Original Thoracic
433
A Cross-Sectional Study of Chest Wall Development in Patients with Pectus Excavatum Pei-Yeh Chang1 Qi Zeng2 Chee-Jen Chang5
Kin-Sun Wong3
Jin-Yao Lai1
1 Division of Pediatric Surgery, Department of Surgery, Chang Gung Memorial
Hospital, Chang-Gung University, College of Medicine, Taoyuan, Taiwan 2 Department of Pediatric Surgery, Beijing Children Hospital, Capital Medical University, Beijing, China 3 Department of Pediatrics, Chang Gung Memorial Hospital, ChangGung University, College of Medicine, Taoyuan, Taiwan 4 Department of Radiology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan 5 Chang Gung Memorial Hospital, Resources Center for Clinical Research, Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
Jeng-Chang Chen1
Chao-Jan Wang4
Address for correspondence Pei-Yeh Chang, MD, Department of Pediatric Surgery, Chang Gung Memorial Hospital, Chang-Gung University, College of Medicine, No.5, Fusing St., Gueishan Township, Taoyuan County 333, Taiwan (e-mail: [email protected]; [email protected]).
Abstract
Keywords
► ► ► ►
chest wall growth chest radiology pectus excavatum
Background We conducted a cross-sectional study to quantify the developmental changes of the thoracic cage in patients with pectus excavatum (PE). Methods The preoperative posteroanterior standing chest radiographs (chest PAs) of 1,197 consecutive patients with PE, together with 1,661 age- and sex-matched minor surgery patients, as a control group, who were seen between June 2005 and February 2013, were reviewed. The maximum width of each rib pair and chest height (H) were measured on the chest PA. Results In the PE group, the normal thoracic contour in younger patients was replaced by a characteristic can-shaped chest wall, which showed protrusion of the upper ribs, an increased H, and a straightened lateral border of the chest cage, as they grew into adulthood. The chest height difference between the PE and control groups increased progressively, from the age of 8 years and most significantly from age 13 to 17 years. No difference was observed in the middle and lower rib widths. Sex did not influence these trends. Conclusion The PE chest wall shows a significant increment in chest height, and upper rib width starts during the period of rapid growth and is maintained into adulthood. The thoracic deformity in patients with PE includes more than just the sternal deformity.
Introduction The natural history of pectus excavatum (PE) is not well known.1 After the Nuss procedure was introduced, the number of patients undergoing surgical corrections of PE increased dramatically, thus providing the opportunity to reexamine the course of this disease. Previously, the lower thoracic wall configurations have been reported to change
received September 15, 2014 accepted November 14, 2014 published online January 20, 2015
curvilinearly up to the age of 10 years and remain constant beyond this age on lateral chest radiographs. 2 Thereafter, other parameters are needed to examine the progression of the disease. This study reviewed the posteroanterior chest radiographs (chest PA) of patients with PE to define the progression of the chest wall deformation in addition to the depression of the sternum.
© 2015 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0034-1396928. ISSN 0171-6425.
Downloaded by: Universite Laval. Copyrighted material.
Thorac Cardiovasc Surg 2015;63:433–436.
Cross-Sectional Study of Chest Wall Development
Chang et al.
Patients and Methods Study Population This is a retrospective observational study. The frontal chest radiographs of 1,197 consecutive patients with PE undergoing surgery, together with 1,661 age- and sex-matched appendectomy, routine health examination, and minor trauma patients, as a control group, who were seen between June 2005 and February 2013, were reviewed and compared. All the patients with PE had a pectus index3 greater than 3.2. All the patients were ethnic Chinese living in China or Taiwan. The study protocol was approved by the Ethics Committees of our hospital (98-3342B 201008005R, 099-05-162, BCH [2010]-59). Informed consent was obtained at the outpatient clinic or by mail from the patients’ parents.
mean standard deviation (SD) or percentage. The means of the measurements of the studied patients and control group were compared using Student t-test. Differences were deemed statistically significant at a p value less than 0.05. The data of the body height of Taiwanese were used for comparison.4
Results Study Population The pectus group included 889 males and 308 females with a mean age of 11.66 7.78 years (range, 3–51 years). The
Chest Pectus Excavatum Protocol Digital chest radiographs were obtained using posteroanterior projection while patients held their breath after deep inspiration, taken within 2 days before surgery. The maximum transversal width at each costal level, from the 1st pair to the 10th pair of ribs (R1–R10), was measured to quantify the changes in the outer boundary of the thoracic walls (►Fig. 1). The height (H) of the thoracic cage was defined as the distance from the right apex to right costophrenic angle, and the width of the thoracic cage (W) was defined as the distance between the right and left costophrenic angles.
