nasal-cpap, surgery, and conservative management treatment ... · evaluation ofsymptoms excessive...

Nasal-CPAP, Surgery, and ConservativeManagement for Treatment ofObstructive Sleep Apnea Syndrome*A Randomized Study

Jukka Lojander, MD; Paula Maasilta, MD, PhiD, FCCP;Markku Partinen, MD, PhD; Pirkko E. Brander, MD, PhD;Tapani Salri, MD, PhD; and Harnu Lehtonen, MD, PhD

Obstructive sleep apnea syndrome (OSAS) is a dis-order characterized by excessive snoring and pe-

riodic breathing with repetitive apneas, hypopneas,and arousals leading to fragmented sleep. This leads todaytime somnolence and cardiovascular complications.

*From the De artments of Pulmonary Medicine (Drs. Lojander

Maasilta, and rander), Neurology (Drs. Partinen and Salmi), andEar, Nose, and Throat Diseases (Dr. Lehtonen), University ofHelsinki, Helsinld, Finland.This study was supported by grants from the Ahokas Foundation,and the fda Montin Foundation, Finland.Manuscript received August 2, 1995; revision accepted February21, 1996.

Reprint requests: Dr. Partinen, Haaga Centre for NeurologicResearch and Rehabilitation, M1dkipellontie 15, FIN-00320 HelsinckiFinland

In a recent study by Young et al,' 2% of women and4% of men in the middle-aged workforce met the di-agnostic criteria for OSAS.

Currently various therapeutic approaches for themanagement of OSAS are available. Conservativemanagement consists of weight loss and positionaltherapy as well as avoidance of tranquilizers and alco-hol at bedtime.2-5 Continuous positive airway pressure(CPAP) provided via nasal mask6 is the most widelyused nonsurgical therapy for OSAS. Uvulopalato-pharyngoplasty (UPPP), linguoplasty, and rmaxillofacialsurgery are applied as surgical alternatives.7,8The aim of this randomized study was to clarify the

Clinical Investigations

Study objective: To assess separately the effectiveness and safety ofnasal-continuous positive airwaypressure (N-CPAP) and that of surgery in comparison to conservative management in patients withobstructive sleep apnea syndrome (OSAS).Design: A randomized study with 1-year follow-up.Setting: A university hospital acting as a referral center for OSAS.Patients: Symptomatic patients with OSAS (72 male and 4 female patients aged 18 to 65 years), whohad oxygen desaturations in the overnight recording.Interventions: After the initial diagnostic workup, patients were considered to be candidates for ei-ther N-CPAP (44 patients) or surgical treatment (uvulopalatopharyngoplasty [UPPP] with or with-out mandibular osteotomy) (32 patients). Within the groups, the patients were then randomized toeither the assigned treatment or conservative management.Main outcome measures: The number of nocturnal oxygen desaturation events of 4% or more perhour in bed (OD14); daytime somnolence; side effects.Results: N-CPAP Group: Compliance with N-CPAP therapy at 1 year was 13 of 21. The most com-mon reason for noncompliance was general intolerance of CPAP. All compliant patients had a nor-mal OD14 (<10), whereas 1 of 20 of their control subjects had a normal finding. Patients receivingactive treatment were significantly less somnolent than their control subjects at 1 year (p<0.05).Surgery Group: At 1 year, 7 of 18 of the surgically treated and 1 of 14 of the conservatively treatedpatients had a normal OD14 (p<0.001). Daytime somnolence was significantly less severe in thesurgically treated patients compared with their control subjects (p<0.001) both at 3 and 12 months.The overall postoperative complication rate was 22%.Conclusions: N-CPAP is an effective therapy for OSAS, but compliance is a problem. Surgical ther-apy (UPPP with or without mandibular osteotomy) needs further evaluation.

