- Email: [email protected]
Customizing a nasal CPAP mask using a silicone elastomer
Customizing a nasal CPAP mask using a silicone elastomer Paul M. McLornan, BDS,a Nancy A. Hansen, CDT, CCA, BS,b and Ronald G. Verrett, DDS, MSc The University of Texas Health Science Center at San Antonio, San Antonio, Tex Nasal continuous positive airway pressure (CPAP) is an effective treatment for obstructive sleep apnea (OSA). Airway obstruction is prevented by delivering air at a constant pressure via a nasal mask worn during sleep. Small nares may cause difficulty in wearing even the smallest standard nasal mask, with wear resulting in discomfort and air leaks. This article describes a method for fabricating a custom nasal CPAP mask using maxillofacial prosthodontic laboratory techniques. (J Prosthet Dent 2008;100:147-152) There is an increasing awareness of obstructive sleep apnea (OSA) as a public health issue that affects 2% to 4% of the middle-aged adult population.1 OSA is the most frequently occurring sleep disorder and is characterized by the absence of airflow in the presence of continuous respiratory effort. This cessation of airflow is related to the anatomic narrowing and/or collapse of the pharynx during sleep, a situation not encountered when awake because of muscle compensation. OSA, and to a lesser degree, snoring, are associated with a wide variety of adverse health outcomes, including cardiovascular problems and daytime sleepiness.2 Continuous positive airway pressure (CPAP), introduced by Sullivan et al in 1981,3 has become the standard of care for treating moderate to severe OSA.4 Nasal CPAP has proven to be a highly effective and safe treatment for OSA. Airway obstruction is prevented by delivering air at a constant pressure via a nasal mask worn during sleep. However, nasal CPAP is not universally tolerated by patients, with compliance rates estimated between
50% and 80%, excluding patients who seek alternative treatment.5 Reasons for noncompliance include air leakage from the mask, noise, the mask is objectionable to a bed partner, the unit is bulky for travel, or there is discomfort associated with wearing a standard mask. Side effects related to the nasal interface have been found to occur in greater than 50% of all CPAP patients.6,7,8 Proper fit of the mask and treatment of nasal conditions are important factors to ensure compliance, because untreated side effects can result in discontinuation of treatment.9,10,11,12 Small nares may cause difficulty in wearing the small standard nasal mask, leading to discomfort, skin abrasion, and air leaks. These problems may be overcome with a customized silicone elastomer nasal CPAP mask.
TECHNIQUE
Impression tray 1. Alter a standard direct nasal CPAP mask (Infinity Direct Nasal
Mask; Fisher & Paykel Healthcare, Inc, Irvine, Calif ) (Fig. 1, A), which will be used as the impression tray, by removing the upper portion of the nasal extensions, leaving the flange and the lower portion to support impression material and maintain orifice-to-orifice orientation. 2. Create retention for the impression material with 32-gauge wire (Great Lakes Orthodontics, Ltd, Tonawanda, NY), adapted to protrude through the nares opening with a loop on the superior extension and extending beyond the base of the CPAP mask. Use wax (Baseplate wax; Dentsply Intl, York, Pa) to secure the wire in place and occlude the nares opening. Fill the mask with autopolymerizing polymethyl methacrylate (PMMA) acrylic resin (DuraLay; Reliance Dental Mfg Co, Worth, Ill) (Fig. 1, B). 3. Mark the desired flange extension of the custom CPAP mask on the external surface of the nose with a surgical marking pen (Accu-line Products, Inc, Hyannis, Mass) (Fig. 2, A), to transfer this marking onto the impression.
Presented as a table clinic at the American College of Prosthodontists annual meeting, November, 2006, Miami, Fla. Assistant Professor, Department of Prosthodontics. Clinical Anaplastologist, Department of Prosthodontics. c Assistant Director, Graduate Prosthodontics. a
b
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Volume 100 Issue 2 4. Gently position the impression tray into the nares to evaluate patient comfort, tray adaptation, and the length of the wire intranasal extension (Fig. 2, B). 5. Place cotton lubricated with petroleum jelly (Clay-Park Labs, Inc, Bronx, NY) into the nares, and make
an impression of the nares and the surrounding area using a medium viscosity vinyl polysiloxane impression material (Reprosil; Dentsply Caulk, Milford, Del) (Fig. 2, C). Gently place the impression tray into position and record the soft tissue contours (Fig. 2, D). Remove, inspect, and disinfect
the resultant impression. 6. Trim and contour the impression to the desired flange extensions. Block out any voids with wax (Baseplate wax; Dentsply Intl), and flow this wax over the cotton on the tips of the impression, retaining the internal contours of the nares (Fig. 3, A).
