International Orthopaedics(SICOT)(1992) 16:207-212
International
Orthopaedics © Springer-Verlag1992
Pulmonary function in adolescents with idiopathic scoliosis K. SakK I, M. Pe~ina 1, and F. PavKK 2 Departmentof OrthopaedicSurgery,Schoolof Medicine,Universityof Zagreb, Croatia 2Departmentof Pulmology,Schoolof Medicine,Universityof Zagreb, Croatia
Summary. Two groups of patients, with an average age of 15 years, have been studied to establish the improvement in pulmonary function after surgical correction in relation to the amount of correction achieved. The first group of 33 patients were treated surgically; an average Cobb angle of 72 ° was reduced to 32.6 °. The second group of 30 patients with an average Cobb angle of 33 ° were not operated on. Results of tests undertaken have shown that pulmonary function was improved by surgical correction, but the improvement does not match the degree of correction achieved. Statistical analysis of the two groups shows a difference in cardiopulmonary function to the advantage of those who were not operated on. This suggests that there is partial irreversibility of ventilation and perfusion in those who are treated surgically. R~sum~. Le but de ce travail est d'dvaluer l'amdlioration de la fonction respiratoire aprds correction chirurgicale des courbures scoliotiques. L~tude a porM sur deux groupes distincts de patients, ~g~s de 15 ans en moyenne. Le premier groupe comportait 33 sujets opdrds d'une scoliose de 72 ° (Cobb), r6duite aprds l'intervention & 32.6 °. Le deuxikme groupe comprenait 30 sujets du m~me gtge avec une scoliose non opdrde de 33 °. Les parambtres fonctionnels cardio-respiratoires, statiques et dynamiques, ont dt~ mesurds - avant et 24 mois aprds l'op~ration - par spiromdtrie et pldthysmographie, par analyse des gaz du sang et par le test de toldrance gt l'effort. Les rdsultats ont montr~ que la correction de la scoliose
Reprint requests to: M. Pedina, School of Medicine, University of Zagreb, Departmentof OrthopaedicSurgery,Salata 7, 41000 Zaga-eb,Croatia
amdliorait la fonction respiratoire, mais que cette amdlioration n'dtait pas proportionnelle ~ l'importance de la correction obtenue. L 'analyse multivariable et l'analyse discriminatoire des patients opdrds et non opdrds, avec le mOme degr( de courbure rachidienne, a montrd une diffdrence des fonctions cardiopulmonaires en faveur des sujets non opdrds. Ces rdsultats suggbrent une irrdversibilitd partielle de la ventilation et de la vascularisation chez les patients qui ont dtd traitds chirurgicalement.
Introduction The natural course of the disease in scoliotic patients show that severe deformity affects cardiopulmonary function significantly [2, 3, 9, 10, 23, 25, 28]. Several reports have demonstrated a correlation between the degree of thoracic curvature and impairment of resting lung mechanics in severe scoliosis [12, 15, 20, 27, 34, 35, 36]. The rate of increase of pulmonary arterial pressure during and after exercise was more closely related to lung volume in terms of measured vital capacity (VA), functional residual capacity (FRC) or total lung capacity (TLC) [29, 30]. The measurement of maximum voluntary ventilation, which is affected by lung volume and respiratory muscle strength, is a useful test to identify impaired ventilatory capacity that may be present in some patients with mild symptomless scoliosis which may progress [17, 19, 24, 31]. In addition to the best possible correction and stabilisation of the spine, improvement in cardiopulmonary function should be a primary aim of surgical treatment [1, 11, 16, 18, 21, 28, 35, 37, 38].
