Pulse oximetry coupled with spirometry in the emergency department helps differentiate an asthma exacerbation from possible vocal cord dysfunction

Purpose Spirometry performed by adolescents with refractory wheeze or stridor and respiratory distress, with normal room air oxygen saturation, may differentiate subjects not having an acute asthma exacerbation (AE−) from those who are (AE+). A subpopulation may also be identified that has flow volume loop (FVL) patterns consistent with vocal cord dysfunction (VCD). Methods Spirometry was performed by adolescents who presented to a pediatric emergency department (ED) with respiratory distress attributed to an acute AE who, after therapy, were still symptomatic and had room air oxygen saturation ≥97%. Spirometry findings were classified as: (a) consistent with an acute AE, (b) variable extrathoracic airway obstruction pattern consistent with VCD, (c) a combination of the two, or (d) normal airflow. Results Of 2,073 adolescent visits for asthma seen in the ED in 2005, 20 encounters among 17 adolescents were examined during the period of 0700–2200 on weekdays when an investigator was available, of which, 15 encounters were classified as AE−. In the AE− group, nine had FVL evidence of variable extrathoracic airway obstruction consistent with VCD, and six had normal spirometry. Three of the five encounters that were AE+ had FVL evidence consistent with VCD. Conclusions Spirometry, performed on therapy-resistant wheezing or stridorous adolescent patients in respiratory distress with oxygen saturation ≥97%, may help differentiate patients who are not having an acute AE from those who are. In those subjects not having an acute AE, respiratory distress may prove to be due to VCD. Pediatr Pulmonol. 2007; 42:605–609. © 2007 Wiley-Liss, Inc.