Exhaled air dispersion during bag-mask ventilation and sputum suctioning - Implications for infection control

Matthew T V Chan,Tony Gin,Thomas Lo,Susanna S Ng,Fanny W Ko,Benny K Chow,David S Hui

doi:10.1038/s41598-017-18614-1

Matthew T V Chan, Tony Gin + Show 5 more

Open Access

https://doi.org/10.1038/s41598-017-18614-1

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Journal: Scientific Reports	Publication Date: Jan 9, 2018
Citations: 70	License type: open-access

Affiliation: Chinese University of Hong Kong

Abstract

Mask ventilation and coughing during oro-tracheal suctioning produce aerosols that enhance nosocomial transmission of respiratory infections. We examined the extent of exhaled air dispersion from a human-patient-simulator during mask ventilation by different groups of healthcare workers and coughing bouts. The simulator was programmed to mimic varying severity of lung injury. Exhaled airflow was marked with tiny smoke particles, and highlighted by laser light-sheet. We determined the normalized exhaled air concentration in the leakage jet plume from the light scattered by smoke particles. Smoke concentration ≥20% was considered as significant exposure. Exhaled air leaked from mask-face interface in the transverse plane was most severe (267 ± 44 mm) with Ambu silicone resuscitator performed by nurses. Dispersion was however similar among anesthesiologists/intensivists, respiratory physicians and medical students using Ambu or Laerdal silicone resuscitator, p = 0.974. The largest dispersion was 860 ± 93 mm during normal coughing effort without tracheal intubation and decreased with worsening coughing efforts. Oro-tracheal suctioning reduced dispersion significantly, p < 0.001, and was more effective when applied continuously. Skills to ensure good fit during mask ventilation are important in preventing air leakage through the mask-face interface. Continuous oro-tracheal suctioning minimized exhaled air dispersion during coughing bouts when performing aerosol-generating procedures.

Highlights

Respiratory failure is a serious complication of emerging infectious respiratory diseases such as severe acute respiratory syndrome (SARS)[1,2], avian influenza[3], influenza A(H1N1)2009 infection[4] and the Middle East Respiratory Syndrome[5]
The mean difference between nurses and anesthesiologists/intensivists, respiratory physicians or medical students, adjusted for the devices used, were 69 (42–96) mm, 72 (45–99) mm and 67 (40–94) mm, respectively, all p < 0.001 (Supplementary Table 1)
Dispersion distances were similar among anesthesiologists/intensivists, respiratory physicians and medical students, p = 0.974

Summary

Introduction

Respiratory failure is a serious complication of emerging infectious respiratory diseases such as severe acute respiratory syndrome (SARS)[1,2], avian influenza[3], influenza A(H1N1)2009 infection[4] and the Middle East Respiratory Syndrome[5]. In a systematic review of aerosol generating procedures that might increase the risk of nosocomial transmission of SARS to healthcare workers, mask ventilation and oro-tracheal suctioning increased the odds ratios (95% confidence intervals, CI) to 2.8 (1.3–6.4) and 6.2 (2.2–18.1), respectively[8]. In this respect, we have previously shown that the dispersion distances of exhaled plume along the sagittal and transverse planes were 200 and 220 mm, respectively, when bag-mask ventilation was attempted in a human-patient-simulator (HPS)[9]. We estimated the spread of exhaled air during episodes of coughing bouts triggered by oro-tracheal suctioning

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