Technologic advances in the treatment of obstructive sleep apnea syndrome

The effect of drug-induced sleep endoscopy on surgical outcomes for obstructive sleep apnea: a systematic review

PURPOSE

Drug-induced sleep endoscopy (DISE) is the most widespread diagnostic tool for upper-airway endoscopic evaluation of snoring and obstructive sleep apnea (OSA). However, a consensus on the effectiveness of DISE on surgical outcomes is still lacking. This study aimed to quantify the effect of DISE on surgical outcomes and to compare DISE with awake examination using the Müller Maneuver (MM).

METHODS

This systematic review was performed according to the PRISMA guidelines. Published studies from the last 30 years were retrieved from the Cochrane Library, MEDLINE, SCOPUS, and PubMed databases. Studies comparing DISE with awake examination, or MM were included. Surgical success rate was defined according to Sher's criteria, achieving a postoperative apnoea-hypopnea index (AHI) value < 20 events per hour and a 50% improvement from preoperative AHI. Outcomes are presented in terms of surgical success, pre- and postoperative AHI, Epworth sleepiness score (ESS), oxygen desaturation index (ODI) and lowest oxygen saturation (LOS).

RESULTS

This review included 8 studies comprising 880 patients. DISE group showed a higher LOS increase, ODI decrease, ESS decrease than non-DISE group (6.83 ± 3.7 versus 3.68 ± 2.9, p<0.001; 19.6 ± 11.2 versus 12.6 ± 10.4, p<0.001; 6.72 ± 4.1 versus 3.69 ± 3.1, p<0.001). Differences in surgical success rate were significant only between DISE and MM (64.04% versus 52.48%, p = 0.016). AHI decrease resulted higher in non-DISE than in DISE group (39.92 ± 24.7 versus 30.53 ± 21.7, p<0.001).

CONCLUSION

Results of this systematic review suggest that the evidence is mixed regarding a positive effect of DISE on surgical outcomes.

Drug therapy for obstructive sleep apnoea in adults

BACKGROUND

The treatment of choice for moderate to severe obstructive sleep apnoea (OSA) is continuous positive airways pressure (CPAP) applied via a mask during sleep. However, this is not tolerated by all individuals and its role in mild OSA is not proven. Drug therapy has been proposed as an alternative to CPAP in some patients with mild to moderate sleep apnoea and could be of value in patients intolerant of CPAP. A number of mechanisms have been proposed by which drugs could reduce the severity of OSA. These include an increase in tone in the upper airway dilator muscles, an increase in ventilatory drive, a reduction in the proportion of rapid eye movement (REM) sleep, an increase in cholinergic tone during sleep, an increase in arousal threshold, a reduction in airway resistance and a reduction in surface tension in the upper airway.

OBJECTIVES

To determine the efficacy of drug therapies in the specific treatment of sleep apnoea.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register of trials. Searches were current as of July 2012.

SELECTION CRITERIA

Randomised, placebo controlled trials involving adult patients with confirmed OSA. We excluded trials if continuous positive airways pressure, mandibular devices or oxygen therapy were used. We excluded studies investigating treatment of associated conditions such as excessive sleepiness, hypertension, gastro-oesophageal reflux disease and obesity.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by The Cochrane Collaboration.