A
B
1 A, Standard direct nasal CPAP mask. B, Impression tray formed by removal of intranares extensions, adapting wire retention substructure, and addition of autopolymerizing acrylic resin.
A
B
C
D
2 A, Desired flange extension of CPAP mask marked on nose. B, Tray adaptation is evaluated. C, Soft tissue contour is recorded with vinyl polysiloxane impression material. D, Tray is seated and impression is completed.
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A
B
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3 A, Flanges trimmed to desired extensions. B, Impression placed in dental stone up to level of bottom of tray. C, Second section fabricated in 2 parts with section 1 land area keyed. First half of second section poured in stone up to flange extension. D, Second half of second section is then poured. Mold fabrication 1. Place the base of the impression tray into a patty of type III dental stone (Microstone; Whip Mix Corp, Louisville, Ky), to the level of the bottom of the impression tray (Fig. 3, B). 2. Smooth and key the stone land area of the first section of the mold, and apply a gypsum separating agent (Al-cote; Dentsply Trubyte, York, Pa). 3. Pour the first part of the second mold section in stone up to the underside of the flange extension and to one half of the width of the impression tray with a tapered inner wall (Fig. 3, C). Smooth with sandpaper (SandWet Ultra Fine, 600 grit; Norton Abrasives, Worcester, Mass) and apply separator, then pour the second part of the second section in dental stone (Fig. 3, D). 4. Box around the nares extension and block out the stone junction between the parts of the second section
McLornan et al
with wax (Utility wax; Dentsply Intl), and key the land area outside of the boxed area. Use a petroleum jelly (Clay-Park Labs, Inc) as an acrylic resin separation agent, then pour PMMA acrylic resin into the boxed area up to the top of the nares extension of the impression; after that, create retention in the resin for the next layer of stone (Fig. 4, A). 5. Remove the wax when the acrylic resin is polymerized and smooth the top of the acrylic resin, exposing the top of the nares extension (Fig. 4, B). 6. Apply tin foil substitute separator (Al-cote; Dentsply Trubyte), and then adapt a strip of boxing wax (Dentsply Intl) around and above this section. Form a stone ring around the resin core. 7. Contour the stone ring to converge downward toward the opening of the nares, leaving a half-inch margin around the nares (Fig. 4, C).
8. Disassemble the mold and remove the tray with the impression, then clean the mold sections with soapy water. 9. Line the inside of the nares portion of the impression with a layer of 24-gauge, pressure-sensitive, adhesive-coated relief wax (Kindt-Collins Company LLC, Cleveland, Ohio) from the top of the nares opening, extending to the inside of the mold (Fig. 5, A), to determine the wall thickness of the nares extension. 10. Block out the flange extension from the inside of both segments of the second part of the mold to allow the nares plugs to be continuous from the tray extension upward to the nares extension (Fig. 5, B). 11. Block out both halves of the mold with wax (Baseplate wax; Dentsply Intl), and place a thin layer of this wax over the top of the tray extension to prevent the nares plug and the acrylic resin tray section from fusing,
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A
B
C 4 A, Area surrounding nares extension is boxed, and acrylic resin is added to top of nares extensions. B, Acrylic resin core smoothed to expose nares extension. C, Stone ring formed around acrylic resin core converging toward opening of mold with margin of acrylic resin exposed around nares.
A
B
5 A, Nares lined with relief wax (arrow) to form thickness of nares extension. B, Block-out wax (arrow) creates airway passage from acrylic resin portion of custom tray to acrylic resin core surrounding nasal extension.
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C
D
5 continued (2 of 2) C, Nares openings are separated with wax and acrylic resin is poured up to keyed stone land area. D, Nares plug in position in left nostril of mask.
