Consensus and evidence-based Indian initiative on obstructive sleep apnea guidelines 2014 (first edition)

Abstract

Obstructive sleep apnea (OSA) and obstructive sleep apnea syndrome (OSAS) are subsets of sleep-disordered breathing. Awareness about OSA and its consequences among the general public as well as the majority of primary care physicians across India is poor. This necessitated the development of the Indian initiative on obstructive sleep apnea (INOSA) guidelines under the auspices of Department of Health Research, Ministry of Health and Family Welfare, Government of India. OSA is the occurrence of an average five or more episodes of obstructive respiratory events per hour of sleep with either sleep-related symptoms or co-morbidities or ≥15 such episodes without any sleep-related symptoms or co-morbidities. OSAS is defined as OSA associated with daytime symptoms, most often excessive sleepiness. Patients undergoing routine health check-up with snoring, daytime sleepiness, obesity, hypertension, motor vehicular accidents, and high-risk cases should undergo a comprehensive sleep evaluation. Medical examiners evaluating drivers, air pilots, railway drivers, and heavy machinery workers should be educated about OSA and should comprehensively evaluate applicants for OSA. Those suspected to have OSA on comprehensive sleep evaluation should be referred for a sleep study. Supervised overnight polysomnography is the “gold standard” for evaluation of OSA. Positive airway pressure (PAP) therapy is the mainstay of treatment of OSA. Oral appliances (OA) are indicated for use in patients with mild to moderate OSA who prefer OA to PAP, or who do not respond to PAP or who fail treatment attempts with PAP or behavioral measures. Surgical treatment is recommended in patients who have failed or are intolerant to PAP therapy.

INTRODUCTION

In obstructive sleep apnea (OSA), repetitive collapse of the upper airway occurs that leads to snoring, frequent episodes of sleep interruption, hypoxemia, hypercapnia, swings in intrathoracic pressure, and increased sympathetic activity. Management of OSA needs a long-term multi-disciplinary approach. Once diagnosed, patients should be properly counseled to manage their illness including co-morbidities through their active participation.

Obstructive sleep apnea is being increasingly recognized as an emerging important public health problem worldwide, including India. Awareness among lay public and even among primary care physicians is dismally low in India. This disorder is common among obese individuals, children, and postmenopausal women. It is usually associated with several co-morbidities such as insulin resistance, metabolic syndrome, diabetes mellitus, hypertension, stroke, coronary artery disease, increased risk of vehicular accidents, and various psychiatric disorders. Though there are guidelines regarding the diagnosis and management of this condition by various bodies in the western world, these recommendations may not be entirely applicable to the developing countries like India. There was a need to develop comprehensive guidelines on OSA in the Indian context. Thus, the consensus and evidence-based Indian initiative on obstructive sleep apnea guidelines (INOSA Guidelines) were developed under the auspices of Department of Health Research, Ministry of Health and Family Welfare, Government of India following a series of meetings and discussions under the convenership of the Department of Medicine, All India Institute of Medical Sciences, New Delhi, with the support of Indian Council of Medical Research. During this first Indian initiative, in light of the available evidence, consensus statements were developed and finalized by the various national experts in the field of sleep medicine including internists, pulmonologists, neurologists, otorhinolaryngologists, endocrinologists, bariatric surgeons, and dental surgeons.

In order to make the guidelines evidence-based, the expert group reviewed the available evidence and graded the recommendations according to the quality of evidence as mentioned in Figure 1.[¹]

Figure 1: Evidence quality - reproduced with permission from: American Academy of pediatrics steering committee on quality improvement and management. Classifying recommendations for clinical practice guidelines, pediatrics 2004;114:874-71

EPIDEMIOLOGY AND RISK FACTORS OF OBSTRUCTIVE SLEEP APNEA

Epidemiology

Obstructive sleep apnea is a major public health problem. The International Classification of Sleep Disorders, Third Edition classifies sleep-disordered breathing into three basic categories: Central sleep apnea syndrome, obstructive sleep apnea syndrome (OSAS), and sleep-related hypoventilation/hypoxia syndrome.[²³] Community-based epidemiological studies from several parts of India have estimated that the prevalence of OSAS is 2.4–4.96% in men and 1–2% in women.[⁴] Table 1 summarizes some of the important definitions.[⁵]