MAIN RESULTS

Thirty trials of 25 drugs, involving 516 participants, contributed data to the review. Drugs had several different proposed modes of action and the results were grouped accordingly in the review. Each of the studies stated that the participants had OSA but diagnostic criteria were not always explicit and it was possible that some patients with central apnoeas may have been recruited.Acetazolamide, eszopiclone, naltrexone, nasal lubricant (phosphocholinamine) and physiostigmine were administered for one to two nights only. Donepezil in patients with and without Alzheimer's disease, fluticasone in patients with allergic rhinitis, combinations of ondansetrone and fluoxetine and paroxetine were trials of one to three months duration, however most of the studies were small and had methodological limitations. The overall quality of the available evidence was low.The primary outcomes for the systematic review were the apnoea hypopnoea index (AHI) and the level of sleepiness associated with OSA, estimated by the Epworth Sleepiness Scale (ESS). AHI was reported in 25 studies and of these 10 showed statistically significant reductions in AHI.Fluticasone in patients with allergic rhinitis was well tolerated and reduced the severity of sleep apnoea compared with placebo (AHI 23.3 versus 30.3; P < 0.05) and improved subjective daytime alertness. Excessive sleepiness was reported to be altered in four studies, however the only clinically and statistically significant change in ESS of -2.9 (SD 2.9; P = 0.04) along with a small but statistically significant reduction in AHI of -9.4 (SD 17.2; P = 0.03) was seen in patients without Alzheimer's disease receiving donepezil for one month. In 23 patients with mild to moderate Alzheimer's disease donepezil led to a significant reduction in AHI (donepezil 20 (SD 15) to 9.9 (SD 11.5) versus placebo 23.2 (SD 26.4) to 22.9 (SD 28.8); P = 0.035) after three months of treatment but no reduction in sleepiness was reported. High dose combined treatment with ondansetron 24 mg and fluoxetine 10 mg showed a 40.5% decrease in AHI from the baseline at treatment day 28. Paroxetine was shown to reduce AHI compared to placebo (-6.10 events/hour; 95% CI -11.00 to -1.20) but failed to improve daytime symptoms.Promising results from the preliminary mirtazapine study failed to be reproduced in the two more recent multicentre trials and, moreover, the use of mirtazapine was associated with significant weight gain and sleepiness. Few data were presented on the long-term tolerability of any of the compounds used.

AUTHORS' CONCLUSIONS

There is insufficient evidence to recommend the use of drug therapy in the treatment of OSA. Small studies have reported positive effects of certain agents on short-term outcomes. Certain agents have been shown to reduce the AHI in largely unselected populations with OSA by between 24% and 45%. For donepezil and fluticasone, studies of longer duration with a larger population and better matching of groups are required to establish whether the change in AHI and impact on daytime symptoms are reproducible. Individual patients had more complete responses to particular drugs. It is possible that better matching of drugs to patients according to the dominant mechanism of their OSA will lead to better results and this also needs further study.

Diagnosis and treatment of sleep disorders: a brief review for clinicians

Sleep disorders encompass a wide spectrum of diseases with significant individual health consequences and high economic costs to society. To facilitate the diagnosis and treatment of sleep disorders, this review provides a framework using the International Classification of Sleep Disorders, Primary and secondary insomnia are differentiated, and pharmacological and nonpharmacological treatments are discussed. Common circadian rhythm disorders are described in conjunction with interventions, including chronotherapy and light therapy. The diagnosis and treatment of restless legs syndrome/periodic limb movement disorder is addressed. Attention is focused on obstructive sleep apnea and upper airway resistance syndrome, and their treatment. The constellation of symptoms and findings in narcolepsy are reviewed together with diagnostic testing and therapy, Parasomnias, including sleep terrors, somnambulism, and rapid eye movement (REM) behavior sleep disorders are described, together with associated laboratory testing results and treatment.

[Anaesthetic management of adult patients with obstructive sleep apnea syndrome]

OBJECTIVE

The purpose of this review article is to update the anaesthetic management of adult patients with obstructive sleep apnoea syndrome (OSAS).

DATA SOURCES

All references obtained from the medical database Medline related to OSAS and anaesthesia from 1963 until May 2006 were reviewed. References included original articles, observations, clinical cases, and reviews published in English or in French.

DATA SYNTHESIS

The anaesthetic literature related to OSAS and anaesthesia is poor. Understanding anatomy and pathophysiology is important for an optimal anaesthetic management. Since the diagnosis is unknown in almost 80-90% of these patients, many undergo general or regional anaesthesia every day without recognition of the main dangers associated with the condition. Recognition of these patients, especially in the preanaesthetic assessment, is an essential step to prevent perioperative complications. Patients with OSAS are very sensitive to sedatives, hypnotics and opioids. The use of these drugs must be controlled and monitored. Anticipation of difficult intubation avoids complications during induction of general anaesthesia and the use of nasal CPAP decreases the incidence of respiratory complications in the perioperative period.

CONCLUSION

Further research is needed in this field of anesthesia. Intraoperative difficulties in the control of airway and postoperative cardiac and respiratory complications may happen. The use of nasal CPAP in the perioperative period makes the anaesthetic management easier and safer.

Is there a link between intermittent hypoxia-induced respiratory plasticity and obstructive sleep apnoea?

