Aerosol Retention Characteristics of Barrier Devices

Abstract

Background: Disease severity in coronavirus disease 2019 (COVID-19) may be associated with inoculation dose. This has triggered interest in intubation barrier devices to block droplet exposure; however, aerosol protection with these devices is not known. This study hypothesized that barrier devices reduce aerosol outside of the barrier.

Methods: Aerosol containment in closed, semiclosed, semiopen, and open barrier devices was investigated: (1) "glove box" sealed with gloves and caudal drape, (2) "drape tent" with a drape placed over a frame, (3) "slit box" with armholes and caudal end covered by vinyl slit diaphragms, (4) original "aerosol box," (5) collapsible "interlocking box," (6) "simple drape" over the patient, and (7) "no barrier." Containment was investigated by (1) vapor instillation at manikin's right arm with video-assisted visual evaluation and (2) submicrometer ammonium sulfate aerosol particles ejected through the manikin's mouth with ventilation and coughs. Samples were taken from standardized locations inside and around the barriers using a particle counter and a mass spectrometer. Aerosol evacuation from the devices was measured using standard hospital suction, a surgical smoke evacuator, and a Shop-Vac.

Results: Vapor experiments demonstrated leakage via arm holes and edges. Only closed and semiclosed devices and the aerosol box reduced aerosol particle counts (median [25th, 75th percentile]) at the operator's mouth compared to no barrier (combined median 29 [-11, 56], n = 5 vs. 157 [151, 166], n = 5). The other barrier devices provided less reduction in particle counts (133 [128, 137], n = 5). Aerosol evacuation to baseline required 15 min with standard suction and the Shop-Vac and 5 min with a smoke evacuator.

Conclusions: Barrier devices may reduce exposure to droplets and aerosol. With meticulous tucking, the glove box and drape tent can retain aerosol during airway management. Devices that are not fully enclosed may direct aerosol toward the laryngoscopist. Aerosol evacuation reduces aerosol content inside fully enclosed devices. Barrier devices must be used in conjunction with body-worn personal protective equipment.

Fig. 1.

Overview of barrier devices. (A) Glove box. (B) Drape tent. (C) Slit box. (D) Aerosol box. (E) Interlocking box. (F) Simple drape.

Fig. 2.

Differences in vapor egress at the arm holes between barrier devices. Arrows show vapor egress. (A) Slit box. (B) Interlocking box. (C) Glove box with no visible vapor egress. The video in the Supplemental Digital Content (http://links.lww.com/ALN/C502) provides additional visualization of vapor egress.

Fig. 3.

Vapor egress (arrows) from the unsealed edge of the interlocking box. The video in the Supplemental Digital Content (http://links.lww.com/ALN/C502) provides additional visualization of vapor egress.

Fig. 4.

Simple drape. (A) no vapor is visible while the simple drape is in place. (B) Vapor is visible at the 175-cm-tall operator’s face during airway management. The video in the Supplemental Digital Content (http://links.lww.com/ALN/C502) provides additional visualization of vapor egress.

Fig. 5.

Smoke evacuation patterns. (A–C) Spontaneous washout follows a linear pattern. (D–F) Effect of different evacuation methods.