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Shrimpton AJ, Brown V, Vassallo J, Nolan JP, Soar J, Hamilton F, Cook TM, Bzdek BR, Reid JP, Makepeace CH, Deutsch J, Ascione R, Brown JM, Benger JR, Pickering AE. A quantitative evaluation of aerosol generation during cardiopulmonary resuscitation. Anaesthesia 2024; 79:156-167. [PMID: 37921438 PMCID: PMC10952244 DOI: 10.1111/anae.16162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2023] [Indexed: 11/04/2023]
Abstract
It is unclear if cardiopulmonary resuscitation is an aerosol-generating procedure and whether this poses a risk of airborne disease transmission to healthcare workers and bystanders. Use of airborne transmission precautions during cardiopulmonary resuscitation may confer rescuer protection but risks patient harm due to delays in commencing treatment. To quantify the risk of respiratory aerosol generation during cardiopulmonary resuscitation in humans, we conducted an aerosol monitoring study during out-of-hospital cardiac arrests. Exhaled aerosol was recorded using an optical particle sizer spectrometer connected to the breathing system. Aerosol produced during resuscitation was compared with that produced by control participants under general anaesthesia ventilated with an equivalent respiratory pattern to cardiopulmonary resuscitation. A porcine cardiac arrest model was used to determine the independent contributions of ventilatory breaths, chest compressions and external cardiac defibrillation to aerosol generation. Time-series analysis of participants with cardiac arrest (n = 18) demonstrated a repeating waveform of respiratory aerosol that mapped to specific components of resuscitation. Very high peak aerosol concentrations were generated during ventilation of participants with cardiac arrest with median (IQR [range]) 17,926 (5546-59,209 [1523-242,648]) particles.l-1 , which were 24-fold greater than in control participants under general anaesthesia (744 (309-2106 [23-9099]) particles.l-1 , p < 0.001, n = 16). A substantial rise in aerosol also occurred with cardiac defibrillation and chest compressions. In a complimentary porcine model of cardiac arrest, aerosol recordings showed a strikingly similar profile to the human data. Time-averaged aerosol concentrations during ventilation were approximately 270-fold higher than before cardiac arrest (19,410 (2307-41,017 [104-136,025]) vs. 72 (41-136 [23-268]) particles.l-1 , p = 0.008). The porcine model also confirmed that both defibrillation and chest compressions generate high concentrations of aerosol independent of, but synergistic with, ventilation. In conclusion, multiple components of cardiopulmonary resuscitation generate high concentrations of respiratory aerosol. We recommend that airborne transmission precautions are warranted in the setting of high-risk pathogens, until the airway is secured with an airway device and breathing system with a filter.
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Affiliation(s)
- A. J. Shrimpton
- Anaesthesia, Pain and Critical Care Sciences, School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - V. Brown
- Critical Care, South Western Ambulance Service NHS Foundation TrustUK
- Great Western Air Ambulance CharityBristolUK
| | - J. Vassallo
- Institute of Naval MedicineGosportUK
- Academic Department of Military Emergency MedicineRoyal Centre for Defence MedicineBirminghamUK
| | - J. P. Nolan
- University of Warwick, Warwick Medical SchoolCoventryUK
- Department of Anaesthesia and Intensive Care MedicineRoyal United HospitalBathUK
| | - J. Soar
- Department of Anaesthesia and Intensive Care MedicineNorth Bristol NHS TrustBristolUK
| | - F. Hamilton
- MRC Integrative Epidemiology UnitUniversity of BristolUK
| | - T. M. Cook
- Department of Anaesthesia and Intensive Care MedicineRoyal United HospitalBathUK
| | - B. R. Bzdek
- School of ChemistryUniversity of BristolBristolUK
| | - J. P. Reid
- School of ChemistryUniversity of BristolBristolUK
| | - C. H. Makepeace
- Langford Vets and Translational Biomedical Research CentreUniversity of BristolUK
| | - J. Deutsch
- Langford Vets and Translational Biomedical Research CentreUniversity of BristolUK
| | - R. Ascione
- Translational Biomedical Research CentreUniversity of BristolBristolUK
- University Hospital Bristol Weston NHS TrustBristolUK
| | - J. M. Brown
- Department of Anaesthesia and Intensive Care MedicineNorth Bristol NHS TrustBristolUK