Although neuroplasticity is an important property of the respiratory motor control system, its existence has been appreciated only in recent years and, as a result, its functional significance is not completely understood. The most frequently studied models of respiratory plasticity is respiratory long-term facilitation (LTF) following acute intermittent hypoxia and enhanced LTF following chronic intermittent hypoxia. Since intermittent hypoxia is a prominent feature of sleep-disordered breathing, LTF and/or enhanced LTF may compensate for factors that predispose to sleep-disordered breathing, particularly during obstructive sleep apnoea (OSA). Long-term facilitation has been studied most frequently in rats, and exhibits interesting properties consistent with a role in stabilizing breathing during sleep. Specifically, LTF: (1) is prominent in upper airway respiratory motor activity, suggesting that it stabilizes upper airways and maintains airway patency; (2) is most prominent during sleep in unanaesthetized rats; and (3) exhibits sexual dimorphism (greatest in young male and middle-aged female rats; smallest in middle-aged male and young female rats). Although these features are consistent with the hypothesis that upper airway LTF minimizes the prevalence of OSA in humans, there is little direct evidence for such an effect. Here we review advances in our understanding of LTF and its underlying mechanisms and present evidence concerning a potential role for LTF in maintaining upper airway patency, stabilizing breathing and preventing OSA in humans. Regardless of the relationship between LTF and OSA, a detailed understanding of cellular and synaptic mechanisms that underlie LTF may guide the development of new drugs to regulate upper airway tone, thereby offsetting the tendency for upper airway collapse characteristic of heavy snoring and OSA.

Drug therapy for obstructive sleep apnoea in adults

BACKGROUND

The treatment of choice for moderate to severe obstructive sleep apnoea (OSA) is continuous positive airways pressure (CPAP) via a mask during sleep. However this is not tolerated by all patients and its role in mild OSA is not proven. Drug therapy has been proposed as an alternative to CPAP in some patients with mild to moderate sleep apnoea and could be of value in patients intolerant of CPAP. A number of mechanisms have been proposed by which drugs could reduce the severity of OSA. These include an increase in tone in the upper airway dilator muscles, an increase in ventilatory drive, a reduction in the proportion of REM sleep, an increase in cholinergic tone during sleep, a reduction in airway resistance and a reduction in surface tension in the upper airway.

OBJECTIVES

To determine the efficacy of drug therapies in the treatment of sleep apnoea.

SEARCH STRATEGY

We carried out searches on the Cochrane Airways Group Specialised Register of trials. Searches were current as of July 2005.

SELECTION CRITERIA

Randomised, placebo controlled trials involving adult patients with confirmed OSA . We excluded trials if continuous positive airways pressure, mandibular devices or oxygen therapy were used. No restriction was placed upon publication language or trial duration.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed studies for inclusion, undertook data extraction according to pre-specified entry criteria, and quality assessment of studies. No response for further information was forthcoming from study authors. Results were expressed as mean differences and 95% Confidence Intervals (CI).

MAIN RESULTS

Twenty-six trials of 21 drugs, involving 394 participants contributed data to the review. Most of the studies were small and many trials had methodological limitations. Each of the studies states that the subjects had OSA but diagnostic criteria were not always explicit and it is possible that some patients with central apnoeas may have been recruited. Six drugs had some impact on OSA severity and two altered daytime symptoms. One study reported that apnoea hypopnea index (AHI) was lower following treatment with intranasal fluticasone compared with placebo (23.3 versus 30.3) in 24 participants with sleep apnoea and rhinitis. Subjective alertness in the daytime also improved. Physostigmine gave an AHI of 41 compared to 54 on placebo (10 participants) and in a similar study Mirtazipine 15 mg produced an AHI of 13 compared to 23.7 for placebo (10 participants). Topical nasal lubricant given twice overnight resulted in an AHI of 14 compared to 24 with placebo (10 participants). These three latter studies were of single night crossover design and so there are no data on the acceptability of these treatments or their effect on symptoms. Paroxetine was shown to reduce AHI to 23.3 compared to 30.3 for placebo, most of the 20 participants tolerated the treatment but there was no improvement in daytime symptoms. Acetazolamide also reduced the AHI (one crossover trial of nine patients, mean difference 24 (95% CI 4 to 44). However there was no symptomatic benefit from the drug and it was poorly tolerated in the long term. Protriptyline led to a symptomatic improvement (improved versus not improved) in two out of three crossover trials (13 participants, Peto Odds Ratio 29.2 (95% CI 2.8 to 301.1) but there was no change in the apnoea frequency. In one trial naltrexone did reduce AHI, but total sleep time favoured placebo. No significant beneficial effects were found for medroxy progesterone, clonidine, mibefradil, cilazapril, buspirone, aminophylline, theophylline doxapram, ondansetron or sabeluzole.