Table 1: Definitions[⁵]

Pathogenesis

Multiple factors [Table 2][⁶⁷] are responsible for pathogenesis of OSA with inter-individual variation. OSA patients have repeated narrowing or obstruction of pharyngeal airway during sleep. It has been suggested that pathophysiological mechanisms, such as anatomic compromise, pharyngeal dilator muscle dysfunction, lowered arousal threshold, ventilatory control instability, and/or reduced lung volume tethering are the pathophysiological mechanisms leading to OSA.[⁸]

Table 2: Risk factors for obstructive sleep apnea[^{6 7}]

Consequences of obstructive sleep apnea

Obstructive sleep apnea and mortality

It has been demonstrated that OSA is associated with increased mortality. Severe sleep disordered breathing (SDB) has a 3.8-fold greater risk for all-cause mortality and 5.2-fold greater risk for cardiovascular mortality than those without SDB (Evidence Quality B).[⁹] The consequences of OSA are described in Table 3.[^{41011121314151617181920212223242526}]

Table 3: Consequences of OSA[^{4 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26}]

Diagnosis of obstructive sleep apnea

History and physical examination

The diagnosis of OSA requires a high index of suspicion. OSA may be suspected during routine health check-up or while evaluating high-risk patients.[²⁷] The chances of underdiagnosis are minimized if individuals with risk factors are subjected to a comprehensive sleep evaluation during routine health check-up. Similarly, high-risk patients like those with congestive heart failure, extreme obesity, diabetes mellitus, coronary artery disease, stroke, nocturnal dysrhythmias including atrial fibrillation, pulmonary hypertension, preoperative patients should have comprehensive sleep evaluation [Boxes 1 and 2].[²⁷] In addition, medical examiners evaluating drivers, pilots, railway drivers, and heavy machinery workers should be educated about OSA and should refer them for evaluation if snoring, daytime sleepiness, or obesity is noted (Evidence Quality B, Strong Recommendation).

Box 1: Symptoms of OSAS

Box 2: Clinical examination finding suggestive of OSAS

In a patient suspected to have OSA, secondary causes such as hypothyroidism, facial abnormality, tonsil/adenoid hypertrophy, and musculoskeletal abnormalities should be ruled out and the patient should be evaluated for consequences of OSA like metabolic syndrome, diabetes mellitus, hypertension, CAD, stroke, and gastroesophageal reflux.[²⁷²⁸] The patient should also be investigated for associated co-morbid illnesses like allergic rhinosinusitis, nasal polyps, asthma, chronic obstructive pulmonary disease (COPD), obesity hypoventilation syndrome, and kyphoscoliosis.[²⁷²⁸] The clinical examination should include detailed anthropometry including measurement of neck circumference, body mass index (BMI), modified Mallampati score, and a comprehensive upper airway assessment.[²⁷]

Other diagnostic investigations

Anthropometric measurements, nasal and upper airway examination, orthodontic assessments, and radiological measurements have low sensitivity and specificity when used alone for diagnosis of OSA.[²⁸] Patients suspected to have OSA should be referred for an appropriate type of sleep study after detailed history, examination, and basic investigations. Various questionnaires for the prediction of OSA are available and can be used prior to sleep study, but the same is not mandatory.

Epworth sleepiness scale

Epworth sleepiness scale (ESS) is a simple, self-administered measurement of sleep propensity during daytime in adults that requires the subject to rate the probability of dozing off in eight different situations that are met in day-to-day life on a scale of 0–3. Thus, the sum of the score can vary from 0 to 24. ESS score >10 is defined as excessive daytime sleepiness and has a sensitivity of 49% and specificity of 80% for predicting OSA[²⁹] (Evidence Quality C, Recommended).

