Airway obstruction, upper airway artifact and response to bronchodilator in asthmatic and healthy children.
BACKGROUND
The forced oscillation technique (FOT) may be affected by the upper airway artifact in children with airway obstruction. The aim was to test the impact of the artifact on FOT ability to diagnose asthma in children as recommended by current guidelines.


METHODS
The FOT was performed in 58 asthmatics and 27 controls before and after salbutamol. Respiratory resistance (Rrs) was measured at 8 Hz with a standard generator (SG), and a head generator (HG) that minimizes the upper airway artifact. The response to salbutamol was computed as change in respiratory resistance (Δ%Rrs) and admittance (Δ%Ars) that almost cancels the effect of the upper airway artifact.


RESULTS
Rrs and Δ%Rrs were significantly larger in patients than controls by HG (respectively P < 0.001 and P = 0.002) but not SG, while Δ%Ars was larger in asthma than control by both (P < 0.04). Best discriminators between patients and controls were Rrs or Δ%Rrs by HG and Δ%Ars by SG.


CONCLUSIONS
In asthmatic children, the upper airway artifact significantly impacts FOT measurements. The diagnostic value may be improved by minimization of the shunt, such as the computation of Δ%Ars.
Service d'explorations fonctionnelles pédiatriques, Hôpital d'enfants, CHU de Nancy, France.
Iulia
I
Ioan
EA 3450 DevAH-Laboratoire de Physiologie, Faculté de Médecine, Université Lorraine, Vandoeuvre, France.
Laurianne
L
Coutier
Service d'explorations fonctionnelles pédiatriques, Hôpital d'enfants, CHU de Nancy, France.|EA 3450 DevAH-Laboratoire de Physiologie, Faculté de Médecine, Université Lorraine, Vandoeuvre, France.
Claude
C
Bonabel
EA 3450 DevAH-Laboratoire de Physiologie, Faculté de Médecine, Université Lorraine, Vandoeuvre, France.
Joris
J
Albrecht
EA 3450 DevAH-Laboratoire de Physiologie, Faculté de Médecine, Université Lorraine, Vandoeuvre, France.
Bruno
B
Demoulin
Service d'explorations fonctionnelles pédiatriques, Hôpital d'enfants, CHU de Nancy, France.|EA 3450 DevAH-Laboratoire de Physiologie, Faculté de Médecine, Université Lorraine, Vandoeuvre, France.
François
F
Marchal
Service d'explorations fonctionnelles pédiatriques, Hôpital d'enfants, CHU de Nancy, France.|EA 3450 DevAH-Laboratoire de Physiologie, Faculté de Médecine, Université Lorraine, Vandoeuvre, France.
Cyril
C
Schweitzer
Service d'explorations fonctionnelles pédiatriques, Hôpital d'enfants, CHU de Nancy, France.|EA 3450 DevAH-Laboratoire de Physiologie, Faculté de Médecine, Université Lorraine, Vandoeuvre, France.
Silvia
S
Varechova
D000402:Airway Obstruction / Q000188:drug therapy* / Q000503:physiopathology; D000403:Airway Resistance / Q000187:drug effects* / Q000502:physiology; D000420:Albuterol / Q000494:pharmacology / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D001993:Bronchodilator Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D016896:Treatment Outcome
D001993:Bronchodilator Agents; D000420:Albuterol
asthma; bronchomotor tone; forced oscillation; respiratory admittance, head generator