(CHEST 1996; 110:114-19)

Key words: nasal-CPAP; obstructive sleep apnea syndrome; randomized clinical study; upper airway surgery; UPPP

Abbreviations: CPAP=continuous positive airnvay pressure; N-CPAP=nasal-CPAP; OD14 and ODIO=oxygen desaturationindex of 4% or 10% per hour in bed; OSAS=obstructive sleep apnea syndrome; UPPP=uvulopalatopharyngoplasty

14

Downloaded From: http://journal.publications.chestnet.org/pdfaccess.ashx?url=/data/journals/chest/21734/ on 06/22/2017

Table 1-Baseline Characteristics of the Patients*

N-CPAP Surgery

Cons (n=23) Active (n=21) Cons (n=14) Active (n=18)

Female/male 1/22 2/19 0/14 1/17Age, yr, median (range) 51 (30-65) 51 (38-63) 48 (36-61) 47(27-62)Body mass index, kg/m2, median (range) 33 (24-41) 29 (24-38) 32 (26-39) 30 (24-39)ODb4, median (range) 29 (10-96) 25 (10-92) 34 (20-68) 45 (21-72)ODIbo, median (range) 7 (0-79) 7 (0-88) 9 (0-39) 17 (0-62)SymnptomsHeavy snorers, No. 21 19 11 14Witnessed apneas, No. 19 17 13 18Excessive daytime somnolence

V7AS,I median score (range) 50 (5-90) 60 (15-80) 60 (10-90) 70 (28-93)Falling asleep wvhen not in bed, No. 15 13 9 16

*In the N-CPAP group, patients were randomized either to conservative management (Cons) or treatment with N-CPAP. Patieilts selected for sur-gical treatment were randomized either to conservative management (Cons) or surgery (UPPP with or without mandibular osteotomy).

'VAS=visual analog scale: 0=none; 100=very severe.

therapeutic role of nasal CPAP as well as that of oper-ative treatment (UPPP with or without mandibularosteotomy) in comparison to conservative manage-ment in patients with OSAS.

MATERIALS AND METHODSPatients

Mental or physical effects were required for a diagnosis ofOSASin addition to a diagn-ostic finding in an overnight polygraphic re-cording (the number ofoxygen desaturations -4% or 10% per hourof time spent in bed) and a "periodic breathing" pattern in bothstatic-charge-sensitixve bed and thermistor channels. Results ofdaytime polysomnography (EEG, electromyogram, and electro-oculogram, in addition to parameters of the overnight polygraphicrecording) were consistent with OSAS in all patients.

Furthermore, mental or physical effects were required. Duringthe time period 1987 to 1992, 268 patients betxveen the ages of 18and 65 years with previously untreated OSAS fulfilling the abovecriteria were seen at our hospital. Patients with asthma and otherCOPD (n=28), periodic leg movements syndrome (n=2), hypothy-roidism (n=2), or other serious concomitant illness, eg, recentischemic cerebral or coronary incident (n=50), wvere excluded aswell as patients for whom somnolence could cause risk or incapac-ity to work (n=39). Patients with body mass index greater than 40kg/M2 (n=26) were excluded from this study. They participated ina randomized active weight-loss study.9 Of the remaining 121 pa-tients fulfilbng the criteria, 45 refused to be randomized. Thecharacteristics, ie, age, body mass index, and oxygen desaturationindex of 4% or more per hour in bed (OD14) of these 45 patientsdid not differ in any significant way from those who were finallyincluded in the study. The characteristics of the study populationare shown in Table 1.

Study Design

All patients were assessed by a team of experts consisting of apulmonary speciabst, a neurologist, a chnical neurophysiologist, anear, nose, and throat specialist, and a maxillofacial surgeon. Basedon clinical history, medical examination, sleep recordings, naso-fiberoscopy, and cephalometric findings, patients were consideredmore suitable for nasal-CPAP (N-CPAP) or for surgery (UPPP withor without mandibular osteotomy). Patients with more than 50%obstruction at the palatal level in the Mueller's maneuver but lessthan 50% obstruction at the epiglottic level were considered to besuitable for UPPP alone.'0 Mandibular osteotomy with hyoid my-

otomy suspension wvas performed together with UPPP, ifthe patienthad a narrow posterior airspace, an inferiorly positioned hyoid, anda sharp sella-nose-mandibular angle." During the study period, itwas our pohcy to operate only on patients with moderate to severeOSAS, ie, patients with more than 20 desaturations of 4% or moreper hour (OD14>20).

NVithin both groups, patients were randomized to either the as-signed treatment or to conservative management (Fig 1) and wereevaluated 3 and 12 months later. The followv-up included an over-night polygraphic recording, symptom monitoring, and clinical as-sessment. Patients using N-CPAP were recorded with the CPAPtherapy.

