Aerosolisation during tracheal intubation and extubation in an operating theatre setting

Abstract

Aerosol-generating procedures such as tracheal intubation and extubation pose a potential risk to healthcare workers because of the possibility of airborne transmission of infection. Detailed characterisation of aerosol quantities, particle size and generating activities has been undertaken in a number of simulations but not in actual clinical practice. The aim of this study was to determine whether the processes of facemask ventilation, tracheal intubation and extubation generate aerosols in clinical practice, and to characterise any aerosols produced. In this observational study, patients scheduled to undergo elective endonasal pituitary surgery without symptoms of COVID-19 were recruited. Airway management including tracheal intubation and extubation was performed in a standard positive pressure operating room with aerosols detected using laser-based particle image velocimetry to detect larger particles, and spectrometry with continuous air sampling to detect smaller particles. A total of 482,960 data points were assessed for complete procedures in three patients. Facemask ventilation, tracheal tube insertion and cuff inflation generated small particles 30-300 times above background noise that remained suspended in airflows and spread from the patient's facial region throughout the confines of the operating theatre. Safe clinical practice of these procedures should reflect these particle profiles. This adds to data that inform decisions regarding the appropriate precautions to take in a real-world setting.

Keywords: aerosol-generating procedures; extubation; intubation; occupational exposure.

Figure 1

Theatre setup showing the location of aerosol measuring equipment.

Figure 2

Particle count and diameter during intubation. (a) Time series of total number concentrations from the Aerodynamic Particle Sizer (APS) with linear and log scales shown in dark and light blue, respectively. Dashed lines represent the detection limit (mean + 3 standard deviations) during an empty theatre (green) and during theatre setup (red). (b) Measured aerosol size distributions over time from the APS, with size represented on the y‐axis and colours showing the number concentration in each size bin. The integrated size distributions correspond to total concentrations.

Figure 3

Particle count and diameter during extubation. (a) – (b) are as for Figure 2.

Figure 4

Particle image velocimetry high‐speed image taken during bag and mask ventilation. The image shows particles travelling from right (cranial) to left (caudal).