Rapid establishment of an ICU using anesthesia ventilators during COVID-19 pandemic: lessons learned

We read with great interest the article by Goh et al. [1], and we thought it might be helpful to share our challenging experience with the deployment of anesthesia ventilators in our ICU when faced with a recent ventilator shortage at our institution.

In April 2020, Massachusetts General Hospital saw a significant surge in demand for ICU beds and ventilators due to an influx of COVID-19 patients. We converted our post-anesthesia care units (PACUs) to ICUs and utilized anesthesia ventilators to care for more than 40 COVID-19 patients. While this experience posed challenges, important lessons were learned.

These PACUs turned ICUs required dedicated anesthesia providers to serve as respiratory therapists to manage and troubleshoot the anesthesia ventilators which are functionally different from standard ICU ventilators. Due to the circle system design of anesthesia ventilators and a lack of circuit water traps, higher gas flow rates and frequent circuit changes were required thereby increasing providers’ risk of exposure. Lack of humidification in the circuit resulted in thicker airway secretions and airway obstruction. The heat and moisture exchanger filters which are utilized on anesthesia ventilators clogged easily leading to frequent high airway pressure alarms. Special attention to the position of the side-stream gas analyzer was also required when the patient was in the prone position because condensation quickly accumulated in the water trap when the circuit connection was in the dependent position. In addition, safe deployment of anesthesia ventilators required integration with the centralized alarm system.

The anesthesia ventilators utilized in our ICUs did not have a volume assist-control ventilation mode which led to dyssynchrony, barotrauma, desaturation, auto positive end-expiratory pressure (auto-PEEP), and hemodynamic instability when volume control was employed without the patient paralyzed. Thus, pressure support (PS) mode became the primary mode of ventilation utilized. An important requirement for use of the PS mode was setting a backup respiratory rate to avoid complications such as hypoventilation when sedatives and/or paralysis were administered. Avoiding adverse events from untimely response to alarms required anesthesia providers to maintain vigilance in the setting of increased alarm fatigue; therefore, a greater than expected staffing model was required to maintain patient safety.

Despite these challenges, the use of anesthesia ventilators provided a unique opportunity to use volatile anesthetics, which have been associated with faster extubation times and opioid-sparing effects [2].

While anesthesia ventilators expanded our capacity, we rapidly learned their limitations and potential benefits for long-term use.