AMonitoring

Transcutaneous arterial oxygen saturation was monitored vith anoximeter finger probe (Biox 3700e Pulse Oximeter Finger Probe;Ohmeda; Boulder, Colo), airflow through the nose and mouth bythermistors, body position with a sensor, and respiratory and bodymovements with a static-charge-sensitive bed method (Bio-matt;Biorec Inc; Helsinki, Finland).' 123 Variables were automaticallyanalyzed by a computer-based program,'4 but all recordings werealso visually evaluated. The number of oxygen desaturation eventsof4% or more per hour in bed (OD14) and 10% or more per hourin bed (ODIjo) were calculated to characterize the severity ofOSAS.Mild disease was defined as an OD14 of 10 to 20, and moderate tosevere disease as showing a higher index.

FIGURE 1. Randomization of the patients. Prior to randomization,patients were evaluated and considered to be candidates for eitherN-CPAP or surgery.

CHEST / 110/1 I JULY, 1996 115


Evaluation of Symptoms

Excessive daytime somnolence was assigned with a visual analogscale.15 The patients also filled in a sleep questionnaire evaluatingcommon symptoms of OSAS. Two questions concerned snoring:"How often do you snore?" (1=never; 2=less frequently than oncea week; 3=once or twice a week; 4=3 to 5 nights a week; 5=everyor almost every night) and "How does your snoring sound" (1=I donot snore; 2=quietly; 3=quite loudly; 4=very loudly; 5=extremeloudly and irregularly). Excessive davtime somnolence was evalu-ated with the questions: "Have you felt like falling asleep during theday when not in bed during the last 3 months?" and "Have you felttired during the day?" (5=daily; 4=3 to 5 days a week; 3=1 to 2 daysa week; 2=less frequently than once a week; 1=never or lessfrequently than once a month).

Treatments

On each visit, all affected patients were advised about smokingcessation and avoidance of alcohol as well as weight reduction, butno specific treatments were programmed.

Treatment with N-CPAP was initiated at hospital during twoconsecutive nights. CPAP was administered via a nasal mask fittedand adjusted individually to abolish all apneas and desaturations.Patients used the NightBird (Bird Products Co; Palm Springs, Cahlor Respironics Sleep Easy System III (Respironics Inc; Monroeville,Pa) or Remstar (Respironics Inc, Murrysville, Pa) equipment.UPPP was performed according to the method of Fujita.7 Man-

dibular osteotomy was performed according to the method ofPowell et al.8

Statistical AnalysisIfwe expect a difference of 22 in the OD14 index with an SD of

20 for any treatment, each group will need to contain at least 12patients for the study to have an 80% power to detect a differenceat the 5% significance level.

Mann-WNJhitney U statistics were used for the testing of twvo in-dependent samples. In the cross-tabulations, the x2 test was usedto compare events in the different groups and at different assess-ment points. Fisher's Exact Test was used when the cell size was lessthan 5.The study xvas approved by the Ethics Committee of the

Department of Pulmonary Medicine. All patients gave theirinformed consent.

RESULTS

Of the 21 patients randomized to treatment withN-CPAP, 6 were not willing to continue CPAP afterthe first night because of failure to adjust to themachine. Two further patients discontinued CPAPtreatment due to nasal problems. These eight patientshad no uniform findings as regards severity of diseaseor other characteristics.

Based on intention to treat, compliance with CPAPat 1 year was 62% (13/21). For those patients whocontinued therapy after the initial hospital nights, thecompliance rate was 87% (13/15). Compliant patientsused the machine a minimum of 5 nights a week anda minimum of 4 h a night. This information was basedon the machine's built-in counter combined with self-reports. The median pressure required was 10 cm H20(range, 7.5 to 18.5). The 13 patients who used N-CPAPregularly reported the following side effects: rhinor-

rhea (7), dry throat and nose (2), mask discomfort (2),and disturbance by the noise of the machine (1).Of the 32 patients, who fulfilled the criteria for sur-

gery, 18 were randomized to surgery and 14 toconservative treatment. For 13 patients, UPPP alonewas performed, whereas 5 patients underwent bothUPPP and mandibular osteotomy.

All postoperative complications following UPPPwere minor: 2 of the 13 patients experienced velopha-ryngeal insufficiency. Ofthe 5 patients in whom UPPPand mandibular osteotomy were performed, 1 had atracheotomy for 1 month postoperatively and 2 hadreoperations for removal of infected material. Theoverall complication rate was 22% (4/18).

