10.14639/0392-100X-N1100
Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a disease characterised by upper airway obstruction during sleep, quite frequent in the general population, even if underestimated. Snoring, sleep apnoea and diurnal hypersomnia are common in these patients. Central obesity plays a key role: it reduces the size and changes the conformation of the upper airways, besides preventing lung expansion, with consequent reduction of lung volumes. Furthermore, obese people are also resistant to leptin, which physiologically stimulates ventilation; as a result, this causes scarce awakening during apnoea. OSAHS diagnosis is based on the combination of clinical parameters, such as apnoea/hypopnoea index (AHI), medical history, physical examination and Mallampati score. The first objective reference method to identify OSAHS is polysomnography followed by sleep endoscopy. Therapy provides in the first instance reduction of body weight, followed by continuous positive airway pressure (CPAP), which still remains the treatment of choice in most patients, mandibular advancement devices (MAD) and finally otolaryngology or maxillofacial surgery. Among surgical techniques, central is barbed reposition pharyngoplasty (BRP), used in the field of multilevel surgery.
application/xml
1827-675X
1100
en
Francesco Antonio Salzano
https://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
orthognatic surgery
Obstructive sleep apnoea/hypopnoea syndrome: relationship with obesity and management in obese patients
Text.Serial.Journal
https://www.actaitalica.it/
41
Reviews
2021-05-14
2020-09-01
2021-05-17
2021-06-10
120-130
1
Francesco Antonio Salzano
2021/05/14
10.14639/0392-100X-N1100
120
Department of Medicine, Surgery and Dentistry, “Scuola Medica Salernitana”, University of Salerno, Baronissi (Salerno), Italy
1827-675X
orthognatic surgery
130
Obstructive sleep apnoea/hypopnoea syndrome: relationship with obesity and management in obese patients
https://www.actaitalica.it/article/download/1100/574
41
ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:120-130; doi: 10.14639/0392-100X-N1100




Review


Obstructive sleep apnoea/hypopnoea syndrome:
relationship with obesity and management in obese
patients
La sindrome da apnee notturne: correlazione con l’obesità e gestione del paziente
obeso
Giovanni Salzano1, Fabio Maglitto1, Antonella Bisogno2 , Luigi Angelo Vaira3, Giacomo De Riu3, Matteo Cavaliere4,
Arianna di Stadio5, Massimo Mesolella6, Gaetano Motta7, Franco Ionna1, Luigi Califano8, Francesco Antonio Salzano2
1
 Maxillo-Facial and ENT Surgery Unit, INT- IRCCS “Fondazione G. Pascale”, Naples, Italy; 2 Department of Medicine, Surgery
and Dentistry, “Scuola Medica Salernitana”, University of Salerno, Baronissi (Salerno), Italy; 3 Maxillofacial Surgery Unit,
University Hospital of Sassari, Sassari, Italy; 4 Department of Otolarhinolaryngology, University Hospital “San Giovanni di Dio e
Ruggi d’Aragona”, Fisciano, Salerno, Italy; 5 Otolaryngology Department, University of Perugia, Perugia, Italy; 6 Department of
Neuroscience, Reproductive and Odontostomatological Science, Ear Nose and Throat Unit, University of Naples “Federico II”,
Naples, Italy; 7 Clinic of Otorhinolaryngology, Head and Neck Surgery Unit, Department of Anesthesiology, Surgical and Emergency
Science, University of Campania “Luigi Vanvitelli”, Naples, Italy; 8 Maxillofacial Surgery Unit, Department of Neurosciences,
Reproductive and Odontostomatological Sciences, University Federico II, Naples, Italy


