Positive Airway Pressure Therapy of Obstructive Sleep Apnea

Transcription

1 종 설 J Kor Sleep Soc / Volume 1 / June, 2006 Positive Airway Pressure Therapy of Obstructive Sleep Apnea Ho-Won Lee, M.D., Sung-Pa Park, M.D. Department of Neurology, Kyungpook National School of Medicine Obstructive sleep apnea (OSA) is serious, potentially life-threatening and very common. Untreated OSA can be associated with cognitive impairment, hypertension, heart disease, stroke, increased motor vehicle accidents, and diminished quality of life. Currently positive airway pressure (PAP) is a preferred treatment for OSA. PAP maintains airway patency by creating a pneumatic splint, and then dramatically reduces or eliminates sleep-related respiratory impairments and normalizes sleep architecture. There are three different types of PAP such as continuous PAP, autotitrating PAP, and bilevel PAP. This article will review CPAP treatment of OSA, including mechanism, indication, efficacy, compliance and optimal pressure titration. And alternative therapies such as autotitrating PAP and bilevel PAP will be considered. Key Words : Sleep apnea, Continuous positive airway pressure, Autotitrating positive airway pressure, Bilevel positive airway pressure Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive collapse of the pharynx during sleep, necessitating recurrentawakenings to reestablish upper airway patency. 1 The Wisconsin Sleep Cohort Study evaluated working age adults and estimated an OSA prevalence of 4% among men and 2% among women, using a definition that required both an apnea/hypopnea index (AHI) of = 5 and symptoms of OSA. Employing a broader definition to include an AHI of = 5 with or without symptoms, they observed a prevalence of 9% among women and 24% among men. 2 Prevalence of Sleep-disordered Breathing in Middle-aged Korean Men and Women (AHI = 5) was 27% in men and 16% in women. 3 When OSA was defined by an AHI = 5 plus excessive daytime sleepiness, its prevalence was 4.5% in men and 3.2% in women. 3 OSA is considered as a risk factor for cardiovascular and cerebrovascular disorders such as hypertension, congestive heart failure, myocardial infarction, and stroke 4-6 * Address of correspondence Sung-Pa Park, M.D. Department of Neurology, Kyungpook National University School of Medicine Samdeok-dong 2-ga 50, Jung-gu, Daegu, , Korea Tel: Fax: neuromd@mail.knu.ac.kr and is also associated with impaired cognitive function and alertness which contribute to the increased rates of motor vehicle accidents. 7,8 Because continuous positive airway pressure (CPAP) is extremely effective in eliminating pharyngeal collapse, improves symptoms, and may reduce cardiovascular sequelae, diagnosis and effective treatment of these patients has important individual as well as public health benefits. 9 This review focuses on OSAS treatment with positive airway pressure. Mechanisms of continuous positive airway pressure Sullivan and co-worker showed CPAP as a treatment for OSAS in adults in Pharyngeal airway collapse occurs when intraluminal pressure is less than the pressure required to keep it from closing (i.e., critical closing pressure). CPAP serves to raise intraluminal pressure such that even a very collapsible pharynx (i.e., one with a very positive critical closing pressure) will maintain patency. Mechanical splinting of the upper airway has been considered as the dominant mechanism of action. An increased functional residual capacity and decreased upper 34 수면

2 Positive Airway Pressure Therapy of Obstructive Sleep Apnea airway edema may be also involved during CPAP. 11 CPAP treatment. 22 Indications for continuous positive airway pressure The American Academy of Sleep Medicine guidelines for CPAP therapy recommend its use not only for moderate to severe OSA but also even for mild OSA, and also recommend for improving self-reported sleepiness and quality life in patients with OSA. 12 CPAP is also recommended as an adjunctive therapy to lower blood pressure in hypertensive patients with OSA. 12 In other group CPAP therapy has been recommended that all symptomatic patients with OSA(who by definition have an AHIof5)shouldreceivetreatment. 