208
K. Sakid et al.: Pulmonary function in adolescents with idiopathic scoliosis
Table 1. Distribution of patients according to sex and age Patients Surgically treated
Conservatively treated
33 11 - 21 years (15.2) 27 females 6 males
30 11 - 18 years (13.5) 29 females 1 male
Table 2. Site and apex of scoliotic curvature in surgically treated patients
Cobb >70 ° Cobb 45 °
56'6° (48 to 70)
46"3° 9"3° (40 to 54) (0 to-25)
Kyphosis 21 to 45 °
>80%
Fig. 2. Changes in vital capacity - percentage of predictability
ed in all patients as shown in Fig. 3 and Table 3. There were no thoracic lordoses after operation and a normal thoracic kyphosis of 20 ° to 45 ° was achieved in 16 patients. Statistical analysis disclosed no correlation between cardiopulmonary function and preand postoperative sagittal curvature of the spine. Upper thoracic scoliosis with a Cobb angle of more than 70 ° was associated with restricted ventilation, latent hypoxaemia during the exercise tolerance test and tachycardia. In lower thoracic idiopathic scoliosis and scoliosis treated conservatively, respiratory function was normal but the latter was associated with a lower 0 2 uptake during the exercise tolerance test (Table 4). The improvement of cardiopulmonary function was confirmed by the differentiation test (Table 5). A surgical correction of 54% was correlated with an increase of VC, FEVh maximum mid-flow rate at 25% to 75%, functional residual capacity, total lung capacity and improved
exercise tolerance. Total airway resistance (Rt) in KPA/1/sec (0.29) did not correlate with FEV1. The analysis of cardiopulmonary function demonstrated a negative correlation of the curves of more than 70 ° with restriction of vital lung capacity, reduced maximum 02 consumption and reduction of exercise tolerance test time. The mean values and standard deviations for both test and control groups are shown in Table 6. Multivariate analysis of variance and discriminatory analysis (Tables 7 and 8) of surgically treated patents with a postoperative angle of 32.6 ° and conservatively treated cases with the same curvature (i. e. 33.1 °) demonstrated a difference of cardiopulmonary function (VC and PaO2) unlike the difference expected in favour of those treated conservatively (Tables 5, 7 and 8). No relevant complications occurred in the surgically treated patients over a 2 year follow up.
210
K. Saki6 et al.: Pulmonary function in adolescents with idiopathic scoliosis
Table 4. Cardiorespiratory function in surgically treated patients and in the control group Percentage of predicted normal values %
Upper thoracic
VC VC (arm span) FEV1 FEV1/VC % MMF25- 75%vc FRC RV TLC PEF MEFso MEF25 PaO2 WATT/rain Uptake Oe ml/kg/min
Lower thoracic
C_ontrol group X -+ SD
Preoperative X-+SD
P_ostoperative X_+SD
Preoperative X+SD
Postoperative X+SD
78+20 68 _+20 75 _+20 87% 83 -+29 105-+ 7 114_+21 79_+ 20 82-+ 21 81 -+ 19 76 + 21 78_+ 7 59 _+ 19
80+16 75 _+ 15 77 _+ 16 91% 107 _+ 19 99_+ 7 109-+ 19 114_+ 10 83 -+ 19 84 -+ 20 81 -+ 18 93-+ 7 76 _+ 19
91 +13 89 _+12 80 _+16 86% 85 -+21 95_+10 107_+ 16 93 _+ 9 87 _+16 84 _+19 82 _+20 95_+ 3 79 _+13
95_+10 95 _+10 83 _+16 90% 105 -+29 98_+11 101 _+ 18 94_+ 9 93 _+16 88 _+19 83 _+20 96_+ 3 83 _+13
92_+10 93 _+10 88 -+ 10 86% 95 -+ 18 110_+10 112_+ 16 96 + 9 83 + 11 86 _+19 91 _+17 88_+ 3 69 _+21
63 _+78
19 _+ 19
80 _+ 9
89 + 12
74 -+21
Discussion
Table 5. Statistical analysis of variables Correlation test
Cobb angle >70°;
VC, 02 ml/kg/min p >0.05 r=-I
Analysis of variance
Upper and lower thoracic scoliosis
VC, FEV1 p 0.05 0.6167 p >0.05
F = 5.906, NDFt = 8, NDF2 = 54 Table 8. Factor pattern for discriminant functions Variable % of predictable values
Matrix of discriminatory function arrangement
PaO2 VC MMF25- 75 RV/TLC FRC/TLC ETT-WAT/min Uptake 02 ml/kg/min Puls/min
0.746 -0.587 0.221 0.221 0.189 0.243 0.146 -0.162
Centroid for surgically treated group: 0.646, centroid for conservatively treated group: ~0.711
