Determining the time to maximal bronchodilator response in asthmatic children

Assessment of bronchodilator response in preschoolers: A systematic review

BACKGROUND

Several techniques can be used to assess bronchodilator response (BDR) in preschool-aged children, including spirometry, respiratory oscillometry, the interrupter technique, and specific airway resistance. However, there has not been a systematic comparison of BDR thresholds across studies yet.

METHODS

A systematic review was performed on all studies up to May 2023 measuring a bronchodilator effect in children 2-6 years old using one of these techniques (PROSPERO CRD42021264659). Studies were identified using MEDLINE, Cochrane, EMBASE, CINAHL via EBSCO, Web of Science databases, and reference lists of relevant manuscripts.

RESULTS

Of 1224 screened studies, 43 were included. Over 85% were from predominantly European ancestry populations, and only 22 studies (51.2%) calculated a BDR cutoff based on a healthy control group. Five studies included triplicate testing with a placebo to account for the within-subject intrasession repeatability. A relative BDR was most consistently reported by the included studies (95%) but varied widely across all techniques. Various statistical methods were used to define a BDR, with six studies using receiver operating characteristic analyses to measure the discriminative power to distinguish healthy from wheezy and asthmatic children.

CONCLUSION

A BDR in 2- to 6-year-olds cannot be universally defined based on the reviewed literature due to inconsistent methodology and cutoff calculations. Further studies incorporating robust methods using either distribution-based or clinical anchor-based approaches to define BDR are required.

Effect of Albuterol Premedication vs Placebo on the Occurrence of Respiratory Adverse Events in Children Undergoing Tonsillectomies: The REACT Randomized Clinical Trial

IMPORTANCE

Tonsillectomy is a common pediatric procedure for the treatment of sleep-disordered breathing and chronic tonsillitis. Up to half of children having this procedure experience a perioperative respiratory adverse event.

OBJECTIVE

To determine whether inhaled albuterol sulfate (salbutamol sulfate) premedication decreases the risk of perioperative respiratory adverse events in children undergoing anesthesia for tonsillectomy.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, triple-blind, placebo-controlled trial (the Reducing Anesthetic Complications in Children Undergoing Tonsillectomies [REACT] trial) was conducted at Perth Children's Hospital (formerly Princess Margaret Hospital for Children), the only tertiary pediatric hospital in Western Australia. Participants included 484 children aged 0 to 8 years who were undergoing anesthesia for tonsillectomy. The study was conducted between July 15, 2014, and May 18, 2017.

INTERVENTIONS

Participants were randomized to receive either albuterol (2 actuations, 200 μg) or placebo before their surgery.

MAIN OUTCOMES AND MEASURES

Occurrence of perioperative respiratory adverse events (bronchospasm, laryngospasm, airway obstruction, desaturation, coughing, and stridor) until discharge from the postanesthesia care unit.

RESULTS

Of 484 randomized children (median [range] age, 5.6 [1.6-8.9] years; 285 [58.9%] boys), 479 data sets were available for intention-to-treat analysis. Perioperative respiratory adverse events occurred in 67 of 241 children (27.8%) receiving albuterol and 114 of 238 children (47.9%) receiving placebo. After adjusting for age, type of airway device, and severity of obstructive sleep apnea in a binary logistic regression model, the likelihood of perioperative respiratory adverse events remained significantly higher in the placebo group compared with the albuterol group (odds ratio, 2.8; 95% CI, 1.9-4.2; P < .001). Significant differences were seen in children receiving placebo vs albuterol in laryngospasm (28 [11.8%] vs 12 [5.0%]; P = .009), coughing (79 [33.2%] vs 27 [11.2%]; P < .001), and oxygen desaturation (54 [22.7%] vs 36 [14.9%]; P = .03).