Clinical prediction rules for obstructive sleep apnea

Various algorithms have been devised for screening and risk stratification of patients suspected to have OSA. The utility of these tools to estimate the clinical severity of OSA and to suggest the likelihood of OSA related consequences have not been studied systematically.[³⁰]

Berlin questionnaire has three categories of questions. Category 1 questions are about snoring with five questions and 2–5 multiple choice answers. Category 2 includes excessive daytime sleepiness with four or more multiple choice answers. Category 3 has BMI and blood pressure. With Berlin questionnaire, OSA was considered probable if two of the categories are positive. The Berlin questionnaire was modified at AIIMS, New Delhi, in 2006 for application in the setting of developing countries.[³¹] Both Berlin questionnaire and modified Berlin questionnaire are moderately accurate (sensitivity and specificity generally <90%) in screening for OSA[³⁰³¹] (Evidence Quality C; Recommended). Although these questionnaires have not been adequately studied, these can be used to screen the patients for OSA. The snoring, daytime tiredness, observed apnea, high blood pressure, BMI, age, neck circumference, and gender (STOP-BANG) questionnaire (Evidence Quality C, Recommended) are the most appropriate questionnaire for the screening in preoperative cases.

Patients who have both symptoms and physical findings suggestive of OSA on comprehensive sleep evaluation along with Epworth's sleepiness score greater than or equal to 10 have a high-risk of OSA and the diagnosis is confirmed and severity determined with objective testing in an expedited manner in order to initiate treatment. Patients who have neither are at low probability and the rest have moderate probability for OSA. Figure 2 shows the algorithm for the diagnosis of OSA.

Figure 2: Algorithm for diagnosis of OSA. *Boxes 1 and 2 †Pulmonary disease, neuromuscular disease, or congestive heart failure. PM: Portable monitoring; PSG: Polysomnography

Types of sleep study

The diagnosis and severity of OSA must be ascertained before initiating the treatment of OSA. The standard diagnostic test for OSA is an attended in-laboratory polysomnography (PSG) or portable monitoring (PM).[²⁷] PSG is supervised by a trained technician with at least seven channels whereas PM is performed without a technician and has fewer channels. Various types of sleep studies are described in Figure 3. In laboratory PSG with electroencephalography (EEG) based sleep staging, the “gold standard” for the diagnosis of OSA is not necessary in all patients suspected to have OSA28. PM with type 3 and 4 devices in conjunction with comprehensive sleep evaluation is adequate for diagnosis of OSA in patients with high pretest probability of moderate to severe OSA without co-morbid sleep or medical disorders such as neuromuscular disease, pulmonary disease, or congestive heart failure (Evidence Quality A, Strong Recommendation).[³²] PSG is mainly useful for patients with symptoms of excessive daytime sleepiness but no objective evidence of OSA on PM [Box 3].

Figure 3: Types of sleep studies. Type 1: Fully attended polysomnography (≥7 channels) in a laboratory setting, Type 2: Fully unattended polysomnography (≥7 channels), Type 3: Limited channel study (usually using 4–7 channels), Type 4: 1 or 2 channels usually using oximetry as one of the parameters, EEG: Electroencephalography; EOG: Electro-oculography; EMG: Electromyography; ECG: Electrocardiography

Box 3: Indications of PM and PSG

Attended in-laboratory polysomnography-type 1 sleep study

Type 1 study or in-laboratory, technician-attended, overnight PSG is the present reference or “gold” standard for evaluation of sleep and sleep-disordered breathing (Evidence Quality A, Strong Recommendation).[³³] The recommended parameters to be evaluated in PSG include sleep state and stages, ventilatory parameters, cardiac function, and limb movements[³⁴] by recording EEG, electro-oculography, electrocardiography, chin and leg electromyography, nasal and oral airflow, chest and abdominal efforts, and pulse oximetry.[³³] The study requires the constant presence of a trained individual with appropriate sleep-related training who can monitor patient compliance, technical adequacy, and relevant patient behavior (Evidence Quality B, Recommended).[²⁷] It is advisable to take prior informed consent for PSG. Social acceptability of full-night PSG for women is an issue in the Indian context. Full-night PSG is recommended for the diagnosis of OSA (Evidence Quality A, Strong Recommendation).

Unattended polysomnography-type 2 sleep study

Type 2 devices can record the same variables as type 1 study in absence of a technician. Thus, type 2 sleep monitoring can be practically used as portable monitors, but is not frequently used in the outpatient setting. Type 2 study may identify apnea-hypopnea index (AHI) suggestive of OSA with high positive likelihood ratio and low negative likelihood ratio, though differences in AHI have been encountered between type 2 study and PSG30[³⁵] (Evidence Quality B, Recommended).