correction of the Cobb angle was achieved. In most patients at least 2 years are needed for optimal improvement [16]. The unsatisfactory results reported by others [8, 21] would have been better if their patients had been followed for more than 2 years after operation. There is a highly significant correlation between the % reduction in compliance and the Cobb angle [24, 32] related to the development of a smaller stiffer chest [29, 39]. Increased airway resistance (FEV1) was measured only in cases with upper thoracic scoliosis, and it decreased after surgical correction. Total bronchial resistance (Rt) increased only slightly, while FEV1 and expiration flows were reduced to a greater extent because of increased expiratory instability of the bronchial walls in scoliosis. After surgical correction, the pulmonary hila assume a more physiological position, and the changing shape of the thorax contributes to improvement in mechanical respiratory function and pulmonary hypertension. Thus the patient is more comfortable when he does not have to make an additional mechanical effort to breath. Our findings agree with those of others who have suggested that permanent damage to pulmonary circulation may occur in patients with curves of more than 70 ° [16, 28]. Conversely, better results have been reported in patients with a preoperative Cobb angle
of more than 90 ° compared with those with a lesser angle [18]. We cannot explain these findings which disagree with our own. After surgical correction of kyphoscoliosis, physiological dead space decreased by 40%, but in patients with a Cobb angle of more than 65 ° no significant improvement in regional lung perfusion was obtained [ 10, 28]. This has been attributed to possible irreversible pulmonary changes, as we have also shown, and suggests that operation should be carried out before the angle reaches 70 °. Milner reported an opposing trend by measuring the highest residual volume in patients with small spinal curvatures [22]. His results support the hypothesis that the determination of lung function in scoliosis is affected regardless of the angle and site of the curve. This has been confirmed in some of our patients with mild scoliosis. Predictions as to which patients will eventually suffer lung or heart failure are still uncertain, but as far as clinical prognosis is concerned the best indications are the site and severity of the scoliosis in terms of Cobb angle, the vital capacity and arterial PO2 by day and at night [12, 31] and the presence or absence of muscular weakness. The deterioration of pulmonary function may be prevented, or stabilisation achieved, by operation [32, 38]. Surgical curve-reducing procedures have been said to improve lung function and prevent long term deterioration [32]. The decision about surgery must be made for each patient and based on subjective data. Definitive answers may be expected after a long term follow up of surgically treated patients and a comparison with long term results in scoliotic patients treated by physical therapy alone [39], or with braces. When using physical treatmer~t Weiss et al. were able to increase vital capacity by 11% and chest expansion by more than 20% [39]. Chest expansion indicates the amount of rib mobilisation achieved which contributes substantially to the prevention or treatment of secondary functional impairment, and particularly of restricted ventilation. In spite of the improvement of respiratory function after surgical correction of the curvature in
212
K. ~akid et al.: Pulmonary function in adolescents with idiopathic scoliosis
patients with scoliosis, our comparative studies of lung function in those treated by operation and by conservative methods clearly demonstrate that some pulmonary ventilation and perfusion changes are partially irreversible. Regardless of the effect of correction, surgical correction of spinal deformities cannot establish pulmonary function which matches the improvement in the curve postoperatively.
