Turkiye Klinikleri J Int Med Sci 2008, 4 1
Evaluation of Patients with Septal Deviation Using
Respiratory Function Tests Before and
After Septoplasty
Septoplasti Ameliyatı Öncesi ve Sonrası Respiratuar Fonksiyon Testleri
Kullanarak Septal Deviasyonlu Hastaları Değerlendirme
*Murat KARAMAN, MD, **Arman TEK, MD, **Arzu TUNCEL, MD, **Tülay ERDEM HABEŞOĞLU, MD * Ümraniye State Hospital for Research and Training, Department of Otorhinolaryngology,
** Haydarpaşa Numune State Hospital for Research and Training, Department of Otorhinolaryngology, İstanbul
ABSTRACT
Objectives: To assess the effect of nasal septal deviation on pulmonary function tests by comparing preoperative and postoperative pulmonary function
tests (PFT).
Material and Methods: Forty patients who had septoplasty were evaluated. Pulmonary functions were measured twice in each subject, one before
sur-gery and the other three months after sursur-gery. The highest level for forced vital capacity (FVC), forced expiratory volume in one second (FEV 1), peak ex-piratory flow (PEF), and maximal exex-piratory flow 75%, 50%, 25% of FVC (FEF 75%, FEF50%, and FEF25%, respectively) were obtained independently. Preoperative and postoperative PFT results were compared.
Results: Postoperative all PFT values, except for FEF 25 value, were significantly higher than the preoperative values. Postoperative FEF 25 value was
significantly lower than preoperative value.
Conclusions: Pulmonary function tests measured by spirometry are not only useful for the diagnosis of pulmonary disease, but also for determining the
upper airway obstruction . Nasal cavity is a part of upper airways and septal deviation is one of the most important diseases which cause nasal obstruc-tion. Correction of nasal obstruction resulted in improvement of pulmonary function tests.
Keywords
Nasal obstruction; septal deviation; pulmonary function tests; pulmonary functions
ÖZET
Amaç: Septal deviasyonlu hastalarda, preoperatif ve postoperatif solunum fonksiyon testi sonuçlarını karşılaştırarak, solunum fonksiyon testlerinin
öne-mini belirlemek.
Gereç ve Yöntemler: Septoplasti ameliyatı yapılan 40 hasta çalışmaya alındı. Her hastaya uygun teknikle ameliyat öncesi bir kez, ameliyattan sonraki 3.
ay bir kez olmak üzere iki kez solunum fonksiyon testi yapıldı. FVC, FEV 1, PEF, FEF %75, FEF%50, FEF%25 değerleri belirlendi. Preoperatif ve po-stoperatif solunum fonksiyon testlerinin sonuçları karşılaştırıldı.
Bulgular: FEF 25 değeri dışındeki tüm postoperatif solunum fonksiyon testi değerleri, preoperatif değerlerden anlamlı olarak yüksek bulundu.
Postope-ratif FEF25 değeri anlamlı olarak preopePostope-ratif değerden düşüktü.
Sonuç: Respiratuar fonksiyon testleri flow volüm spirometri ile ölçüldü. Spirometri sadece akciğer hastalıklarında yararlı değil, fakat üst solunum yolu
tı-kanıklıklarının belirlenmesinde de kullanılır. Nazal kavite üst solunum yolunun bir kısmını oluşturur ve septal deviasyon, nazal tıkanıklığa neden olan en önemli patolojik hastalıklardan biridir. Bu çalışmanın amacı, septoplasti ameliyatının öncesi ve sonrasında respiratuar fonksiyon testlerindeki değişiklik-leri belirlemek.