Portable monitoring/out-of-center sleep testing/home sleep testing/unattended limited channel testing (type 3 and 4 sleep study)

Portable monitoring or out-of-center sleep testing (OCST) as a diagnostic test for OSA has evolved as an alternative to PSG27 due to convenience and lower cost. The disadvantage of PM or OCST, however, is that AHI may be falsely low.[³⁰³⁶] This is because in the absence of EEG recording in these tests, actual sleep time cannot be determined and the denominator is the total recording time instead of the total sleep time. Comprehensive sleep evaluation should always be done prior to PM studies.[²⁷]

The diagnosis and severity assessment should be performed using the same definitions as used for PSG. PM should be performed only in conjunction with comprehensive sleep evaluation and in the presence of a practitioner eligible for conducting sleep studies (Evidence Quality B, Recommended).[³²] Overall, PM (type 3 and 4) may be useful, cost-effective, convenient, and speedy method of diagnosis if the patient is selected carefully. Hospital-based PSG is the investigation of choice for patients who cannot be investigated adequately at home or whose home study result does not match with the clinical suspicion of the investigating physician.[²⁸]

Preoperative evaluation of obstructive sleep apnea

The incidence of postoperative desaturation, respiratory failure, postoperative cardiac events, and Intensive Care Unit transfers is higher in patients with OSA (Evidence Quality A, Strong Recommendation).[³⁷] Both PSG and PM are helpful in diagnosing and categorizing the severity of OSA, but PM reduces the likelihood of delay in the surgery, inconvenience and high cost of laboratory study. Alternatively, in a case at high-risk of OSA, sleep study may be deferred if it is not feasible or causes delay in surgery. Instead, a standby positive airway pressure (PAP) device with a close monitoring may be advised.[³⁸] Patients who have previously been diagnosed to have OSA must be asked to use PAP preoperatively and postoperatively.

Diagnostic criteria for obstructive sleep apnea

The diagnostic criteria for OSA are summarized in Box 4.

Box 4: Criteria for diagnosis of OSA[²]

Optimal continuous positive airway pressure titration

Optimal PAP to treat OSA is the effective pressure that eliminates sleep-disordered breathing events in all sleep positions and stages, particularly rapid eye movement (REM) sleep, improving sleep quality without creating any untoward pressure-related side effects for the patient.

Titration effectiveness has been described by a grading system, detailed below.[³⁹]

• Optimal titration: AHI <5/h and includes supine REM sleep
• Good titration: AHI <10/h or reduced by 50% if the baseline <15/h and includes supine REM
• Adequate titration: AHI cannot be reduced to less than 10/h, but is reduced by 75% from baseline or criterion for optimal or good titration is attained, but without supine REM sleep
• Unacceptable titration: Any one of the above grades is not met, which requires a repeat titration.

Process of positive airway pressure titration

Continuous positive airway pressure (CPAP) titration is done by starting at a minimum pressure of 4 cm water (H₂O) which is then increased by 1 cm H₂O to a maximum of 20 cm H₂O every 5 min or more, with the target of eliminating all the events (Evidence QualityA, Strong Recommendation).[⁴⁰] If this pressure does not allow adequate titration, bilevel positive airway pressure (BPAP) titration is recommended (Evidence Quality C, Recommended).[⁴¹] Ideally, 15 min of supine REM sleep must be a part of the titration.

Split night versus single night titration

Full-night PSG with attended manual PAP titration is regarded as the gold standard for prescription of PAP therapy (Evidence Quality A, Strong Recommendation). However, split-night study that is, initial PSG followed by 3 h of PAP titration may be performed if AHI is >40 events/h during the first 2 h or between 20 and 40 events/h with clinical judgment regarding definitiveness of prescribing PAP therapy (Evidence Quality A, Strong Recommendation). It is recommended that the arousals should be abolished with PAP; otherwise, a repeat study with PSG is indicated for PAP titration.[⁴²] Auto-PAP titration using auto-PAP devices that monitor snoring, apnea or hypopnea by airflow, flow contour, and/or impedance by forced oscillation technique can be tried during attended titration with PSG (Evidence Quality B, Recommended) to determine a fixed PAP level in patients with moderate to severe OSA without significant co-morbid illness such as congestive heart failure (CHF), COPD, central sleep apnea or hypoventilation syndromes (Evidence Quality B, Recommended).

