Page 73 - JSOM Winter 2021

Updated Considerations for the Use of Anesthesia Gas Machines

in a Critical Care Setting During the Coronavirus Disease Pandemic

Charles D. Wickens, CCE, BSEE, MBA *;
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Brian Delmonaco, MD ; Tomer Pelleg, DO 3

ABSTRACT
The latest surge of the coronavirus disease 2019 (SARS-CoV-2 ventilation modes or flow capabilities, and they require spe-
virus) pandemic continues to create an unprecedented need cial considerations and attention to prevent potential patient
for mechanical ventilation in critically ill patients. The U.S. harm (Table 1).
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Food and Drug Administration (FDA) recognized that the ad-
ditional need for ventilators, on March 22, 2020 and issued
guidance outlining a policy intended to help increase availabil- Prior to Patient Use Machine Checkout
ity of relevant technologies. The FDA included guidance for Typically, a dedicated anesthesiologist or certified registered
healthcare facilities facing shortages of mechanical ventilators nurse anesthetist is required to operate the anesthesia ma-
to consider alternative devices capable of delivering breaths chine. For long-term ventilatory support, the caregiver rou-
2
or pressure support including anesthesia machines. Anesthe- tinely performs ventilator control checks, confirming valid and
sia machine manufacturers have published guidelines for the effective ventilator settings, and makes the necessary ventilator
off-label use of anesthesia machines in critical care settings. calibration adjustments to ensure that there is an acceptable
Capable of providing mechanical ventilation, anesthesia ma- gas exchange.
chines do not deliver ventilation modes and flow capabilities
commonly used outside the operating room (OR). A paucity of Most anesthesia machines are designed to be tested, calibrated,
published information exists to describe the operation of anes- and assessed for readiness every 24 hours to ensure safe oper-
thesia machines, their technological and practical limitations, ation. If device testing is not performed, flow measurements
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and special considerations to prevent harm when re-purposed. may be inaccurate. In contrast to those of most ICU venti-
We provide technical information and practical guidance for lators, the flow measurements of most anesthesia machines
the safe use of anesthesia machines in critically ill patients out- cannot be calibrated during operation. Several anesthesia ma-
side the OR. chines delineate inaccuracies in flow measurement via monitor
color changes, although this is not uniform. Most anesthesia
Keywords: considerations; critical care; anesthesia machine manufacturers recommend a complete system test
(not only a leakage test) once daily.

To perform the system test, the patient must be disconnected
Introduction
from the anesthesia machine. During this time, sufficient ven-
The latest surge of the coronavirus disease 2019 (SARS-CoV-2 tilation of the patient (e.g., via manual bag-valve mask ven-
virus) pandemic continues to create an unprecedented need for tilation or an alternative ventilatory device) must be ensured
mechanical ventilation in critically ill patients. The US Food because these system tests can take up to 8 minutes to perform.
and Drug Administration (FDA) recognized the need for ad- In preparation for system testing, it is important to inspect
ditional ventilators on March 22, 2020, and issued guidance and remove any condensation from the piston membrane.
outlining a policy intended to help increase the availability of Although typical ICU ventilators notify providers via alarms,
relevant technologies. The FDA guidance for healthcare facil- special care must be taken when using anesthesia machines to
1
ities facing shortages of mechanical ventilators was to consider ensure the CO absorber is not exhausted, the gas measure-
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alternative devices capable of delivering breaths or pressure ment water trap is not full, water hasn’t accumulated within
support, including anesthesia machines. While doing so would the breathing circuit, and condensation in filters and heat and
constitute an off-label use, anesthesia machine manufactur- moisture exchangers are not excessive.
ers, the Anesthesia Patient Safety Foundation (APSF), and the
American Society of Anesthesiologists (ASA) have guidelines Regarding cleaning the machine between patients, if the
for anesthesia machine use in the intensive care unit (ICU) ; proper viral filters have been used appropriately, there should
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there is limited published information describing their use and be little increased risk of passing the COVID-19 virus to a sub-
the technological as well as practical limitations. While an- sequent patient via the anesthesia machine. Existing hospital
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esthesia machines are capable of providing mechanical venti- procedures for cleaning anesthesia machines between patients
lation, they do not have the frequently used mechanical ICU should be followed, including wiping external surfaces and
*Correspondence to cwickens@samhealth.org
1 Charles Wickens is affiliated with Clinical Engineering, Good Samaritan Regional Medical Center, Corvallis, OR, and Biomedical Engineering
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Technology, Portland Community College, Portland, OR. Drs Brian Delmonaco and Tomer Pelleg are both affiliated with Good Samaritan
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Regional Medical Center.
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