Anahtar Sözcükler
Burun tıkanıklığı; septum deviasyonu; solunum fonksiyon testleri; solunum fonksiyonu
Çalıșmanın Dergiye Ulaștığı Tarih: 01.09.2010 Çalıșmanın Basıma Kabul Edildiği Tarih: 11.02.2011
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Correspondence Murat KARAMAN, MD
Ümraniye State Hospital for Research and Training, Department ofOtorhinolaryngology, İstanbul
IN TRO DUC TI ON
hro nic up per air way obs truc ti on is fre qu ently un re cog ni zed or mis di ag no sed as ot her con di ti ons such as ast hma or chro nic airf low obs -truc ti on (CA O). Cli ni cal fe a tu res such as stri dor may le ad to di ag no sis or it may ini ti ally be sus pec ted from the re sults of pul mo nary func ti on tests or de red for anot her re a son. The clas si fi ca ti on of up per air way obs -truc ti on (UA O) ba sed on the lo ca ti on of the le si on (in trat ho ra cic or ex trat ho ra cic) and the na tu re of the le-si on (fi xed or va ri ab le) must be emp ha le-si zed. The air-way may be di vi ded func ti o nally in to thre e le vels: pe rip he ral air ways with a di a me ter of 2 mm or less; lar ger or ma jor air ways from 2 mm di a me ter up to the ma -in ca ri na; and the up per air ways which -inc lu de the trac he a, larynx, pharynx, and no se or mo uth. The ef-fects of any obs truc ti on of the up per air ways will de-pend on se ve ral va ri ab les which inc lu de (a) the si ze of the air ways at the si te of obs truc ti on, (b) the lo ca ti on of the obs truc ti on, (c) the na tu re of the le si on, and (d) pha se of res pi ra ti on.1
Whet her a le si on pro du ces symptoms or not de-pends on the se ve rity of the obs truc ti on. For ins tan ce, it has be en shown that a le si on which re du ces the di a -me ter of the up per air way to abo ut 8 mm pro du ces symptoms on exer ci se. A 5 mm di a me ter air way at the si te of obs truc ti on pro du ces ins pi ra tory obs truc ti on at rest gi ving ri se to the cha rac te ris tic physi cal fin ding of stri dor.1
Ex trat ho ra cic up per air way is sur ro un ded by ath-mosp he ric pres su re whe re as the in trat ho ra cic up per air-way is sur ro un ded by ple u ral pres su re. The dif fe ren ce bet we en the in trat ho ra cic pres su re and the ex ter nal pres-su re is trans mu ral pres pres-su re. If the ex ter nal pres pres-su re ex-ce eds the in trat rac he al pres su re, i.e., in case of, a po si ti ve trans mu ral pres su re, the air way tends to col lap -se. A ne ga ti ve trans mu ral pres su re tends to open the air-way.1
The na tu re of the obs truc ti on, whet her it is stiff or pli ab le, de ter mi nes the se ve rity of changes in re la ti on to chan ges in trans mu ral pres su re. In this con text, a stiff le si on (sep tal de vi a ti on) ca u ses a fi xed obs truc ti on. The ef fects of a fi xed UA O, that is, one that do es not chan -ge in se ve rity with the pha se of res pi ra ti on, will not be af fec ted by the le vel of the obs truc ti on. A fi xed ex trat -ho ra cic UA O will ca u se the sa me ef fects as a fi xed
intrat ho ra cic obs truc ti on. With an up per air way obs truc ti -on, flow at hig her lung vo lu mes may be li mi ted by the obs truc ti on. At lo wer lung vo lu mes, flow may be li mi -ted not by the up per air way obs truc ti on but by the col-lap se of in trat ho ra cic air ways. Ge ne rally, flow me a su re ments ma de at low lung vo lu mes ref lect the func ti on of pe rip he ral air ways only, whe re as tho se ma -de at high lung vo lu mes ref lect both up per and lo wer air way func ti on.1
The flow vo lu me plot of a for ced ex pi ra tory and ins pi ra tory vi tal ca pa city ma ne u ver wo uld be par ti cu larly help ful in ca te go ri zing UA O. They si mu la te ma -jor air way obs truc ti on by ha ving nor mal sub jects bre ath thro ugh fi xed re sis tan ces, and have fo und that flow ra te in cre a sed to a cer ta in le vel early in both ins pi ta ri on and ex pi ra ti on and than pla te a u ed. The pla te -a u w-as re -ac hed -at lo wer flow r-a tes -as the re sis t-an ces we re prog res si vely in cre a sed. The ef fect of a fi xed le-si on, eit her in trat ho ra le-sic or ex trat ho ra le-sic, will be ap-pa rent du ring both ins pi ra ti on and ex pi ra ti on. With a fi xed UA O, the pla te a u and li mi ta ti on of flow is se en both in the ex pi ra tory and ins pi ra tory flow vo lu me lo -ops.1
Spi ro metry; a simp le plot of a FVC ma ne u ver of vo lu me versus ti me, the ti med spi rog ram, al so gi ves so me clu es to the pre sen ce of up per air way obs truc ti -on. Rot man et al2com pa red va ri o us tests in pa ti ents
with up per air way obs truc ti on and chro nic obs truc ti -ve pul mo nary di se a se and nor mal sub jects. In this study, they iden ti fi ed fo ur va ri ab les which usu sally dis tin gu ish pa ti ents with up per air way obs truc ti ons from pa ti ents with chro nic airf low obs truc ti on. The va lu es are ob ta i ned from the flow vo lu me plot and the spi rog ram.