MEDICAL MANAGEMENT OF OBSTRUCTIVE SLEEP APNEA

General measures, including pharmacotherapy[^4344454647]

The general measures in the management of OSA are summarized in Box 5.

Box 5: General measures for treating OSA[^{43 44 45 46 47}]

Pharmacotherapy in obstructive sleep apnea

Several drugs have been tried in OSA in small trials and the data at present are insufficient to recommend primary drug treatment in OSA. Wake promoting agents modafinil and armodafinil are the only agents approved for excessive daytime sleepiness (EDS) despite adequate PAP therapy in OSA patients (Evidence Quality A, Strong Recommendation).[⁴⁸⁴⁹]

Positive airway pressure therapy

Introduction

The principle of PAP in OSA is based on providing air under positive pressure through an interface (nasal or face mask), thus creating a pneumatic splint in the upper airway which prevents collapse of the pharyngeal airway, acting at all potential levels of obstruction.[⁵⁰] PAP is the most effective and widely used treatment for OSA and is the first-line therapy for moderate to severe OSA. PAP improves quality of life, in terms of clear-cut reductions in daytime sleepiness and quality of life measures. The effective PAP therapy reduces snoring and nocturnal respiratory disturbances and improves nocturnal oxygenation and sleep architecture. Benefits of PAP therapy include reduced daytime sleepiness, improved driving performance, health status, and improvement in neurocognitive performance. Positive effects on cardiovascular outcomes, such as hypertension, cardiac arrhythmias, nocturnal ischemia, left ventricular function, and even overall mortality have been reported.[⁵¹⁵²⁵³]

Indications for CPAP and BPAP-CPAP is currently the “gold standard” for the treatment of moderate to severe OSA (AHI >15 h), and an option for less severe OSA. Treatment of OSA is indicated with the following criteria on PSG (Evidence Quality A, Strong Recommendation).[^10545556]

• AHI or (RDI) ≥15 events/h
• AHI (or RDI) ≥5 but <15 events/h with any of the following symptoms:
• Excessive daytime sleepiness (confirmed by either a score of <10 on ESS or inappropriate daytime napping (e.g., during driving, conversation, or eating) or sleepiness that interferes with daily activities on a regular basis
• Impaired cognition or mood disorders
• Hypertension
• Ischemic heart disease
• History of stroke
• Cardiac arrhythmias
• Pulmonary hypertension.

All these factors have to be taken into account while planning treatment of OSA. Currently, three types of PAP devices are available for treatment of OSA - Continuous PAP (CPAP), BPAP, and automatic self-adjusting positive airway pressures (APAP). CPAP devices generate a fixed continuous pressure during inspiration and expiration. In BPAP, the pressure alternates between a fixed inspiratory and lower expiratory level during the respiratory cycle, which allows differential titration of the inspiratory (IPAP) and expiratory positive airway pressures (EPAP). In APAP, the pressure changes throughout the night in response to changes in airflow, respiratory events, and snoring. There is no evidence base to choose the modality of PAP.

The role of supplemental oxygen-Supplemental oxygen (O₂) is used after adequate CPAP/BPAP titration, for residual sleep-related hypoxemia. Specifically, O₂ supplementation is done during the PAP titration study, if the SpO₂ is <88% for 5 or more minutes in the absence of sleep-disordered breathing events, and oxygen flow rate is increased at a rate of 1 L/min every 15 min to target SpO₂ ≥88%. Patients on O₂ prior to PAP titration usually need a higher amount of O₂ with the PAP device due to flow related dilution of the supplied O₂. Supplemental O₂ is to be connected to the PAP device outlet and not to the mask. The possibility of a rise in CO₂ due to the supplemental O₂ is to be kept in mind, and should be monitored with an arterial blood gas next day after disconnecting the PAP device.

Recommendations for APAP[⁵⁷⁵⁸]- APAP is a concept based on continuously adjusting positive airway pressure to meet the patient's variable needs to maintain a patent airway, thereby reducing the overall mean airway pressure. This could be done in an unattended setting such as the patient's home, and potentially enhances tolerability and compliance. Figure 4 summarizes PAP prescription.

