Efficacy and Safety of Increasing Doses of Inhaled Albuterol in Children With Acute Wheezing Episodes

Efficacy and Safety of Increasing Doses of Inhaled Albuterol in Children With Acute Wheezing Episodes

Efficacy and Safety of Increasing Doses of Inhaled Albuterol Administered by Metered Dose Inhalers in Children With Acute Wheezing Episodes

Metered dose inhalers with spacers are devices capable of providing higher rates of lung deposition of drugs such as beta agonists when compared to conventional nebulizers, but there is no consensus about the optimal dose when this is the device of choice and there is evidence that younger children need proportionally higher doses of albuterol (in μg/kg) when compared to older children. Other factors that may interfere with response to albuterol treatment include the genetics of the beta adrenergic receptor (ADRβ2) and infectious etiology of the wheezing attack. This study will assess the effectiveness of a dose regimen that prioritizes higher doses of albuterol, with doses in μg/kg higher for younger children. Security of this new dosing regimen will be assessed by monitoring clinical side effects and serum levels of albuterol, but the investigators will also examine the presence of 12 different respiratory viruses in these patients and evaluate the influence of ADRβ2 receptor genetics in the response to albuterol. The primary outcome measure will be the need for hospitalization. Secondary outcomes will include a change in clinical score, respiratory rate and forced expiratory volume in the first second, the need for additional treatments and length of stay in the emergency room for those not hospitalized.

This is a prospective, randomized, double blinded, controlled study. The patients will be randomly assigned to one of the treatment groups (experimental or control groups). The patients will be assessed 1 hour later and every 30 minutes thereafter until discharge. Following 4 hours in the emergency room, any patient who do not meet the discharge criteria (PRAM score ≤ 3 and SpO2 ≥ 92%) will be admitted to the hospital. Each patient's attending physician will determine the need for additional therapies following the first hour. Identification of respiratory viruses in the nasal lavage samples wil be performed using the CLART PneumoVir® kit. Albuterol plasmatic levels will be analyzed via HPLC (High Performance Liquid Chromatography). To genotype the ADBR2 receptor (blood samples), the gene regions encompassing the Arg16Gly, Gln27Glu, and Arg19Cys Thr164Ile polymorphisms will be amplified via PCR. The resultant amplimers were then sequenced. A sample of 124 patients (62 in each group) was calculated to provide an 80% power with which to detect a significant difference of at least 30 minutes in the lengths of stay between the groups. The chi-square test will be used to compare hospital admission rates and tremor rates. For all other outcomes, t-tests for mean comparisons (variables with a normal distribution), a Mann Whitney test (nonparametric data) and ANOVA with repeated measures will be used.

Albuterol dosages during the first hour include 900 mcg (up to 15 kg), 1200 mcg (> 15 to 20 kg), 1500 mcg (> 20 to 25 kg) and 1800 mcg (> 25 kg).

The Experimental group will receive higher doses of albuterol in the first hour: 900 mcg (up to 15 kg), 1200 mcg (> 15 to 20 kg), 1500 mcg (> 20 to 25 kg) and 1800 mcg (> 25 kg).

The Control group will receive the following doses of albuterol in the first hour 600 mcg (up to 25 kg) or 1200 mcg (> 25 kg)

Hospital admission was defined as the need to stay in the emergency room for more than 4 hours, due to the failure to meet the discharge criteria (PRAM score ≤ 3 and pulse oximetry, ≥ 92%)

Change in FEV1 one hour post-treatment in comparison with baseline. Spirometry was performed only in subjects older than 6 years and who could perform the maneuver properly.

Change in the Pediatric Respiratory Assessment Measure (PRAM) score one hour post-treatment in comparison with baseline. The PRAM score is used to assess the severity of asthma attacks, it ranges from 0 to 15, and the higher the score, the greater the severity of the attack. We calculated the difference between the PRAM score measured one hour post treatment and the PRAM score at baseline (PRAM score 1 hour - PRAM score baseline). The larger the absolute value of the difference, the better the outcome (e.g., a difference of -4 indicates a better outcome that a difference of -2). minimum value of the difference (Albuterol - Higher Dose, experimental group): -8 maximum value of the difference (Albuterol - Higher Dose, experimental group): 0 minimum value of the difference (Albuterol - Lower Dose, control group): -8 maximum value of the difference (Albuterol - Lower Dose, control group): 0