References 1. Banta JV, Sung Min P (1983) Improvement in pulmonary function in patients having combined anterior and posterior spine fusion for myelomeningocoele scoliosis. Spine B: 765-770 2. Bergofsky EH, Turino GM, Fishmen AP (1959) Cardiorespiratory failure in kyphoscoliosis. Medicine 38: 263-317 3. Bjure J, Grimby G, Kasalicby J, Lindh M, Nachemson A (1970) Respiratory impairment and airway closure in patients with untreated idiopathic scoliosis. Thorax 25: 451 - 456 4. Brace RA, Kasumi F, Hosmer PH (1973) Maximal oxygen intake and nomographic assessment of functional aerobic impairment in cardiovascular disease. Am Heart J 85: 546- 551 5. CECA Collection d'Hygibne et de M6decine du Travail: Aide - Mdmoire pour la pratique de l'examen de la fonction ventilatoire par la spirographie. Conmaission des Communaut6s Europ6ennes, Luxembourg, 1971 6. Cherniack RM, Raber MB (1972) Normal standards for ventilatory functions using an automated wedge spirometer. Am Rev Resp Dis 106:38-46 7. Cooley WW, Lohnes PR (1971) Multivariate data analysis. Wiley, New York 8. Daruwalla JS, Clark DW, Tan WC, Balasubramaniam P (1989) La fonction respiratoire dans les scolioses idiopatiques de 1'adolescent tralt~e par instrumentation de Harrington associ6e ou non ~tun cerclage sous lamaire segmentaire. Rev Chir Orthop 75:490-492 9. Davies G, Reid L (1971) Effects of scoliosis on growth of alveoli and pulmonary arteries and on fight ventricle. Arch Dis Child 46:623-627 10. Dollery CT, Gillam PMS, Hugh-Jones P, Zorab PA (1965) Regional lung function in kyphoscoliosis. Thorax 20: 175-181 11. Gazioglu K, Goldstein LA, Femi-Pearse D, Yu PN (1968) Pulmonary function in idiopathic scoliosis. Comparative evaluation before and after orthopaedic correction. J Bone Joint Surg [Am] 50:391-399 12. Guilleminault C, Kurland G, Winkle R, Miles LE (1981) Severe kyphoscoliosis breathing and sleep "Quasimodo" syndrome during sleep. Chest 79: 626- 630 13. Jaeger MJ, Otis AB (1964) Measurement of airway resistance with a volume displacement body plethysmograph. JAppl Physiol 19:813-817 14. Johnson B, Westgate H (1970) Methods of predictive vital capacity in patients with thoracic scoliosis. J Bone Joint Surg 52A: 1433-1439 15. Kafer ER (1977) Respiratory and cardiovascular function in scoliosis. Bull Eur Physiopath Respir 13: 299-321 16. Kumano K, Tsuyama N (1982) Pulmonary function before and after surgical correction of scoliosis. J Bone Joint Surg [Am] 64:242-249
17. Leech JA (1986) Cardiorespiratory status in relation to mild deformity in adolescent idiopathic scoliosis. J Pediatr 106: 1 4 3 - 149 18. Lindh M, Bjure J (1975) Lung volume in scoliosis before and after correction by the Harrington instrumentation method. Acta Orthop Scand 46:934-948 19. Lonstein JE, Carlson MJ (1984) The Prediction of Curve Progression in Untreated Idiopathic Scoliosis During Growth. J Bone Joint Surg 66A: 1061-1071 20. Mankin HJ, Graham JJ, Schack J (1964) Cardiopulmonary function in mild and moderate idiopathic scoliosis. J Bone Joint Surg [Am] 4 6 : 5 3 - 6 2 21. Meister R, Heine J (1973) Vergleichende Untersuchungen der Lungenfraktion bei jugendlicben Scoliose-Patienten vor und nach der Operation nach Han-ington. Z Orthop 111: 749-755 22. Milner AD, Milner ME (1986) Influence of site and severity of scoliosis on lung function in idiopathic adolescent scoliotic. European Spinal Deformities Society First Congress, Rome, Abstracts Book, pp 93 23. Moe JH, Winter RB, Bradford DS, Lonstein JE (1987) Scoliosis and other spinal deformities. Sannders, Philadelphia 24. Muirhead A, Conner A (1985) The assessment of lung function in children with scoliosis. J Bone Joint Surg [Br] 67: 699 - 702 25. Nachemson A (1968) A long term follow-up study of nontreated scoliosis. Acta Orthop Scand 39:466-476 26. Polgar G, Weng TR (1969) The functional development of the respiratory system. Am Rev Resp Dis 120:625-695 27. Secker Walker RH, Ho JE, Gill JS (1979) Observation on regional ventilation and perfusion in kyphoscoliosis. Respiration 30:194-203 28. Shannon DC, Riseborough EJ, Kazemi H (1971) Ventilation perfusion relationships