Critical Errors in Inhaler Technique among Children Hospitalized with Asthma

Many studies have shown that improved control can be achieved for most children with asthma if inhaled medications are taken correctly and adequately.^1-3 Drug delivery studies have shown that bioavailability of medication with a pressurized metered-dose inhaler (MDI) improves from 34% to 83% with the addition of spacer devices. This difference is largely due to the decrease in oropharyngeal deposition,^1,4,5 and therefore, the use of a spacer with proper technique has been recommended in all pediatric patients.^1,6

Poor inhaler technique is common among children.^1,7 Previous studies of children with asthma have evaluated inhaler technique, primarily in the outpatient and community settings, and reported variable rates of error (from 45% to >90%).^8,9 No studies have evaluated children hospitalized with asthma. As these children represent a particularly high-risk group for morbidity and mortality,^10,11 the objectives of this study were to assess errors in inhaler technique in hospitalized asthmatic children and identify risk factors for improper use.

As part of a larger interventional study, we conducted a prospective cross-sectional study at a tertiary urban children’s hospital. We enrolled a convenience sample of children aged 2-16 years admitted to the inpatient ward with an asthma exacerbation Monday-Friday from 8 AM to 6 PM. Participants were required to have a diagnosis of asthma (an established diagnosis by their primary care provider or meets the National Heart, Lung, and Blood Institute [NHLBI] criteria¹), have a consenting adult available, and speak English. Patients were excluded if they had a codiagnosis of an additional respiratory disease (ie, pneumonia), cardiac disease, or sickle cell anemia. The Institutional Review Board approved this study.

We asked caregivers, or children >10 years old if they independently use their inhaler, to demonstrate their typical home inhaler technique using a spacer with mask (SM), spacer with mouthpiece (SMP), or no spacer (per their usual home practice). Inhaler technique was scored using a previously validated asthma checklist (Table 1).¹² Certain steps in the checklist were identified as critical: (Step 1) removing the cap, (Step 3) attaching to a spacer, (Step 7) taking six breaths (SM), and (Step 9) holding breath for five seconds (SMP). Caregivers only were also asked to complete questionnaires assessing their literacy (Brief Health Literacy Screen [BHLS]), confidence (Parent Asthma Management Self-Efficacy scale [PAMSE]), and any barriers to managing their child’s asthma (Barriers to Asthma Care). Demographic and medical history information was extracted from the medical chart.

Inhaler technique was evaluated in two ways by comparing: (1) patients who missed more than one critical step with those who missed zero critical steps and (2) patients with an asthma checklist score <7 versus ≥7. While there is a lot of variability in how inhaler technique has been measured in past studies, these two markers (75% of steps and critical errors) were the most common.⁸

We assessed a number of variables to evaluate their association with improper inhaler technique. For categorical variables, the association with each outcome was evaluated using relative risks (RRs). Bivariate P-values were calculated using chi-square or Fisher’s exact tests, as appropriate. Continuous variables were assessed for associations with each outcome using two-sample t-tests. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression analyses. Using a model entry criterion of P < .10 on univariate tests, variables were entered into a multivariable logistic regression model for each outcome. Full models with all eligible covariates and reduced models selected via a manual backward selection process were evaluated. Two-sided P-values <.05 were considered statistically significant.