13 Efficacy of CPAP therapy CPAP treatment have been shown to experience a reduction in subjective as well as objective measures of daytime sleepiness and have been demonstrated to improve quality of life in symptomatic patients with even mild OSA CPAP use has clearly been shown to have a favorable impact on daytime sleepiness in sleepy patients with OSA, driving performance as measured by driving simulators, and also accident rates. In addition, even 34 hours per night of CPAP use can improve measures of cognition and daytime vigilance. 17,18 The risk for hypertension engendered by OSA is increasingly acknowledged but the impact of PAP on hypertension remains controversial. 19,20 Cheyne-Stoke breathing (CSB) is an independent predictor of mortality from congestive heart failure. CPAP has been shown to eliminate CSB and decrease mortality in patients with thispattern of periodic breathing. 21 OSA has been associated with increased levels of soluble cell adhesion molecules which are correlated with atherosclerosis which could contribute to the increased cardiovascular and cerebrovascular morbidity associated with OSAS, but there was a trend towards increased vasodilatation following OptimalCPAPforthetreatment of OSA The optimal prescription for positive airway pressure therapy in a patient with OSA is that which most effectively prevents the adverse consequences of OSA, while causing the least patient discomfort and the lowest risk of complications. When a decision is made to prescribe CPAP, the patient and physician both need to understand the consequences of OSA that are being addressed with this prescription. Having selected target consequences for a given patient, the clinician must translate them into measurable treatment goals. To be practical these treatment goals should include both clinical and physiological parameters. Clinical goals are required because physiological parameters may not be totally predictive of clinical successbecause factors such as body position, nasal congestion, alcohol use and differencebetween the sleep lab and the patient's home erode the predictive value of the physiological goals. The physiological goals can be assessed at the time of CPAP titration and will allow the clinician to predict how successful a given level of CPAP will eliminate target consequences in that individual patient. A central element of the CPAP prescription is the pressure level, which is typically derived through a titration study. The CPAP pressure is gradually increased eliminating apneasand hypopneas first, then snoring and all other respiratory effort-related arousals in all body positions and sleep stages. Even after apneas, hypopneas and snoring are eliminated there is persistence of inspiratory flow limitation and elevated esophageal pressure which has the highest sensitivity for detecting residual upper airway obstruction. Inspiratory flow limitation is the parameter that correlates best with excessive esophageal pressure swings. 23 Then Titration to eliminate inspiratory flow limitation can yield a pressure that is possibly more successful than CPAP, at Vol.3, No.1 / June,

3 Ho-Won Lee Sung-Pa Park a pressure-level based on titration to eliminate apnea, hypopnea, and snoring. 24 In an individual patient though, optimal CPAP is a moving target. This pressure is likely to decrease with chronic CPAP use and to increase with factors outside of the sleep laboratory such as weight gain, nasal congestion, change in body position, or alcohol use. 25,26 As such, a highly accurate determination of optimal CPAP pressure at the time of titration may result in either over or undertreatment. To avoid either of these situations the clinician must follow up with the patient to reassess the course of the CPAP treatment and change the CPAP prescription if treatment goals are not being met. Compliance with CPAP therapy Despite the potential advantages of nasal CPAP in OSA, discomfort from the facial mask, the air pressure, and nasal symptoms often limit the extent to which patients are willing to use this therapy. Between 4.5% and 50% of patients refuse CPAP after a single night's use in the laboratory and another 20% stop treatment primarily because of lack of benefit. 27 Estimates from various studies suggest that, on average, patients use the treatment only 4to5hourspernight. 