Clinical Consultation: Nebulizers as a source of allergens

How significant is the risk of nebulizersbeing contaminated with allergens?What preventive measures doyou recommend?

Recent reports have identified potential risks of nebulizer use in patients with environmental allergies.^1,2 One report described 2 children with asthma and cockroach allergy who had life-threatening worsening of asthma after using a nebulizer to treat an exacerbation.¹

One of the children, who had poorly controlled known cockroach allergy and asthma, had used a nebulizer at his grandmother's house because of persistent symptoms after using an albuterol inhaler several times at school. Within minutes of using the nebulizer, severe respiratory distress developed. The child required emergency medical ser-vices (EMS) and was intubated in the field. He was subsequently treated in the ICU for several days. Inspection of the nebulizer equipment revealed 3 small cockroaches in the medication reservoir.¹

The other child, who had intermittent asthma, had an acute exacerbation, and his nebulizer was retrieved from the garage.¹ Within minutes of receiving the first treatment, he had severe worsening of symptoms and was taken to the emergency department (ED). The child was treated in the ED overnight with albuterol and systemic corticosteroids, with clinical improvement. He was discharged with instructions to continue albuterol nebulization treatments at home for the next 24 to 48 hours.

Despite the child's concerns at home that "the medicine made him sick," his family dispensed the first dose; within minutes, severe respiratory distress developed, requiring EMS treatment. He was intubated in the field and given subcutaneous epinephrine. The child was treated in the ICU for several days, with clinical improvement.

A saline washing from the child's nebulizer medication reservoir was sent for antigen analysis. The washing was positive for Blattella germanica 1 and 2 allergen at a level of 0.18 and 0.22 units/mL, respectively. The nebulizer's tubing and storage box were examined, and small insects were discovered and later identified by an entomologist as infantile German cockroaches.¹

These case reports led to a pilot study² that examined discarded nebulizer equipment from an investigation of nebulizer use in underserved children with asthma. Discarded nebulizer reservoirs (N = 17) were randomly collected and sent in a blinded fashion for antigen analysis and tested for common indoor allergens, including cat, dog, mouse, dust mite, and cockroach allergens. Additional control samples were tested; these included samples "spiked" with allergen extracts, saline and albuterol nebulizer solution, and samples that had been planted for 2 weeks in homes with cats and dogs and in homes without animals. Some of the planted home reservoirs were kept in zipped plastic bags, and others were left in open containers.

Measurable allergen was found in 29% of the randomly collected nebulizer reservoirs from homes of underserved children with asthma.² The reservoirs with measurable allergen levels included 1 with dog allergen, 2 with cockroach allergen, and 3 with mouse allergen. Of the nebulizer reservoirs that were planted in homes, only samples from homes with pets had detectable allergen levels, and the allergen was specific for the type of animal present. None of the reservoirs that were kept in sealed plastic bags had measurable allergen levels.

The clinical relevance of these levels is unknown, since the nebulizer equipment was not linked to clinical data. However, the levels of cockroach allergen found were in the same range found in the previous case report that led to a severe exacerbation. Other allergen levels that were found could potentially lead to life-threatening exacerbations in certain patients.

Further study is needed in a larger sample size to confirm the frequency of allergen contamination of nebulizers in different populations, to determine the clinical relevance of such contamination, and to determine what storage methods may prevent contamination. In the interim, clinicians should make their patients aware of potential contamination and advise them to clean and dry the nebulizer equipment and to store it in a sealed plastic bag when not in use.

To our readers:

We would like to correct an error that appeared in the February 2006 issue. On page 66, in Table 7, the correct dosage for ceftriaxone should be "1-2 g IM or IV daily." The error was ours, not the authors.' We apologize for any inconvenience this may have caused.

References:

REFERENCES

1. Bollinger ME, Wolf B, Schwindt C, Hamilton RG. Contamination of nebulizer equipment with cockroach allergen: there's a bug in the system!

Ann Allergy Asthma Immunol.

2004;92:475-477.
2. Bollinger ME, Butz A, Mudd K, Hamilton RG. Con-tamination of nebulizers with environmental allergens.

Ann Allergy Asthma Immunol.

2005;95:429-432.