Regional lung function in scoliosis

Locoregional lung ventilation distribution in girls with adolescent idiopathic scoliosis and healthy adolescents. The immediate effect of Schroth 'derotational breathing' exercise in a controlled-trial

BACKGROUND

Scoliosis curves present transverse plane deviations due to vertebral rotation. The Schroth method supports thoracic derotation by training patients to exert "derotational" breathing based on assumed enhanced ventilation in areas called "humps" in scoliosis and a patient's ability to voluntarily direct ventilation in less ventilated areas called "flats."

OBJECTIVE

To assess the asymmetric ventilation distribution and the ability of patients to direct their ventilation to perform derotational breathing.

METHODS

Twelve girls with adolescent idiopathic scoliosis and 12 healthy girls performed 3 × 3 min of rest, maximal, and derotational breathing. Electrical impedance tomography was used to record locoregional lung ventilation distribution (LLVD) within 4 thoracic regions of interest: anterior right (ROI 1), anterior left (ROI 2), posterior right (ROI 3), and posterior left (ROI 4) quadrants. Humps and flats were the sums of ROI '2 + 3' and ROI '1 + 4,' respectively.

RESULTS

Overall, no difference in LLVD was observed in the flats and humps between groups. At rest, the LLVD in the humps was more elevated than that in the flats (51.5 ± 8.1% versus 43.6 ± 7.9%; p = .021) when considering both groups. Maximal and derotational breathing led to a more homogeneous LLVD between the humps and flats.

CONCLUSION

The postulated derotational breathing effect was not confirmed.

Lung function asymmetry in children with congenital and infantile scoliosis

BACKGROUND CONTEXT

Progressive scoliosis alters lung function by reducing chest wall compliance and excursion and rotating intrathoracic contents, producing an increasingly asymmetric lung size. The effect of this distortion on regional lung perfusion and ventilation has not been described in children with congenital and infantile forms of scoliosis. The severity of scoliosis is often described by the Cobb angle of the spine, but the relationship between Cobb angle and lung function asymmetry between concave and convex lungs has not been described in this group of children.

PURPOSE

To describe the frequency of asymmetric lung perfusion and ventilation among children with congenital or infantile thoracic scoliosis before surgical treatment and the relationship between Cobb angle and asymmetry of lung function.

STUDY DESIGN/SETTING

Prospective comparison of lung perfusion scans and spine film findings in children evaluated in two pediatric spine referral clinics for expansion thoracoplasty and vertical expandable prosthetic titanium rib (VEPTR) implantation.

PATIENT SAMPLE

Thirty-nine children, aged 1 year 8 months to 15 years 6 months, with congenital or infantile forms of scoliosis who are clinically stable outpatients and have neither primary pulmonary disease nor neuromuscular weakness.

OUTCOME MEASURES

1) Cobb angle measurements from weightbearing spine films and 2) right and left contributions to total lung perfusion and total lung ventilation compared with normal values.

METHODS

Lung perfusion scans using technetium-labeled albumin macroaggregates were performed in all children; 15 of the children also underwent ventilation lung scans using aerosolized technecium-labeled diethylenetriaminepentaacetic acid (DTPA). The degree of asymmetry between right and left lung function from the normal right-to-left lung distribution was correlated with the Cobb angle of the spine. Ventilation and perfusion asymmetry between right and left lungs was also compared.

RESULTS

Sixteen of the 25 children with congenital scoliosis had fused ribs; 13 additional children had infantile scoliosis. Cobb angles ranged from 30 degrees to 112 degrees in the group (median=71 degrees ), with the concave lung being the left lung in 61% of cases. Lung function relations between the right and left lungs were abnormal (>5% deviation from the normal 55% right [R]/45% left [L]) in 21 (54%) patients. Right-left contributions to lung perfusion ranged from 86% R/14% L to 26% R/74% L among the 39 children. Lung function in the concave lung was reduced below the normal proportion in only 20 children (51%). Lung function asymmetry, measured as the deviation from the normal contributions of the right and left lungs, did not correlate with Cobb angle values (r=.14, p=.4). Ventilation asymmetry and perfusion asymmetry were concordant and correlated closely (r=.93, p<.0001).

CONCLUSIONS

Asymmetric ventilation and perfusion between the right and left lungs occurs in more than half of the children with severe congenital and infantile thoracic scoliosis. However, the severity of lung function asymmetry does not relate to Cobb angle measurements. Asymmetry in lung function is influenced by deformity of the chest wall in multiple dimensions, and cannot be ascertained by chest radiographs alone.

Respiratory failure and pulmonary hypertension associated with Klippel-Feil syndrome

A 28-year-old woman with a deformed thorax and kyphoscoliosis associated with Klippel-Feil syndrome developed respiratory failure with pulmonary hypertension. Pulmonary 133Xe ventilation and 99mTc-MAA perfusion scintigraphies showed maldistributions of lung ventilation and perfusion, and noticeably delayed 133Xe washout from the lungs. Dynamic breathing MR imaging showed poor and/or asynchronous respiratory movements of the chest wall and diaphragm. These findings indicate that the perfusion-ventilation imbalance, the decreased ventilatory turnover, and expiratory flow from the alveolar space partly derived from the impaired respiratory mechanics may be responsible for the respiratory complications in this patient.

Mechanical inefficiency of the thoracic cage in scoliosis

The mechanism of impairment of ventilatory function in idiopathic scoliosis has been studied in 23 children, all girls, and compared with 27 normal children and 24 normal young adult females. The vital capacity, FEV 1, gas transfer factor, and the maximum static expiratory airway pressure were all significantly reduced. total lung capacity and the maximum inspiratory pressure were lower than in the normal subjects, but the difference was not significant. Restriction of thoracic cage movement by a belt showed that the thorax in the children with scoliosis was as mobile as in the normal subjects. The results are explained in terms of the characteristic deformity in scoliosis which causes one hemi-thorax to become relatively smaller than the other. It is concluded that this causes an inherent mechanical inefficiency of ventilation which is likely to contribute to respiratory failure in these subjects.