28 The adverse effects of CPAP have been well recognized (Table 1). 29 Management strategies for CPAP adverse effects include (i) good mask fit from a wide selection of commercially available types and protective covering for skin abrasion and eye discomfort (use eye patch if necessary), (ii) topical nasal spray and heated humidification for nasal symptoms and throat dryness which are common complaint, (iii) chin strap, heated humidification and orofacial mask for mask leak and upper airway dryness, (iv) pressure ramp, autotitrating positive airway pressureand bilevel positive airway pressure for pressure related problems, (v) placing device further from bed, using longer tubing and newer interface for noise intolerance, and (vi) education and support for poor motivation/disorder perception. Table 1. Side effects of nasal continuous positive airway pressure Problem Mask related Skin abrasion or rash Conjunctivitis from air leak Pressure or airflow related Chest discomfort Aerophagia Sinus discomfort Smothering sensation Difficulty exhaling Difficulty initiating and/or maintaining sleep Pneumothorax or pneumomediastinum Pneumoencephalus Problem relate to the nasal route Rhinorrhea Nasal congestion, nasal or oral dryness Epistaxis (may be massive, especially in anticoagulated patients) Other Noise Cumbersomeness or inconvenience Spousal intolerance Management Strategy Optimize mask fit from wide selection of commercially available types of masks, select nonallergenic material Protective skin covering Customized mask Reinforce hygienic care of device Eye patch Pressure lamp Reduce pressure with bilevel positive airway pressure Try to reduce requisite pressure using oral appliance + CPAP Heated humidification Saline nasal spray Topical nasal steroid preparation Consider trial of nasal aerosol of ipratropium bromide solution Chin strap for oral dryness Desensitization over time Oronasal mask interface Longer tubing to move device further from bedside Intensifyeducation of patient and spouse Recommend attending a patient support grout (A.W.A.K.E Network of the American Sleep Apnea Association) Alternative positive airway pressure modalities Autotitrating positive airway pressure (APAP) The current practice is to perform CPAP titration in the laboratory with a full polysomnography (PSG). A number of APAP devices are commercially available. They monitor different parameters to detect breathing events and 36 수면

4 Positive Airway Pressure Therapy of Obstructive Sleep Apnea utilize a variety of algorithms to determine when and how much to increase or decrease pressure. In general the devices measure one or more of the following: snoring (airway vibration), airflow reductions (apnea or hypopnea), and the flow vs. time profile (airflow limitation). Recently, devices using the forced oscillation technique to monitor impedance have been developed. 30 Most devices start with a low baseline pressure (usually 3-4 cm H2O) and then increase pressure, as needed. An absence of monitored events prompts a gradual pressure decrease. This approach provides the minimum effective pressure needed to maintain airway patency as circumstances change (e.g., body position, or appearance of REM sleep). The potential advantages of APAP over fixed pressure CPAP are (i) that it eliminates the need for a CPAP calibration night; but the cost-effectiveness of eliminating the need for a CPAP calibration night has not been established, (ii) that it eliminates the need for future recalibration of CPAP, and (iii) that it improves CPAP compliance since the pressure rises and falls to deliver the minimum pressure required to keep the airway patent and hence lower mean pressures throughout the night. The following issues need to be considered (i) the opportunity to increase a patient's acceptance and compliance through interaction with a technician is less, (ii) it is unsafe for patients with respiratory failure or cardiac disease because of the risk of prolonged central apneas or hypoventilation accompanied by excessive hypoxemia and arrhythmias, (iii) severe mask leakage interfering with autotitration may not be recognized unless this is monitored, and (iv) the need for full PSG in the event of failed APAP therapy. 