Quantitative Assessment of Viral Dispersion Associated with Respiratory Support Devices in a Simulated Critical Care Environment

Abstract

Rationale: Patients with severe coronavirus disease (COVID-19) require supplemental oxygen and ventilatory support. It is unclear whether some respiratory support devices may increase the dispersion of infectious bioaerosols and thereby place healthcare workers at increased risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Objectives: To quantitatively compare viral dispersion from invasive and noninvasive respiratory support modalities. Methods: This study used a simulated ICU room with a breathing-patient simulator exhaling nebulized bacteriophages from the lower respiratory tract with various respiratory support modalities: invasive ventilation (through an endotracheal tube with an inflated cuff connected to a mechanical ventilator), helmet ventilation with a positive end-expiratory pressure (PEEP) valve, noninvasive bilevel positive-pressure ventilation, nonrebreather face masks, high-flow nasal oxygen (HFNO), and nasal prongs. Measurements and Main Results: Invasive ventilation and helmet ventilation with a PEEP valve were associated with the lowest bacteriophage concentrations in the air, and HFNO and nasal prongs were associated with the highest concentrations. At the intubating position, bacteriophage concentrations associated with HFNO (2.66 × 10 4 plaque-forming units [PFU]/L of air sampled), nasal prongs (1.60 × 10 4 PFU/L of air sampled), nonrebreather face masks (7.87 × 10 2 PFU/L of air sampled), and bilevel positive airway pressure (1.91 × 10 2 PFU/L of air sampled) were significantly higher than those associated with invasive ventilation ( P < 0.05 for each). The difference between bacteriophage concentrations associated with helmet ventilation with a PEEP valve (4.29 × 10 –1 PFU/L of air sampled) and bacteriophage concentrations associated with invasive ventilation was not statistically significant. Conclusions: These findings highlight the potential differential risk of dispersing virus among respiratory support devices and the importance of appropriate infection prevention and control practices and personal protective equipment for healthcare workers when caring for patients with transmissible respiratory viral infections such as SARS-CoV-2.

Mitigating Viral Dispersion during Respiratory Support Procedures in the ICU

“…In this issue of the Journal , Avari and colleagues (pp. 1112–1118 ) used a mannequin that simulated the breathing pattern of spontaneously breathing patients with mild to moderate respiratory distress and exhaled a constant breath-to-breath viral load of a bacteriophage generated by a vibrating mesh nebulizer as a surrogate for SARS-CoV-2 ( 5 ). They simulated the clinical situation in a negative-pressure ICU room.…”

“…They simulated the clinical situation in a negative-pressure ICU room. Viral dispersion was quantitated at various locations in the room during invasive mechanical ventilation via a cuffed orotracheal tube and a filter placed at the expiratory port of the ventilator and was compared with noninvasive respiratory support using nasal prongs, HFNO, a nonrebreather face mask with N99 high-efficiency particulate air filter, helmet ventilation with positive end-expiratory pressure (PEEP) valve, and bilevel positive-pressure NIV ( 5 ). The lowest bacteriophage concentrations occurred during invasive mechanical ventilation, whereas the highest concentrations were recorded while using HFNO or nasal prongs.…”

“…Moreover, viral concentrations were highest closer to the mouth and lower toward the foot end of the bed. The variability in bioaerosol dispersion led the investigators to conclude that the risk of transmitting infection, and appropriate infection control, differs among several respiratory procedures used in the ICU ( 5 ).…”

“…A major strength of Avari and colleagues’ investigation was to use a bacteriophage to model viral exposure, unlike previous studies that used nonviral particles (References 17–21 in Reference 5 ). Viruses can spread in the hospital environment by airborne transmission.…”

“…Avari and colleagues reported that viral aerosol dispersion was reduced to levels comparable to those seen with invasive mechanical ventilation when a helmet device fitted with a PEEP valve was used ( 5 ). Likewise, in previous investigations it was reported that connecting a filter to an oxygen mask (e.g., HiOx Oxygen mask [Novus Medical Inc] or Respan’s Tavish mask) reduced aerosol dispersion ( 10 ).…”