AUTHORS' CONCLUSIONS

There is insufficient evidence to recommend the use of drug therapy in the treatment of OSA. Small studies have reported positive effects of certain agents on short-term outcome. Certain agents have been shown to reduce the AHI in largely unselected populations with OSA by between 24 and 45%. For fluticasone, mirtazipine, physostigmine and nasal lubricant, studies of longer duration are required to establish whether this has an impact on daytime symptoms. Individual patients had more complete responses to particular drugs. It is likely that better matching of drugs to patients according to the dominant mechanism of their OSA will lead to better results and this also needs further study.

Dilation of the oropharynx via selective stimulation of the hypoglossal nerve

The functional effects of selective hypoglossal nerve (HG) stimulation with a multi-contact peripheral nerve electrode were assessed using images of the upper airways and the tongue in anesthetized beagles. A biphasic pulse train of 50 Hz frequency and 2 s duration was applied through each one of the tripolar contact sets of the nerve electrode while the pharyngeal images were acquired into a computer. The stimulation current was limited to 20% above the activation threshold for maximum selectivity. The images showed that various contact sets could generate several different activation patterns of the tongue muscles resulting in medial and/or lateral dilation and closing of the airways at the tongue root. Some of these patterns translated into an increase in the oropharyngeal size while others did not have any effect. The pharyngeal sizes were not statistically different during stimulation either between the two different positions of the head (30 degrees and 60 degrees), or when the lateral contacts were compared with the medial ones. The contacts that had the least effect generated an average of 53 +/- 15% pharyngeal dilation relative to the best contacts, indicating that the results are marginally sensitive to the contact position around the HG nerve trunk. These results suggest that selective HG nerve stimulation can be a useful technique to produce multiple tongue activation patterns that can dilate the pharynx. This may in turn increase the size of the patient population who can benefit from HG nerve stimulation as a treatment method for obstructive sleep apnea.

Effects of selective hypoglossal nerve stimulation on canine upper airway mechanics

Electrical stimulation of the hypoglossal (XII) nerve has been demonstrated as an effective approach to treating obstructive sleep apnea. The physiological effects of conventional modes of stimulation (i.e., genioglossus activation or whole XII nerve stimulation), however, have yielded inconsistent and only partial alleviations of hypopneic or apneic events. Although selective stimulation of the multifasciculated XII nerve offers many stimulus options, it is not clear how these will functionally affect the upper airway (UAW). To study these effects, animal experiments in eight beagles were performed to investigate changes in the UAW resistance and critical pressure during simulated expiration (n = 4) and inspiration (n = 4). During expiration, nonselective XII nerve stimulation yielded the greatest improvement in UAW resistance (-0.66 +/- 0.11 cm H2O x l(-1) x min(-1)), compared with that for selective activation of the geniohyoid (-0.29 +/- 0.09 cm H2O x l(-1) x min(-1)), genioglossus (-0.31 +/- 0.12 cm H2O x l(-1) x min(-1)), and hyoglossus/styloglossus (0.37 +/- 0.06 cm H2O x l(-1) x min(-1)) muscles. For simulated inspiration, on the other hand, only whole XII nerve stimulation (-0.9 +/- 0.4 cm H2O) and coactivation of the genioglossus + hyoglossus/styloglossus muscles (-1.18 +/- 0.6 cm H2O) produced significant (P < 0.05) improvements in UAW stability (i.e., lowered critical pressure), compared with baseline (-0.52 +/- 0.32 cm H2O). The results of this study suggest that a multicontact nerve electrode can be used to achieve both UAW dilation and patency, comparable to that obtained with nonselective stimulation, by selectively activating the various branches of the XII nerve.

Interventions to improve compliance with continuous positive airway pressure for obstructive sleep apnoea

BACKGROUND

Continuous Positive Airways Pressure (CPAP) is currently considered to be the cornerstone of therapy for sleep apnoea (OSA). However compliance with this treatment is frequently poor, which may lead to ongoing symptoms of sleep disruption, daytime sleepiness and poor waking cognitive function. Mechanical and psychological/educational interventions have been proposed to try to increase the hours of use of CPAP therapy.

OBJECTIVES

To determine the efficacy of interventions designed to increase compliance with CPAP.

SEARCH STRATEGY

We searched the Cochrane Airways Group Sleep Apnoea Specialised Register (January 2004).

