Effects of emphysema and lung volume reduction surgery on transdiaphragmatic pressure and diaphragm length.

STUDY OBJECTIVES: To determine the effect of emphysema and lung volume reduction surgery (LVRS) on diaphragm length (Ldi) and its capacity to generate transdiaphragmatic pressure (Pdi). DESIGN: Prospective clinical trial with a parallel group design. SETTING: Laboratory investigations in normal volunteers recruited by advertisement and in emphysema outpatients being evaluated for elective LVRS. STUDY POPULATION: Thirteen normal subjects and 13 emphysema patients matched for age and sex. Six emphysema patients underwent LVRS. MEASUREMENTS: Ldi and maximal Pdi during static inspiratory efforts (PdiMax) were measured at three different lung volumes (LVs). Pdi during maximal bilateral phrenic nerve twitch stimulation (PdiTw) was measured at functional residual capacity (FRC). All measurements were repeated at 3, 6, and 12 months postoperatively. RESULTS: Ldi, PdiMax, and PdiTw were lower in emphysema patients than in normal subjects at their respective LVs. PdiMax and PdiTw at FRC returned within the normal range after LVRS in emphysema patients. The relationships between PdiMax and LV or Ldi were shifted respectively to higher LV and shorter Ldi in emphysema patients relative to normal subjects, both before and after LVRS. LVRS effected craniad displacement of the diaphragm but no change in rib cage dimensions. Improvements in dyspnea and quality of life after LVRS correlated with changes in LV and Ldi but not with changes in airway caliber. CONCLUSION: Adaptive mechanisms, consistent with sarcomere deletion, tend to restore diaphragm strength in emphysema patients at FRC, which are fully expressed after LVRS. Lung remodeling by LVRS may alter pleural surface pressure distribution, causing a sustained change in chest wall shape.

Loss of brain volume in endogenous Cushing's syndrome and its reversibility after correction of hypercortisolism.

Chronic exposure to excess glucocorticoids results in cognitive and psychological impairment. A few studies have indicated that cerebral atrophy can be found in patients with Cushing's syndrome (CS), but its evolution after cure has not been studied extensively. We report the presence of apparent cerebral atrophy in CS and its reversibility after the correction of hypercortisolism. Thirty-eight patients with CS, including 21 with Cushing's disease and 17 with adrenal CS were studied. The control groups consisted of 18 patients with other non-ACTH-secreting sellar tumors and 20 normal controls. Twenty-two patients with CS were reevaluated after cure. Subjective loss of brain volume was present in 86% of patients with Cushing's disease and 100% of patients with adrenal CS. The values for third ventricle diameter, bicaudate diameter, and subjective evaluation were significantly increased in CS groups in comparison with the control group (P < or = 0.001). Imaging reevaluated at 39.7 +/- 34.1 months after achieving eucortisolism showed an improvement of the third ventricle diameter (P = 0.001), bicaudate diameter (P < 0.0005), and subjective evaluation (P = 0.05). We conclude that brain volume loss is highly prevalent in CS and is at least partially reversible following correction of hypercortisolism.