following correction of Kyphoscoliosis. JAMA 217:579-584 29. Sheerson JM (1978) The cardiorespiratory response to exercise in the thoracic scoliosis. Thorax 33: 457- 463 30. Sheerson JM (1988) Respiratory consequences of spinal fusion. The Eigth Phillip Zorab Scoliosis Symposium - Prognosis in Scoliosis. London, Abstracts Book, pp 32 31. Smith PL, Haponik EF (1984) The effects of oxygen in patients with sleep apnea. Am Rev Resp Dis 130:958-965 32. Smith RM, Hamlin GW, Dickson RA (1991) Respiratory deficiency in experimental idiopathic scoliosis. Spine 16: 94-99 33. Sorbini CA, Grassi V, Solinas E, Muiesan G (1968) Arterial oxygen tension in relation to age in healthy subjects. Respiration 25:3 - 13 34. Swank SM, Winter RB, Moe JH (1982) Scoliosis and cor l?ulmonale. Spine 7: 343- 354 35. Saki6 Katarina, Pedina M, Pavi~i6 Fadila, ~akid ~ (1987) Pulmonary function in operatively treated patients with idiopathic scoliosis. Internation Symposium on Scoliosis. Portoro~, Abstracts Book, pp 60 36. Zorab PA, Prime FJ, Harrison A (1979) Lung function in young persons after spinal fusion for scoliosis. Spine 4: 22-28 37. Weber B, Smith JP, Briscoe WA, Friedman SA, King TKC (1975) Pulmonary function in asymptomatic adolescents with idiopathic scoliosis. AM Rev Respir Dis 111:389-397 38. Weinstein SL (1988) Can Surgery be justified in view of the Long term results in unfused patients. The Eigth Phillip Zorab Scoliosis Symposium - Prognosis in Scoliosis, London, Abstracts, pp 16 39. Weiss HR (1991) The effect of an exercise programm on vital capacity and rib mobility in patients with idiopathic scoliosis. Spine 16:88-93
International
Orthopaedics © Springer-Verlag1992
Pulmonary function in adolescents with idiopathic scoliosis K. SakK I, M. Pe~ina 1, and F. PavKK 2 Departmentof OrthopaedicSurgery,Schoolof Medicine,Universityof Zagreb, Croatia 2Departmentof Pulmology,Schoolof Medicine,Universityof Zagreb, Croatia
Summary. Two groups of patients, with an average age of 15 years, have been studied to establish the improvement in pulmonary function after surgical correction in relation to the amount of correction achieved. The first group of 33 patients were treated surgically; an average Cobb angle of 72 ° was reduced to 32.6 °. The second group of 30 patients with an average Cobb angle of 33 ° were not operated on. Results of tests undertaken have shown that pulmonary function was improved by surgical correction, but the improvement does not match the degree of correction achieved. Statistical analysis of the two groups shows a difference in cardiopulmonary function to the advantage of those who were not operated on. This suggests that there is partial irreversibility of ventilation and perfusion in those who are treated surgically. R~sum~. Le but de ce travail est d'dvaluer l'amdlioration de la fonction respiratoire aprds correction chirurgicale des courbures scoliotiques. L~tude a porM sur deux groupes distincts de patients, ~g~s de 15 ans en moyenne. Le premier groupe comportait 33 sujets opdrds d'une scoliose de 72 ° (Cobb), r6duite aprds l'intervention & 32.6 °. Le deuxikme groupe comprenait 30 sujets du m~me gtge avec une scoliose non opdrde de 33 °. Les parambtres fonctionnels cardio-respiratoires, statiques et dynamiques, ont dt~ mesurds - avant et 24 mois aprds l'op~ration - par spiromdtrie et pldthysmographie, par analyse des gaz du sang et par le test de toldrance gt l'effort. Les rdsultats ont montr~ que la correction de la scoliose
Reprint requests to: M. Pedina, School of Medicine, University of Zagreb, Departmentof OrthopaedicSurgery,Salata 7, 41000 Zaga-eb,Croatia
amdliorait la fonction respiratoire, mais que cette amdlioration n'dtait pas proportionnelle ~ l'importance de la correction obtenue. L 'analyse multivariable et l'analyse discriminatoire des patients opdrds et non opdrds, avec le mOme degr( de courbure rachidienne, a montrd une diffdrence des fonctions cardiopulmonaires en faveur des sujets non opdrds. Ces rdsultats suggbrent une irrdversibilitd partielle de la ventilation et de la vascularisation chez les patients qui ont dtd traitds chirurgicalement.