31 This would imply added cost to the patient if purchase of the APAP device has already occurred. The American Academy of Sleep Medicine does not support (i) the use of unattended APAP to either initially determine pressures for fixed CPAP or for self-adjusting APAP treatment in CPAP-naive patients, (ii) APAP titration or APAP treatment for patients with congestive cardiac failure, lung disease such as chronic obstructive pulmonary disease, and nocturnal arterial oxyhemoglobin desaturation due to conditions other than OSA, and for patients who do not snore (either due to palate surgery or naturally) because APAP devices relies on vibration or sound in the device's algorithm, and (iii) the use of APAP devices for split-night studies. 32 It recommends that (i) certain APAP devices may be used during attended titration to identify by PSG, a single pressure for use with standard CPAP for treatment of OSA, (ii) once an initial successful CPAP or APAP titration has been determined by PSG, certain APAP devices may be used in the self-adjusting mode for unattended treatment of patients with OSA, (iii) patients being treated with fixed CPAP on the basis of APAP titration or being treated with APAP must be followed to determine treatment effectiveness and safety, and (iv) a re-evaluation and, if necessary, a standard attended CPAP titration should be performed if symptoms do not resolve or the CPAP or APAP treatment otherwise appears to lack efficacy. 32 Bilevel positive airway pressure (BPAP) During sleep, airway resistance and the propensity for airway closure are greater during inspiration compared to expiration. BPAP allows independent inspiratory and expiratory pressure adjustments so that the patient expires against a lower pressure. The American Academy of Sleep Medicine recommends that (i) BPAP is an optional therapy in some cases where high pressure is needed and the patient experiences difficulty exhaling against a fixed pressure or coexisting central hypoventilation is present and (ii) BPAP may be useful in treating some forms of restrictive lung disease or hypoventilation syndromes associated with daytime hypercapnia. Conclusions Despite the prevalence of OSA, no ideal therapy has emerged to date. CPAP is currently the treatment of choice for OSA. There is good evidence supporting the use of CPAP to treat not only moderate to severe OSA but also even in mild OSA. Unfortunately, many patients are not Vol.3, No.1 / June,

5 Ho-Won Lee Sung-Pa Park willing or able to tolerate CPAP therapy. There are continuous improvement strategies, such as reinforced education support. Alternative therapies such as APAP or BPAP may benefit specific subgroups of patients. Although positive airway pressure remains an imperfect intervention, it has continued to evolve and improve such that patients who would not have been able to use this therapy even in the recent past can benefit from it today. REFERENCES 1. White DP. Sleep-related breathing disorder. 2. Pathophysiology of obstructive sleep apnoea. Thorax 1995;50: Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;32: Kim JK, In KH, Kim JH, et al. Prevalence of sleep-disordered breathing in middle -aged Korean men and women. Am J Respir Crit Care Med 2004;170: Becker HF, Jerrentrup A, Ploch T, et al. Effect of nasal continuous positive airway pressure treatment on blood pressure in patients with obstructive sleep apnea. Circulation 2003; 107: Nieto FJ, Young TB, Lind BK, et al. Association of sleepdisordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study. JAMA 2000; 283: Peppard PE, Young T, Palta M, Skatrud J. Prospective study of the association between sleep-disordered breathing and hypertension. N Engl J Med 2000;342: Teran-Santos J, Jimenez-Gomez A, Cordero-Guevara J: The association between sleep apnea and the risk of traffic accidents. Cooperative Group Burgos-Santander. N Engl J Med 1999;340: Barnes M, McEvoy RD, Banks S, et al. Efficacy of positive airway pressure and oral appliance in mild to moderate obstructive sleep apnea. Am J Respir Crit Care Med 2004;170: Loube D, Gay PC, Strohl KP, Pack AI, White DP, Collop NA. Indications for positive airway pressure treatment of adult