Functional changes are associated with tracheal structural abnormalities in patients with acromegaly

Abstract

IntroductionAlthough impaired pulmonary function and respiratory sleep disorders are described as responsible for increased mortality in acromegalic patients, little is known about the tracheal abnormalities in this group of patients. Thus, the objectives of this study were to describe the tracheal structural abnormalities and correlate these changes with the respiratory function and clinical data of acromegalic patients.Material and methodsThis is a cross-sectional study that was carried out at two university hospitals. Twenty acromegalic patients underwent spirometry, forced oscillation technique, and computed tomography (CT) assessments. Dyspnea and daytime sleepiness were assessed using the Modified Medical Research Council (MMRC) scale and the Epworth Sleepiness Scale (ESS), respectively. Forty matched subjects served as controls.ResultsThe acromegalic patients exhibited larger median ratios between forced expiratory flow and forced inspiratory flow at 50% of the forced vital capacity (FEF50%/FIF50%) (2.05 vs. 1.06, p = 0.0001) compared with healthy volunteers. In the CT analysis, acromegalic patients exhibited larger median differences between their cervical and thoracic tracheal diameters (Δ tracheal diameters) (3 vs. 1 mm; p = 0.003). An association was found between FEF50%/FIF50% and the following variables: mean resistance (Rm), cervical tracheal diameter, and Δ tracheal diameters. Rm also exhibited a negative correlation with cervical tracheal diameter. Neither the MMRC scale nor the ESS exhibited any significant correlation with large airway obstruction (LAO) indices or with the measured tracheal diameters.ConclusionsAcromegalic patients have tracheal structural abnormalities which are associated with functional indicators of LAO but not with clinical data.

Computed tomography airway lumen volumetry in patients with acromegaly: Association with growth hormone levels and lung function

“…A positive and strong correlation was also noted between the FEF 50% /FIF 50% ratio and the Δ tracheal diameters obtained through inspiratory CT but not through expiratory CT. This finding may be explained by the tendency towards tracheal collapse deriving from the development of negative intraluminal pressure during inspiration, which disappears during expiration, when the direction of transmural pressure, with the subsequent opening of the airways, is inverted …”

“…29 We found that patients with acromegaly show higher values of the FEF 50% /FIF 50% ratio than control subjects. 4,23,26 In the flow-volume loop obtained through spirometry, an increased FEF 50% /FIF 50% ratio has been used as an extrathoracic large airway obstruction (LAO) marker, as there is limitation of the airflow during inspiration in the presence of narrowed airways due to the propagation of negative intraluminal pressure in this portion of the airway. 4 In this study, this finding was corroborated by the higher SI based on airway lumen volumetry measurements.…”

“…This finding may be explained by the tendency towards tracheal collapse deriving from the development of negative intraluminal pressure during inspiration, which disappears during expiration, when the direction of transmural pressure, with the subsequent opening of the airways, is inverted. 4 There is growing interest in using FOT to assess lung function because the measurements are taken during spontaneous breathing; the technique provides new reactive and resistive parameters for understanding ventilation mechanics, and the parameters provided by FOT present a good correlation with the findings from CT scans. 6,12 We observed that Rm (which is associated with airway calibre) was higher in patients with acromegaly than in the controls.…”

“…Anatomical distortions of the thorax geometry and changes in soft tissues, joints, the respiratory mucosa, lung volume and respiratory muscle activity have been reported in previous studies . With regard to functional abnormalities related to the respiratory tract in patients with acromegaly, few studies have specifically approached this topic, particularly in the trachea and large airways, which have been considered a ‘forgotten zone’, with potential for obstructive events …”

“…2,3 With regard to functional abnormalities related to the respiratory tract in patients with acromegaly, few studies have specifically approached this topic, particularly in the trachea and large airways, which have been considered a 'forgotten zone', with potential for obstructive events. [3][4][5] The advent of multislice CT brought significant advances in imaging diagnosis in all fields of medicine. In addition, using imaging analysis programmes, it is possible to estimate lung volumes and correlate them with classic tools for the measurement of lung function.…”