title: Ventilation and perfusion lung scintigraphy of allergen-induced airway responses in atopic asthmatic subjects.
abstract: BACKGROUND
  Both ventilation (V) and perfusion (Q) of the lungs are altered in asthma, but their relationships with allergen-induced airway responses and gas exchange are not well described.
  
  
  METHODS
  The effects of aerosolized allergen provocation of V/Q abnormalities in nonsmoking, male atopic asthmatics (six dual responders and two isolated early responders) were compared with measurements of airflow limitation (forced expiratory volume in 1 s [FEV(1)]), gas exchange (arterial oxygen saturation, arterial oxygen partial pressure and alveolar-arterial oxygen gradient) and airway reactivity (provocative concentration of histamine causing a decrease of 20% in FEV(1)). V and Q lung scans at 30 min and 6 h following allergen challenge and changes in all variables were compared with prechallenge data. Digital image data were registered to baseline scans, and quantitative comparisons of changes made were supported by qualitative assessments of the images.
  
  
  RESULTS
  All subjects showed evidence of impaired gas exchange, as reflected by lowered arterial oxygen tension and widened alveolar arterial oxygen gradients. Baseline V/Q scans were abnormal, and there were allergen-induced changes in V and Q at 30 min, with scans at 6 h showing additional changes in Q, particularly in dual responders. Allergen-induced gas trapping was evident at 30 min and was sustained at 6 h.
  
  
  CONCLUSIONS
  Regional patterns of V and Q derived from lung scintigraphy showed a wider range of disturbances than were indicated by the magnitude of airflow limitation and arterial hypoxemia following allergen provocation, and they remained abnormal despite normalization of FEV(1). Imaging of regional abnormalities of gas exchange may be relevant in the evaluation of patients with asthma.
authors: Department of Respiratory Medicine, Sunderland Royal Hospital, Sunderland, UK. parames@mcmaster.ca
authors: Krishnan
authors: K
authors: Parameswaran
authors: Andrew C
authors: AC
authors: Knight
authors: Niall P
authors: NP
authors: Keaney
authors: E David
authors: ED
authors: Williams
authors: Ian K
authors: IK
authors: Taylor
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D000485:Allergens / Q000008:administration & dosage*; D001249:Asthma / Q000000981:diagnostic imaging* / Q000276:immunology / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000379:methods; D005541:Forced Expiratory Volume; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D011659:Pulmonary Gas Exchange; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012129:Respiratory Function Tests; D013668:Technetium Tc 99m Aggregated Albumin; D014692:Ventilation-Perfusion Ratio
chemical_list: D000485:Allergens; D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin
references: J Nucl Med. 1995 Jun;36(6):1115-22
references: 7769437
references: Lancet. 1996 Apr 6;347(9006):937-40
references: 8598758
references: Eur Respir J. 1996 Jun;9(6):1278-82
references: 8804949
references: Am J Respir Crit Care Med. 1996 Nov;154(5):1505-10
references: 8912772
references: J Allergy Clin Immunol. 1997 Jul;100(1):44-51
references: 9257786
references: Eur Respir J. 1998 Jul;12(1):3-5
references: 9701405
references: Proc Am Thorac Soc. 2004;1(4):329-37
references: 16113454
references: Am Rev Respir Dis. 1978 Sep;118(3):511-24
references: 707879
references: Am Rev Respir Dis. 1978 Sep;118(3):525-36
references: 707880
references: Lung. 1979;156(3):185-94
references: 470434
references: Br J Radiol. 1983 Feb;56(662):109-12
references: 6218852
references: Clin Sci (Lond). 1984 May;66(5):525-31
references: 6705479
references: J Nucl Med. 1984 May;25(5):564-70
references: 6233406
references: Eur J Nucl Med. 1984;9(11):502-7
references: 6519110
references: Thorax. 1985 Jul;40(7):519-25
references: 3898461
references: Eur J Nucl Med. 1986;12(1):16-20
references: 3732305
references: Eur J Respir Dis Suppl. 1986;143:22-7
references: 3462009
references: Eur J Respir Dis Suppl. 1986;143:44-7
references: 3462015
references: Eur J Respir Dis Suppl. 1986;143:62-6
references: 3462018
references: Thorax. 1986 Jul;41(7):542-51
references: 3491441
references: Am Rev Respir Dis. 1987 Jan;135(1):264-7
references: 3800152
references: Am Rev Respir Dis. 1988 May;137(5):1055-61
references: 3195803
references: Lancet. 1991 Mar 23;337(8743):690-4
references: 1672176
references: Am Rev Respir Dis. 1991 Jul;144(1):88-94
references: 2064144
references: Eur Respir J. 1992 Nov;5(10):1176-83
references: 1486962
references: Allergy. 1993;48(17 Suppl):138-42; discussion 143-5
references: 8109706
references: Respiration. 1994;61(2):68-73
references: 8008990