleep, due to sedation involved. Different sedative agents in different doses, administrated in bolus infusion, have been described (2, 6, 9, 10). Bolus infusion, although it is frequently used, determines variation of serum and tissular levels of the drug. In addition to this, the fact that different anesthesiologists do the exam may also determine different sedation effects, regardless of the technique to be used (6). Choice drug has been 1% Porpofol once it presents fast effect and metabolization and low incidence of side effects such as nausea, vomit, headache and displeasure.

In this study, we used slow and gradual manual infusion technique, not bollus infusion. We should point out that the initial phase of this study involving group 1 meant our knowledge and development of technique, providing exam's improvement and mainly safety and lower risk to future patients to be submitted to this procedure out of surgical environment. Anesthesiology team was made of 4 professionals, which did not allow a standardization of drug use.

Collapsibility results, when both groups are compared, demonstrate the existence of a probable specificity of this exam to preview the occurrence of pharynx obstruction in patients having sleep breathing disorders. Concerning pharynx obstruction level and collapsibility degree, there is nothing we can state currently, once we need to improve infusion technique to reach an ideal sedation plan which reproduces as physiological as possible. Occurrence of snoring and mainly apnea/hypopnea in patients of group 1 demonstrates non-reproduction of physiological sleep. Concerning group 2, we may observe that in most patients UA collapse occurs in more than one level (upper and lower pharynx) which a collapsibility degree of at least 50% (degree 2). Such finding may represent a more accurate topographic diagnosis of the disease and thus avoid undertreatment of such patients.

The correct level of sedation in Somnoendoccopy is of extreme importance to obtain muscular relaxation enough to recreate snoring and partial and/or complete UA collapse, without apnea or breathing depression (4, 6). Consequently, more recent studies have demonstrated concern in developing new sedation techniques, aiming at standardizing anesthesiologists' action and cancel variables which may harm reproduction of physiological sleep (4, 11).

Roblin and cols (2001) developed a controlled infusion system called "Target-Controlled Infusion" which, based on pharmacokinetic and pharmacodymanic characteristics of propofol, keeps a certain serum level of the drug, previously defined, allowing a control of sedation intensity, through slow and continuous infusion programmed by the device (11).


CONCLUSION

Somnoendoscopy represents a great advance in diagnostic approach of patients having OSAHS, once it allows a direct and dynamic evaluation, under endoscopic view, of UA during sleep. In our first experience, it appeared to be a safe procedure, since there is training and necessary support equipment. Manual infusion technique, even if it is slow and gradual, does not reproduce an ideal sedation which allows a proper muscular relaxation, without breathing depression. However, standardization of anesthesiologists' participation and evolution of sedation technique with the use of controlled infusion bombs will allow reproduction of physiological sleep. Consequently, we may precisely define, through objective evaluation, localization and kind of pharynx obstruction, in addition to snoring generation area, allowing, the indication of the most proper treatment to patient, and if it is surgical, increasing our success rates.


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1. Chair of the Sociedade Brasileira de Laringologia e Voz (Voice and Laryngology Institution) (2001-2003) - Director of the Otorhinolaryngology and Head & Neck Surgery Center of São Paulo.
2. Otorhinolaryngologist (Assistant Doctor of the Otorhinolaryngology and Head & Neck Surgery Center of São Paulo and of the Otorhinolaryngology department of Hospital e Maternidade São Camilo - Pompéia - São Paulo).
3. Otorhinolaryngology physician.
4. Physician (Resident doctor of the Otorhinolaryngology and Head & Neck Surgery Center of São Paulo.

Núcleo de Otorrinolaringologia e Cirurgia de Cabeça e Pescoço de São Paulo

José Antonio Pinto
Mail address:
Al. dos Nhambiquaras, 159 CEP 04090-010 São Paulo/SP Fone/fax:(11) 5573.1970 E-mail: japorl@uol.com.br

This article was submitted to SGP (Sistema de Gestão de Publicações) of R@IO on May 16th, 2007 (code # 252) and approved on June 12th, 2007.