SUMMARY
Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a disease characterised by upper
airway obstruction during sleep, quite frequent in the general population, even if underesti-
                                                                                                    Received: September 1, 2020
mated. Snoring, sleep apnoea and diurnal hypersomnia are common in these patients. Central
                                                                                                    Accepted: December 28, 2020
obesity plays a key role: it reduces the size and changes the conformation of the upper airways,
besides preventing lung expansion, with consequent reduction of lung volumes. Furthermore,
                                                                                                    Correspondence
obese people are also resistant to leptin, which physiologically stimulates ventilation; as a re-
                                                                                                    Fabio Maglitto
sult, this causes scarce awakening during apnoea. OSAHS diagnosis is based on the combina-          Maxillo-Facial and ENT Surgery Unit, INT-IRCCS
tion of clinical parameters, such as apnoea/hypopnoea index (AHI), medical history, physical        “Fondazione G. Pascale”, Naples, Italy
examination and Mallampati score. The first objective reference method to identify OSAHS            Tel. +39 081 5903384. Fax +39 081 5903461
is polysomnography followed by sleep endoscopy. Therapy provides in the first instance re-          E-mail: fmaglitto@gmail.com
duction of body weight, followed by continuous positive airway pressure (CPAP), which still
remains the treatment of choice in most patients, mandibular advancement devices (MAD)              Funding
and finally otolaryngology or maxillofacial surgery. Among surgical techniques, central is          None.
barbed reposition pharyngoplasty (BRP), used in the field of multilevel surgery.
                                                                                                    Conflict of interest
KEY WORDS: OSAHS, obesity, CPAP, pharyngoplasty, orthognatic surgery                                The Authors declare no conflict of interest.

RIASSUNTO                                                                                             How to cite this article: Salzano G, Maglitto
La sindrome da apnee notturne è una malattia caratterizzata da ostruzione delle vie aeree supe-       F, Bisogno A, et al. Obstructive sleep apnoea/
riori durante il sonno, abbastanza frequente nella popolazione generale, anche se sottovalutata.      hypopnoea syndrome: relationship with obesity
Russamenti, apnee notturne e ipersonnia diurna sono comuni in questi pazienti. L’obesità svol-        and management in obese patient. Acta Otorhi-
ge un ruolo chiave: riduce le dimensioni e modifica la conformazione delle vie aeree superiori,       nolaryngol Ital 2021;41:120-130. https://doi.
oltre a prevenire l’espansione polmonare, con conseguente riduzione dei volumi polmonari. Le          org/10.14639/0392-100X-N1100
persone obese sono anche resistenti alla leptina, che stimola fisiologicamente la ventilazione;
di conseguenza, questo provoca uno scarso risveglio durante l’apnea. La diagnosi si basa sulla      © Società Italiana di Otorinolaringoiatria
                                                                                                    e Chirurgia Cervico-Facciale
combinazione di parametri clinici, come indice di apnea / ipopnea (AHI), anamnesi, valutazione
clinica e Mallampati score. La prima indagine strumentale per identificare pazienti OSAHS è
                                                                                                                   OPEN ACCESS
la polisonnografia seguita dalla sleep endoscopy. La terapia prevede in primo luogo la riduzio-
ne del peso corporeo, seguita dalla ventilazione a pressione positiva continua delle vie aeree      This is an open access article distributed in accordance with
                                                                                                    the CC-BY-NC-ND (Creative Commons Attribution-Non-
(CPAP), che rimane ancora ad oggi il trattamento di scelta nella maggior parte dei pazienti,        Commercial-NoDerivatives 4.0 International) license. The
dispositivi di avanzamento mandibolare (MAD) e infine diversi approcci chirurgici. Tra le tec-      article can be used by giving appropriate credit and mentio-
niche chirurgiche la faringoplastica (BRP), rappresenta la tecnica prescelta.                       ning the license, but only for non-commercial purposes and
                                                                                                    only in the original version. For further information: https://
PAROLE CHIAVE: OSAHS, obesità, CPAP, faringoplastica, chirurgia ortognatica                         creativecommons.org/licenses/by-nc-nd/4.0/deed.en




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                                                                                                            OSAHS and obesity




