Lucas Neves de Andrade Lemes

Instrumentation for the analysis of respiratory system disorders during sleep: Design and application

Sleep breathing disorders are estimated to be present in 2%–4% of middle-aged adults. Serious adverse consequences, such as systemic arterial hypertension, myocardial infraction, and cerebrovascular disease, can be related to these conditions. Intellectual deficits associated with attention, memory, and problem-solving have also been associated with a poor quality of sleep. The main causes of these disorders are obstructions resulting from repetitive narrowing and closure of the pharyngeal airway, which have been monitored by indirect measurements of temperature, displacement, and other highly invasive procedures. The measurement of mechanical impedance of the respiratory system by the forced oscillation technique (FOT) has recently been suggested to quantify the respiratory obstruction during sleep. It is claimed that the noninvasive and dynamic characteristics of this technique would allow a noninvasive and accurate analysis of these events. In spite of this high scientific and clinical potential, there...

Forced oscillation technique in the sleep apnoea/hypopnoea syndrome: identification of respiratory events and nasal continuous positive airway pressure titration.

Sleep breathing disorders (SBD) are related to obstructions resulting from repetitive narrowing and closure of the pharyngeal airway. Their diagnoses and treatment are critically dependent on an accurate identification of and discrimination between types of respiratory events. However, these disorders have been diagnosed using indirect or invasive measurements, which resulted in serious doubts concerning the correct evaluation of breathing events. The forced oscillation technique (FOT) has recently been suggested as a clinical tool able to accurately and non-invasively quantify respiratory obstruction during sleep. The present study investigates the morphology of the impedance signal during different sleep respiratory events and evaluates the ability of impedance measurements in providing adequate nasal continuous positive airway pressure (nCPAP) titration. The results evidenced characteristic patterns in impedance signal morphology that are useful in the identification and classification of abnormal respiratory events. Moreover, significantly higher impedance values were obtained during apnoea and hypopnoea events when compared with normal values (p < 0.01). Studies using impedance measurements to adjust nCPAP showed a significant reduction (p < 0.01) of abnormal respiratory events, and a consequent normalization of the patients. These findings support the use of the FOT as a versatile clinic diagnostic tool helping SBD diagnosis and treatment.

Drug-induced sleep endoscopy in the obstructive sleep apnea: comparison between NOHL and VOTE classifications

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete collapse of the pharynx that result in a decrease in oxyhemoglobin saturation. Nasofibrolaryngoscopy under induced sleep is a promising alternative for identifying sites of upper airway obstruction in patients with OSA. This study aimed to compare the obstruction sites screened by drug-induced sleep endoscopy (DISE) using the Nose oropharynx hypopharynx and larynx (NOHL) and Velum oropharynx tongue base epiglottis (VOTE) classifications. We also determined the relationship between OSA severity and the number of obstruction sites and compared the minimum SaO2 levels between DISE and polysomnography (PSG). This was a prospective study in 45 patients with moderate and severe OSA using DISE with target-controlled infusion of propofol bispectral index (BIS) monitoring. The retropalatal region was the most frequent obstruction site, followed by the retrolingual region. Forty-two percent of patients had obstruction in the epiglottis. Concentrically shaped obstructions were more prevalent in both ratings. The relationship between OSA severity and number of obstruction sites was significant for the VOTE classification. Similar minimum SaO2 values were observed in DISE and PSG. The VOTE classification was more comprehensive in the analysis of the epiglottis and pharynx by DISE and the relationship between OSA severity and number of affected sites was also established by VOTE. The use of BIS associated with DISE is a reliable tool for the assessment of OSA patients.