| | - J. R. Benger
- Faculty of Health and Applied SciencesUniversity of the West of EnglandBristolUK
| | - A. E. Pickering
- Department of AnaesthesiaUniversity Hospitals Bristol and WestonBristolUK
- Anaesthesia, Pain and Critical Care Sciences, School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
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Shrimpton AJ, Brown JM, Gregson FKA, Cook TM, Scott DA, McGain F, Humphries RS, Dhillon RS, Reid JP, Hamilton F, Bzdek BR, Pickering AE. Quantitative evaluation of aerosol generation during manual facemask ventilation. Anaesthesia 2022; 77:22-27. [PMID: 34700360 PMCID: PMC8653000 DOI: 10.1111/anae.15599] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2021] [Indexed: 01/13/2023]
Abstract
Manual facemask ventilation, a core component of elective and emergency airway management, is classified as an aerosol-generating procedure. This designation is based on one epidemiological study suggesting an association between facemask ventilation and transmission during the SARS-CoV-1 outbreak in 2003. There is no direct evidence to indicate whether facemask ventilation is a high-risk procedure for aerosol generation. We conducted aerosol monitoring during routine facemask ventilation and facemask ventilation with an intentionally generated leak in anaesthetised patients. Recordings were made in ultraclean operating theatres and compared against the aerosol generated by tidal breathing and cough manoeuvres. Respiratory aerosol from tidal breathing in 11 patients was reliably detected above the very low background particle concentrations with median [IQR (range)] particle counts of 191 (77-486 [4-1313]) and 2 (1-5 [0-13]) particles.l-1 , respectively, p = 0.002. The median (IQR [range]) aerosol concentration detected during facemask ventilation without a leak (3 (0-9 [0-43]) particles.l-1 ) and with an intentional leak (11 (7-26 [1-62]) particles.l-1 ) was 64-fold (p = 0.001) and 17-fold (p = 0.002) lower than that of tidal breathing, respectively. Median (IQR [range]) peak particle concentration during facemask ventilation both without a leak (60 (0-60 [0-120]) particles.l-1 ) and with a leak (120 (60-180 [60-480]) particles.l-1 ) were 20-fold (p = 0.002) and 10-fold (0.001) lower than a cough (1260 (800-3242 [100-3682]) particles.l-1 ), respectively. This study demonstrates that facemask ventilation, even when performed with an intentional leak, does not generate high levels of bioaerosol. On the basis of this evidence, we argue facemask ventilation should not be considered an aerosol-generating procedure.
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Affiliation(s)
- A. J. Shrimpton
- Anaesthesia, Pain and Critical Care Sciences, School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - J. M. Brown
- Department of Anaesthesia and Intensive Care MedicineNorth Bristol NHS TrustBristolUK
| | | | - T. M. Cook
- Department of Anaesthesia and Intensive Care MedicineRoyal United Hospital NHS TrustBathUK
| | - D. A. Scott
- Department of Critical CareUniversity of Melbourne; St. Vincent's Hospital MelbourneAustralia
| | - F. McGain
- Western HealthFootscrayVictoriaAustralia
| | - R. S. Humphries
- Climate Science CentreCSIRO Oceans and AtmosphereAspendaleVictoriaAustralia
| | - R. S. Dhillon
- Department of NeurosurgerySt Vincent's Hospital MelbourneFitzroyVictoriaAustralia
| | - J. P. Reid
- School of ChemistryUniversity of BristolBristolUK
| | - F. Hamilton
- Department of Population Health SciencesUniversity of BristolBristolUK
| | - B. R. Bzdek
- School of ChemistryUniversity of BristolBristolUK
| | - A. E. Pickering
- Anaesthesia, Pain and Critical Care Sciences, School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
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Shrimpton AJ, Gregson FKA, Brown JM, Cook TM, Bzdek BR, Hamilton F, Reid JP, Pickering AE. A quantitative evaluation of aerosol generation during supraglottic airway insertion and removal. Anaesthesia 2021; 76:1577-1584. [PMID: 34287820 DOI: 10.1111/anae.15542] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2021] [Indexed: 12/30/2022]
Abstract
