Abnormal flow volume loops in patients with intrathoracic Hodgkin's disease

Study objectives: To study the incidence of upper airway obstruction, as me asured on the flow volume loop (FVL), in patients with bulky mediastinal Ho dgkin's disease; to correlate the FVL with CT of the chest; and to follow t he changes in the FVL after treatment of the tumor. Design: Retrospective study of pulmonary function tests (PFTs) and chest CT s performed as part of a clinical trial for Hodgkin's disease. Setting: Memorial Sloan-Kettering Cancer Center, a comprehensive cancer car e center. Patients: Twenty-five patients (15 men and 10 women; age range, 20 to 57 ye ars) with bulky mediastinal Hodgkin's disease enrolled in a clinical trial of chemotherapy followed by external beam radiation therapy, Measurements and results: Fourteen of 25 patients (56%) had an abnormal FVL prior to therapy; after chemotherapy, only 7 of 25 patients (28%) had an a bnormal FVL, The abnormal patterns seen were either those typical of fixed obstruction or variable extrathoracic obstruction. No patient had a pattern typical of variable intrathoracic obstruction, On chest CT scan, 16 patien ts had grade-I tracheal deformity; 6 had grade-II deformity, and 3 had grad e-III deformity. All three patients with grade-III deformity had a fixed ob struction pattern, as did three patients with a grade-I pattern. Patients w ith a fixed pattern on FVL had significant decreases in inspiratory and exp iratory flow rates. Conclusion: FVL abnormalities suggesting upper airway obstruction occurred in > 50% of patients with bulky mediastinal Hodgkin's disease. A fixed patt ern of obstruction was associated with the lower flow rates and severe trac heal distortion on CT; these patients may warrant special attention prior t o general anesthesia or invasive procedures. Asymptomatic patients with abn ormal FVLs but normal tracheal profiles need not undergo extensive evaluati on, No patients showed the expected pattern typical of intrathoracic obstru ction, but rather the major effect was on the inspiratory loop. The authors speculate on the mechanism for this unexpected finding.