7 Silicone elastomer is sequentially injected into mold 6 Multisectional stone and resin mold consists of (from bottom to top): section 1 - stone and acrylic resin; section sections. 2 – stone (2 parts); section 3 – stone and acrylic resin; section 4 – acrylic resin (2 parts).
then reassemble the mold. 12. Place keys around the stone ring that converge downward. Separate the nares opening with wax (Dentsply Intl), and apply petroleum jelly (ClayPark Labs, Inc) on the stone and resin lubricant (DuraLay; Reliance Dental Mfg Co) on the exposed resin. 13. Prepare a thin mixture of PMMA to form the nares plug and pour it into the nares opening up to the keyed stone land area (Fig. 5, C). Once the acrylic resin is polymerized, repeat this step on the other side to form nares plugs that are continuous but separate from the resin tray section (Fig. 5, D).
McLornan et al
Processing 1. Mark the completed mold with orientation lines. Disassemble the multisectional stone and acrylic resin mold (Fig. 6), and clean each section with soapy water. 2. Apply the separating agent (Alcote; Dentsply Trubyte) inside the mold and pack (inject) the mold using a silicone elastomer material (A2000; Factor II, Lakeside, Ariz) (Fig. 7). Inject the silicone sequentially as sections 1 to 3 of the mold are rebuilt. 3. Position the nares plug, section
4, while holding the mold together, and gently push into place. Repeat this step with the other nares plug. 4. Place the mold in a press and hand tighten until no further closure is possible. Place the silicone elastomer in a dry heat oven at 71°C for 2 hours to allow polymerization. 5. Separate the mold sections, remove the polymerized silicone mask, trim the silicone flash, and finish using a sharp blade and silicone finishing burs (Brasseler USA, Savannah, Ga), then compare with the form of the standard direct nasal mask (Fig. 8, A).
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A
B
8 A, Standard unmodified nasal mask (left) and customized nasal mask (right). B, Custom nasal mask adapted to nares and attached to CPAP machine. Clinical insertion 1. Place the custom nasal mask on the patient and evaluate for comfort. 2. Demonstrate connection to the CPAP machine (Fig. 8, B), and review the overnight usage of the customized nasal mask. 3. Schedule the patient for followup appointments at 24 hours and at 7 days.
SUMMARY The custom nasal CPAP mask demonstrates an intimate adaptation to the internal and external anatomy of the nose and overcomes 3 of the reasons often cited for noncompliance with CPAP masks: air leakage from the mask, noise, and discomfort. The customized mask additionally minimizes the side effect of skin abrasion and allows the patient to use the CPAP machine at a lower positive pressure. Given the high incidence of side effects associated with the CPAP nasal interface and the significant rates of noncompliance that have been reported, the need for a customized mask seems evident. The disadvantages of this method are the addi-
tional patient appointment time and the laboratory expense of the customized mold. Further refinement of the processing technique is necessary to improve cost effectiveness.
REFERENCES 1. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleepdisordered breathing among middle-aged adults. N Engl J Med 1993;328:1230-5. 2. Shamsuzzaman AS, Gersh BJ, Somers VK. Obstructive sleep apnea: implications for cardiac and vascular disease. JAMA 2003;290:1906-14. 3. 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;18:862-5. 4. Kushida CA, Littner MR, Hirshkowitz M, Morgenthaler TI, Alessi CA, Bailey D, et al. Practice parameters for the use of continuous and bilevel positive airway pressure devices to treat adult patients with sleep-related breathing disorders. Sleep 2006;29:375-80. 5. Littner M, Hirshkowitz M, Davila D, Anderson WM, Kushida CA, Woodson BT, 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;25:143-7. 6. Pépin JL, Krieger J, Rodenstein D, Cornette A, Sforza E, Delguste P, et al. Effective compliance during the first 3 months of continuous positive airway pressure. A European prospective study of 121 patients. Am J Respir Crit Care Med 1999;160:11249.