Downloaded by: Universite Laval. Copyrighted material.
434
Measurements and Data Analysis The measurements were recorded by two radiology technicians, under the supervision of a pediatric radiologist at the three hospitals in Taiwan, and by one pediatric surgeon and one pediatric radiologist in China. The protocol was tested for intra- and interdigitizer reliability. Data were expressed as the
Fig. 1 Measurement of the maximum width of the rib pairs and chest height and width. Thoracic and Cardiovascular Surgeon
Vol. 63
No. 5/2015
Fig. 2 Comparison of the body height; chest height; and the second, fifth, and ninth rib pair widths between the control and pectus groups at different ages. Significant at the 0.05 level; Significant at the 0.01 level.
control group included 941 males and 717 females with a mean age of 13.50 7.18 years (range, 2–33 years).
Observer Agreement The intra- and interdigitizer reliability of each rib pair distance, H, and W, were tested for the first 50 cases at each hospital. The correlation coefficients ranged from 0.925 to 0.975.
Chest Radiographic Findings In the early stage of pectus (i.e., age 3–5 years), patients had greater widths at all rib levels, whereas the chest height did not differ significantly (►Fig. 2) compared with that in the control subjects. At elementary school age, there was no difference in rib width, H, or W compared with the control subjects. As the patients became teenagers, the silhouette of the pectus osseous thorax on chest PA changed from a bell shape to a cylindrical shape with a rectangular outer contour (►Fig. 3). The chest walls of the teenage and adult patients with PE demonstrated three distinct features: (1) pronounced outward protrusion of the upper ribs, as shown by the increase in the second rib pair width, (2) an increase in chest height, and (3) a straightened lateral border of the lower thoracic cage (►Fig. 4). The chest height difference between the PE and control groups increased progressively, from the age of 8 years, particularly from age 13 to 17 years, whereas their average body height remained the same as that of the control group (►Fig. 2). There was no difference in the middle and lower rib widths, parameters that stabilized in the teenage years and older. Sex did not affect these trends.
Discussion Before the introduction of the Nuss procedure, parents and pediatricians were concerned about the invasive nature of a thoracoplasty; consequently, only a small proportion of children with pectus underwent surgical intervention. Recently, the Nuss procedure has been acknowledged as a relatively atraumatic, effective procedure for correcting PE.5 The number of patients undergoing this surgery has increased rapidly
Chang et al.
worldwide. The large number of patients enabled us to reexamine the nature of this disease. The advancement in modern imaging modalities, such as computer-aided measurements, offers an unprecedented opportunity to explore the geometric changes of the chest wall in patients who have PE with higher accuracy and better correlation between institutes. In the past, the depression of the sternum was the major focus regarding problems in pectus patients. Derveaux et al found that the lower thoracic configuration changed curvilinearly up to the age of 10 years and remained constant beyond this age on lateral chest X-rays.2 The results indicated that patients with a chronological age of 10 years or younger had a high estimated probability of deformity progression. A possible explanation of why the deformation ceased at 10 years is that the depression of the sternal end progressed to such a degree that further narrowing of the gap between the sternum and vertebral body was impossible. A cardiac shift can no longer provide space for depression of the sternum. In our previous study on pectus,6 we found no significant decrease in the Haller pectus index with increasing age. Because the sternal depression cannot progress, the lateral view of the chest wall cannot provide further information concerning chest wall changes after 10 years of age. Therefore, no correlation of the degree of sternal depressions with the change in the chest height was provided in the present study. ►Fig. 2 shows that the thoracic changes in patients with PE can be divided into several stages. At age 3 to 5 years, the chest wall of PE patients may be more compliant. The lateral wall responds to the depression of the sternal end by widening the outer contour of each rib. The lateral contour of the chest wall may not change significantly from that of the normal population while the patients were at elementary school age. The chest wall changes became more evident starting from 8 years of age and more prominent from 13 to 17 years of age, and remained the same thereafter. The characteristic changes of the chest wall were the changes in H and upper rib pair width. The thoracic deformity in patients with PE included more than just the sternal deformity, whereas the patients’ body
Fig. 3 The pectus osseous thorax changes on chest PA in different age groups. Left chest PA in a 14-year-old patient showing a bell-shaped chest wall. The right chest PA is that of a 19-year-old patient mimicking a can-shaped chest contour and characterized by an increased chest height and flat lateral border of the lower chest wall.
