A quantitative evaluation of aerosol generation during cardiopulmonary resuscitation.

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.

The comparison of aerosol exposures to endoscopy personnel performing diagnostic upper gastrointestinal endoscopy in patients with and without head box: A randomized control trial.

BACKGROUND AND AIMS: Esophagogastroduodenoscopy (EGD) has been identified as an aerosol-generating procedure (AGP) during the COVID-19 pandemic. The risk of AGP and benefits of utilizing protective measures have never been fully studied. METHODS: A randomized control, open-label study in patients scheduled for diagnostic EGD between September and December 2021 was conducted. Patients were randomly assigned to either head box group or without head box group (control group). Particles were measured with six-size particle counters at the nurse anesthetist and endoscopist position. Primary composite outcomes were the mean difference of aerosol particle levels during and before EGD at the nurse anesthetist face position and at the endoscopist face position. Secondary outcomes were factors increasing aerosol particle levels and safety of the head box. RESULTS: From 196 enrolled patients, 190 were analyzed. Baseline characteristics were not different between the two groups. The mean distance between endoscopist face and patient mouth was 67.2 ± 4.9 cm. The mean differences of 0.3-, 0.5-, and 1.0-µm particles during the procedure and at baseline before the procedure at nurse anesthetist position and the mean differences of 0.3-µm particles at the endoscopist position was found to have decreased in the head box group and increased in the control group (P < 0.001, 0.001, 0.014, and P < 0.001, respectively). Cough, burping, and body movement increased aerosol particles. No additional adverse events were observed in the head box group. CONCLUSIONS: EGD with the head box is safe and can reduce significant aerosolization to endoscopy personnel including nurse anesthetists and endoscopists.

Tracing ΦX174 bacteriophage spreading during aerosol-generating procedures in a dental clinic.

OBJECTIVE: The aim of this study was to test the plausibility of using the ΦX174 bacteriophage as a tracer of viral aerosols spreading in a dental aerosol-generating procedure (AGP) model. METHODS: ΦX174 bacteriophage (~ 108 plaque-forming units (PFU)/mL) was added into instrument irrigation reservoirs and aerosolized during class-IV cavity preparations followed by composite fillings on natural upper-anterior teeth (n = 3) in a phantom head. Droplets/aerosols were sampled through a passive approach that consisted of Escherichia coli strain C600 cultures immersed in a LB top agar layer in Petri dishes (PDs) in a double-layer technique. In addition, an active approach consisted of E coli C600 on PDs sets mounted in a six-stage cascade Andersen impactor (AI) (simulating human inhalation). The AI was located at 30 cm from the mannequin during AGP and afterwards at 1.5 m. After collection PDs were incubated overnight (18 h at 37 °C) and bacterial lysis was quantified. RESULTS: The passive approach disclosed PFUs mainly concentrated over the dental practitioner, on the mannequin's chest and shoulder and up to 90 cm apart, facing the opposite side of the AGP's source (around the spittoon). The maximum aerosol spreading distance was 1.5 m in front of the mannequin's mouth. The active approach disclosed collection of PFUs corresponding to stages (and aerodynamic diameters) 5 (1.1-2.1 µm) and 6 (0.65-1.1 µm), mimicking access to the lower respiratory airways. CONCLUSION: The ΦX174 bacteriophage can be used as a traceable viral surrogate in simulated studies contributing to understand dental bioaerosol's behavior, its spreading, and its potential threat for upper and lower respiratory tract. CLINICAL RELEVANCE: The probability to find infectious virus during AGPs is high. This suggests the need to continue characterizing the spreading viral agents in different clinical settings through combination of passive and active approaches. In addition, subsequent identification and implementation of virus-related mitigation strategies is relevant to avoid occupational virus infections.

Droplet nuclei are generated during colonoscopy and are decreased by the use of carbon dioxide and water immersion technique.