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing interventions to improve compliance with CPAP usage were considered for inclusion in the review.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed articles for inclusion in the review and extracted data. Attempts were made to obtain additional unpublished data from the trialists.

MAIN RESULTS

24 studies met the inclusion criteria with 1007 participants. Each of the mechanical interventions was compared with fixed CPAP alone. Auto-CPAP (13 studies): A small, significant difference was observed in compliance but this effect disappeared when we took account of the variation between the studies. There may be a subgroup of patients who respond better than others. Most participants preferred auto-CPAP to fixed CPAP where this was measured. Bi-level PAP (3 studies): No significant differences were observed in compliance. One small study found no difference in preference. Patient titrated CPAP (1 study): No significant difference was observed in compliance. Humidification(1 study): This small study found no significant difference in compliance. Educational/psychological interventions (6 studies): One small study demonstrated superior compliance in patients treated with cognitive behavioural therapy + CPAP versus CPAP alone but only after 12 weeks. In one, larger study intensive support including home visits increased hours of use. No other study demonstrated significant effects in favour of active treatment.

REVIEWERS' CONCLUSIONS

The effect of Auto-CPAP in increasing hours of use in unselected patients starting this treatment remains unclear. Different pooled analyses gave conflicting results and it may be that carefully selected participants may respond more favourably than others. The evidence in support of Bi-PAP, self-titration and humidification is lacking and studies are required in these areas. There is some evidence that psychological/educational interventions improve CPAP usage. This requires confirmation in larger studies of longer duration, with rigorous follow-up. The cost-benefit ratio of such interventions requires assessment. Future studies need to consider the effects of treatment in participants who are poorly compliant. The studies assembled were characterised by high machine usage in the control groups, and low withdrawal rates making it less likely that any benefit could be demonstrated.

Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a major public health problem in the US that afflicts at least 2% to 4% of middle-aged Americans and incurs an estimated annual cost of 3.4 billion dollars. At Stanford, we utilize a multispecialty team approach combining the expertise of sleep medicine specialists (adult and pediatric), maxillofacial and ear, nose, and throat surgeons, and orthodontists to determine the most appropriate therapy for complicated OSA patients. The major treatment modality for children with OSA is tonsillectomy and adenoidectomy with or without radiofrequency treatment of the nasal inferior turbinate. Children with craniofacial anomalies resulting in maxillary or mandibular insufficiency may benefit from palatal expansion or more invasive maxillary/mandibular surgery. Continuous positive airway pressure (PAP) therapy is used in children with OSA who are not surgical candidates or have failed surgery. As a last resort, tracheotomy may be used in patients with persistent or severe OSA who do not respond to other measures. The cornerstone of treatment in adults utilizes PAP: continuous PAP, bilevel PAP, or auto PAP. Treatment of nasal obstruction, appropriate titration, attention to mask-fit issues, desensitization for claustrophobia, use of heated humidification for nasal dryness and nasal pain with continuous PAP, patient education, regular follow-up, use of compliance software (in selected individuals), and referral to support groups (AWAKE) are measures that can improve patient compliance. Adjunctive treatment modalities include lifestyle/behavioral/pharmacologic measures. Oral appliances can be used in patients with symptomatic mild sleep apnea or upper airway resistance syndrome. Patients who are unwilling or unable to tolerate continuous PAP or who have obvious upper airway obstruction may benefit from surgery. Surgical success depends on appropriate patient selection, the procedure performed, and the experience of the surgeon. Phase I surgeries have a success rate of 50% to 60%, whereas phase II surgeries have a success rate greater than 90%.

Pharmacotherapies for Obstructive Sleep Apnoea

Obstructive sleep apnoea (OSA) is common, causes considerable morbidity and probably contributes to mortality particularly through associated cardiovascular disease. The physical therapy of continuous positive airway pressure (CPAP) is extremely effective in the majority of patients but most patients would prefer an alternative. Intuitively, OSA should be amenable to pharmacotherapy. The upper airway of affected individuals can be narrowed but is patent during wakefulness. Collapse of the airway during sleep occurs when negative intra-luminal pressure generated by inspiratory effort exceeds the tone of the upper airway dilators. This mismatch may be in part due to respiratory drive instability but the state-dependent fall in drive to the airway dilator muscles is the biggest factor in most patients. Various drugs have been investigated as treatment for OSA. Acetazolamide, theophylline, nicotine, opioid antagonists and medroxyprogesterone have been used to increase respiratory drive. Clonidine has been tested with the aim of reducing rapid eye movement sleep when OSA is often most severe. Various antidepressants have been used to suppress rapid eye movement sleep and to preferentially activate the upper airway dilators. The drug trials have often been of poor design and none has included more than a few patients. Most of the drugs have been found to be ineffective and those that have worked for some patients (acetazolamide and protriptyline) have produced intolerable adverse effects. There have been recent advances in the understanding of the neurotransmitters involved in the control of sleep and the upper airway motor neurones, offering the possibility of novel approaches to the drug treatment of OSA for those patients who cannot tolerate or do not benefit from CPAP. It seems likely that a better understanding of the mechanisms of OSA in individual patients and tailoring of drug therapy will be the way forward.