Introduction                                                    but also obesity 17. On the other hand, neuromuscular fac-
                                                                tors can also cause airway obstruction in OSAHS: among
Obstructive sleep apnoea/hypopnoea syndrome, also
                                                                them, sleeping in the supine position, which facilitates the
known as OSAHS, is a disease characterised by intermit-
                                                                occurrence of apnoea because of posterior repositioning of
tent and repeated episodes of complete or partial upper
                                                                the tongue by gravitational effect 18, and alcohol and smok-
airway obstruction during sleep: these episodes are more
                                                                ing, which promote relaxation of airway muscles 19.
than five per hour and are usually associated with recurrent
                                                                In this pathophysiological context, however, particular at-
oxyhaemoglobin desaturations, sympathetic hyperactivity
                                                                tention must be paid to obesity, about which this review is
and variation of intrathoracic pressures, which eventually
                                                                concerned.
lead to sleep fragmentation, tiredness and excessive diurnal
sleepiness 1,2.
As demonstrated by several epidemiologic studies, OS-           The interactions between OSAHS and obesity
AHS is a fairly common condition in the general popula-         Nowadays obesity is widely recognised as the most impor-
tion, with a prevalence of 24% in men and 9% in women           tant risk factor for OSAHS: a 10% weight gain increases
aged between 30 and 60 years; in the paediatric population,     the risk of developing this disease by six-times 20 and ac-
OSAHS may appear at all ages, from neonatal to adoles-          cording to recent estimates more than half of obese people
cence, with an estimated prevalence included between 2          are affected by OSAHS 4. Particularly at risk are people
and 5.7%. However, despite this frequency, OSAHS is an          affected by central or visceral obesity, with prevalent fat
under-reported condition, identified only in 5-10% of af-       deposition in the trunk and neck area, also known as an-
fected subjects 3-5.                                            droid obesity, because typically male 21.
OSAHS symptomatology is dominated by snoring, in ad-            The higher prevalence of OSAHS in obese subjects is not
dition to frequent awakenings, choking, disrupted sleep         limited to adults, but also to children and adolescents: in
and insomnia 6 and to a lesser extent nocturia 7. Chronic       fact, obese children have a 46% prevalence of OSAHS 22, a
fatigue, daytime sleepiness and hypersomnia, secondary to       finding further aggravated by the obesity epidemic in pae-
sleep fragmentation, are the most significant diurnal symp-     diatric age 23. In turn, children and adolescents with OSA
toms1, which are potentially disabling and dangerous: in        have more than a six-fold increased risk of metabolic syn-
fact, excessive diurnal sleepiness represents a significant     drome compared to children and adolescents without OS-
cause of motor vehicle crashes, which in OSAHS popula-          AHS. The presence of obesity and daytime hypoventilation
tion are two-fold and up to seven-fold greater than a control   (PaCO2 ³ 45 mmHg) configure another syndrome defined
population 8.                                                   as Obesity Hypoventilation Syndrome (OHS). In more
Although all these symptoms affect the quality of life, the     than 90% of cases OHS is linked with OSAHS; however,
clinical relevance of OSAHS is mainly due to its strong         the presence of OSAHS is not necessary for diagnosis of
association with hypertension, metabolic syndrome, dia-         OHS 24.
betes, heart failure, coronary artery disease, arrhythmias,     Obesity may alter the normal mechanics of the upper air-
stroke, pulmonary hypertension 9, neurocognitive disor-         ways and thus contribute to the pathophysiology of OS-
ders, especially those regarding attention and concentration    AHS mainly in two ways: through the lipid backlog in
domains 10, and mental disorders, such as depression and        peripharyngeal tissues and the increased respiratory effort
anxiety.                                                        related to abdominal weight 13. In addition, a role in the
All OSAHS symptoms are due to the pharyngeal muscles            relationship between obesity and OSAHS is also played by
hypotonia, especially during REM sleep 11, which is the         leptin and other factors, such as hypoxia, increased sympa-
cause of an initial subobstruction with increased resistance    thetic tonus, oxidative stress, inflammation and endothelial
of upper airways, responsible for hypopnoea and snoring;        dysfunction 25.
at a later time the obstruction turns complete, with respira-
tory airflow arrest and therefore obstructive apnoea 12.
The airflow obstruction becomes clinically relevant if ana-
                                                                Lipid backlog in pharyngeal structures
tomic or neuromuscular factors acting on pharynx are pre-       Upper airway structural alterations in obesity are in first
sent 13: accordingly, risk factors in the onset of OSAHS are    place related to adipose deposition in peripharyngeal tis-
all anatomical conditions that reduce the calibre of upper      sues and in pharyngeal lumen, lateral wall and muscles:
airways, such as septum deviation, nasal polyps, turbinate,     this consequently leads to collapse of lateral, rather than
adenotonsillar and lingual tonsil hypertrophy, tumours, ret-    anterior, pharyngeal structures and to a greater susceptibil-
rognathia and inferior displacement of the hyoid bone 14-16,    ity to OSAHS 26.