Many guidelines consider supraglottic airway use to be an aerosol-generating procedure. This status requires increased levels of personal protective equipment, fallow time between cases and results in reduced operating theatre efficiency. Aerosol generation has never been quantitated during supraglottic airway use. To address this evidence gap, we conducted real-time aerosol monitoring (0.3-10-µm diameter) in ultraclean operating theatres during supraglottic airway insertion and removal. This showed very low background particle concentrations (median (IQR [range]) 1.6 (0-3.1 [0-4.0]) particles.l-1 ) against which the patient's tidal breathing produced a higher concentration of aerosol (4.0 (1.3-11.0 [0-44]) particles.l-1 , p = 0.048). The average aerosol concentration detected during supraglottic airway insertion (1.3 (1.0-4.2 [0-6.2]) particles.l-1 , n = 11), and removal (2.1 (0-17.5 [0-26.2]) particles.l-1 , n = 12) was no different to tidal breathing (p = 0.31 and p = 0.84, respectively). Comparison of supraglottic airway insertion and removal with a volitional cough (104 (66-169 [33-326]), n = 27), demonstrated that supraglottic airway insertion/removal sequences produced <4% of the aerosol compared with a single cough (p < 0.001). A transient aerosol increase was recorded during one complicated supraglottic airway insertion (which initially failed to provide a patent airway). Detailed analysis of this event showed an atypical particle size distribution and we subsequently identified multiple sources of non-respiratory aerosols that may be produced during airway management and can be considered as artefacts. These findings demonstrate supraglottic airway insertion/removal generates no more bio-aerosol than breathing and far less than a cough. This should inform the design of infection prevention strategies for anaesthetists and operating theatre staff caring for patients managed with supraglottic airways.
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Affiliation(s)
- A J Shrimpton
- Pain and Critical Care Sciences and School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - F K A Gregson
- School of Chemistry, University of Bristol, Bristol, UK
| | - J M Brown
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
| | - T M Cook
- Department of Anaesthesia and Intensive Care Medicine, Royal United Hospital NHS Trust, Bath, UK
| | - B R Bzdek
- School of Chemistry, University of Bristol, Bristol, UK
| | - F Hamilton
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - J P Reid
- School of Chemistry, University of Bristol, Bristol, UK
| | - A E Pickering
- Pain and Critical Care Sciences and School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
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Newsom RB, Amara A, Hicks A, Quint M, Pattison C, Bzdek BR, Burridge J, Krawczyk C, Dinsmore J, Conway J. Comparison of droplet spread in standard and laminar flow operating theatres: SPRAY study group. J Hosp Infect 2021; 110:194-200. [PMID: 33549768 PMCID: PMC7860961 DOI: 10.1016/j.jhin.2021.01.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/20/2021] [Accepted: 01/26/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND Reducing COVID-19 transmission relies on controlling droplet and aerosol spread. Fluorescein staining reveals microscopic droplets. AIM To compare the droplet spread in non-laminar and laminar air flow operating theatres. METHODS A 'cough-generator' was fixed to a theatre trolley at 45°. Fluorescein-stained 'secretions' were projected on to a series of calibrated targets. These were photographed under UV light and 'source detection' software measured droplet splatter size and distance. FINDINGS The smallest droplet detected was ∼120 μm and the largest ∼24,000 μm. An average of 25,862 spots was detected in the non-laminar theatre, compared with 11,430 in the laminar theatre (56% reduction). The laminar air flow mainly affected the smaller droplets (<1000 μm). The surface area covered with droplets was: 6% at 50 cm, 1% at 2 m, and 0.5% at 3 m in the non-laminar air flow; and 3%, 0.5%, and 0.2% in the laminar air flow, respectively. CONCLUSION Accurate mapping of droplet spread in clinical environments is possible using fluorescein staining and image analysis. The laminar air flow affected the smaller droplets but had limited effect on larger droplets in our 'aerosol-generating procedure' cough model. Our results indicate that the laminar air flow theatre requires similar post-surgery cleaning to the non-laminar, and staff should consider full personal protective equipment for medium- and high-risk patients.