Introduction The natural course of the disease in scoliotic patients show that severe deformity affects cardiopulmonary function significantly [2, 3, 9, 10, 23, 25, 28]. Several reports have demonstrated a correlation between the degree of thoracic curvature and impairment of resting lung mechanics in severe scoliosis [12, 15, 20, 27, 34, 35, 36]. The rate of increase of pulmonary arterial pressure during and after exercise was more closely related to lung volume in terms of measured vital capacity (VA), functional residual capacity (FRC) or total lung capacity (TLC) [29, 30]. The measurement of maximum voluntary ventilation, which is affected by lung volume and respiratory muscle strength, is a useful test to identify impaired ventilatory capacity that may be present in some patients with mild symptomless scoliosis which may progress [17, 19, 24, 31]. In addition to the best possible correction and stabilisation of the spine, improvement in cardiopulmonary function should be a primary aim of surgical treatment [1, 11, 16, 18, 21, 28, 35, 37, 38].
208
K. Sakid et al.: Pulmonary function in adolescents with idiopathic scoliosis
Table 1. Distribution of patients according to sex and age Patients Surgically treated
Conservatively treated
33 11 - 21 years (15.2) 27 females 6 males
30 11 - 18 years (13.5) 29 females 1 male
Table 2. Site and apex of scoliotic curvature in surgically treated patients
Cobb >70 ° Cobb 45 °
56'6° (48 to 70)
46"3° 9"3° (40 to 54) (0 to-25)
Kyphosis 21 to 45 °
>80%
Fig. 2. Changes in vital capacity - percentage of predictability
ed in all patients as shown in Fig. 3 and Table 3. There were no thoracic lordoses after operation and a normal thoracic kyphosis of 20 ° to 45 ° was achieved in 16 patients. Statistical analysis disclosed no correlation between cardiopulmonary function and preand postoperative sagittal curvature of the spine. Upper thoracic scoliosis with a Cobb angle of more than 70 ° was associated with restricted ventilation, latent hypoxaemia during the exercise tolerance test and tachycardia. In lower thoracic idiopathic scoliosis and scoliosis treated conservatively, respiratory function was normal but the latter was associated with a lower 0 2 uptake during the exercise tolerance test (Table 4). The improvement of cardiopulmonary function was confirmed by the differentiation test (Table 5). A surgical correction of 54% was correlated with an increase of VC, FEVh maximum mid-flow rate at 25% to 75%, functional residual capacity, total lung capacity and improved
exercise tolerance. Total airway resistance (Rt) in KPA/1/sec (0.29) did not correlate with FEV1. The analysis of cardiopulmonary function demonstrated a negative correlation of the curves of more than 70 ° with restriction of vital lung capacity, reduced maximum 02 consumption and reduction of exercise tolerance test time. The mean values and standard deviations for both test and control groups are shown in Table 6. Multivariate analysis of variance and discriminatory analysis (Tables 7 and 8) of surgically treated patents with a postoperative angle of 32.6 ° and conservatively treated cases with the same curvature (i. e. 33.1 °) demonstrated a difference of cardiopulmonary function (VC and PaO2) unlike the difference expected in favour of those treated conservatively (Tables 5, 7 and 8). No relevant complications occurred in the surgically treated patients over a 2 year follow up.