1) FIF 50%≤ 100 L/min 2) FEF 50% /FIF 50%≥ 1
3) FEV 1/PEFR≥ 10 ml/min (The PEFR is pro por -ti o na tely mo re re du ced by the UA O com pa red to the FEV1)
4) FEV1/FEV 0.5≥1.5 (The FEV 0.5 is pro por ti o -na tely mo re re du ced by obs truc ti on of the up per air way than FEV 1) the ra ti o can be ob ta i ned from the spi rog -ram tra cing alo ne.2
The ab bre vi a ti ons used abo ve are as fol lows; FIF 50%, for ced ins pi ra tory flow at 50 per cent of the vi tal ca pa city, FEF 50%, for ced ex pi ra tory flow at 50 per-cent of the vi tal ca pa city, PEFR, pe ak ex pi ra tory flow
ra te me a su red in lit res per mi nu te; FEV 1, for ced ex pi -ra tory vo lu me in one se cond me a su red in mi li me ters; and FEV 0.5, for ced ex pi ra tory vo lu me in ½ se cond me a su red in mi li me ters. The se va lu es are re a dily ava i -lab le from most pul mo nary func ti on -labs and may be inc lu ded in a com pu ter prin to ut in tho se with au to ma -ted re por ting. The inc lu si on of one or mo re of the se in-di ces in ro u ti ne re por ting sho uld le ad to un sus pec ted ca ses of up per air way obs truc ti on be ing dis co ve red as well as the ir use in pa ti ents al re ady sus pec ted of ha ving such prob lems.2
So me re cent stu di es re por ted that al te ra ti ons of nor mal na sal physi o logy ef fects pul mo nary func ti -ons con si de rably and the re la ti -ons hips bet we en up per and lo wer air ways can not be neg lec ted.3,4Most of
the pul mo nary pat ho lo gi es are ca u sed by in co or di na ti on of ip si la te ral pul mo nary and na sal ca vity ref le -xes.5
Sin ce most le si ons which ca u se UA O re qu i re sur gi cal treatment, an ana to mi cal and pat ho lo gic di agno sis is re qu i red fol lo wing iden ti fi ca ti on of a physi -o l-o gic ab n-or ma lity. In this pa per, we did n-ot ar gu e the ne ces sity of pul mo nary func ti on tests for the pa ti ents who had sep tal de vi a ti on, sin ce the obs truc ti on are a can be ea sily fo und with physi cal exa mi na ti on. The aim of this study was to de ter mi ne the pul mo nary func ti on test al te ra ti ons be fo re and af ter sep top -lasty.
MA TE RI AL AND MET HODS
From March to July 2006, a to tal of 40 pa ti ents who had sep top lasty we re en rol led in the study. The study gro up inc lu ded 25 ma les and 15 fe ma les with a me an age of 32 ye ars (ran ge of 1857 ye ars). Di ag -no sis of sep tal de vi a ti on was ba sed on his tory and de-ta i led na sal exa mi na ti on inc lu ding an te ri or rhi nos copy and na sal en dos copy. Na sal obs truc ti on was gra ded ac cor ding to sep tal de vi a ti on as fol lows: nor mal struc tu re (0), mild de vi a ti on (1), mo de ra te vi a ti on (2), se ve re de vi a ti on (3), and mo re se ve re de-vi a ti on (4) Pa ti ents with tur bi na te hyper trophy, al ler gic rhi ni tis, na sal poly po sis and chro nic pul mo -nary di se a se we re exc lu ded. No me di cal tre at ment was used be fo re sur gery.