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The fatty deposits responsible of this enhanced collapsibil-      penditure 37. At least three possible mechanisms have been
ity are particularly pronounced in men with central obe-          proposed to mediate leptin resistance, including a failure
sity compared to women with peripheral adiposity. During          of circulating leptin to reach its targets in the brain because
sleep, when neuromuscular activity is reduced, central obe-       of limited permeability of the blood-brain barrier; a down-
sity then can obliterate the pharyngeal lumen, increasing         regulation of the leptin receptors on the cell surface; and/
surrounding tissue pressures and leading to elevations in         or an inhibition of the leptin-receptor signalling pathway 38.
pharyngeal collapsibility 11: these patients will have a very     Besides the action on satiety, leptin is also a potent ven-
low sleep quality, as well as a high risk of cardiovascular       tilation stimulant acting on central respiratory control nu-
disease 27.                                                       clei 12: from this point of view, leptin resistance is implicat-
In addition, patients with OSAHS show an oval shape of            ed in the pathogenesis of OSAHS through impaired central
pharyngeal lumen and this shape further reduces the ability       regulation of upper airway patency and diaphragmatic con-
of muscles to dilate the pharynx 28.                              trol 39. Furthermore, high levels of plasma leptin are also
                                                                  related to obesity hypoventilation 40.
Reduction of lung volumes                                         However, hyperleptinaemia is associated with OSAHS it-
                                                                  self 41, with a positive correlation between plasma leptin
Obesity, and especially central obesity, also acts on lung        levels and severity of disease and independence from BMI
volumes, causing their reduction. Indeed, fat accumulating        or waist circumference 42.
in the thorax and abdomen prevents regular lung expansion:
this provokes a fall of functional residual capacity (FRC) 11,
with a subsequent loss of caudal traction on upper airway
                                                                  Inflammation
structures 29. As caudal traction decreases, pharyngeal and       Adipose tissue is an abundant source of pro-inflammatory
global airway collapsibility substantially grow 30, leading to    cytokines, including tumour necrosis factor (TNF-α) and
a reduction in axial tension within the pharyngeal wall 31,       interleukin-6 (IL-6) 43. These cytokines may be responsi-
but also to a decrease in ventilation of the lung bases, to       ble of defects in neuromuscular control of the upper airway
ventilation-perfusion mismatch and to enlargement of the          leading to OSAHS seen especially in patients with visceral
alveolar-arterial PO2 difference 32. Low FRC also predis-         obesity 44. TNF-α, in particular, exerts somnogenic effects
poses to instability of the respiratory control system. In        on the central nervous system 45 stimulating membrane ex-
the long run, the presence of recurrent airway obstruction,       pression and release of its soluble receptor TNF-α receptor
intermittent hypoxia and associated arousals causes oscil-        I (TNFαRI). The levels of TNFαRI in plasma fall with the
lation of systemic and pulmonary arterial blood pressures,        use of CPAP 46, which corroborates the potential role of
triggering or exacerbating heart disease 33.                      inflammation in the natural history of OSAHS.

The role of leptin                                                OSAHS and obesity: a biunivocal relationship
Metabolic and humoral factors that determine the distribu-        Although obesity is the main risk factor for the development
tion of adiposity may be responsible for OSAHS. Among             of OSAHS, some authors have suggested that OSAHS can
these there is leptin, a satiety hormone produced by adi-         cause weight gain and therefore obesity 46: in fact, it seems
pocytes that, in physiological conditions, is released into       that these two conditions form a vicious cycle where each
the circulation in proportion to body adiposity 34: in fact, it   results in the worsening of the other 47 and whose main ac-
is produced in abundance by subcutaneous adipose tissue,          tors include reduced physical activity, insulin resistance
particularly in women, and limits central obesity. From adi-      and increased leptin and ghrelin levels 22 (Fig. 1).
pose tissue, leptin circulates to the brain, where it interacts   One of the most prominent symptoms of OSAHS is exces-
with receptors in the hypothalamus to suppress appetite and       sive daytime somnolence 1, which may result in decreased
regulate body composition and adiposity distribution 35.          physical activity, in turn responsible for weight gain if not
Obese subjects have elevated levels of circulating leptin, on     associated with reduced caloric intake 48: patients with OS-
one hand essentially because of the increase of adipocytes        AHS are at high risk of obesity, with consequent worsen-
and fat mass, but on the other for central resistance to lep-     ing of their apnoeas 48. This relationship is also confirmed
tin 12,36: consequently, in obesity the central satiety effects   by the fact that OSAHS treatment improve alertness and
of leptin is abrogated 12.                                        daytime activity, while untreated patients tend to gain
Leptin resistance is defined as a failure of high-circulating     weight 49,50.
levels of leptin to decrease hunger and promote energy ex-        The appearance of obesity in patients affected by OSAHS



122
                                                                                                                        OSAHS and obesity




