- Loutfi Sami Aboussouan, MD
Loutfi Sami Aboussouan, MD
- Cleveland Clinic Foundation
- James K Stoller, MD, MS
James K Stoller, MD, MS
- Section Editor — Chronic Obstructive Pulmonary Disease
- Jean Wall Bennett Professor of Medicine, Samson Global Leadership Academy Endowed Chair
- Cleveland Clinic Lerner College of Medicine
- Chairman, Education Institute, Cleveland Clinic
- Section Editors
- Peter J Barnes, DM, DSc, FRCP, FRS
Peter J Barnes, DM, DSc, FRCP, FRS
- Editor-in-Chief — Pulmonary, Critical Care, and Sleep Medicine
- Section Editor — Asthma
- Professor of Medicine
- National Heart and Lung Institute, Imperial College, London
- Robert A Wood, MD
Robert A Wood, MD
- Editor-in-Chief — Allergy and Immunology
- Section Editor — Pediatric Allergy
- Professor of Pediatrics
- Johns Hopkins University School of Medicine
Spirometry, which includes measurement of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), is the most readily available and most useful pulmonary function test. The flow-volume loop (also called a spirogram) is a plot of inspiratory and expiratory flow (on the Y-axis) against volume (on the X-axis) during the performance of maximally forced inspiratory and expiratory maneuvers.
The normal expiratory portion of the flow-volume curve is characterized by a rapid rise to the peak flow rate, followed by a nearly linear fall in flow as the patient exhales toward residual volume (figure 1). The inspiratory curve, in contrast, is a relatively symmetrical, saddle-shaped curve. The flow rate at the midpoint of exhalation (between total lung capacity and residual volume) is normally approximately equivalent to the flow rate at the midpoint of inspiration.
Changes in the contour of the loop can aid in the diagnosis and localization of airway obstruction . Characteristic flow-volume loop patterns are also often found in certain forms of restrictive disease, although flow-volume studies are not considered primary diagnostic aids in the evaluation of these disorders.
An overview of flow-volume loops will be presented here. A general review of pulmonary function testing, including the indications for spirometry, is provided separately. (See "Overview of pulmonary function testing in adults".)
OBSTRUCTIVE PULMONARY DISEASE
A frequently recognized abnormality in the flow-volume loop is the concave upward or "scooped-out," or "coved" pattern encountered in asthma or chronic obstructive pulmonary disease (COPD) (figure 2). Maximal expiratory flow rates during the latter two-thirds of an expiratory maneuver are largely effort independent (ie, flow cannot be accelerated by increased expiratory effort), and vary directly with the elastic recoil of the lung and inversely with the airway resistance upstream of the equal pressure point.
- Aboussouan LS, Stoller JK. Diagnosis and management of upper airway obstruction. Clin Chest Med 1994; 15:35.
- Miller RD, Hyatt RE. Obstructing lesions of the larynx and trachea: clinical and physiologic characteristics. Mayo Clin Proc 1969; 44:145.
- Miller RD, Hyatt RE. Evaluation of obstructing lesions of the trachea and larynx by flow-volume loops. Am Rev Respir Dis 1973; 108:475.
- Sharief N, Wiseman NW, Higgins M, Chernick V. Abnormal flow-volume loop leading to the diagnosis of bronchogenic cyst. Pediatr Pulmonol 1999; 27:218.
- Gamsu G, Borson DB, Webb WR, Cunningham JH. Structure and function in tracheal stenosis. Am Rev Respir Dis 1980; 121:519.
- Vander Els NJ, Sorhage F, Bach AM, et al. Abnormal flow volume loops in patients with intrathoracic Hodgkin's disease. Chest 2000; 117:1256.
- Harrison BD. Upper airway obstruction--a report on sixteen patients. Q J Med 1976; 45:625.
- Bahrainwala AH, Simon MR, Harrison DD, et al. Atypical expiratory flow volume curve in an asthmatic patient with vocal cord dysfunction. Ann Allergy Asthma Immunol 2001; 86:439.