Thoracic and Cardiovascular Surgeon
Vol. 63
No. 5/2015
435
Downloaded by: Universite Laval. Copyrighted material.
Cross-Sectional Study of Chest Wall Development
Cross-Sectional Study of Chest Wall Development
Chang et al. study, the chest frontal films did not offer further information on the severity of the pectus deformity. Our study had several limitations. First, this study provided a two-dimensional analysis of the thoracic wall; however, the analysis should be performed in three dimensions. The frontal chest radiograph may not be unified due to the possibility of different depths of respiration. We could not differentiate the increased height owing to the different diaphragm positions in both controls and children with pectus deformities. Measurement from the bottom of the T-12 vertebrae to the top of the T-1 vertebrae would reflect thoracic height in a more standardized manner.
Conclusion This study presents a comprehensive analysis of the pattern of change in the PE chest wall. The thoracic deformity in PE children consisted of more than the sternal deformity. The thoracic silhouette on the frontal chest radiograph revealed that the normal bell-shaped thoracic cage in young patients evolute into an elongated, cylindrical-shaped thoracic silhouette in adolescence and adulthood. A longitudinal developmental study on the thoracic wall configurations of patients with PE is difficult but necessary in the future to confirm our observations.
References 1 Brochhausen C, Turial S, Müller FK, et al. Pectus excavatum:
2
Fig. 4 The lateral contour of the left chest wall. The central figure shows the cross section of each rib at the outer boundary. The dot represents the average width of each rib pair at various ages. The lateral border of the lower chest wall straightens, and the chest height increases as the patients grow into adolescence. These differences become prominent during the teenage years.
height did not differ significantly from that of the normal controls. We postulated that the increased lung height and upper part of the chest bulging gradually compensate for the rigid and flat constriction of the central part of the chest. In a study on the effect of impeding regional chest wall excursion on regional lung function, Forkert7 found that restriction of the lower chest wall impeded expansion of the lower thoracic cage, while the upper thoracic cage expanded normally. This phenomenon might help explain why H increased, and the upper ribs widened in response to the depressed, rigid lower chest wall. In the past, lateral chest radiographs were used to define the severity of PE. The pectus index can be calculated using chest lateral film8 and has also been used to provide information concerning the benefits of the Nuss procedure.9 In our
Thoracic and Cardiovascular Surgeon
Vol. 63
No. 5/2015
3
4 5
6
7 8
9
history, hypotheses and treatment options. Interact Cardiovasc Thorac Surg 2012;14(6):801–806 Derveaux L, Clarysse I, Ivanoff I, Demedts M. Preoperative and postoperative abnormalities in chest X-ray indices and in lung function in pectus deformities. Chest 1989;95(4):850–856 St Peter SD, Juang D, Garey CL, et al. A novel measure for pectus excavatum: the correction index. J Pediatr Surg 2011;46(12): 2270–2273 Huang YC. Body mass index reference for Taiwanese children and adolescents. J Med Sci 2002;22:221–226 Kelly RE Jr, Shamberger RC, Mellins RB, et al. Prospective multicenter study of surgical correction of pectus excavatum: design, perioperative complications, pain, and baseline pulmonary function facilitated by internet-based data collection. J Am Coll Surg 2007;205(2):205–216 Zeng Q, Lai JY, Wang CJ, et al. A cross sectional study of lung volume development in pectus excavatum patients: estimating the total lung volume from chest computed tomograph using three dimensional volumetric reconstruction. J Pediatr Surg 2010;45:2322–2327 Forkert L. Effect of regional chest wall restriction on regional lung function. J Appl Physiol 1980;49(4):655–662 Mueller C, Saint-Vil D, Bouchard S. Chest X-ray as a primary modality for preoperative imaging of pectus excavatum. J Pediatr Surg 2008;43(1):71–73 Lawson ML, Barnes-Eley M, Burke BL, et al. Reliability of a standardized protocol to calculate cross-sectional chest area and severity indices to evaluate pectus excavatum. J Pediatr Surg 2006; 41(7):1219–1225
Downloaded by: Universite Laval. Copyrighted material.
