Anesthesia Machine Use, Protection and Decontamination during the COVID-19 Pandemic

Suwimon  Tangwiwat

Authors

Suwimon Tangwiwat Siriraj Hospital

Abstract

Anesthesia providers commonly cross-contaminate
their workspace and subsequently put patients at risk for
a health care-acquired infection. Controlling infection to
prevent the spread of SARS-CoV-2 is the primary public
healthcare intervention used. Anesthesiologists need to
participate in standardized infection control strategy to
contain COVID-19 viral transmission. Breathing system
filters will protect the anesthesia machine from internal
contamination and protect the environment when the
circuit is disconnected. The type of filter selected for an
anesthesia machine used is important for efficacy and
humidity concerns. Performance of filters designed to
protect against bacteria and viruses is measured using
the Bacterial or Viral Filtration Efficiency (BFE and VFE)
is reported for all commercial filters (>99.99%). APSF/ASA
recommend that a heat and moisture exchange filter
(HMEF) should be placed at the endotracheal tube
connection to the breathing circuit, and a second HMEF
or filter should be placed on the expiratory hose where it
connects to the anesthesia machine. Not only is the
second filter a reasonable backup to protect the machine
from any particles that pass the primary filter, but it
significantly amplifies the effectiveness of the first filter.
The complications associated with HMEF may increase
the resistance to gas flow, ventilation, dead space and
blockage with liquid. The airway mounted filter will need

to be changed between every patient, whereas the

expiratory limb filter seems like an option to leave in place
between patients 24-48 hours depend on the type of HMEF
or according with the manufacturer’s recommendations.

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