210
K. Saki6 et al.: Pulmonary function in adolescents with idiopathic scoliosis
Table 4. Cardiorespiratory function in surgically treated patients and in the control group Percentage of predicted normal values %
Upper thoracic
VC VC (arm span) FEV1 FEV1/VC % MMF25- 75%vc FRC RV TLC PEF MEFso MEF25 PaO2 WATT/rain Uptake Oe ml/kg/min
Lower thoracic
C_ontrol group X -+ SD
Preoperative X-+SD
P_ostoperative X_+SD
Preoperative X+SD
Postoperative X+SD
78+20 68 _+20 75 _+20 87% 83 -+29 105-+ 7 114_+21 79_+ 20 82-+ 21 81 -+ 19 76 + 21 78_+ 7 59 _+ 19
80+16 75 _+ 15 77 _+ 16 91% 107 _+ 19 99_+ 7 109-+ 19 114_+ 10 83 -+ 19 84 -+ 20 81 -+ 18 93-+ 7 76 _+ 19
91 +13 89 _+12 80 _+16 86% 85 -+21 95_+10 107_+ 16 93 _+ 9 87 _+16 84 _+19 82 _+20 95_+ 3 79 _+13
95_+10 95 _+10 83 _+16 90% 105 -+29 98_+11 101 _+ 18 94_+ 9 93 _+16 88 _+19 83 _+20 96_+ 3 83 _+13
92_+10 93 _+10 88 -+ 10 86% 95 -+ 18 110_+10 112_+ 16 96 + 9 83 + 11 86 _+19 91 _+17 88_+ 3 69 _+21
63 _+78
19 _+ 19
80 _+ 9
89 + 12
74 -+21
Discussion
Table 5. Statistical analysis of variables Correlation test
Cobb angle >70°;
VC, 02 ml/kg/min p >0.05 r=-I
Analysis of variance
Upper and lower thoracic scoliosis
VC, FEV1 p 0.05 0.6167 p >0.05
F = 5.906, NDFt = 8, NDF2 = 54 Table 8. Factor pattern for discriminant functions Variable % of predictable values
Matrix of discriminatory function arrangement
PaO2 VC MMF25- 75 RV/TLC FRC/TLC ETT-WAT/min Uptake 02 ml/kg/min Puls/min
0.746 -0.587 0.221 0.221 0.189 0.243 0.146 -0.162
Centroid for surgically treated group: 0.646, centroid for conservatively treated group: ~0.711
correction of the Cobb angle was achieved. In most patients at least 2 years are needed for optimal improvement [16]. The unsatisfactory results reported by others [8, 21] would have been better if their patients had been followed for more than 2 years after operation. There is a highly significant correlation between the % reduction in compliance and the Cobb angle [24, 32] related to the development of a smaller stiffer chest [29, 39]. Increased airway resistance (FEV1) was measured only in cases with upper thoracic scoliosis, and it decreased after surgical correction. Total bronchial resistance (Rt) increased only slightly, while FEV1 and expiration flows were reduced to a greater extent because of increased expiratory instability of the bronchial walls in scoliosis. After surgical correction, the pulmonary hila assume a more physiological position, and the changing shape of the thorax contributes to improvement in mechanical respiratory function and pulmonary hypertension. Thus the patient is more comfortable when he does not have to make an additional mechanical effort to breath. Our findings agree with those of others who have suggested that permanent damage to pulmonary circulation may occur in patients with curves of more than 70 ° [16, 28]. Conversely, better results have been reported in patients with a preoperative Cobb angle
of more than 90 ° compared with those with a lesser angle [18]. We cannot explain these findings which disagree with our own. After surgical correction of kyphoscoliosis, physiological dead space decreased by 40%, but in patients with a Cobb angle of more than 65 ° no significant improvement in regional lung perfusion was obtained [ 10, 28]. This has been attributed to possible irreversible pulmonary changes, as we have also shown, and suggests that operation should be carried out before the angle reaches 70 °. Milner reported an opposing trend by measuring the highest residual volume in patients with small spinal curvatures [22]. His results support the hypothesis that the determination of lung function in scoliosis is affected regardless of the angle and site of the curve. This has been confirmed in some of our patients with mild scoliosis. Predictions as to which patients will eventually suffer lung or heart failure are still uncertain, but as far as clinical prognosis is concerned the best indications are the site and severity of the scoliosis in terms of Cobb angle, the vital capacity and arterial PO2 by day and at night [12, 31] and the presence or absence of muscular weakness. The deterioration of pulmonary function may be prevented, or stabilisation achieved, by operation [32, 38]. Surgical curve-reducing procedures have been said to improve lung function and prevent long term deterioration [32]. The decision about surgery must be made for each patient and based on subjective data. Definitive answers may be expected after a long term follow up of surgically treated patients and a comparison with long term results in scoliotic patients treated by physical therapy alone [39], or with braces. When using physical treatmer~t Weiss et al. were able to increase vital capacity by 11% and chest expansion by more than 20% [39]. Chest expansion indicates the amount of rib mobilisation achieved which contributes substantially to the prevention or treatment of secondary functional impairment, and particularly of restricted ventilation. In spite of the improvement of respiratory function after surgical correction of the curvature in
212
K. ~akid et al.: Pulmonary function in adolescents with idiopathic scoliosis
patients with scoliosis, our comparative studies of lung function in those treated by operation and by conservative methods clearly demonstrate that some pulmonary ventilation and perfusion changes are partially irreversible. Regardless of the effect of correction, surgical correction of spinal deformities cannot establish pulmonary function which matches the improvement in the curve postoperatively.