Figure 4: Comprehensive approach to PAP prescription. PAP: Positive airway pressure; PSG/PM: Polysomnography/portable monitoring; APAP: Auto-titrating positive airway pressure; CPAP: Continuous positive airway pressure

• Certain APAP devices may be useful for attended titration with PSG to identify a single pressure for use with standard CPAP (also called fixed CPAP [f-CPAP]) for management of moderate to severe OSA (Evidence Quality B, Optional Recommendation)
• Patients who are being treated with APAP itself, or f-CPAP calculated on the basis of APAP titration must have close clinical follow-up to monitor treatment effectiveness. In the event of an inadequate symptomatic or objective response with APAP therapy, a standard attended CPAP titration should be done
• Self-adjusting positive airway pressures devices are not recommended for split-night titration (Evidence Quality A, Strong Recommendation)
• Patients with CHF, COPD, and CSA are not currently considered candidates for APAP titration or treatment (Evidence Quality A, Not Recommended).

Positive airway pressures compliance.[⁵⁹] The treatment of sleep apnea with PAP has inherent problems with initial acceptance and long-term adherence, together called compliance due to discomfort from the mask interface, positive pressure itself, need for daily night use, and long-term therapy. Compliance with PAP is a significant problem, and nasal congestion and mask intolerance are the most common complaints that reduce PAP compliance.

Some patients cannot tolerate PAP because of the initial discomfort of sudden application of pressure, or discomfort perceived in exhaling against high pressure. Most PAP devices have a pressure “ramp”, where the pressure rise can be slow until it attains the target pressure, over as much as 45 min. An option for reducing expiratory pressure is BPAP, which allows independent adjustment of inspiratory and expiratory pressures though the comfort benefits of BPAP have not been categorically demonstrated. Pressure-relief CPAP reduces the discomfort of breathing against high pressure during expiration by lowering the pressure at the onset of expiration. Recent Cochrane database review has concluded that pressure-relief CPAP did not improve compliance.[⁶⁰] Similarly, APAP, with a lower mean pressure through the night has a minimal impact on improving compliance.

Adverse effects of PAP therapy-Adverse effects of PAP therapy are summarized in Table 4.

Table 4: Adverse effects of PAP therapy

Oral appliances

Background and rationale

Oral appliances (OA) are an established treatment option for snoring and mild to moderate OSA in selected cases and not in severe OSA. OAs are less cumbersome than PAP therapy and should be considered for patients who have failed or refused PAP treatment, for those with snoring or mild to moderate OSA.[⁶¹⁶²] Dental professionals trained in sleep medicine should prescribe and prepare appropriately fitting OA for the treatment of OSA.

Types of oral appliances

Mandibular repositioning appliance

Mandibular repositioning appliance (MRA) works by bringing the mandible forward, thereby increasing the airway volume. It can be either fixed (predetermined advancement), titratable (adjustable) or either a one-piece or a two-piece appliance. The titratable MRA has an adjustable mechanism that allows progressive advancement of the mandible after initial construction until the optimal mandibular position is achieved. Single-piece or nonadjustable appliances often have to be made again if the initial jaw advancement is insufficient.[⁶²⁶³]

Tongue retaining appliances

Tongue retaining appliances (TRA) are indicated for patients with large tongue and when the use of MRA is limited due to edentulous ridges. Once the patient is using the appliance routinely, overnight PSG is required to assess the clinical response objectively.[⁶²⁶³]

Effects of oral appliances therapy

Effects of OA therapy are summarized in Table 5.[^{616364656667686970}] Contraindications to OA therapy.[⁶²⁷¹⁷²] Contraindications to OA therapy are summarized in Box 6.

Table 5: Effects of OAs

Box 6: Contraindications to OA therapy[^{62 71 72}]

Predictors of response to oral appliances[⁷³⁷⁴]

Predictors of response to OAs are summarized in Box 7. Adverse effects of OA.[⁷⁵⁷⁶⁷⁷] Adverse effects of OAs are summarized in Box 8.