                                                                          Diagnosis of OSAHS
                                                                          The first step to diagnose OSAHS and understand its sever-
                                                                          ity is to obtain the apnoea-hypopnoea index (AHI), which
                                                                          is the mean number of sleep apnoeas and hypopneas per
                                                                          hour. Based on the AHI, OSAHS is then defined as 5 or
                                                                          more episodes of apnoea or hypopnoea per hour of sleep
                                                                          with associated symptoms (e.g., excessive daytime sleepi-
                                                                          ness, fatigue, impaired cognition) or 15 or more obstruc-
                                                                          tive apnoea-hypopnea events per hour of sleep without
                                                                          symptoms 59,60: in this way, OSAHS is classified as “mild”
                                                                          between 5 and 14 events, “moderate” between 15 and 29
Figure 1. Possible mechanisms at the base of relationship between OSAHS   and “severe” when more than 30 episodes occur per hour
and obesity.
                                                                          of sleep 59. It should be emphasised that the diagnosis of
                                                                          OSAHS does not change between obese and non-obese pa-
is also potentially influenced by a change in dietary habits              tients. Obesity is only a causal factor for the syndrome that
in favour of high caloric items, such as refined carbohy-                 can worsen the pathological picture. It is implicated that
drates, which leads to positive energy balance seen in this               it has shown bidirectional causality with each other, and
population 38, maybe as a form of stress response 51.                     that it may have mutual interaction with the other metabolic
OSAHS may predispose individuals to obesity also be-                      dysregulations.
cause of disrupted metabolism. In fact, sleep fragmentation               However, medical history and physical examination are
and deprivation are associated with increased glucose toler-              the cornerstones of clinical diagnosis. Patients should be
ance and insulin resistance, with consequent increased risk               interrogated about their nocturnal and daytime symptoms,
for obesity and diabetes 52. The exact mechanism leading                  extending questions to bedpartner to know other important
to insulin resistance in patients with OSAHS is not fully                 information about the patient’s sleep. Furthermore, given
understood: a proposed hypothesis is that sleep depriva-                  the close association between OSAHS and cardiovascular
tion itself determines peripheral decreased insulin sensitiv-             disease, OSAHS should be suspected in individuals af-
ity, with a long-term progressive exhaustion of its reserves              fected by systemic or pulmonary hypertension, metabolic
in pancreatic islands; on the other hand, another potential               syndrome, heart failure, or arrhythmias 1.
mechanism of insulin resistance may involve the elevated                  Physical examination of affected patients should include
sympathetic activity in OSAHS 53. However, it has been ob-                respiratory, cardiovascular and neurologic systems 60 and,
served that insulin sensitivity improves after almost three               especially in case of obese patients, should be comprehen-
months of treatment with continuous positive airway pres-                 sive of determination of some anthropometric parameters,
sure (CPAP), one of cornerstones of OSAHS therapy 54.                     which, if increased, raise the probability of OSAHS and
It has been suggested that hyperleptinaemia may be a prog-
                                                                          pharyngeal obstruction. The most important of these pa-
nostic marker for OSAHS 42; at same time, several studies
                                                                          rameters is body mass index (BMI), which becomes an
have confirmed that OSAHS may directly influence leptin
                                                                          alarm value if over 29.9. The measurement of neck circum-
metabolism. Because in patients with OSAHS leptin levels
                                                                          ference allows estimating the risk of suffering from OS-
are high independently of body fat content, it was postulat-
ed that OSAHS is associated with resistance to the weight-                AHS: this risk is clearly increased if the neck circumfer-
reducing effects of leptin 41, with increased appetite and                ence is greater than 41 cm in women and 43 cm in men 61.
body weight. These effects cease when treatment with na-                  Furthermore, with a simple inspection of the oral cavity, it
sal CPAP is initiated 55,56 and reduction in circulating leptin           is possible to evaluate the Mallampati score and to quantify
levels was not restricted to the CPAP therapy only, but also              the degree of tonsillar hypertrophy 62: in general, if the Mal-
reported after surgical intervention with uvulopalatophar-                lampati score is low, the degree of tonsillar hypertrophy
yngoplasty 57.                                                            will be greater, with a consequently higher risk of OSAHS.
Another relatively recent discovered hormone that regu-                   After clinical evaluation of the patient, it is necessary to
lates appetite and body weight is ghrelin, a hormone which                confirm the suspicion of OSAHS, in order to assess its se-
stimulates appetite and whose levels are increased in OS-                 verity and guide therapeutic choices: the gold standard is
AHS patients 58: therefore, in these patients it contributes to           polysomnography, rather than night cardiorespiratory mon-
higher caloric intake and obesity.                                        itoring and endoscopy, including sleep endoscopy.