The Journal of Prosthetic Dentistry
7. Hoffstein V, Viner S, Mateika S, Conway J. Treatment of obstructive sleep apnea with nasal continuous positive airway pressure. Patient compliance, perception of benefits, and side effects. Am Rev Respir Dis 1992;145:841-5. 8. Sanders MH, Gruendl CA, Rogers RM. Patient compliance with nasal CPAP therapy for sleep apnea. Chest 1986;90:330-3. 9. Kribbs NB, Pack AI, Kline LR, Smith PL, Schwartz AR, Schubert NM, et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis 1993;147:887-95. 10.Massie CA, Hart RW. Clinical outcomes related to interface type in patients with obstructive sleep apnea/hypopnea syndrome who are using continuous positive airway pressure. Chest 2003;123:1112-8. 11.Meurice JC, Dore P, Paquereau J, Neau JP, Ingrand P, Chavagnat JJ, et al. Predictive factors of long-term compliance with nasal continuous positive airway pressure treatment in sleep apnea syndrome. Chest 1994;105:429-33. 12.Pépin JL, Leger P, Veale D, Langevin B, Robert D, Lévy P. Side effects of nasal continuous positive airway pressure in sleep apnea syndrome. Study of 193 patients in two French sleep centers. Chest 1995;107:37581. Corresponding author: Dr Paul M. McLornan Department of Prosthodontics (7912) The University of Texas Health Science Center at San Antonio 7703 Floyd Curl Dr. San Antonio, TX 78229-3900 Fax: 210-567-6376 E-mail: [email protected] Copyright © 2008 by the Editorial Council for The Journal of Prosthetic Dentistry.
McLornan et al
50% and 80%, excluding patients who seek alternative treatment.5 Reasons for noncompliance include air leakage from the mask, noise, the mask is objectionable to a bed partner, the unit is bulky for travel, or there is discomfort associated with wearing a standard mask. Side effects related to the nasal interface have been found to occur in greater than 50% of all CPAP patients.6,7,8 Proper fit of the mask and treatment of nasal conditions are important factors to ensure compliance, because untreated side effects can result in discontinuation of treatment.9,10,11,12 Small nares may cause difficulty in wearing the small standard nasal mask, leading to discomfort, skin abrasion, and air leaks. These problems may be overcome with a customized silicone elastomer nasal CPAP mask.
TECHNIQUE
Impression tray 1. Alter a standard direct nasal CPAP mask (Infinity Direct Nasal
Mask; Fisher & Paykel Healthcare, Inc, Irvine, Calif ) (Fig. 1, A), which will be used as the impression tray, by removing the upper portion of the nasal extensions, leaving the flange and the lower portion to support impression material and maintain orifice-to-orifice orientation. 2. Create retention for the impression material with 32-gauge wire (Great Lakes Orthodontics, Ltd, Tonawanda, NY), adapted to protrude through the nares opening with a loop on the superior extension and extending beyond the base of the CPAP mask. Use wax (Baseplate wax; Dentsply Intl, York, Pa) to secure the wire in place and occlude the nares opening. Fill the mask with autopolymerizing polymethyl methacrylate (PMMA) acrylic resin (DuraLay; Reliance Dental Mfg Co, Worth, Ill) (Fig. 1, B). 3. Mark the desired flange extension of the custom CPAP mask on the external surface of the nose with a surgical marking pen (Accu-line Products, Inc, Hyannis, Mass) (Fig. 2, A), to transfer this marking onto the impression.
Presented as a table clinic at the American College of Prosthodontists annual meeting, November, 2006, Miami, Fla. Assistant Professor, Department of Prosthodontics. Clinical Anaplastologist, Department of Prosthodontics. c Assistant Director, Graduate Prosthodontics. a
b
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Volume 100 Issue 2 4. Gently position the impression tray into the nares to evaluate patient comfort, tray adaptation, and the length of the wire intranasal extension (Fig. 2, B). 5. Place cotton lubricated with petroleum jelly (Clay-Park Labs, Inc, Bronx, NY) into the nares, and make
an impression of the nares and the surrounding area using a medium viscosity vinyl polysiloxane impression material (Reprosil; Dentsply Caulk, Milford, Del) (Fig. 2, C). Gently place the impression tray into position and record the soft tissue contours (Fig. 2, D). Remove, inspect, and disinfect
the resultant impression. 6. Trim and contour the impression to the desired flange extensions. Block out any voids with wax (Baseplate wax; Dentsply Intl), and flow this wax over the cotton on the tips of the impression, retaining the internal contours of the nares (Fig. 3, A).
A
B
1 A, Standard direct nasal CPAP mask. B, Impression tray formed by removal of intranares extensions, adapting wire retention substructure, and addition of autopolymerizing acrylic resin.
A
B
C
D
2 A, Desired flange extension of CPAP mask marked on nose. B, Tray adaptation is evaluated. C, Soft tissue contour is recorded with vinyl polysiloxane impression material. D, Tray is seated and impression is completed.