Cardiovascular Mortality and MorbidityA 58-year-old man considered to be a candidate for

N-CPAP and randomized to conservative managementdied during the study period. The immediate cause ofhis death was cardiac arrest, confirmed at autopsy.Another patient randomized to conservative manage-ment in the CPAP group experienced a transientischemic cerebral attack. None of the patients receiv-ing N-CPAP experienced any cardiovascular compli-cations. During the study period, among the patientswho had undergone surgery, one non-Q myocardialinfarction and one transient ischemic cerebral attackoccurred.

Overnight Polygraphic RecordingsAll of the 12 CPAP patients and 1 of the corre-

sponding control group had a normal OD14 (' 10) at1 year (p<0.001) (Table 2). Seven of the surgicalpatients and 1 of their control subjects had a normalOD14 at 1 year (p<0.02).When patients who were operated on were com-

pared with their control subjects, improvement inOD1 and ODI1o failed to reach statistical significanceeither at the 3- or 12-month assessment. However, thepatients who underwent surgery had postoperativelystatistically significantly lower ODl4s at 1 year incomparison to initial assessment (median OD14, 14 vs45; p<0.01).

Clinical MonitoringSubjective symptoms were evaluated at 3- and 12-

month visits. In the questionnaire, a change of at leasttwo value points was regarded as significant. Whenpatients receiving N-CPAP were compared with theircontrol subjects, the improvement in excessive daytimesomnolence reached statistical significance at 12months (p<0.01) by means of the visual analog scalesmethod, and also when assessed with the question,"Have you felt like falling asleep during the day whennot in bed during the last 3 months?" (p<0.05). The

Clinical Investigations116


Table 2-Findings in the Patients With Sleep Apnea Syndrome Randomized to Either Conservative Management(Cons) or N-CPAP at 3 and 12 Months After Randomization

3 mo 12 mo

Cons (n=22) Active (n= 14) Cons (n=20) Active (n=13)

OD14, median (SD) 27 (2-78) 1(0-7)* 15 (0-73) 0(0-2)*ODIIo, median (SD) 4 (0-75) 0 (0-3)* 1(0-57) 0 (0-0)*SymptomsHeavy snorers, No. 16 8 13 5Excessive daytime somnolence

VAS,l median score (SD) 36 (0-93) 15 (5-63) 49 (8-81) 24 (0-41)tFalling asleep when not in bed, No. 11 3 7 1

*p<0.001, with conservatively managed patients compared with patients receiving N-CPAP.tSee Table 1 footnote.tp<0.05, with conservatively managed patients compared with patients receiving N-CPAP.

patients who had been operated on were significantlyless somnolent than their control subjects both at 3(p<O.OO1) and 12 months (p<0.05) when evaluatedwith the visual analog scale (Tables 2 and 3). In thequestionnaire, reported somnolence symptoms weresignificantly less for surgically treated patients at3-month (p<0.01) and 12-month (p<0.05) visits. Re-ported snoring disappeared or diminished only mod-erately in the patients receiving N-CPAP. At 1 year, thesurgically treated patients had benefited from the op-eration in regards to snoring, 40% reported less frequentsnoring, and 75% reported less disturbing snoring.

Four patients who had been randomized to conser-vative management either had to be placed on a reg-imen ofN-CPAP (n= 1) or had to be operated on (n=3)during the study period because of their worseningsymptoms, particularly their tendency to fall asleepwhile driving. Five patients refused to come to thefollow-up visits because of moving to another place orsome other personal reasons. They all were known tobe alive at the end of the study.

DISCUSSION

This study was planned to compare the therapeuticeffect of N-CPAP and surgery (UPPP with or without

mandibular osteotomy) with conservative manage-ment in the treatment of OSAS. To our knowledge,only one randomized study about the effects ofN-CPAP has been published before our study. Ourresults are in concordance with those earlier results.16However, we believe that our study is the firstrandomized trial about the effects of upper airwaysurgery in the treatment of OSAS.We were slow in recruiting, because many patients

were not willing to be randomized. Our study popula-tion, however, did not differ significantly regarding theseverity of OSAS or other patient characteristics fromthose not participating. Thus, our study is not biased inthis respect.The diagnosis of OSAS at our hospital is based on

polygraphy using the static-charge-sensitive bedmethod, oximetry, and thermistors for monitoringventilation. This method has been validated previous-ly.'13"4 In a previous study, Douglas et al17 have shownthat the sleep apnea/hypopnea syndrome can be diag-nosed with clinically relevant accuracy without poly-somnography by recording oximetry combined withbreathing pattern and time spent in bed.17 Our methodwith overnight polygraphic recording will detect pa-tients with OSAS who have apneas/hypopneas with