436
433
A Cross-Sectional Study of Chest Wall Development in Patients with Pectus Excavatum Pei-Yeh Chang1 Qi Zeng2 Chee-Jen Chang5
Kin-Sun Wong3
Jin-Yao Lai1
1 Division of Pediatric Surgery, Department of Surgery, Chang Gung Memorial
Hospital, Chang-Gung University, College of Medicine, Taoyuan, Taiwan 2 Department of Pediatric Surgery, Beijing Children Hospital, Capital Medical University, Beijing, China 3 Department of Pediatrics, Chang Gung Memorial Hospital, ChangGung University, College of Medicine, Taoyuan, Taiwan 4 Department of Radiology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan 5 Chang Gung Memorial Hospital, Resources Center for Clinical Research, Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
Jeng-Chang Chen1
Chao-Jan Wang4
Address for correspondence Pei-Yeh Chang, MD, Department of Pediatric Surgery, Chang Gung Memorial Hospital, Chang-Gung University, College of Medicine, No.5, Fusing St., Gueishan Township, Taoyuan County 333, Taiwan (e-mail: [email protected]; [email protected]).
Abstract
Keywords
► ► ► ►
chest wall growth chest radiology pectus excavatum
Background We conducted a cross-sectional study to quantify the developmental changes of the thoracic cage in patients with pectus excavatum (PE). Methods The preoperative posteroanterior standing chest radiographs (chest PAs) of 1,197 consecutive patients with PE, together with 1,661 age- and sex-matched minor surgery patients, as a control group, who were seen between June 2005 and February 2013, were reviewed. The maximum width of each rib pair and chest height (H) were measured on the chest PA. Results In the PE group, the normal thoracic contour in younger patients was replaced by a characteristic can-shaped chest wall, which showed protrusion of the upper ribs, an increased H, and a straightened lateral border of the chest cage, as they grew into adulthood. The chest height difference between the PE and control groups increased progressively, from the age of 8 years and most significantly from age 13 to 17 years. No difference was observed in the middle and lower rib widths. Sex did not influence these trends. Conclusion The PE chest wall shows a significant increment in chest height, and upper rib width starts during the period of rapid growth and is maintained into adulthood. The thoracic deformity in patients with PE includes more than just the sternal deformity.
Introduction The natural history of pectus excavatum (PE) is not well known.1 After the Nuss procedure was introduced, the number of patients undergoing surgical corrections of PE increased dramatically, thus providing the opportunity to reexamine the course of this disease. Previously, the lower thoracic wall configurations have been reported to change
received September 15, 2014 accepted November 14, 2014 published online January 20, 2015
curvilinearly up to the age of 10 years and remain constant beyond this age on lateral chest radiographs. 2 Thereafter, other parameters are needed to examine the progression of the disease. This study reviewed the posteroanterior chest radiographs (chest PA) of patients with PE to define the progression of the chest wall deformation in addition to the depression of the sternum.
© 2015 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0034-1396928. ISSN 0171-6425.
Downloaded by: Universite Laval. Copyrighted material.
Thorac Cardiovasc Surg 2015;63:433–436.
Cross-Sectional Study of Chest Wall Development
Chang et al.
Patients and Methods Study Population This is a retrospective observational study. The frontal chest radiographs of 1,197 consecutive patients with PE undergoing surgery, together with 1,661 age- and sex-matched appendectomy, routine health examination, and minor trauma patients, as a control group, who were seen between June 2005 and February 2013, were reviewed and compared. All the patients with PE had a pectus index3 greater than 3.2. All the patients were ethnic Chinese living in China or Taiwan. The study protocol was approved by the Ethics Committees of our hospital (98-3342B 201008005R, 099-05-162, BCH [2010]-59). Informed consent was obtained at the outpatient clinic or by mail from the patients’ parents.
mean standard deviation (SD) or percentage. The means of the measurements of the studied patients and control group were compared using Student t-test. Differences were deemed statistically significant at a p value less than 0.05. The data of the body height of Taiwanese were used for comparison.4
Results Study Population The pectus group included 889 males and 308 females with a mean age of 11.66 7.78 years (range, 3–51 years). The
Chest Pectus Excavatum Protocol Digital chest radiographs were obtained using posteroanterior projection while patients held their breath after deep inspiration, taken within 2 days before surgery. The maximum transversal width at each costal level, from the 1st pair to the 10th pair of ribs (R1–R10), was measured to quantify the changes in the outer boundary of the thoracic walls (►Fig. 1). The height (H) of the thoracic cage was defined as the distance from the right apex to right costophrenic angle, and the width of the thoracic cage (W) was defined as the distance between the right and left costophrenic angles.