References 1. Banta JV, Sung Min P (1983) Improvement in pulmonary function in patients having combined anterior and posterior spine fusion for myelomeningocoele scoliosis. Spine B: 765-770 2. Bergofsky EH, Turino GM, Fishmen AP (1959) Cardiorespiratory failure in kyphoscoliosis. Medicine 38: 263-317 3. Bjure J, Grimby G, Kasalicby J, Lindh M, Nachemson A (1970) Respiratory impairment and airway closure in patients with untreated idiopathic scoliosis. Thorax 25: 451 - 456 4. Brace RA, Kasumi F, Hosmer PH (1973) Maximal oxygen intake and nomographic assessment of functional aerobic impairment in cardiovascular disease. Am Heart J 85: 546- 551 5. CECA Collection d'Hygibne et de M6decine du Travail: Aide - Mdmoire pour la pratique de l'examen de la fonction ventilatoire par la spirographie. Conmaission des Communaut6s Europ6ennes, Luxembourg, 1971 6. Cherniack RM, Raber MB (1972) Normal standards for ventilatory functions using an automated wedge spirometer. Am Rev Resp Dis 106:38-46 7. Cooley WW, Lohnes PR (1971) Multivariate data analysis. Wiley, New York 8. Daruwalla JS, Clark DW, Tan WC, Balasubramaniam P (1989) La fonction respiratoire dans les scolioses idiopatiques de 1'adolescent tralt~e par instrumentation de Harrington associ6e ou non ~tun cerclage sous lamaire segmentaire. Rev Chir Orthop 75:490-492 9. Davies G, Reid L (1971) Effects of scoliosis on growth of alveoli and pulmonary arteries and on fight ventricle. Arch Dis Child 46:623-627 10. Dollery CT, Gillam PMS, Hugh-Jones P, Zorab PA (1965) Regional lung function in kyphoscoliosis. Thorax 20: 175-181 11. Gazioglu K, Goldstein LA, Femi-Pearse D, Yu PN (1968) Pulmonary function in idiopathic scoliosis. Comparative evaluation before and after orthopaedic correction. J Bone Joint Surg [Am] 50:391-399 12. Guilleminault C, Kurland G, Winkle R, Miles LE (1981) Severe kyphoscoliosis breathing and sleep "Quasimodo" syndrome during sleep. Chest 79: 626- 630 13. Jaeger MJ, Otis AB (1964) Measurement of airway resistance with a volume displacement body plethysmograph. JAppl Physiol 19:813-817 14. Johnson B, Westgate H (1970) Methods of predictive vital capacity in patients with thoracic scoliosis. J Bone Joint Surg 52A: 1433-1439 15. Kafer ER (1977) Respiratory and cardiovascular function in scoliosis. Bull Eur Physiopath Respir 13: 299-321 16. Kumano K, Tsuyama N (1982) Pulmonary function before and after surgical correction of scoliosis. J Bone Joint Surg [Am] 64:242-249
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