Simplified oscillation method for assessing nasal obstruction non-invasively and under spontaneous ventilation: a pilot study

The clinical application of the current methods of measuring nasal obstruction has been limited by complicated, invasive and stressful procedures that require the full co-operation of the patient. A pilot study is described where a simple way of evaluating nasal obstruction, based on oscillation methods, was investigated. The technique did not disturb spontaneous breathing and required little co-operation and comprehension. Significant differences were obtained when clinically classified normal (5.2 +/- 1.8 cmH2O l(-1) s) and patient (10.6 +/- 5.9 cmH2O l(-1) s) groups were evaluated (p<0.01). A significant reduction (p<0.02) was also observed in impedance results before (8.5 +/- 1.1 cmH2O l(-1) s) and after (5.2 +/- 1.7 cmH2O l(-1) s) clinically successful nasal surgery, closely reflecting the clinical conditions of the subjects. This simple forced oscillation technique showed good potential for future clinical applications in the pre-screening of nasal patients and the evaluation of therapeutic surgery.

Nonattended home automated continuous positive airway pressure titration: comparison with polysomnography

OBJECTIVE

Automatic adjusting nasal continuous positive airway pressure titration (APAP) has been introduced as an alternative method of establishing pressures for patients with sleep apnea. The performance and accuracy of APAP in nonattended home environment are controversial. This study assessed APAP polysomnographic outcomes and accuracy in a nonattended home environment.

STUDY DESIGN AND SETTING

We conducted a retrospective consecutive case series of 24 consecutive patients who had nonattended APAP and simultaneous full polysomnography (PSG).

RESULTS

APAP was tolerated and reduced obstructive Apnea-Hypopnea Index (AHI) to <10 events/h in all patients. Mean AHI decreased from 38.4 (21.2) to 5.9 (6.6) events/h. Central apneas worsened in one patient. A therapeutic pressure was determined in 91% of patients. Autoset accurately measured residual AHI compared with PSG (R = 0.77, P < 0.001). APAP overestimated the AHI by 1.4 events/h.

CONCLUSIONS

Nonattended APAP is successful in many patients in determining a therapeutic positive pressure setting. Reported AHI via Autoset is similar to that of PSG.

SIGNIFICANCE

APAP reduces AHI and is tolerated in a nonattended environment.

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.

Acoustic reflection: review and clinical applications for sleep-disordered breathing

Sleep-disordered breathing (SDB) affects more than 4% of the adult population with an even higher prevalence within high-risk groups. Nasal continuous positive air pressure, although considered the current gold standard treatment for SDB, demonstrates poor patient compliance. Alternative therapies, such as palatal surgeries and airway orthotics, lack validated candidacy selection protocols, resulting in varying success rates. Although much has been published over the last several years regarding the effect of these therapies on the upper airway, no publication has presented an accounting of the use of acoustic reflection (AR) to evaluate airway characteristics pre- and post-treatment with these alternative therapies. This article will review AR and our current knowledge base of the pathological airway characteristics that can be assessed through AR. It will include the advantages, limitations, and potential clinical usefulness of this diagnostic modality in the treatment of patients with SDB.

Drug treatments for obstructive sleep apnoea

BACKGROUND

The treatment of choice for moderate to severe obstructive sleep apnoea (OSA) is continuous positive airway pressure (CPAP) via a mask during sleep. However this is not tolerated by all patients and its role in mild OSA is not proven. Drug therapy has been proposed as an alternative to CPAP in some patients with mild to moderate sleep apnoea. The mechanisms by which drugs might reduce OSA include; a reduction in the proportion of rapid eye movement (REM) sleep (during which apnoeas tend to be more frequent), an increase in ventilatory drive or an increase in upper airway muscle tone during sleep.