Downloaded by: Universite Laval. Copyrighted material.
434
Measurements and Data Analysis The measurements were recorded by two radiology technicians, under the supervision of a pediatric radiologist at the three hospitals in Taiwan, and by one pediatric surgeon and one pediatric radiologist in China. The protocol was tested for intra- and interdigitizer reliability. Data were expressed as the
Fig. 1 Measurement of the maximum width of the rib pairs and chest height and width. Thoracic and Cardiovascular Surgeon
Vol. 63
No. 5/2015
Fig. 2 Comparison of the body height; chest height; and the second, fifth, and ninth rib pair widths between the control and pectus groups at different ages. Significant at the 0.05 level; Significant at the 0.01 level.
control group included 941 males and 717 females with a mean age of 13.50 7.18 years (range, 2–33 years).
Observer Agreement The intra- and interdigitizer reliability of each rib pair distance, H, and W, were tested for the first 50 cases at each hospital. The correlation coefficients ranged from 0.925 to 0.975.
Chest Radiographic Findings In the early stage of pectus (i.e., age 3–5 years), patients had greater widths at all rib levels, whereas the chest height did not differ significantly (►Fig. 2) compared with that in the control subjects. At elementary school age, there was no difference in rib width, H, or W compared with the control subjects. As the patients became teenagers, the silhouette of the pectus osseous thorax on chest PA changed from a bell shape to a cylindrical shape with a rectangular outer contour (►Fig. 3). The chest walls of the teenage and adult patients with PE demonstrated three distinct features: (1) pronounced outward protrusion of the upper ribs, as shown by the increase in the second rib pair width, (2) an increase in chest height, and (3) a straightened lateral border of the lower thoracic cage (►Fig. 4). The chest height difference between the PE and control groups increased progressively, from the age of 8 years, particularly from age 13 to 17 years, whereas their average body height remained the same as that of the control group (►Fig. 2). There was no difference in the middle and lower rib widths, parameters that stabilized in the teenage years and older. Sex did not affect these trends.
Discussion Before the introduction of the Nuss procedure, parents and pediatricians were concerned about the invasive nature of a thoracoplasty; consequently, only a small proportion of children with pectus underwent surgical intervention. Recently, the Nuss procedure has been acknowledged as a relatively atraumatic, effective procedure for correcting PE.5 The number of patients undergoing this surgery has increased rapidly
Chang et al.
worldwide. The large number of patients enabled us to reexamine the nature of this disease. The advancement in modern imaging modalities, such as computer-aided measurements, offers an unprecedented opportunity to explore the geometric changes of the chest wall in patients who have PE with higher accuracy and better correlation between institutes. In the past, the depression of the sternum was the major focus regarding problems in pectus patients. Derveaux et al found that the lower thoracic configuration changed curvilinearly up to the age of 10 years and remained constant beyond this age on lateral chest X-rays.2 The results indicated that patients with a chronological age of 10 years or younger had a high estimated probability of deformity progression. A possible explanation of why the deformation ceased at 10 years is that the depression of the sternal end progressed to such a degree that further narrowing of the gap between the sternum and vertebral body was impossible. A cardiac shift can no longer provide space for depression of the sternum. In our previous study on pectus,6 we found no significant decrease in the Haller pectus index with increasing age. Because the sternal depression cannot progress, the lateral view of the chest wall cannot provide further information concerning chest wall changes after 10 years of age. Therefore, no correlation of the degree of sternal depressions with the change in the chest height was provided in the present study. ►Fig. 2 shows that the thoracic changes in patients with PE can be divided into several stages. At age 3 to 5 years, the chest wall of PE patients may be more compliant. The lateral wall responds to the depression of the sternal end by widening the outer contour of each rib. The lateral contour of the chest wall may not change significantly from that of the normal population while the patients were at elementary school age. The chest wall changes became more evident starting from 8 years of age and more prominent from 13 to 17 years of age, and remained the same thereafter. The characteristic changes of the chest wall were the changes in H and upper rib pair width. The thoracic deformity in patients with PE included more than just the sternal deformity, whereas the patients’ body
Fig. 3 The pectus osseous thorax changes on chest PA in different age groups. Left chest PA in a 14-year-old patient showing a bell-shaped chest wall. The right chest PA is that of a 19-year-old patient mimicking a can-shaped chest contour and characterized by an increased chest height and flat lateral border of the lower chest wall.