obstructive sleep apnea patients: a consensus statement. Chest 1999;115: Sullivan CE, Issa FG, Berthon-Jones M, Eves L. Reversal of obstructive sleep apnoea by continuous positive airway pressure applied through the nares. Lancet 1981;1: Van de Graaff WB. Thoracic influence on upper airway patency. J Appl Physiol 1988;65: Kushida CA, Litter MR, Hirshkowitz M, et al. Practice parameters for use of continuous and bilevel positive airway pressure devices to treat patients with sleep-related breathing disorders. Sleep 2006;29: Loube DI, Gay PC, Strohl KP, Pack AI, White DP, Collop NA. Indications for positive airway pressure treatment of adult obstructive sleep apnea patients: a consensus statement. Chest 1999;115: Monasterio C, Vidal S, Duran J, et al. Effectiveness of continuous positive airway pressure in mild sleep apneahypopnea syndrome. Am J Respir Crit Care Med 2001;164: Engleman HM, Kingshott RN, Wraith PK, Mackay TW, Deary IJ, Douglas NJ. Randomized placebo controlled crossover trial of continuous positive airway pressure for mild sleep apnea/ hypopnea syndrome. Am J Respir Crit Care Med 1999;159: Profant J, Ancoli-Israel S, Dimsdale JE. A randomized, controlled trial of 1 week of continuous positive airway pressure treatment on quality of life. Heart Lung 2003;32: Kajaste S, Brander PE, Telakivi T, Partinen M, Mustajoki P. A cognitive-behavioral weight reduction program in the treatment of obstructive sleep apnea syndrome with or without initial nasal CPAP: a randomized study. Sleep Med 2004;5: George CF. Reduction in motor vehicle collisions following treatment of sleep apnea with nasal CPAP. Thorax 2001;56: Dimsdale JE, Loredo JS, Profant J. Effect of continuous positive airway pressure on blood pressure: a placebo trial. Hypertension 2000;35: Faccenda JF, Mackay TW, Boon NA, Douglas NJ. Randomized placebo-controlled trial of continuous positive airway pressure on blood pressure in the sleep apnea-hypopnea syndrome. Am J Respir Crit Care Med 2001;163: Sin DD, Logan AG, Fitzgerald FS,LiuPP,BradleyTD.Effects of continuous positive airway pressure on cardiovascular outcomes in heart failure patients with and without Cheyne- Stokes respiration. Circulation 2000;102: Duchna HW, Guilleminault C, Stoohs RA, et al. Vascular reactivity in obstructive sleep apnea syndrome. Am J Respir Crit Care Med 2000;161: Montserrat JM, Ballester E, Olivi H, et al. Time-course of stepwise CPAP titration: behavior of respiratory and neurological variables. Am J Respir Crit Care Med 1995;152: Ayappa I, Norman RG, Hosselet JJ, Gruenke RA, Walsleben JA, Rapoport DM. Relative occurrence of flow limitation and snoring during continuous positive airway pressure titration. Chest 1998; 114: Oksenberg A, Silverberg DS, Arons E, Radwan H. The sleep supine position has a major effect on optimal nasal continuous positive airway pressure: relationship with rapid eye movements and non-rapid eye movements sleep, body mass index, respiratory disturbance, and age. Chest 1999;116: Jokic R, Klimaszewski A, Guruswamy S, Fitzpatrick MF. Continuous positive airway pressure requirements during the first month of treatment in patients with severe obstructive sleep apnea. Chest 1998;114: McArdle N, Devereux G, Heidarnejad H, Engleman HM, Mackay TW, Douglas NJ. Long-term use of CPAP therapy for sleep apnea/hypopnea syndrome. Am. J. Respir. Crit Care Med 38 수면

6 Positive Airway Pressure Therapy of Obstructive Sleep Apnea 1999; 159: Kribbs NB, Pack AI, Kline LR, et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis 1993;147: Malhotra A, Ayas NT, Epstein LJ. The art and science of continuous positive airway pressure therapy in obstructive sleep apnea. Curr. Opin. Pulm. Med 2000;6: Randerath WJ, Schraeder O, Galetke W, Feldmeyer F, Ruhle KH. Autoadjusting CPAP therapy based on impedance efficacy, compliance and acceptance. Am J Respir Crit Care Med 2001; 163: Teschler H, Berthon-Jones M. Intelligent CPAP systems: clinical experience. Thorax 1998;53: Littner M, Hirshkowitz M, Davila D, et al. Practice parameters for the use of auto-titrating continuous positive airway pressure devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome. An American Academy of Sleep Medicine report. Sleep 2002;25: Vol.3, No.1 / June,