Box 7: Predictors of response to oral appliances[^{73 74}]

Box 8: Adverse effects of OAs[^{75 76 77}]

Compliance with oral appliances

The compliance depends on benefits and discomfort. Various studies reported different level of compliance for different types of OAs in OSA; it ranges from 51% to 88%. Among the various types of OA, compliance is better with mandibular advancement devices (MAD) than any other appliance (Evidence Quality C).[⁷⁴⁷⁷⁷⁸]

Other recent advances in the treatment of OSA-Nasal EPAP device is a single-use device applied over the nostrils that functions like an inspiratory valve allowing unimpeded inspiration but offers resistance to expiration, creating an EPAP. This resultant EPAP cannot be titrated. In a large randomized controlled trial (RCT), the nasal EPAP device significantly improved AHI (43% vs. 10%) and ESS at three months as compared to a sham device. However, some patients do not show any improvement in AHI with nasal EPAP, and among the responders not all would achieve an AHI <10 events/h. The clear-cut indication for nasal EPAP devices is still not well defined.[⁷⁹]

SURGICAL TREATMENT OF OBSTRUCTIVE SLEEP APNEA

Positive airway pressure therapy has been considered to be the first-line of management for patients with OSAS.[⁸⁰] However, some patients may prefer alternative treatment options because they are unable to tolerate, and are noncompliant[⁸¹] or do not benefit from PAP therapy. The lack of randomized controlled trials comparing PAP therapy and surgical treatment make it very difficult to attain a consensus in selecting the appropriate management option.[⁸²] The decision for surgical management should be strictly individualized after careful assessment of the patient with due importance given to the sites of obstruction. The following description provides insight into the procedures that are currently available and their potential role in routine management.

Evaluation of level of obstruction

The most significant concern in the assessment of airway is that it can only be performed in an awake patient and the scenario hardly simulates the exact status during sleep. Apart from drug-induced sleep nasoendoscopy[⁸³⁸⁴⁸⁵] in patients who are planned for surgery and fiberoptic nasopharyngoscopy with Mueller maneuver (FNMM),[⁸⁶] other methods such as cephalometry, acoustic analysis, somnofluoroscopy, computed tomography, and sleep magnetic resonance imaging are not recommended for routine use to assess the level of obstruction.

Surgeries in Obstructive sleep apnea: Surgical options in OSA are site directed surgeries and bariatric surgery (BS).

Nasal and nasopharyngeal surgery-Patients with OSAS frequently have nasal obstruction that results in snoring and mild sleep apnea, but nasal blockage per se does not lead to severe OSA.

• Nasal surgery (correction of anatomical defects) alone is not a useful method of treatment of moderate to severe sleep apnea (Evidence Quality B, Not recommended)[⁸⁷]
• It also improves the compliance with PAP and also improves its effectiveness (Evidence Quality B, Recommended).[⁸⁷⁸⁸]

Maxillomandibular surgeries

Malpositioning of maxilla and mandible contribute to OSAS by reducing the posterior hypopharyngeal space. The role of surgery in the correction of such anatomical abnormalities is summarized in Table 6.[^{89909192939495969798}]

Table 6: Maxillomandibular surgeries

Role of bariatric surgery for treatment of obstructive sleep apnea syndrome

Bariatric surgery is a surgery done in order to create caloric restriction and/or malabsorption for weight loss. The commonly performed bariatric procedures are adjustable gastric banding, Roux-en-Y gastric bypass, sleeve gastrectomy (SG), and biliopancreatic diversion (BPD).

Impact of bariatric surgery on obstructive sleep apnea

Following BS, there is improvement of postoperative sleep quality, reduction in daytime sleepiness, improvement in quality of life, decrease in use of PAP, and decrease in use of high PAP pressure requirement. Gastric bypass was the most successful procedure in improving or resolving OSA followed by gastroplasty, BPD, and gastric banding being the least effective procedure.[⁹⁹] However, in the majority of the patients (62%), the mean residual AHI after surgery was more than 15 events/h. This indicates that there is a persistent residual disease, even though there has been considerable improvement. As such, all patients should undergo repeat PSG after surgical weight loss and those patients who have residual disease consistent with moderately severe OSA need continued treatment with PAP. The available evidence suggests that that the patients cured of OSA were less obese and younger than those who had residual OSA after BS.[¹⁰⁰]

In a recent meta-analysis of 13,900 patients who underwent BS, 79% of patients experienced either resolution or improvement of their sleep apnea. BS is strongly recommended[¹⁰¹] for obese OSA patients with BMI ≥ 35kg/m² (Evidence Quality B).

ACKNOWLEDGMENT

Atul Malhotra, University of California, San Diego, USA.