Albuterol determination in the plasma was carried out at at discharge or hospital admission (up to 4 hours post treatment), dosage was accomplished by High Performance Liquid Chromatography.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment)

Changes in glucose serum levels at discharge or hospital admission (up to 4 hours post treatment) in comparison with baseline.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment) in comparison with baseline.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment)

Change in the Pediatric Respiratory Assessment Measure (PRAM) score at discharge or hospital admission (up to 4 hours post treatment) in comparison with baseline. The PRAM score is used to assess the severity of asthma attacks, it ranges from 0 to 15, and the higher the score, the greater the severity of the attack. We calculated the difference between the PRAM score measured at discharge or admission and the PRAM score at baseline (PRAM score discharge or admission - PRAM score baseline). The larger the absolute value of the difference, the better the outcome (e.g., a difference of -4 indicates a better outcome that a difference of -2). minimum value of the difference (Albuterol - Higher Dose, experimental group): -9 maximum value of the difference (Albuterol - Higher Dose, experimental group): 0 minimum value of the difference (Albuterol - Lower Dose, control group): -9 maximum value of the difference (Albuterol - Lower Dose, control group): 1

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment) in comparison with baseline.

Changes in potassium serum levels at discharge or hospital admission (up to 4 hours post treatment) in comparison with baseline.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment) in comparison with baseline.

Changes in bicarbonate serum levels at discharge or hospital admission (up to 4 hours post treatment) in comparison with baseline.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment) in comparison with baseline.

Changes in respiratory rate at discharge or hospital admission (up to 4 hours post treatment) in comparison with baseline.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment) in comparison with baseline.

Changes in pulse oximetry at discharge or hospital admission (up to 4 hours post treatment) in comparison with baseline.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment) in comparison with baseline.

Changes in heart rate at discharge or hospital admission (up to 4 hours post treatment) in comparison with baseline.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment)

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment)

Admission rates in patients with and without any of the following viruses detected by PCR in nasal lavage samples: Adenovirus; Bocavirus; Coronavirus; Enterovirus (Echovirus); Influenza (A H3N2, A H1N1/2009, B and C); Metapneumovirus (subtypes A and B); Parainfluenza 1, 2, 3 and 4 (subtypes A and B); Rhinovirus; Respiratory Syncytial Virus type A and Respiratory Syncytial Virus type B.

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment)

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment)

Admission rates in patients with the Arg16Gly polymorphisms of the beta-2 adrenergic receptor (Arg16Gly, Arg16Arg and Gly16Gly genotypes).

at discharge or admission (up to 4 hours post treatment, minimum 1 hour, maximum 4 hours post treatment)

Inclusion Criteria: Aged 2 to 18 years; History of two or more previous episodes of wheezing treated with bronchodilators in the last year; Wheezing attacks characterized by coughing, difficulty breathing and auscultation of expiratory wheezing or prolonged expiration; Intensity of wheezing attacks defined by PRAM score as moderate or severe (PRAM ≥ 5). Exclusion Criteria: Pre-existing chronic diseases such as bronchopulmonary dysplasia, cystic fibrosis, bronchiolitis obliterans or other chronic pulmonary or cardiovascular disease; Initial clinical status indicating immediate ventilatory support, need for subcutaneous or intravenous bronchodilators; Decreased level of consciousness; Using a β-agonist in the four hours prior to arrival. Use of corticosteroids in the last 24h.

Muchao FP, Souza AV, Souza JME, Silva Filho LVRFD. Association between beta-2 adrenergic receptor variants and clinical outcomes in children and adolescents with acute asthma. Einstein (Sao Paulo). 2022 Mar 25;20:eAO6412. doi: 10.31744/einstein_journal/2022AO6412. eCollection 2022.

Muchao FP, Souza JM, Torres HC, De Lalibera IB, de Souza AV, Rodrigues JC, Schvartsman C, da Silva Filho LV. Albuterol via metered-dose inhaler in children: Lower doses are effective, and higher doses are safe. Pediatr Pulmonol. 2016 Nov;51(11):1122-1130. doi: 10.1002/ppul.23469. Epub 2016 May 12.