PURPOSE: Normal room air oxygen saturation measured by pulse oximetry in adolescents presenting with refractory wheeze and respiratory distress may suggest a condition other than status asthmaticus. Spirometry performed by these individuals may delineate those that are not in status asthmaticus (SA-) from those who are (SA+). A subpopulation may also be identified that has flow volume loop (FVL) patterns consistent with vocal cord dysfunction (VCD).
METHODS: Spirometry was performed by adolescent patients who presented to the emergency department (ED) at Columbus Children’s Hospital with respiratory distress attributed to acute asthma who, after therapy, were still symptomatic with room air oxygen saturation ≥ 97%. Spirometry findings were classified as: a) small airway obstruction consistent with SA+ (FEV1 ≤ 65% or concave expiratory loop), b) variable extrathoracic airway obstruction pattern consistent with VCD (truncated inspiratory loop), c) a combination of the two or d) normal airflow.
RESULTS: In 17 patients, age 12-17 years, with a total of 20 ED encounters, 15 encounters were classified as SA- on spirometry. (Table) The difference in the mean percent predicted FEV1 between the SA- (99.5% ± 11.2) and SA+ (68.2% ± 12.5) groups was statistically significant (p<0.0001 two-sided t-test). In the SA- group, nine had FVL evidence of variable extrathoracic airway obstruction consistent with VCD and six had normal spirometry. (Figure) Three of the five encounters that were SA+ also had FVL evidence of VCD.
CONCLUSION: Spirometry, performed on therapy-resistant wheezing or stridorous adolescent patients with oxygen saturation ≥ 97%, may help differentiate patients who are not in status asthmaticus from those who are. In a significant percent of these persistently symptomatic patients who are not in status asthmaticus, respiratory distress may be due to VCD.
CLINICAL IMPLICATIONS: In adolescents seen in the ED with acute respiratory distress with normal oxygen saturation after therapy, performing spirometry may help differentiate those subjects who are not experiencing status asthmaticus from those subjects who are. Additionally, spirometry may identify a subpopulation whose acute dyspnea may be due to VCD.
DISCLOSURE: Paul Nolan, None.