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A
B
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3 A, Flanges trimmed to desired extensions. B, Impression placed in dental stone up to level of bottom of tray. C, Second section fabricated in 2 parts with section 1 land area keyed. First half of second section poured in stone up to flange extension. D, Second half of second section is then poured. Mold fabrication 1. Place the base of the impression tray into a patty of type III dental stone (Microstone; Whip Mix Corp, Louisville, Ky), to the level of the bottom of the impression tray (Fig. 3, B). 2. Smooth and key the stone land area of the first section of the mold, and apply a gypsum separating agent (Al-cote; Dentsply Trubyte, York, Pa). 3. Pour the first part of the second mold section in stone up to the underside of the flange extension and to one half of the width of the impression tray with a tapered inner wall (Fig. 3, C). Smooth with sandpaper (SandWet Ultra Fine, 600 grit; Norton Abrasives, Worcester, Mass) and apply separator, then pour the second part of the second section in dental stone (Fig. 3, D). 4. Box around the nares extension and block out the stone junction between the parts of the second section
McLornan et al
with wax (Utility wax; Dentsply Intl), and key the land area outside of the boxed area. Use a petroleum jelly (Clay-Park Labs, Inc) as an acrylic resin separation agent, then pour PMMA acrylic resin into the boxed area up to the top of the nares extension of the impression; after that, create retention in the resin for the next layer of stone (Fig. 4, A). 5. Remove the wax when the acrylic resin is polymerized and smooth the top of the acrylic resin, exposing the top of the nares extension (Fig. 4, B). 6. Apply tin foil substitute separator (Al-cote; Dentsply Trubyte), and then adapt a strip of boxing wax (Dentsply Intl) around and above this section. Form a stone ring around the resin core. 7. Contour the stone ring to converge downward toward the opening of the nares, leaving a half-inch margin around the nares (Fig. 4, C).
8. Disassemble the mold and remove the tray with the impression, then clean the mold sections with soapy water. 9. Line the inside of the nares portion of the impression with a layer of 24-gauge, pressure-sensitive, adhesive-coated relief wax (Kindt-Collins Company LLC, Cleveland, Ohio) from the top of the nares opening, extending to the inside of the mold (Fig. 5, A), to determine the wall thickness of the nares extension. 10. Block out the flange extension from the inside of both segments of the second part of the mold to allow the nares plugs to be continuous from the tray extension upward to the nares extension (Fig. 5, B). 11. Block out both halves of the mold with wax (Baseplate wax; Dentsply Intl), and place a thin layer of this wax over the top of the tray extension to prevent the nares plug and the acrylic resin tray section from fusing,
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A
B
C 4 A, Area surrounding nares extension is boxed, and acrylic resin is added to top of nares extensions. B, Acrylic resin core smoothed to expose nares extension. C, Stone ring formed around acrylic resin core converging toward opening of mold with margin of acrylic resin exposed around nares.
A
B
5 A, Nares lined with relief wax (arrow) to form thickness of nares extension. B, Block-out wax (arrow) creates airway passage from acrylic resin portion of custom tray to acrylic resin core surrounding nasal extension.
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C
D
5 continued (2 of 2) C, Nares openings are separated with wax and acrylic resin is poured up to keyed stone land area. D, Nares plug in position in left nostril of mask.
7 Silicone elastomer is sequentially injected into mold 6 Multisectional stone and resin mold consists of (from bottom to top): section 1 - stone and acrylic resin; section sections. 2 – stone (2 parts); section 3 – stone and acrylic resin; section 4 – acrylic resin (2 parts).
then reassemble the mold. 12. Place keys around the stone ring that converge downward. Separate the nares opening with wax (Dentsply Intl), and apply petroleum jelly (ClayPark Labs, Inc) on the stone and resin lubricant (DuraLay; Reliance Dental Mfg Co) on the exposed resin. 13. Prepare a thin mixture of PMMA to form the nares plug and pour it into the nares opening up to the keyed stone land area (Fig. 5, C). Once the acrylic resin is polymerized, repeat this step on the other side to form nares plugs that are continuous but separate from the resin tray section (Fig. 5, D).
