PFT Corner #41 Helium Flow-Volume Loop in an Asthmatic Patient

Acres JC , Kryger MH . Clinical significance of pulmonary function tests: upper airway obstruction. Chest 1981;80:207–211.

Robertson DR , Swinburn CR , Stone TN , Gibson GJ . Effects of an external resistance on maximum flow in chronic obstructive lung disease: implications for recognition of coincident upper airway obstruction. Thorax 1989;44:461–468.

Lavelle TF Jr , Rotman HH , Weg JG . Isoflow-volume curves in the diagnosis of upper airway obstruction. Am Rev Respir Dis 1978;117:845–852.

Tenholder MF , Moser RJ , Koval JC , Bennett LL , Rajagopal KR . The flow volume loop in upper airway obstruction masquerading as asthma. Immunol Allerg Prac 1987;9:33–43.

Christopher KL , Wood RP II , Eckert RC , Blager FB , Raney RA , Souhrada JF . Vocal-cord dysfunction presenting as asthma. N Engl J Med 1983;308:1566–1570.

Armstrong JB , Williams J. PFT Corner #37-A case of "flat" spirometry. Respir Care 1990;35:909–912.

Gelb AF , Tashkin DP , Epstein JD , Zamel N. Nd-YAG laser surgery for severe tracheal stenosis physiologically and clinically masked by severe diffuse obstructive pulmonary disease. Chest 1987;91:166–170.

Miller RD , Hyatt RE . Obstructing lesions of the larynx and trachea: clinical and physiologic characteristics. Mayo Clin Proc 1969;44:145–161.

Rotman HH , Liss HP , Weg JG . Diagnosis of upper airway obstruction by pulmonary function testing. Chest 1975;68:796–799.

Owens GR , Murphy DMF . Spirometric diagnosis of upper airway obstruction. Arch Intern Med 1983;143:1331–1334.

Drazen JM , Loring SH , Ingram RH Jr . Localization of airway constriction using gases of varying density and viscosity. J Appl Physiol 1976;41:396–399.

Berend N , Nelson NA , Rutland J , Marlin GE , Woolcock AJ . The maximum expiratory flow-volume curve with air and a low-density gas mixture: an analysis of subject and observer variability. Chest 1981;80:23–30.

Li K-YR , Tan LT-K , Chong P , Dosman JA . Between-technician variation in the measurement of spirometry with air and helium. Am Rev Respir Dis 1981;124:196–198.

Dawson A. Low-density gas spirometry. In: Clausen JL , ed. Pulmonary function testing guidelines and controversies: equipment, methods, and normal values. San Diego: Academic Press, 1982:99–103.

Despas PJ , Leroux M , Macklem PT . Site of airway obstruction in asthma as determined by measuring maximal expiratory flow breathing air and a helium-oxygen mixture. J Clin Invest 1972;51:3235–3243.

Antic R , Macklem PT . The influence of clinical factors on site of airway obstruction in asthma. Am Rev Respir Dis 1976;114:851–859.