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G. Salzano et al.




Objective sleep studies                                             Given the limits of classic waking endoscopy, nowadays
                                                                    the gold standard for the diagnosis of obstructive sites in
First step: polysomnography
                                                                    patients with OSAHS is drug-induced sleep/sedation en-
One method used to screen obstructive sleep apnoea is the
                                                                    doscopy (DISE), i.e. endoscopy performed during induced
continuous recording of oxygen saturation during sleep.
                                                                    sleep 66 in an operating room 67. It is a relatively quick and
This method is economic and easily practicable; however,
                                                                    simple technique that can be performed on an outpatient
it is often not sufficiently sensible or specific and its utility
                                                                    basis, targeting possible vibration and obstruction sites 68,
in clinical practice is poor 63.
                                                                    in addition to degree and pattern of collapse 13. Several an-
On the contrary, polysomnography is the gold standard for
                                                                    aesthetic drugs may be used to induce sleep, alone or in
the diagnosis of OSAHS, because it consents to identify
affected patients and to stratify disease severity, in addi-        association, among which the most used is propofol. DISE
tion to recognition of co-existing sleep disorders, includ-         can be used in all patients with snoring or OSAHS; never-
ing other forms of sleep-disordered breathing. Usually per-         theless, it is contraindicated in patients with severe respira-
formed in a laboratory during the sleep of patient, the exam        tory pathology, while coronary or heart failure are relative
allows measurement and recording of several physiological           contraindications to propofol 69.
variables, including pulse oximetry, electroencephalogram,          The obstruction implicated in abnormal respiratory events
electro-oculogram, nasal and oral airflow measurements,             are clumsily attributable to four regions: retrovelar area,
chest wall movements, electromyogram and electrocardio-             oropharynx, hypopharynx and larynx, each of which pre-
gram. An obstructive apnoea is defined as a cessation of            sents various structures that can induce obstruction 70. Sev-
airflow for at least 10 sec despite ongoing inspiratory ef-         eral systems are used to describe and classify obstructing
fort; instead, hypopnea is defined by one of the following          and vibrating structures noticed with DISE: one is NOHL
three features: more than 50% airflow reduction, moderate           classification 71, which also includes nasal obstruction (N)
airflow reduction (50%) associated with oxyhaemoglobin              that may equally well be assessed during wakefulness, in
desaturation and moderate airflow reduction with electro-           addition to the oropharynx (Fig. 2) and retropalatal area (O)
encephalographic evidence of awakening 57.                          (Fig. 3), hypopharynx and retrolingual area (H) (Fig. 4) and
                                                                    larynx (L) (Figs. 5, 6). For each district, NOHL classifica-
Endoscopy                                                           tion evaluates collapse/vibration degree (from 0 if absent,
                                                                    to 4 if superior to 75%) and obstruction pattern (anteropos-
In patients with OSAHS, pharyngeal obstruction may be               terior, transverse or circumferential). In addition, including
located at multiple levels (soft palate, lateral pharyngeal         nasal cavity, this classification introduces a therapeutic as-
wall, tonsils, tongue base, epiglottis) and its identification      pect unlike other classifications based on anatomic descrip-
is important for proper treatment. To date, to identify the         tion alone: in fact, to understand the correct obstructive
site of upper airway obstruction nasopharyngolaryngos-              site and the type of obstructive pattern is mandatory for the
copy is mandatory, because this exam allows for complete            choice of the proper surgical technique 13.
visualisation of the pharynx 13. Currently, there are two
methods for performing endoscopy in OSAHS patients:
during wakefulness with Müller’s manoeuvre and during
drug-induced sleep (the so-called sleep endoscopy).
Nasopharyngoscopy with Müller’s manoeuvre (maximum
inspiration with both the mouth and the nose occluded,
in way to simulate apnoea) is routinely used to identify
the sites responsible for increase in airflow resistance: in
physiological conditions, after manoeuvre, the airway lu-
men remains patent (Müller -), while in OSAHS patients
it narrows (Müller +). However, the use of endoscopy
with Müller’s manoeuvre is controversial and shows some
limitations: in the first instance, is not an objective test be-
cause the degree of pharyngeal collapse closely depends
on inspiratory effort during the manoeuvre; furthermore,
it investigates the dynamic behaviour of the upper airway
during wakefulness, whereas hypotonia and pharyngeal
collapse typically occur during sleep 64,65.                        Figure 2. Sleep endoscopy showing oropharynx obstruction.



