Beta2-agonist drugs are used for the treatment of asthma and work by opening the airways to help people breathe more easily. Beta2-agonists can be given to people in two different ways – intravenously (directly thorough a vein) and via an inhaler. Inhalers are one of the most important treatments for people with acute severe asthma. The question this review considered was whether treatment would offer additional benefit if patients received these drugs both ways (by breathing them via an inhaler and receiving them directly through a vein) than by just inhaling them alone. This review examined all the randomised controlled trials on the use of intravenous beta2-agonists in addition to inhaled beta2-agonists with existing standard care (such as steroids either taken as tablets of by injection) in severe acute asthma.
We found three trials involving 104 people (75 children and 29 adults) with acute asthma. There was no significant difference in adults receiving intravenous beta-agonists as well as standard care in the one small trial considering this comparison. We also looked at length of stay in the emergency department. Two reported shorter recovery time or quicker discharge from the emergency department in patients also receiving intravenous beta-agonists. One trial reported that more children experienced tremor if they had received injected beta-agonists whereas another trial, with adults, reported no significant difference in adverse effects. As there are so few trials and so few included patients we cannot be sure about the reliability of these findings.
This review found that until more, larger, high quality clinical trials in this area are conducted it is not possible to judge whether there is any enhanced benefit using additional intravenous beta2-agonists in children or adults with severe acute asthma compared with inhaled beta2-agonists alone.
There is very limited evidence from one study (Browne 1997) to support the use of IV beta2-agonists in children with severe acute asthma with respect to shorter recovery time, and similarly there is limited evidence (again from one study Browne 1997) suggesting benefit with regard to pulmonary index scores; however this advantage needs to be considered carefully in relation to the increased side effects associated with IV beta2-agonists. We identified no significant benefits for adults with severe acute asthma. Until more, adequately powered, high quality clinical trials in this area are conducted it is not possible to form a robust evaluation of the addition of IV beta2-agonists in children or adults with severe acute asthma.
Inhaled beta-agonist therapy is central to the management of acute asthma. This review evaluates the benefit of an additional use of intravenous beta2-agonist agents.
To determine the benefit of adding intravenous (IV) beta2-agonists to inhaled beta2-agonist therapy for acute asthma treated in the emergency department.
Randomised controlled trials (RCTs) were identified using the Cochrane Airways Group Register which is a compilation of systematic searches of MEDLINE, EMBASE, CINAHL, and CENTRAL as well as handsearching of 20 respiratory journals. Bibliographies from included studies and known reviews were also searched. Primary authors and content experts were contacted to identify eligible studies. The search was performed in September 2012.
Only RCTs were considered for inclusion. Studies were included if patients presented to the emergency department with acute asthma and were treated with IV beta2-agonists with inhaled beta2-agonist therapy and existing standard treatments versus inhaled beta2-agonists and existing standard treatments.
Two review authors independently extracted data and confirmed their findings with corresponding authors of trials. We obtained missing data from authors or calculated from data present in the papers. We used fixed-effect model for odds ratios (OR) and for mean differences (MD) we used both fixed-effect and random-effects models and reported 95% confidence intervals (CI).
From 109 potentially relevant studies only three (104 patients) met our inclusion criteria: Bogie 2007 (46 children), Browne 1997 (29 children) and Nowak 2010 (29 adults). Bogie 2007 investigated the addition of intravenous terbutaline to high dose nebulised albuterol in children with acute severe asthma, requiring intensive care unit (ICU) admission. Browne 1997 investigated the benefit of adding intravenous salbutamol to inhaled salbutamol in children with acute severe asthma in the emergency department. Nowak 2010 investigated addition of IV bedoradrine to standard care (nebulised albuterol, ipratropium and oral corticosteroids) among adults, and was reported as a conference abstract only.
There was no significant advantage (OR 0.29; 95%CI 0.06 to 1.38, one trial, 29 adults) for adding IV bedoradrine to standard care (nebulised albuterol, ipratropium and oral corticosteroids) with regard to hospitalisation rates.
Various outcome indicators for the length of stay were reported among the trials. Browne 1997 reported a significantly shorter recovery time (in terms of cessation of 30 minute salbutamol) for children in the IV salbutamol with inhaled salbutamol group (four hours) versus the 11.1 hours for the inhaled salbutamol group (P = 0.03). Time to cessation of hourly nebuliser was also significantly shorter (P = 0.02) for the IV plus inhaled salbutamol group (11.5 hours versus 21.2 hours), and they were ready for emergency patient discharge on average 9.7 hours earlier than the inhaled salbutamol group (P < 0.05). In a paediatric ICU study Bogie 2007 reported no significant advantage in length of paediatric ICU admission (hours) for adding IV terbutaline to nebulised albuterol (MD -12.95, 95% CI: -38.74, 12.84).
Browne 1997 reported there were only six out of 14 children with a pulmonary index score above six in the IV plus inhaled salbutamol group at two hours compared with 14 of the 15 in the inhaled salbutamol group (P = 0.02)
In Browne 1997 there was a higher proportion of tremor in the IV plus inhaled salbutamol group than in the inhaled salbutamol group (P < 0.02). Nowak 2010 did not report any statistically significant adverse effects associated with adding IV bedoradrine to standard care (nebulised albuterol, ipratropium and oral corticosteroids). Troponin levels were elevated in three children in the IV terbutaline + nebulised albuterol group at 12 and 24 hours in Bogie 2007