All pa ti ents had sep top lasty un der lo cal anest he sia. Na sal packs we re re mo ved on the se cond day of the ir pos to pe ra ti ve pe ri od and they we re or de red for sa li ne na sal ir ri ga ti on thre e ti mes a day. They we re cal led back
for the con trol vi sit pos to pe ra ti vely at 1stwe ek,1stmonth
and 3rdmonth. The im pro ve ment of na sal obs truc ti on
symptoms was es ti ma ted and PFT va lu es we re al so me -a su red two ti mes in -all p-ar ti ci p-ants; one be fo re sur gery and the anot her thre e months af ter the sur gery. The im-pro ve ment of na sal obs truc ti on was eva lu a ted with sub-jec ti ve pa ra me ters. All pa ti ents to ok a qu es ti on na i re at pos to pe ra ti ve 3rdmonth vi sit.
The qu es ti on na i re inc lu ded only one qu es ti on, “How can yo u des cri be the im pro ve ment of yo ur na sal obs truc ti on?”. The re sults we re re cor ded as sub jec ti ve va lu es and gra ded as no ne (0), mild (1), mo da ra te (2), well (3), ex cel lent (4).
The PFT va lu es inc lu ded; for ced vi tal ca pa city (FVC), for ced ex pi ra tory vo lu me first se cond (FEV 1), FEV1 /FVC ra ti o, pe ak ex pi ra tory flow (PEF), FEF 25%, FEF 50%, FEF 75% and FEF 25/75 ra ti o. All the pre o pe ra ti ve and pos to pe ra ti ve PFT va lu es re -cor ded as ob jec ti ve va lu es and com pa red. We ha ve in-for med all pa ti ents abo ut the study and the ir in in-for med con sents we re ob ta i ned. Sin ce this study do es not ne -ed any et hics com mit te e ap pro val, we did not apply for it.
SSttaa ttiiss ttii ccaall AAnnaallyy ssiiss
SPSS (Sta tis ti cal Pac ka ge for so ci al Sci en ce) for Win dows 15. 0 prog ram was used for sta tis ti cal sis and Pa i red T Test was used for qu an ti ta ti ve analy-sis.
RE SULTS
On the first vi sit, na sal obs truc ti on was gra ded ac cor ding to sep tal de vi a ti on. Twenty pa ti ents’ sep tal de vi a ti on we re severe, 12 of them we re mo da ra te and four of them we re mild (Tab le 1) and they all had flow vo lu me spi ro metry. The PFT va lu es we re re cor -ded.
Turkiye Klinikleri J Int Med Sci 2008, 4 3
Table 1. Distrubition of patients according to their nasal obstruc-tion score. Septal Deviation Degree Patient (n) % 0 0 0 1 4 10 2 12 30 3 20 40 4 4 10
Af ter sep top lasty, im pro ve ment of na sal obs truc ti -on was fo und as fol lows: 70% (n: 28) gra ded it as ex cel-lent, 20% (n: 8) gra ded it as well and 10% (n:4) gra ded it as mo de ra te (Tab le 2). All of the pa ti ents in di ca ted that they co uld bre at he mo re com for tably. At the sa me vi sit they al so had spi ro metry. Pa i red samp le t Test was used for com pa ring pre o pe ra ti ve and pos to pe ra ti ve PFT va lu es (Tab le 3).
Pos to pe ra ti ve all pre dic ti on and ave ra ge PFT va l-u es, ex cept for ced ex pi ra tory flow 25 (FEF 25), we re sta tis ti cally sig ni fi cantly in cre a sed (p< 0.01). FEF 25 va lu e was sta tis ti cally sig ni fi cantly dec re a sed (p< 0.01) .
DIS CUS SI ON
Na sal ca vity is one of the most im por tant parts of the up per air ways and it is of ten neg lec ted in physi o -lo gi cal stu di es on pul mo nary func ti on. It has many func ti ons such as res pi ra ti on, de fen se of lo wer airways, war ming and mo is tu ri zing the ins pi red air. Na -sal ca vity has de fen se mec ha nisms for lo wer air ways by sti mu la ting the tri ge mi nal and ol fac tory ner ves in the na sal mu co sa to start the sne e zing ref lex.6Prac ti
-cally, we know that the re are re la ti ons hips bet we en the
res pi ra ti on and many or gans with ref lex mec ha nisms including ear, thro at, he art, lungs, di ap hragm and ab-do mi nal or gans.7, 8
The re are a num ber of stu di es abo ut the re la ti ons -hips of na sal ca vity and pul mo nary func ti on. O gu ra and Harvey9sta ted that na sal obs truc ti on co uld chan ge the
pul mo nary func ti ons by na so pul mo nary ref lex system. Mink5re por ted a re la ti ons hip bet we en na sal ca vity and
ip si la te ral he mit ho rax. In this study, pa ti ents with na sal ste no sis had a li mi ted mo bi lity ran ge of ip si la te ral di ap -hrag m (2-5 cm) du ring res pi ra ti on. Wid di com be10re por
-ted that the na sal ca vi ti es pro du ced a pres su re dif fe ren ce bet we en nos trils and lungs.
