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 × 10⁴ plaque-forming units [PFU]/L of air sampled), nasal prongs (1.60 × 10⁴ PFU/L of air sampled), nonrebreather face masks (7.87 × 10² PFU/L of air sampled), and bilevel positive airway pressure (1.91 × 10² 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.

Keywords: COVID-19; bacteriophage; bioaerosol; critical care; simulation.

Figure 1.

Schematic of the simulation facility and sensor positions. L1 is 10 cm above the level of the mouth, L2 is 40 cm vertically above the mouth (intubating position), L3 is 40 cm above and 30 cm behind the mouth (airway expert position), L4 is 100 cm above the ground and beside the bed (assistant hand position), L5 is 275 cm above the ground and beside the bed (assistant face position), and L6 is 100 cm above the ground and 180 cm from the mouth toward the foot of the bed. For the clinical relevance of L1–L6, also see Figure E1 in the online supplement. L1–L6 = locations 1–6.

Figure 2.

Logarithmic normalized bacteriophage concentration of six respiratory modalities at L1–L6. The asterisks represent the statistically significant modalities when compared with invasive ventilation at each location using the Kruskal-Wallis method (P < 0.05; a summary of pairwise comparisons is presented in Table E3 of the online supplement). Each experiment was run in triplicate (n = 3), and the error bars represent the SDs. BiPAP = bilevel positive airway pressure; HFNO = high-flow nasal oxygen; L1–L6 = locations 1–6; PEEP = positive end-expiratory pressure.