McLornan et al
Processing 1. Mark the completed mold with orientation lines. Disassemble the multisectional stone and acrylic resin mold (Fig. 6), and clean each section with soapy water. 2. Apply the separating agent (Alcote; Dentsply Trubyte) inside the mold and pack (inject) the mold using a silicone elastomer material (A2000; Factor II, Lakeside, Ariz) (Fig. 7). Inject the silicone sequentially as sections 1 to 3 of the mold are rebuilt. 3. Position the nares plug, section
4, while holding the mold together, and gently push into place. Repeat this step with the other nares plug. 4. Place the mold in a press and hand tighten until no further closure is possible. Place the silicone elastomer in a dry heat oven at 71°C for 2 hours to allow polymerization. 5. Separate the mold sections, remove the polymerized silicone mask, trim the silicone flash, and finish using a sharp blade and silicone finishing burs (Brasseler USA, Savannah, Ga), then compare with the form of the standard direct nasal mask (Fig. 8, A).
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A
B
8 A, Standard unmodified nasal mask (left) and customized nasal mask (right). B, Custom nasal mask adapted to nares and attached to CPAP machine. Clinical insertion 1. Place the custom nasal mask on the patient and evaluate for comfort. 2. Demonstrate connection to the CPAP machine (Fig. 8, B), and review the overnight usage of the customized nasal mask. 3. Schedule the patient for followup appointments at 24 hours and at 7 days.
SUMMARY The custom nasal CPAP mask demonstrates an intimate adaptation to the internal and external anatomy of the nose and overcomes 3 of the reasons often cited for noncompliance with CPAP masks: air leakage from the mask, noise, and discomfort. The customized mask additionally minimizes the side effect of skin abrasion and allows the patient to use the CPAP machine at a lower positive pressure. Given the high incidence of side effects associated with the CPAP nasal interface and the significant rates of noncompliance that have been reported, the need for a customized mask seems evident. The disadvantages of this method are the addi-
tional patient appointment time and the laboratory expense of the customized mold. Further refinement of the processing technique is necessary to improve cost effectiveness.
REFERENCES 1. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleepdisordered breathing among middle-aged adults. N Engl J Med 1993;328:1230-5. 2. Shamsuzzaman AS, Gersh BJ, Somers VK. Obstructive sleep apnea: implications for cardiac and vascular disease. JAMA 2003;290:1906-14. 3. 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;18:862-5. 4. Kushida CA, Littner MR, Hirshkowitz M, Morgenthaler TI, Alessi CA, Bailey D, et al. Practice parameters for the use of continuous and bilevel positive airway pressure devices to treat adult patients with sleep-related breathing disorders. Sleep 2006;29:375-80. 5. Littner M, Hirshkowitz M, Davila D, Anderson WM, Kushida CA, Woodson BT, 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;25:143-7. 6. Pépin JL, Krieger J, Rodenstein D, Cornette A, Sforza E, Delguste P, et al. Effective compliance during the first 3 months of continuous positive airway pressure. A European prospective study of 121 patients. Am J Respir Crit Care Med 1999;160:11249.
The Journal of Prosthetic Dentistry
7. Hoffstein V, Viner S, Mateika S, Conway J. Treatment of obstructive sleep apnea with nasal continuous positive airway pressure. Patient compliance, perception of benefits, and side effects. Am Rev Respir Dis 1992;145:841-5. 8. Sanders MH, Gruendl CA, Rogers RM. Patient compliance with nasal CPAP therapy for sleep apnea. Chest 1986;90:330-3. 9. Kribbs NB, Pack AI, Kline LR, Smith PL, Schwartz AR, Schubert NM, et al. Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis 1993;147:887-95. 10.Massie CA, Hart RW. Clinical outcomes related to interface type in patients with obstructive sleep apnea/hypopnea syndrome who are using continuous positive airway pressure. Chest 2003;123:1112-8. 11.Meurice JC, Dore P, Paquereau J, Neau JP, Ingrand P, Chavagnat JJ, et al. Predictive factors of long-term compliance with nasal continuous positive airway pressure treatment in sleep apnea syndrome. Chest 1994;105:429-33. 12.Pépin JL, Leger P, Veale D, Langevin B, Robert D, Lévy P. Side effects of nasal continuous positive airway pressure in sleep apnea syndrome. Study of 193 patients in two French sleep centers. Chest 1995;107:37581. Corresponding author: Dr Paul M. McLornan Department of Prosthodontics (7912) The University of Texas Health Science Center at San Antonio 7703 Floyd Curl Dr. San Antonio, TX 78229-3900 Fax: 210-567-6376 E-mail: [email protected] Copyright © 2008 by the Editorial Council for The Journal of Prosthetic Dentistry.
McLornan et al