13 December 2010
A study has found that inhalation volumes for children aged 2 to 7 years using spacers are larger than expected. Because only a few tidal breaths are required for efficient drug delivery oral bronchodilators should not be necessary for most young children. Around 15,000 items of beta2 agonist syrups were prescribed in the quarter up to March 2010. It is unknown for which ages of patients these were prescribed, but if some were for children then a review of this route of administration for beta2 agonists is required.
Level of evidence:
Level 3 (other evidence) according to the SORT criteria.
Healthcare professionals involved in caring for children with asthma should be familiar with the BTS/SIGN British asthma guideline. This advises that, in children aged 0 to 5 years, a pressurised metered dose inhaler (pMDI) and spacer is the preferred method of delivery of beta2 agonists or inhaled steroids. A face mask is required until the child can breathe reproducibly using the spacer mouthpiece.
Oral bronchodilators are less effective and have more adverse effects than inhaled bronchodilators. They should be used only in patients who are unable to use an inhaler device. This study suggests that two or three tidal breaths are sufficient to deliver an effective dose of drug in children aged 2 to 7 years using a pMDI plus spacer. Adequate compliance using this route of administration may be better than previously thought.
What is the background to this?
Although medication for young children is commonly delivered using a pMDI and spacer, asthma guidelines do not generally give specific instructions regarding the correct method for breathing through a spacer because there are no data on the number of breaths needed for optimal drug delivery. This study was designed to determine the number of tidal breaths required to inhale medication effectively through different types of spacer, and to determine the efficacy of a single maximal inhalation for drug delivery in young children.
Breathing patterns were recorded for children aged 2 to 7 years inhaling placebo from different spacers (three groups: n=34, n=84 and n=10). These patterns were then transferred individually to a breathing simulator and simulated drug delivery with different numbers of tidal breaths, and with a single maximum breath, were compared.
What does this study claim?
The study found that mean inhalation volumes using a spacer were higher than expected with tidal breathing (384 to 445ml). With small volume spacers (Aerochamber Plus and Funhaler) there was no significant difference in drug delivery between two tidal breaths and nine tidal breaths. With the Volumatic large volume spacer, there was no significant difference in drug delivery between three and nine tidal breaths. However, drug delivery was significantly lower with two tidal breaths, compared with nine tidal breaths (see below for details). In addition, in young children, single maximal inhalation did not result in improved drug delivery, compared with tidal breathing.
The study has limitations, including the small number of children assessed (10 children in one group), the use of disease-orientated outcomes, and the assessment of drug delivery using breathing simulation. In addition, it was not designed to determine drug doses delivered to patients’ lungs and cannot be applied to children who need to use a mask with the spacer. Nevertheless it provides useful information regarding the use of spacers in young children. As the authors of the study point out, when pMDIs and spacers are used for young children and infants, cooperation during administration is the most important determinant for efficient drug delivery. Preschool-aged children, who are known to have short attention spans, may be more likely to cooperate with treatment if they are required to take fewer breaths through spacers.
According to the BTS/SIGN British asthma guideline, in children aged 0 to 5 years, a pMDI and spacer is the preferred method of delivery of beta2 agonists or inhaled steroids. A face mask is required until the child can breathe reproducibly using the spacer mouthpiece. Where this is ineffective a nebuliser may be required.
The spacer should be compatible with the pMDI being used. The drug should be administered by repeated single actuations of the metered dose inhaler into the spacer, each followed by inhalation, with minimal delay between pMDI actuation and inhalation. As we have seen in this study, tidal breathing is as effective as single breaths.
Is there a role for bronchodilator syrups?
The BNF advises that, for children under five years who require a bronchodilator for occasional relief of asthma, this should preferably be given by inhalation because it is less effective and has more side-effects when given by mouth. In addition, the SPC for Ventolin syrup states that this preparation is suitable oral therapy for children and adults who are unable to use an inhaler device. This study suggests that children aged between 2 and 7 years can effectively use a pMDI plus spacer with two or three tidal breaths, so the place in therapy of the syrup is very limited. However, data from the NHS Prescription Services shows that around 15,000 items were still being prescribed as beta2 agonist syrups in the quarter up to March 2010.
Design: Sub-study from a 12-month clinical trial comparing the Funhaler and Aerochamber Plus spacers.
Patients, intervention and comparison: Included 2 to 6 year old children with asthma who were receiving inhaled steroids. Three separate groups were investigated. The first (n=34) was recruited at the beginning of the trials and drug delivery with two tidal breaths was compared with nine tidal breaths using the Aerochamber Plus or Funhaler. The second (n=84) was investigated at the end of the 12-month trial and children were screened for their ability to perform a single maximal inhalation. The third group (n=10) was selected from the previous two groups and included the first two subjects for each year of age who could perform a single maximal inhalation. Tidal breathing and single maximal breathing patterns were recorded for these children using placebo, and then drug delivery was simulated, with 4 different spacers (149ml Aerochamber Plus, 225ml Funhaler, 750ml Volumatic and 500ml modified plastic drink bottle) in a pseudo-randomised order.
Outcomes and results: With tidal breathing, mean inhalation volumes were almost double that expected, ranging from 384mL to 445mL.
There was no significant difference in drug delivery between two and nine tidal breaths for the two small volume spacers. Mean values for drug delivery with an Aerochamber Plus were 40% (95%CI 34% to 46%) of the total dose with two tidal breaths and 41% (95%CI 36% to 47%) with nine tidal breaths. Mean drug delivery values with these breath numbers with a Funhaler were 39% (95%CI 34% to 43%) and 38% (95%CI 35% to 42%), respectively.
With a Volumatic, mean drug delivery values with two and nine tidal breaths were 37% (95%CI 33% to 41%) and 43% (95%CI 40% to 46%), respectively (P=0.02); there was no significant difference in drug delivery with three versus nine tidal breaths (mean 40%, 95%CI 36% to 44%). With the modified soft drink bottle, there was no significant difference in drug delivery between two, five and nine tidal breaths.
Drug delivery was not improved with a single maximal breath with any device. All the 7 year old children could perform a single maximal inhalation, compared with 84% of those aged 6, 76% of those aged 5, 38% of those aged 4 and 20% of those aged 3.
Sponsorship: The authors indicated they have no financial relationships relevant to this article to disclose
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