Table 3-Findings in Patients With Sleep Apnea Syndrome Randomized to Either Conservative Management (Cons) orOperative Treatment (UPPP, With or Without Manddibular Osteotomy) at 3 and 12 Months After Randomi2zation

3 mo 12 mo

Cons (n=13) Active (n=17) Cons (n=10) Active (n=16)

OD14, median (SD) 24 (5-62) 13 (0-62) 23 (4-68) 14 (3-54)OD110, median (SD) 5 (0-33) 1 (0-55) 6 (0-37) 3 (0-40)SymptomsHeavy snorers, No. 11 7 10 7*Excessive daytime somnolence

VAS,f median score (SD) 56 (11-100) 13 (0-71)t 72 (33-86) 27 (5-86)*Falling asleep when not in bed, No. 11 3* 7 3§

*p<O.Ol, with conservatively managed patients compared wvith surgical patients.tSee Table 1 footnote.p<O.OOl, with conservatively managed patients compared with surgical patients.Tp<0.00, with conservatively managed patients compared with surgical patients.

CHEST/ 110/1 /JULY, 1996 117


desaturations. Furthermore, patients with obstructivepulmonary disease were excluded.

All patients who used the CPAP machine regularlyhad an OD14 within the normal range. If we considerthose 13 patients of the 21 who used the CPAP regu-larly as treatment successes, acceptability ofCPAP was62% (13/21). One of 23 patients in the conservativelytreated group had an OD14 within the normal range at1 year.

Thirty-eight percent of the patients randomized toCPAP did not even start the therapy or used CPAP lessthan 4 h per night. This finding confirms the results ofHoffstein et al18 that most patients use N-CPAP onlypart of the night and not always every night. Fur-thermore, in accordance with prior studies, ournoncompliant patients had no specific pretreatmentcharacteristics that would have predicted poor com-pliance.18"9 Because excessive daytime somnolencehas been reported to decrease rapidly after startingCPAP treatment,20 it is possible that our patients didnot apply N-CPAP for long enough periods to ensuremaximal subjective benefit.

Most ofour surgical patients underwent UPPP only.If an OD14 value in normal range, ie, <10 and notmerely a reduction in that index, is considered to in-dicate long-term success following treatment ofOSAS,only one third of our patients were successes after op-erative treatment. This is despite the fact that prior toselection of the treatment, we applied all the criteriasuggested by Fujita7 and Powell et al8 for evaluation ofoperative suitability. Our results, however, are inaccordance with other studies reporting follow-up af-ter UPPP.21 Furthermore, the therapeutic effect ofUPPP at 1 year may even lead to an excessively opti-mistic view of the longer-term results.22The patients in this study who were treated opera-

tively showed definite improvement in daytime som-nolence despite insufficient improvement of ODL, orODI,o. The fact that subjective symptoms improvemore than do objective polygraphic findings followingUPPP has been documented also by other studies.23Theoretically, this might indicate that threshold forarousal diminishes. Such a situation might lead to moresevere and prolonged apneas and thus to an increasedfrequency of cardiovascular complications. FollowingUPPP, all patients regardless of symptoms, shouldpreferably have a repeated overnight recording andobjective measurement of daytime sleepiness. Unfor-tunately, owing to financial reasons, we were not ableto evaluate daytime sleepiness objectively, ie, with themultiple sleep latency test.

In this study, the complication rate following UPPPwas low compared with that reported in the literature.9This may be due to chance. The complications follow-ing mandibular osteotomy in our study may reflect

initial methodologic obstacles that lessened the sur-geon's eagerness.

In conclusion, N-CPAP is effective in the treatmentof OSAS, but suboptimal compliance is a problem.UPPP with or without mandibular osteotomy in thetreatment of OSAS has a poor success rate even inwell-preselected patients. Long-term follow-up studiesregarding different treatment regimens are still needed.