124
                                                                                                                         OSAHS and obesity




Figure 3. Sleep endoscopy showing retropalatal area obstruction.   Figure 5. Sleep endoscopy showing larynx collapse (type closing door).




Figure 4. Sleep endoscopy showing hypopharynx obstruction.         Figure 6. Sleep endoscopy showing larynx collapse (type closing book).



Therapeutic options for obese patients                             OSAHS 72,73. The ideal strategy is to tailoring surgery on
with OSAHS                                                         every single case.

The variety of symptoms and signs of OSAHS has made
this disease the subject of study for many specialists in-
                                                                   Behavioural options: lifestyle changes
cluding neurologists, pneumologists and otolaryngolo-              and weight loss
gists who have introduced the main surgical therapeutic            In the first instance, OSAHS therapy is behavioural, based
options. Recently, the dentist and maxillofacial surgeon           on lifestyle changes and weight loss, that to date are cor-
have been introduced in management of OSAHS and their              nerstones of treatment 25. The most effective behavioural
contribution seems to play an increasingly important role.         measure is weight loss 1, which helps to reduce OSAHS
However, since this pathology involves many organs and             severity up to arrive sometimes to its resolution 74: in pa-
systems, it is clear that many specialists are involved in         tients with mild disease, a weight loss of 10.7 kg is asso-
it. All these specialists, including cardiologists, must be        ciated by 40% reduction in AHI, while in obese patients
involved in a diagnostic and therapeutic path and a mul-           with moderate to severe sleep apnoea the reduction of
tidisciplinary strategy with the aim of obtaining satisfac-        AHI is of 67% and in patients with severe OSAHS benefit
tory therapeutic results in the treatment of patients with         even more 75.