CONCLUSIONS AND RELEVANCE

Albuterol premedication administered before tonsillectomy under general anesthesia in young children resulted in a clinically significant reduction in rates of perioperative respiratory adverse events compared with the rates in children who received placebo. Premedication with albuterol should be considered for children undergoing tonsillectomy.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry identifier: ACTRN12614000739617.

Bronchodilator responsiveness in children with asthma is not influenced by spacer device selection

INTRODUCTION

Spacer devices optimize delivery of aerosol therapies and maximize therapeutic efficacy. We assessed the impact of spacer device on the prevalence and magnitude of bronchodilator response (BDR) in children with asthma.

METHODS

Children with physician confirmed asthma and parentally reported symptoms in the last 12 months were recruited for this study. Each participant completed two separate visits (5-10 days apart) with spirometry performed at baseline and following cumulative doses of salbutamol (200, 400, 800, and 200 μg) delivered by either a small volume disposable spacer or a large volume multi-use spacer. Spacer type was alternated for each participant during each visit. The primary outcome was the effect of spacer type on bronchodilator responsiveness. The secondary outcome was to assess the relationships between spacer device, salbutamol dose and the proportion of children with a clinically relevant BDR.

RESULTS

Thirty-two children (mean age 11.8 years) completed both visits. Change in lung function following bronchodilators was increased using the large volume spacer, for relative but not absolute increase in FEV₁ [mean difference (95% confidence intervals): 1.28% (0.02, 2.54; P = 0.047) and 0.013 L (-0.01, 0.04; P = 0.288)], respectively. There was no observed difference in FVC by spacer type. Overall, 59% (n = 19) of children exhibited a clinically relevant BDR at 400 µg of salbutamol for any spacer and was independent of spacer type.

CONCLUSION

Spacer device was not associated with clinically important differences in lung function following bronchodilator inhalation in children with asthma. At a recommended dose of 400 μg, some children with asthma may have their bronchodilator responsiveness misclassified.

Determining the optimal time to assess the reversibility of airway obstruction

Context:

The optimal time to interpret bronchodilator reversibility remains controversial. This time may affect a positive diagnosis and manage asthma and chronic obstructive pulmonary disease (COPD).

Aims:

We sought to document the time when maximum respiratory function is reached after inhalation of salbutamol and to define the optimal time of bronchodilator response to assess the reversibility or non reversibility of airway obstruction.

Subjects and Methods:

This prospective analytical study was spread over 8 months and included 58 patients with asthma or COPD with airway obstruction. Spirometry was performed before and at 5, 10, 15, 20, and 30 min after salbutamol inhalation (200 mcg) administered through pressurized metered-dose inhalers and large volume spacer.

Results:

After salbutamol inhalation, the mean individual peak bronchodilation occurred at 20 min for the forced vital capacity and at 30 min for the forced expiratory volume in 1 s. The percentage of reversible patients in our sample was guideline dependent. It increased from 53% to 67.2% when using the American Thoracic Society/European Respiratory Society definition compared to using the Global Initiative for Chronic Obstructive Lung Disease. The maximum number of reversible patients was significantly different at 20 min compared to 5 and 10 min.

Conclusions:

Interpreting bronchodilator reversibility after 20 min was the ideal time to judge the reversibility or nonreversibility in obstructive ventilatory disorders in adults.

Effect of extending the time after bronchodilator administration on identifying bronchodilator responsiveness in a pediatric pulmonary clinic

OBJECTIVES

American Thoracic Society/European Respiratory Society (ATS/ERS) spirometry interpretation guidelines recommend ≥15 min between pre- and post-bronchodilator testing to evaluate for a bronchodilator response. We aimed to lengthen the time between albuterol administration and post-bronchodilator testing to adhere to ATS/ERS guidelines and evaluated if lengthening this wait time would increase the percentage of patients classified as bronchodilator responsive.