REFERENCES1 Young T, Palta M, Dempsey J, et al. The occurrence of

sleep-disordered breathing among middle-aged adults. N Engi JMed 1993; 328:1230-35

2 Rubinstein I, Colapinto N, Rotstein E, et al. Improvement inupper airway function after weight loss in patients with obstruc-tive sleep apnea. Am Rev Respir Dis 1988; 138:1192-95

3 George C, Millar T, Kryger M. Sleep apnea and body positionduring sleep. Sleep 1988; 11:90-9

4 Dolly F, Block A. Effect of flurazepam on sleep-disorderedbreathing and noctural oxygen desaturation in asymptomaticsubjects. Am J Med 1982; 73:239-43

5 Issa F, Sullivan C. Alcohol, snoring and sleep apnea. J NeurolNeurosurg Psychiatr 1982; 45:353-59

6 Sullivan C, Issa F, Berthon-Jones M, et al. Home treatment ofobstructive sleep apnoea with continuous positive airway pressureapplied through nose-mask. Bull Eur Physiopathol Respir 1984;20:49-54

7 Fujita S. Surgical treatment of obstructive sleep apnea: UPPP andlinguoplasty (laser midline glossectonmy). In: Gwlleminault C,Partinen M, eds. Obstructive sleep apnea syndrome: clinical re-search and treatment. New York: Raven Press, 1990; 129-51

8 Povell N, Riley R, Guilleminault C. Maxillofacial surgery forobstructive sleep apnea. In: Guilleminault C, Partinen M, eds.Obstructive sleep apnea syndrome: clinical research and treat-ment. New York: Raven Press, 1990; 153-82

9 Kajaste S, Telakivi T, Mustajoki P, et al. Effects of a cognitive-behavioural programme on overweight in obstructive sleepapnoea. J Sleep Res 1995; 3:245-49

10 Sher AE, Thorpy MJ, Shprintzen RJ, et al. Predictive value ofMuller maneuver in selection of patients for uvulopalatopharyn-goplasty. Laryngoscope 1985; 95:1483-87

11 Jamieson A, Guilleminault C, Partinen M, et al. Obstructive sleepapneic patients have craniomandibular abnormalities. Sleep 1986;9:469-77

12 Alihanka J, Saarikivi I, Vaahtoranta K. A new method forlong-tern monitoring of the ballistocardiogram, heart rate andrespiration. Am J Physiol 1981; 240:R384-92

13 Svanborg E, Larsson H, Carlsson-Nordlander B, et al. A limiteddiagnostic investigation for obstructive sleep apnea syndrome.Chest 1990; 98:1341-45

14 Salmi T, Telakivi T, Partinen M. Evaluation of automatic analy-sis of SCSB, airflow and oxygen saturation signals in patients withsleep related apneas. Chest 1989; 96:255-61

15 Aitken RC. Measurement offeelings using visual analogue scales.Proc R Soc Med 1969; 62:981-93

16 Engleman HM, Martin SE, Deary IJ, et al. Effect of continuouspositive airway pressure treatment on daytime function in sleepapnoea/hypopnoea syndrome. Lancet 1994; 343:572-75

17 Douglas NJ, Thomas S, Jan MA. Clinical value of polysomnog-raphy. Lancet 1992; 339:347-50

18 Hoffstein V, Viner S, Mateika S, et al. Treatment of obstructivesleep apnea with nasal continuous positive airway pressure:patient compliance, perception of benefits, and side effects. AmRev Respir Dis 1992; 145:841-45

19 Engleman HM, Martin Ee, Douglas NJ. Compliance with CPAP

Clinical Investigations1t8


therapy in patients with the sleep apnea/hypopnea syndrome. AmRev Respir Dis 1993; 147:A682

20 Lamphere J, Roehrs T, Wittig R, et al. Recovery of alertness af-ter CPAP in apnea. Chest 1989; 96:1364-67

21 Larsson H, Carlsson-Nordlander B, Svanborg E. Long-time fol-low-up after UPPP for obstructive sleep apnea syndrome. ActaOtolaryngol 1991; 11:582-90

22 Partinen M, Guilleminauilt C. Daytime sleepiness and vascularmorbidity at 7-year follow-up in obstructive sleep apnea patients.Chest 1990; 97:27-32

23 Zorick F, Roehrs T, Conway W, et al. Effects of uvulo-palatopharyngoplasty on the daytime sleepiness associated withsleep apnea syndrome. Bull Eur Physiopathol Respir 1983; 19:600-03

CHEST/ 110/1 /JULY, 1996 119


nasal-cpap, surgery, and conservative management treatment ... · evaluation ofsymptoms excessive...

Documents