                                                                                                                                        125
G. Salzano et al.




Weight loss also allows to attenuate cardiometabolic abnor-       and insulin sensitivity in patients with concomitant type 2
malities associated to OSAHS, with beneficial changes in          diabetes. In obese patients, CPAP treatment of OSAHS is
cholesterol, insulin resistance, leptin, inflammatory mark-       also able to determine weight loss and decrease of intra-
ers and endothelial function 76,77.                               abdominal fat, probably because of decreased daytime hy-
The first way to achieve weight loss is through conservative      persomnolence and increased physical activity 1. Reduction
strategies, such as diet, exercise and medications: in par-       of visceral fat is also seen in patients without significant
ticular, in sedentary overweight/obese adults, exercise may       weight loss.
be beneficial for treatment of OSAHS not only because it          Despite all these benefits, noncompliance is evident in a
facilitates weight loss 78, but also because it seems to rise     significant proportion of patients 86, for which CPAP is
respiratory drive and to stabilise muscle tone in the upper       poorly tolerated because of size and noise of the equipment,
airway 79. Exercise and the Mediterranean diet, however,          but also for adverse effects, which include irritation, pain,
have positive effects on the severity of OSAHS even inde-         rash and skin breakdown at mask contact points, dryness
pendently of weight loss.                                         or irritation of the nasal and pharyngeal membranes, nasal
Nevertheless, in many cases weight loss is hard to achieve        congestion, rhinorrhoea and eye irritation 1. Furthermore,
and maintain using conservative strategies, and bariatric         the benefits of CPAP therapy on metabolic parameters in
surgery has emerged as an alternative treatment of severe         subjects with mild and moderate OSAHS also remain un-
or complicated obesity, which offers a dramatic weight re-        clear. Up to now, no studies have determined whether the
duction, often maintained for up to 10 years 80, but also         efficacy of CPAP is still adequate at more than 3 months
important results in reference to sleep apnoea severity and       after the start of the treatment 87.
cardiometabolic disturbances. Obese patients undergoing
bariatric surgery have shown a prevalence of OSAHS more           Mandibular advancement devices (MAD)
than 70% and it has been demonstrated that at one year lat-
er gastric banding surgery they present significant increases     In case of failure or in patients who refuse CPAP, a thera-
in rapid eye movement and slow-wave sleep, with reduced           peutic alternative is represented by mandibular advance-
daytime sleepiness. Overall, patients undergoing bariatric        ment devices (MAD), which maintain the patency of the
surgery (regardless of the type of intervention) show an          airways posterior to the tongue advancing and/or closing
average reduction of 15 kg/m2 in BMI and 36 events/hour           the jaw during the sleep 87, promoting advancement of the
in the AHI, suggesting that every 1 unit reduction in BMI         tongue, increased tension of the pharyngeal walls, impos-
translates to a reduction of 2.3 units in the AHI. However,       sibility of the jaw to post-rotate and, consequently, prevent
OSAHS resolves completely only in 4% of subjects treated          airway obstruction 88.
with bariatric surgery, perhaps because most of these pa-         Ideally, the patient should be treated by the dentist with in-
tients, despite significant reduction in weight, remain over-     dividualised and adjustable devices for his/her case, where-
weight.                                                           by the application is preceded by dental arch impressions
                                                                  or scans. Once applied, the device should allow progressive
                                                                  adjustment of the mandibular protrusion 89, ensuring the
Continuous positive airway pressure (CPAP)                        maximum comfort, without algic symptoms affecting the
Continuous positive airway pressure (CPAP) is now con-            muscle component or the temporomandibular joint (TMJ).
sidered the treatment of choice for OSAHS, especially in          However, it is important to start using the device gradually,
severe forms, by virtue of its remarkable effectiveness in        increasing the time of use day by day. At the end of the
reducing symptoms and the possible sequelae of the dis-           gradual MAD adjustment period, which can take from 3 to
ease 81-84. It consists in continuous insufflation of air under   5 months, a new polysomnography should be performed to
pressure through nose during sleep, which prevent partial         quantify the obtained gains 20.
or complete collapse of the upper airway 1.                       Although less effective than CPAP, MAD have given posi-
Polysomnographic studies have demonstrated that treat-            tive results in the treatment of OSAHS 90, although limited
ment with CPAP is able to restore patency of the airway           to the moment in which patient is using the device 20, which
and to reverse apnoea and hypopnoea, with regression of           are preferentially indicated for mild or moderate OSAHS 91.
symptoms, improvement of daytime sleepiness and neuro-            Compared to CPAP, these devices have the advantage of
cognitive performance, and clear reduction of AHI 85. In          being unobtrusive, make no noise and are potentially less
addition, nasal CPAP may lead to reduced incidence of car-        expensive, and are generally preferred by patients. Presci-
diovascular events, to improvement of blood pressure and          notto et al. reported a success rate of 64.3% using MAD 92.
metabolic abnormalities 1 and to better glycaemic control         Nevertheless, they may be associated with some adverse



126
                                                                                                                        OSAHS and obesity




effects: among these, one that occurs in practically every        and suprahyoid musculature) attached to the maxilla, man-
individual who wears a MAD for a prolonged period of              dible and hyoid bone 1. Adjunctive procedures, such as cer-
time is tooth movement 93.                                        vical lipectomy, adenotonsillectomy and others, may also
                                                                  be done during the same surgical procedure 100. The rate
Surgery                                                           of success is 60% on a long-term basis using this surgical
                                                                  procedure 100. MMA is particularly appropriate for patients
Some OSAHS cases require surgical modifications of the            with skeletal hypoplasia, retrognathia and severe OSAHS,
anatomy of the upper airway. In this case, appropriate pa-        since it ensures substantial and consistent reduction in AHI,
tient selection and surgeon experience are crucial for thera-     greater than those obtained with UPPP, with few adverse
peutic success 1.                                                 events; nevertheless, it is relatively expensive 20.
Surgical options include several procedures, with different       However, in the context of OSAHS surgery, other proce-
degrees of invasiveness, with the aim to remove respiratory       dures are also included, such as radiofrequency ablation,
obstructive factors in the anatomical districts of ENT inter-     whose purpose is to modify the anatomic site of the ob-
est 1: in over 75% of cases, however, these interventions are     struction acting on nasal turbinates, tongue base and palate,
directed to the nose, palate and lateral walls of the pharynx     with minimal invasiveness and very few risks. These pro-
and, among them, the most popular procedures are uvu-             cedures may be considered for patients whose main com-
lopalatopharyngoplasty (UPPP) and lateral pharyngoplasty          plaint is snoring, with little or no apnoea.
techniques 94. On the other hand, soft tissue modifications
can also be obtained by maxillofacial skeletal surgery, and
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