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Affiliation(s)
- R B Newsom
- School of Health and Care Professions, University of Portsmouth, Portsmouth, UK.
| | - A Amara
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, UK
| | - A Hicks
- Respiratory Medicine, Portsmouth Hospitals University NHS Trust, UK
| | - M Quint
- Respiratory Physiotherapy, Portsmouth Hospitals University NHS Trust, UK
| | - C Pattison
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, UK
| | - B R Bzdek
- NERC, School of Chemistry, University of Bristol, UK
| | - J Burridge
- School of Mathematics, University of Portsmouth, UK
| | - C Krawczyk
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, UK
| | - J Dinsmore
- Anaesthesia, Portsmouth Hospitals University NHS Trust, UK
| | - J Conway
- Respiratory Sciences, Brunel University, London, UK
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Shrimpton A, Gregson FKA, Cook TM, Brown J, Bzdek BR, Reid JP, Pickering AE. A quantitative evaluation of aerosol generation during tracheal intubation and extubation: a reply. Anaesthesia 2020; 76 Suppl 3:16-18. [PMID: 33368170 DOI: 10.1111/anae.15345] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2020] [Indexed: 11/26/2022]
Affiliation(s)
- A Shrimpton
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - F K A Gregson
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - T M Cook
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - J Brown
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - B R Bzdek
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - J P Reid
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - A E Pickering
- University of Bristol and North Bristol NHS Trust, Bristol, UK
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Brown J, Gregson FKA, Shrimpton A, Cook TM, Bzdek BR, Reid JP, Pickering AE. A quantitative evaluation of aerosol generation during tracheal intubation and extubation. Anaesthesia 2020; 76:174-181. [PMID: 33022093 PMCID: PMC7675579 DOI: 10.1111/anae.15292] [Citation(s) in RCA: 129] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 12/18/2022]
Abstract
The potential aerosolised transmission of severe acute respiratory syndrome coronavirus‐2 is of global concern. Airborne precaution personal protective equipment and preventative measures are universally mandated for medical procedures deemed to be aerosol generating. The implementation of these measures is having a huge impact on healthcare provision. There is currently a lack of quantitative evidence on the number and size of airborne particles produced during aerosol‐generating procedures to inform risk assessments. To address this evidence gap, we conducted real‐time, high‐resolution environmental monitoring in ultraclean ventilation operating theatres during tracheal intubation and extubation sequences. Continuous sampling with an optical particle sizer allowed characterisation of aerosol generation within the zone between the patient and anaesthetist. Aerosol monitoring showed a very low background particle count (0.4 particles.l−1) allowing resolution of transient increases in airborne particles associated with airway management. As a positive reference control, we quantitated the aerosol produced in the same setting by a volitional cough (average concentration, 732 (418) particles.l−1, n = 38). Tracheal intubation including facemask ventilation produced very low quantities of aerosolised particles (average concentration, 1.4 (1.4) particles.l−1, n = 14, p < 0.0001 vs. cough). Tracheal extubation, particularly when the patient coughed, produced a detectable aerosol (21 (18) l−1, n = 10) which was 15‐fold greater than intubation (p = 0.0004) but 35‐fold less than a volitional cough (p < 0.0001). The study does not support the designation of elective tracheal intubation as an aerosol‐generating procedure. Extubation generates more detectable aerosol than intubation but falls below the current criterion for designation as a high‐risk aerosol‐generating procedure. These novel findings from real‐time aerosol detection in a routine healthcare setting provide a quantitative methodology for risk assessment that can be extended to other airway management techniques and clinical settings. They also indicate the need for reappraisal of what constitutes an aerosol‐generating procedure and the associated precautions for routine anaesthetic airway management.
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Affiliation(s)
- J Brown
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
| | - F K A Gregson
- School of Chemistry, University of Bristol, Bristol, UK
| | - A Shrimpton
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - T M Cook
- Department of Anaesthesia and Intensive Care Medicine, Royal United Hospital NHS Trust, Bath, UK
| | - B R Bzdek
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - J P Reid
- School of Chemistry, University of Bristol, Bristol, UK
| | - A E Pickering
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK.,University Hospitals Bristol, Bristol, UK
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