The pressure required to force liquid through breathing system filters

Area of Science:

• Medical Engineering
• Infection Control
• Respiratory Care

Background:

• Breathing system filters are crucial in preventing cross-infection in healthcare settings.
• Liquid ingress into breathing circuits can compromise filter efficacy and patient safety.
• Understanding filter performance under pressure is vital for clinical application.

Purpose of the Study:

• To quantify the pressure at which liquid penetrates various breathing system filters.
• To compare the liquid penetration resistance of different filter types (electrostatic vs. pleated) and sizes (adult vs. paediatric).

Main Methods:

• Twenty-three breathing system filters (12 adult, 11 paediatric) were tested.
• Filters were subjected to increasing water pressure using a U-tube manometer setup.
• The pressure at which liquid first appeared on the patient side was recorded for five samples of each filter type.

Main Results:

• Significant variations in liquid penetration pressure were observed across different filter models.
• Adult electrostatic filters demonstrated substantially lower liquid penetration pressures (median 1.18 kPa) compared to adult pleated filters (median 8.04 kPa).
• Paediatric electrostatic filters exhibited similar low liquid penetration pressures (median 0.98 kPa) to their adult counterparts.

Conclusions:

• Electrostatic breathing system filters, both adult and paediatric, are more susceptible to liquid penetration at lower pressures than pleated filters.
• The findings highlight the importance of considering filter type and potential liquid ingress when selecting breathing system filters to mitigate cross-infection risks.