Ac cor ding to Al bert and Win ters7and Edi son and
Kerth,8oral res pi ra ti on can not cre a te suf fi ci ent lung
elas ti city in pa ti ents with na sal obs truc ti on. Be ca u se of
Table 2. Improvement of nasal obstruction at postoperative third month. Improvement Patient (n) % Excellent 28 70 Well 8 20 Moderate 4 10 No improvement 0 0 Total 40 100
Tablo 3. The mean values of preoperative and postoperative respiratory function test results.
Preoperative Mean ±± SD Postoperative Mean ±± SD p
FVC(lt) Average 4.19 ± 0.84 4.43 ± 0.86 0.001** Prediction% 97.05 ± 1.39 102.69 ± 1.14 0.001** FEV1(lt) Average 3.54 ± 0.68 3.74 ± 0.70 0.001** Prediction% 97.06 ± 1.59 102.74 ± 1.61 0.001** FEV1/FVC Average 83.06 ± 2.06 84.30 ± 2.22 0.001** Prediction% 101.61 ± 1.17 103.13 ± 1.95 0.001** PEF(lt/sn) Average 8.01 ± 1.38 8.46 ± 1.40 0.001** Prediction% 93.93 ± 1.18 99.26 ± 0.72 0.001** FEF25/75 (lt/sn) Average 4.19 ± 0.57 4.30 ± 0.57 0.001** Prediction% 96.05 ± 1.39 98.53 ± 1.23 0.001** FEF25(lt/sn) Average 7.50 ± 1.10 7.32 ± 1.09 0.001** Prediction% 101.62 ± 0.79 99.12 ± 0.59 0.001** FEF50(lt/sn) Average 4.74 ± 0.58 4.97 ± 0.59 0.001** Prediction% 97.08 ± 1.05 101.78 ± 1.06 0.001** FEF75(lt/sn) Average 2.07 ± 0.34 2.29 ± 0.35 0.001** Prediction% 93.94 ± 2.09 103.82 ± 2.43 0.001**
Paired Sample t test was used ** p<0.01
FVC: Forced Vital Capacity; FEV1: Forced Expiratory Volume first second; FEV1/FVC: Forced Expiratory Volume first second/ Forced Vital Capacity PEF: Peak Expiratory Flow; FEF25/75: Forced Expiratory Flow 25/75; FEF25: Forced Expiratory Flow 25; FEF50: Forced Expiratory Flow 50; FEF75: Forced Expiratory Flow 75.
we ak ven ti la ti on, ate lec ta sis can be ob ser ved in mic ro a re as of lungs. It was sta ted that ‘na sal re sis tan ce is ne -ces sary for pul mo nary elas ti city’. They ag re ed that both na sal re sis tan ce and na sal ref le xes in cre a se the pul mo -nary ac ti vi ti es.
PEF in di ca tes pul mo nary high flow vo lu me, whi -le FEV1 in di ca tes pul mo nary low flow vo lu me. The re-fo re PEF is use ful re-for na sal obs truc ti on but FEV1 is not a sen si ti ve test for this. In up per air way obs truc ti ons, FEV1 can be nor mal whi le PEF is ab nor -mal.11Si mi larly FEF 25/75 va lu e can be fo und in low
le vels.
At the 3rdmonth vi sit af ter sur gery, 90% of pa ti
-ents de fi ned the ir na sal obs truc ti on im pro ve ment as ex-cel lent or well, 10% of them de fi ned it as mo de ra te. We me a su red pul mo nary func ti on and ca pa city with spi ro -metry. Even tu ally me an FVC va lu e me a su red as 97.05% pre o pe ra ti vely sig ni fi cantly in cre a sed to 102.69% pos to pe ra ti vely. PEF va lu es, which is a sen si ti ve test ftor up -per air way obs truc ti on, was 93.93% pre o pe ra ti vely whi le it was 98.53% pos to pe ra ti vely. Pre o pe ra ti ve and pos to pe ra ti ve FEF 25/75 va lu es we re 96.05% and 98.53%, res pec ti vely. Pre o pe ra ti ve FEF 25 va lu es dec re a sed from 101.62% to 99.12%. FEF 50 va lu es in cre -a sed from 97.08% to 101.78%. A sig ni fi c-ant in cre -a se
was fo und at FEF 75 va lu es (pre o pe ra ti ve 93.94 and pos to pe ra ti ve 103.82%).