OBJECTIVES

To determine the efficacy of drug therapies in the treatment of sleep apnoea.

SEARCH STRATEGY

Searches were carried out on the Cochrane Airways Group RCT Register. Additional hand searching was performed as relevant.

SELECTION CRITERIA

Double blind, randomised placebo controlled trials were included, involving patients with confirmed obstructive sleep apnoea. Trials were excluded if continuous positive airways pressure, mandibular devices or oxygen therapy were used. No restriction was placed upon publication language or trial duration.

DATA COLLECTION AND ANALYSIS

A total of 51 references were identified by electronic searches. 42 studies were retrieved for selection and 9 trials were included in the review. The results for 91 patients were available. No response for further information was forthcoming from the study authors. Results were expressed as (WMD) and 95% Confidence Intervals (95% CI) MAIN RESULTS: Only acetazolamide reduced the Hypopnoea Index (1 crossover trial of 9 patients, Weighted Mean Difference -24; 95%Confidence Intervals (95% CI): -4, -44). However there was no symptomatic response and the drug was poorly tolerated. Protriptyline led to a symptomatic improvement (improved vs not improved) in two out of three crossover trials (13 patients, Peto Odds Ratio 29.2; 95%CI 2.8, 301.1) but there was no change in the apnoea frequency. No beneficial effects were found for medroxy progesterone, clonidine, buspirone, aminophylline, theophylline or sabeluzole.

REVIEWER'S CONCLUSIONS

The data available do not support the use of drugs as a therapy for OSA. Although the studies examined had limitations there was little to justify further trials of these particular drugs.

Combined Temperature-Controlled Radiofrequency Tongue Reduction and UPPP in Apnea Surgery

The objective of this study was to investigate the effects on outcomes and morbidity of combining temperature-controlled radiofrequency (TCRF) tongue reduction with uvulopalatopharyngoplasty (UPPP) as an initial site-directed approach to the surgical treatment of obstructive sleep apnea syndrome (OSAS). This investigation was a prospective, nonrandomized, open-enrollment study of 20 consecutive eligible patients with OSAS. Seven patients had a single-level velopharyngeal obstruction (Fujita type I or IIa), and they were assigned to undergo UPPP only (group 1). Thirteen patients had a multilevel velopharyngeal and retroglossal obstruction (Fujita type IIb), and they were assigned to undergo TCRF tongue reduction in addition to UPPP (group 2). Patients who had only a retroglossal obstruction (Fujita type III) were not included in this study. Following their initial operation, nine patients in group 2 underwent two subsequent in-office TCRF tongue treatments under local anesthesia. Three patients in group 2 were lost to followup, and one patient underwent only one TCRF procedure at the initial operation; data on the latter patient are included in some of the outcomes measures reported here where indicated, but no data are reported on the three who were lost to followup. The primary post-treatment outcomes measures were the results of comparative polysomnography and clinician and patient evaluations regarding morbidity and symptom improvement. Analysis of these data showed that there was no difference between the two groups in terms of postoperative pain or dysphagia following the initial operative session. The degree of symptom improvement in the two groups was similar. Overall success rates—as measured by the apnea/hypopnea index (group 1: 57.1% success; group 2: 50.0%) and by the apnea index (group 1: 71.4% success; group 2: 70.0%)—were statistically comparable, given the small size of the sample (figures are based on 10 patients in group 2). The author concludes that combining TCRT tongue reduction with UPPP in patients with multilevel obstruction improves response rates to a degree that is comparable to that seen with UPPP alone in patients with single-level velopharyngeal obstruction. Moreover, the combination treatment does not increase the risk of additional pain, morbidity, and complications compared with UPPP alone.

Diagnosis and management of sleep apnea syndrome

Sleep apnea is the cessation of breathing during sleep. These episodes result in hypoxemia and sleep disruption; thus the consequences are both cardiorespiratory and neural. Sleep apnea syndrome is defined by a constellation of signs and symptoms, with the main presenting symptom being excessive daytime sleepiness. A diagnosis requires documentation of episodes of abnormal breathing during sleep. This disorder, once thought to be very rare, is so common that it is unlikely that any busy clinician has not encountered a case. Facilities for the evaluation of sleep breathing disorders are now available in most communities. With the introduction of continuous positive airway pressure and other treatments, most patients have complete resolution of their disabling symptoms.