Thoracic and Cardiovascular Surgeon
Vol. 63
No. 5/2015
435
Downloaded by: Universite Laval. Copyrighted material.
Cross-Sectional Study of Chest Wall Development
Cross-Sectional Study of Chest Wall Development
Chang et al. study, the chest frontal films did not offer further information on the severity of the pectus deformity. Our study had several limitations. First, this study provided a two-dimensional analysis of the thoracic wall; however, the analysis should be performed in three dimensions. The frontal chest radiograph may not be unified due to the possibility of different depths of respiration. We could not differentiate the increased height owing to the different diaphragm positions in both controls and children with pectus deformities. Measurement from the bottom of the T-12 vertebrae to the top of the T-1 vertebrae would reflect thoracic height in a more standardized manner.
Conclusion This study presents a comprehensive analysis of the pattern of change in the PE chest wall. The thoracic deformity in PE children consisted of more than the sternal deformity. The thoracic silhouette on the frontal chest radiograph revealed that the normal bell-shaped thoracic cage in young patients evolute into an elongated, cylindrical-shaped thoracic silhouette in adolescence and adulthood. A longitudinal developmental study on the thoracic wall configurations of patients with PE is difficult but necessary in the future to confirm our observations.
References 1 Brochhausen C, Turial S, Müller FK, et al. Pectus excavatum:
2
Fig. 4 The lateral contour of the left chest wall. The central figure shows the cross section of each rib at the outer boundary. The dot represents the average width of each rib pair at various ages. The lateral border of the lower chest wall straightens, and the chest height increases as the patients grow into adolescence. These differences become prominent during the teenage years.
height did not differ significantly from that of the normal controls. We postulated that the increased lung height and upper part of the chest bulging gradually compensate for the rigid and flat constriction of the central part of the chest. In a study on the effect of impeding regional chest wall excursion on regional lung function, Forkert7 found that restriction of the lower chest wall impeded expansion of the lower thoracic cage, while the upper thoracic cage expanded normally. This phenomenon might help explain why H increased, and the upper ribs widened in response to the depressed, rigid lower chest wall. In the past, lateral chest radiographs were used to define the severity of PE. The pectus index can be calculated using chest lateral film8 and has also been used to provide information concerning the benefits of the Nuss procedure.9 In our
Thoracic and Cardiovascular Surgeon
Vol. 63
No. 5/2015
3
4 5
6
7 8
9
history, hypotheses and treatment options. Interact Cardiovasc Thorac Surg 2012;14(6):801–806 Derveaux L, Clarysse I, Ivanoff I, Demedts M. Preoperative and postoperative abnormalities in chest X-ray indices and in lung function in pectus deformities. Chest 1989;95(4):850–856 St Peter SD, Juang D, Garey CL, et al. A novel measure for pectus excavatum: the correction index. J Pediatr Surg 2011;46(12): 2270–2273 Huang YC. Body mass index reference for Taiwanese children and adolescents. J Med Sci 2002;22:221–226 Kelly RE Jr, Shamberger RC, Mellins RB, et al. Prospective multicenter study of surgical correction of pectus excavatum: design, perioperative complications, pain, and baseline pulmonary function facilitated by internet-based data collection. J Am Coll Surg 2007;205(2):205–216 Zeng Q, Lai JY, Wang CJ, et al. A cross sectional study of lung volume development in pectus excavatum patients: estimating the total lung volume from chest computed tomograph using three dimensional volumetric reconstruction. J Pediatr Surg 2010;45:2322–2327 Forkert L. Effect of regional chest wall restriction on regional lung function. J Appl Physiol 1980;49(4):655–662 Mueller C, Saint-Vil D, Bouchard S. Chest X-ray as a primary modality for preoperative imaging of pectus excavatum. J Pediatr Surg 2008;43(1):71–73 Lawson ML, Barnes-Eley M, Burke BL, et al. Reliability of a standardized protocol to calculate cross-sectional chest area and severity indices to evaluate pectus excavatum. J Pediatr Surg 2006; 41(7):1219–1225
Downloaded by: Universite Laval. Copyrighted material.
436