METHODS

We compared the proportion of patients with a positive bronchodilator response between two groups of children with asthma, one group in which post-bronchodilator administration wait times were not standardized (pre-intervention) to another in which the wait time was extended to 15 min to adhere to ATS/ERS standards (post-intervention). We also determined the effect of this intervention on clinic appointment duration.

RESULTS

The analysis included 271 patients (145 pre-intervention and 126 post-intervention). The average wait time in the pre-intervention group was 6.5 ± 2.1 (mean ± SD) minutes compared to 16.2 ± 3.2 min (P < 0.001) post intervention, and clinic times increased from 83.0 ± 29.6 min to 91.7 ±22.5 min (P < 0.007) from the pre- to post-intervention group, respectively. In adjusted regression analysis, there was no significant change in FEV₁ % predicted between the two groups.

CONCLUSIONS

In a busy pediatric pulmonary clinic, while we successfully lengthened time between albuterol administration and post-bronchodilator testing in the vast majority of patients, no difference was seen in the percentage of patients classified as bronchodilator responsive. Results from this study appear to question the ATS/ERS recommended 15 min post-bronchodilator administration wait time for children.

The relationship of the bronchodilator response phenotype to poor asthma control in children with normal spirometry

OBJECTIVE

To determine the relationship of poor asthma control to bronchodilator response (BDR) phenotypes in children with normal spirometry.

STUDY DESIGN

Children with asthma were assessed for clinical indexes of poorly controlled asthma. Pre- and post-bronchodilator spirometry were performed, and the percent BDR was determined. Multivariate logistic regression assessed the relationship of the clinical indices to BDR at ≥ 8%, ≥ 10%, and ≥ 12% BDR thresholds.

RESULTS

There were 510 controller naïve children and 169 on controller medication. In the controller naïve population the mean age (± 1 SD) was 9.5 (3.4); 57.1% were male, 85.7% Hispanic. Demographics were similar in both populations. In the adjusted profile, significant clinical relationships were found particularly to positive BDR phenotypes ≥ 10% and ≥ 12% versus negative responses including younger age, (OR 2.0, 2.5; P < .05), atopy (OR 1.9, 2.6; P < .01), nocturnal symptoms in females (OR 3.4, 3.8; P < .01); β₂ agonist use (OR 1.7, 2.8; P < .01); and exercise limitation (OR 2.2, 2.5; P < .01) only in the controller naïve population.

CONCLUSIONS

The BDR phenotype ≥ 10% is significantly related to poor asthma control, providing a potentially useful objective tool in controller naïve children even when the pre-bronchodilator spirometry result is normal.

Lung function measurement in the assessment of childhood asthma: recent important developments

PURPOSE OF REVIEW

To present three clinically important developments related to the utilization of pulmonary function to objectively assess the asthmatic child.

RECENT FINDINGS

The new asthma guidelines (2007) have added the forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio to the FEV1 as spirometric criteria for classifying asthma. Although a better indicator of airway obstruction, it has not clearly been shown to correlate with clinical criteria. The normal cut point for the ratio used in the guidelines of 85% for children may be too high, and compared to the lower limits of normal of 80%, could result in unnecessary treatment in some children. The bronchodilator response (BDR) phenotype reflects airway lability and has been associated with biomarkers of inflammation and responsiveness to inhaled corticosteroids as well as predicting long-term outcomes. Several studies have shown improved spirometric techniques in preschoolers as well as defining normal values in this age group. Impulse oscillometry (IOS), which is less demanding than spirometry, has been shown to identify asthmatic preschoolers in some cases better than spirometry and possibly identifying obstruction in the peripheral airways. It may also be a more useful test than spirometry in evaluating long-term drug studies.

SUMMARY

In addition to the FEV1/FVC ratio to detect airway obstruction, the BDR phenotype would appear to give important additional information regarding airway lability and inflammation, and should be included as routine spirometry. IOS is a promising test to identify asthmatic preschoolers, but more studies are needed to determine exactly what it measures and what constitutes normal values.