- Gelb AF, Tashkin DP, Epstein JD, et al. Physiologic characteristics of malignant unilateral main-stem bronchial obstruction. Diagnosis and Nd-YAG laser treatment. Am Rev Respir Dis 1988; 138:1382.
- Gelb AF, Tashkin DP, Epstein JD, et al. Diagnosis and Nd-YAG laser treatment of unsuspected malignant tracheal obstruction. Chest 1988; 94:767.
- Gascoigne AD, Corris PA, Dark JH, Gibson GJ. The biphasic spirogram: a clue to unilateral narrowing of a mainstem bronchus. Thorax 1990; 45:637.
- Rhodes, ML. End inspiratory plateau: Flow volume loop (FVL) in localized bronchial stenosis. Am Rev Respir Dis 1980; 121:s182.
- Neagos, GR, Martinez, FJ, Deeb, GM, et al. Diagnosis of unilateral mainstem bronchial obstruction following single-lung transplantation with routine spirometry. Chest 1993; 103:1255.
- Haponik EF, Bleecker ER, Allen RP, et al. Abnormal inspiratory flow-volume curves in patients with sleep-disordered breathing. Am Rev Respir Dis 1981; 124:571.
- Sanders MH, Martin RJ, Pennock BE, Rogers RM. The detection of sleep apnea in the awake patient. The 'saw-tooth' sign. JAMA 1981; 245:2414.
- Hoffstein V, Wright S, Zamel N. Flow-volume curves in snoring patients with and without obstructive sleep apnea. Am Rev Respir Dis 1989; 139:957.
- Zamel N. Flow volume curve: the "saw-tooth" sign. Eur J Respir Dis 1986; 69:73.
- Vincken WG, Gauthier SG, Dollfuss RE, et al. Involvement of upper-airway muscles in extrapyramidal disorders. A cause of airflow limitation. N Engl J Med 1984; 311:438.
- Schiffman PL. A "saw-tooth" pattern in Parkinson's disease. Chest 1985; 87:124.
- Ramírez J, León I, Rivera LM. Episodic laryngeal dyskinesia. Clinical and psychiatric characterization. Chest 1986; 90:716.
- Rendleman N, Quinn SF. The answer is blowing in the wind: a pedunculated tumour with saw tooth flow-volume loop. J Laryngol Otol 1998; 112:973.
- Garcia-Pachon E. Tracheobronchomalacia: a cause of flow oscillations on the flow-volume loop. Chest 2000; 118:1519.
- Haponik EF, Munster AM, Wise RA, et al. Upper airway function in burn patients. Correlation of flow-volume curves and nasopharyngoscopy. Am Rev Respir Dis 1984; 129:251.
- Katz I, Zamel N, Slutsky AS, et al. An evaluation of flow-volume curves as a screening test for obstructive sleep apnea. Chest 1990; 98:337.
- Al-Bazzaz F, Grillo H, Kazemi H. Response to exercise in upper airway obstruction. Am Rev Respir Dis 1975; 111:631.
- Modrykamien AM, Gudavalli R, McCarthy K, et al. Detection of upper airway obstruction with spirometry results and the flow-volume loop: a comparison of quantitative and visual inspection criteria. Respir Care 2009; 54:474.
- Watson MA, King CS, Holley AB, et al. Clinical and lung-function variables associated with vocal cord dysfunction. Respir Care 2009; 54:467.
- Couriel JM, Hibbert M, Olinsky A. Assessment of proximal airway obstruction in children by analysis of flow-volume loops. Br J Dis Chest 1984; 78:36.
- Guntupalli KK, Bandi V, Sirgi C, et al. Usefulness of flow volume loops in emergency center and ICU settings. Chest 1997; 111:481.
- OBSTRUCTIVE PULMONARY DISEASE
- UPPER AIRWAY OBSTRUCTION
- Variable extrathoracic obstruction
- Variable intrathoracic obstruction
- Fixed upper airway obstruction
- Extraluminal airway obstruction
- Variable obstruction at the thoracic inlet
- Mainstem bronchial obstruction
- Saw-tooth pattern
- RESTRICTIVE DISEASE
- SUMMARY AND RECOMMENDATIONS