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Nebulisers

 

Nebulisers are widely used to deliver medicines and vaccines in an aerosol form to the respiratory system. To achieve the intended treatment, aerosol particles are deposited in specific parts of the respiratory tract. In general, it is considered that aerosol particles with an aerodynamic diameter of:

  • >5 µm are deposited in the upper airways;
  • 2 µm to 5 µm are deposited in the lower airways, and;
  • <2 µm are deposited in the alveoli:

The performance profile of the nebuliser is a key component in achieving successful patient outcomes and testing of nebuliser is essential to ensure these devices deliver medication effectively and safely.

SMTL test the performance characteristics of nebulisers for the Welsh NHS and medical device industry in accordance with the international standard BS EN ISO 27427. The standard recommends using a drug tracer sodium fluoride as the test substance as it is considered to provide more comparable outcomes. Key aspects of nebuliser testing covered the standard include:

  • Aerosol Output and Output Rate (Annex C): Measuring the rate at which the nebuliser delivers the medication and the following performance results are measured:
  1. Aerosol Output - mass or volume of aerosol emitted by the nebulizing system at the aerosol outlet port for the given fill volume
  2. Aerosol Output Rate - mass or volume of aerosol emitted by the nebulizing system per unit of time (1st minute of nebulisation)
  3. Percentage of Fill Volume - aerosol output expressed as a percentage of the fill volume
  4. Residual Volume: volume of liquid remaining in the nebulizing system when the nebulizer stops generating an aerosol
  • Particle Size Distribution (Annex D): Measures the size of aerosol particles produced by the nebuliser to assess effective respiratory delivery and include the following performance results:
  1. Mass Median Aerodynamic Diameter (MMAD) - particle size at which 50% of the mass of the active component are contained in droplets of smaller or equal aerodynamic diameter
  2. Respirable fraction (Cumulative percentage below 5 μm) - faction of aerosol droplets below 5 μm in diameter expressed as a percentage of the total aerosol distribution

 

These tests help ensure that nebulisers are reliable and effective for patients. If you have any specific questions or need more details, please contact SMTL smtl.info@wales.nhs.uk

 

Relevant Standards

  • BS EN ISO 27427 Anaesthetic and respiratory equipment — Nebulizing systems and components - Annex C & D

nebuliser