Reply to Dijemeni et al.’s comments concerning: “The comparability of drug-induced sedation classification systems”

classification [3]. BIS has been shown to be a relevant parameter in the orientation of the depth of sedation with propofol by target controlled infusion technique, avoiding deep sedations and severe desaturations. The mean of lowest oxygen saturation values was higher in DISE (85%) than in PSG (78%). The 2014 European position paper [4] in relation with the DISE classification system, which aimed to represent patterns of obstruction in terms of obstruction structures and/or levels of obstruction, was based on studies available at that moment. Building upon new research, the European position can be updated. The description in the VOTE classification (sites) appears to be more precise, or even easier, than the NOHL classification (levels), but the DISE imagens during the apnea are often not as clear as we would like. We can always find cases that will not fit into the classification systems chosen to describe the findings. We believe that whatever classification that is used will always present shortcomings. More studies are important to identify and select a classification that can minimize biases. We agree that classification standardization will be an important step, especially among world-wide research centers [5]. Additional correlations between the DISE findings, through the classifications that are being used, and other polysomnographic outcome, such as the oxygen desaturation index, also need to be considered. Moreover, another relevant aspect to consider is the observers’ experience in the identification of the anatomical structures during an apnea event (sites and levels) and the capacity of reproduction of the results. New questions and answers are valuable to demonstrate the usefulness of the DISE in the evaluation of patients with OSA, be it for surgical indication or contraindication, and be it for clinical treatment. The authors are thankful for the overall positive opinion expressed about our paper “Drug-induced sleep endoscopy in the obstructive sleep apnea: comparison between NOHL and VOTE classifications” [1] in the letter to the editor entitled “The comparability of drug-induced sedation classification systems”. We wish briefly to reply to the questions raised by the authors of the letter. Our study correlated the severity of obstruction sleep apnea (OSA) with obstruction sites (VOTE) (p value O1 = 0.05 and O2 = 0.04), not identifying this correlation between obstruction levels (NOHL) (p value O1 = 0.21 and O2 = 0.14). Regarding the epiglottis, the VOTE classification [2] is more detailed, since it allows to identify the form and degree of obstruction, different from the NOHL

Systematic review: the influence of nasal obstruction on sleep apnea

INTRODUCTION Obstructive sleep apnea syndrome (OSAS) is a common disorder that can lead to cardiovascular morbidity and mortality, as well as to metabolic, neurological, and behavioral consequences. It is currently believed that nasal obstruction compromises the quality of sleep when it results in breathing disorders and fragmentation of sleep. However, recent studies have failed to objectively associate sleep quality and nasal obstruction. OBJECTIVE The aim of this systematic review is to evaluate the influence of nasal obstruction on OSAS and polysomnographic indices associated with respiratory events. METHODS Eleven original articles published from 2003 to 2013 were selected, which addressed surgical and non-surgical treatment for nasal obstruction, performing polysomnography type 1 before and after the intervention. RESULTS/CONCLUSIONS In most trials, nasal obstruction was not related to the apnea-hypopnea index (AHI), indicating no improvement in OSAS with reduction in nasal resistance. However, few researchers evaluated other polysomnography indices, such as the arousal index and rapid eye movement (REM) sleep percentage. These could change with nasal obstruction, since it is possible that the nasal obstruction does not completely block the upper airways, but can increase negative intrathoracic pressure, leading to sleep fragmentation.

Correlation between the oropharyngo-laryngoscopic findings and the severity of obstructive sleep apnea.

OBJECTIVE To correlate anatomical and functional changes of the oral cavity, pharynx and larynx to the severity of obstructive sleep apnea syndrome (OSAS). METHODS We conducted a cross-sectional study of 66 patients of both genders, aged between 21 and 59 years old with complaints of snoring and / or apnea. All underwent full clinical evaluation, including physical examination, nasolarybgoscopy and polisonography. We classified individuals into groups by the value of the apnea-hypopnea index (AHI), calculated measures of association and analyzed differences by the Kruskal-Wallis and chi-square tests. RESULTS all patients with obesity type 2 had OSAS. We found a relationship between the uvula projection during nasoendoscopy and OSAS (OR: 4.9; p-value: 0.008; CI: 1.25-22.9). In addition, there was a major strength of association between the circular shape of the pharynx and the presence of moderate or severe OSAS (OR: 9.4, p-value: 0.002), although the CI was wide (1.80-53.13). The septal deviation and lower turbinate hypertrophy were the most frequent nasal alterations, however unrelated to gravity. Nasal obstruction was four times more common in patients without daytime sleepiness. The other craniofacial anatomical changes were not predictors for the occurrence of OSAS. CONCLUSION oral, pharyngeal and laryngeal disorders participate in the pathophysiology of OSAS. The completion of the endoscopic examination is of great value to the evaluation of these patients.