The re sults of our study are similar with the re-sults of Ga it man,12Owens and Murphy13and Rot man
et al.2On the ot her hand, pre vi o us stu di es did not
indi ca te a re la ti ons hip bet we en pre o pe ra ti ve and pos to -pe ra ti ve FEV 1/FVC va lu es, be fo re our study. The re are many investigations on lary nge al obs truc ti on and pul mo nary func ti ons.2,11,13,14We eva lu a ted the re la ti
-ons hip bet we en na sal obs truc ti on and lungs with ob-jec ti ve da ta such as PFT va lu es. Our sig ni fi cant re sults sup port the cla ims of the many rhi no lo gists li ke Cott -le.5,12,14,15
CONC LU SI ON
Na sal obs truc ti on du e to sep tal de vi a ti on has a ne -ga ti ve ef fect on pul mo nary fuc ti ons. This ne -ga ti ve ef-fect can be eva lu a ted with pul mo nary func ti on tests me a su red by flow vo lu me spi ro metry and can be re du -ced af ter a suc cess ful sep top lasty. The pul mo nary func-ti on tests are use ful in di ag no sis and fol low-up for both up per air way obs truc ti ons and pul mo nary func ti on al-te ra ti ons. Cor rec ti on of na sal obs truc ti on re sul al-ted in im-pro ve ment of pul mo nary func ti on tests.
Turkiye Klinikleri J Int Med Sci 2008, 4 5
1. Modrykamien AM, Gudavalli R, McCarthy K, Liu X, Stoller JK. Detection of upper airway obstruction with spirometry results and the flow-volume loop: a comparison of quantita-tive and visual inspection criteria. Respiratory Care 2009;54(4):448-9.
2. Rotman HH, Liss HP, Weg JG. Diagnosis of upper airway ob-struction by pulmonary function testing. Chest 1975;68(6): 796-9.
3. Slavin RG. Asthma and sinusitis. J Allergy Clin Immunol 1992;90(3):534-7.
4. Spector SL. The role of allergy in sinusitis in adults. J Allergy Clin Immunol 1992;90(3):518-20.
5. Mink PJ. Physiologia der oberen luftwege. Leipzing: Verlag Vogel, 1920.
6. Nishihira S, Mccaffray TV. Reflex control of nasal blood ves-sels. Otolaryngol Head Neck Surg 1987;96(3):273-7. 7. Albert MS, Winters RW. Acid base equilibrium of
blood in normal infants. Pediatrics 1966;37(5):7-28. 8. Edison BD, Kerth JD. Tonsilloadenoid hyperirophy resulting
in Cor Pulmonale. Arch Otolaryngol 1973; 98(2):205-28.
9. Ogura JH, Harvey JE. Nasopulmonary mechanics-experi-mental evidence of the influence of the upper airvay upon the lower. Acta Otolaryngol (Stockh) 1971;71(2):123-32. 10. Widdicombe JG. The Physiology of the nose. Clinical Chest
Medicine 1986; 7(2):159-70.
11. Seraman SS, Gaissert HA. Upper airway obstruction. In: Fish-man AP, ed. FishFish-man's pulmonary disease and disorders. 3rd
ed. New York:Mc Graw-Hill Book Company; 1998. p.783-801.
12. Gaitman A. Changes in bronchial resistance after surgical treatment of obstruction of the upper airways. Vestn Otorino-larngol 1989;3(9):21-3.
13. Owens GR, Murphy DM. Spirometric diagnosis of upper air-way obstruction. Arch Intern Med 1983;143(7):1331-4. 14. Mellisant CF, Van Noord JA, Van de Woestijine KP, Demedts
M. Comparison of dynamic lung function indices during forced and quiet breathing in upper airvay obstruction, asthma, and emphysema. Chest 1990;98(2):77-83.
15. Cottle MH. Rhinomanometry. Kansas City, Missouri: Amer-ican Rhinologic Society; 1980.