OBJECTIVES: The COVID-19 pandemic has raised concerns on whether colonoscopies (CS) carry a transmission risk. The aim was to determine whether CS are aerosol-generating procedures. METHODS: This was a prospective observational trial including all patients undergoing CS at the Prince of Wales Hospital from 1 June to 31 July 2020. Three particle counters were placed 10 cm from each patient's anus and near the mouth of endoscopists and nurses. The particle counter recorded the number of particles of size 0.3, 0.5, 0.7, 1, 5, and 10 µm. Patient demographics, seniority of endoscopists, use of CO2 and water immersion technique, and air particle count (particles/cubic foot, dCF) were recorded. Multilevel modeling was used to test all the hypotheses with a post-hoc analysis. RESULTS: A total of 117 patients were recruited. During CS, the level of 5 µm and 10 µm were significantly higher than the baseline period (P = 0.002). Procedures performed by trainees had a higher level of aerosols when compared to specialists (0.3 µm, P < 0.001; 0.5 µm and 0.7 µm, P < 0.001). The use of CO2 and water immersion techniques had significantly lower aerosols generated when compared to air (CO2 : 0.3, 0.5, and 0.7 µm: P < 0.001; water immersion: 0.3 µm: P = 0.048; 0.7 µm: P = 0.03). There were no significant increases in any particle sizes during the procedure at the endoscopists' and nurses' mouth. However, 8/117 (6.83%) particle count tracings showed a simultaneous surge of all particle sizes at the patient's anus and endoscopists' and nurses' level during rectal extubation. CONCLUSION: Colonoscopy generates droplet nuclei especially during rectal extubation. The use of CO2 and water immersion techniques may mitigate these risks.

Visualization of airborne droplets generated with dental handpieces and verification of the efficacy of high-volume evacuators: an in vitro study.

BACKGROUND: The COVID-19 pandemic led to concerns about the potential airborne transmission of the virus during dental procedures, but evidence of actual transmission in clinical settings was lacking. This study aimed to observe the behavior of dental sprays generated from dental rotary handpieces and to evaluate the effectiveness of high-volume evacuators (HVEs) using laser light sheets and water-sensitive papers. METHODS: A dental manikin and jaw model were mounted in a dental treatment unit. Mock cutting procedures were performed on an artificial tooth on the maxillary left central incisor using an air turbine, a contra-angle electric micromotor (EM), and a 1:5 speed-up contra-angle EM (×5EM). Intraoral vacuum and extraoral vacuum (EOV) were used to verify the effectiveness of the HVEs. The dynamics and dispersal range of the dental sprays were visualized using a laser light sheet. In addition, environmental surface pollution was monitored three-dimensionally using water-sensitive papers. RESULTS: Although the HVEs were effective in both the tests, the use of EOV alone increased vertical dispersal and pollution. CONCLUSIONS: The use of various types of HVEs to reduce the exposure of operators and assistants to dental sprays when using dental rotary cutting instruments is beneficial. The study findings will be helpful in the event of a future pandemic caused by an emerging or re-emerging infectious disease.

Head and neck cancer recurrence with limited mouth opening, radiation fibrosis and confirmed COVID-19 infection: Approach to airway management.

We present a case that describes the airway management of a patient with recurrent head and neck cancer and confirmed COVID-19 infection. Securing airway of these patients with anticipated difficulty and at the same time limiting virus exposure to providers can be challenging. The risk of aerosolization during awake tracheal intubation is extreme as it carries a high risk of transmitting respiratory infections. A multidisciplinary team discussion before the procedure highlighted aspects of both airway management and the urgency of surgical procedure where particular care and modifications are required. Successful flexible bronchoscopy and intubation was done under inhalational anaesthetics with spontaneous breathing. Although fiberoptic intubation during sleep,in anticipated difficult airways, have led to enhanced intubation time, this technique was opted to minimize the risk of aerosol generation associated with topicalisation, coughing and hence reduced incidence of cross infection to health care workers.

Management of abdominal gas leakage from surgical trocars in laparoscopic surgery: a preclinical study.

Introduction: There is an ongoing concern about the potential infectious risk due to pneumoperitoneal gas leakage from surgical trocars in laparoscopic surgery. We aimed to visually confirm the presence of leakage from trocars and investigate the changes in the leakage scale according to intra-abdominal pressures and trocar types. Material and methods: We established a porcine pneumoperitoneum model and performed experimental forceps manipulation using 5-mm grasping forceps with 12-mm trocars. The gas leakage, if any, was imaged using a Schlieren optical system, which can visualize minute gas flow invisible to the naked eye. For measuring the scale, we calculated the gas leakage velocity and area using image analysis software. Four types of unused and exhausted disposable trocars were compared. Results: Gas leakage was observed from trocars during forceps insertion and removal. Both the gas leakage velocity and area increased as the intra-abdominal pressure increased. Every type of trocar we handled was associated with gas leakage, and exhausted disposable trocars had the largest scale gas leakage. Conclusions: We confirmed gas leakage from trocars during device traffic. The scale of leakage increased with high intra-abdominal pressure and with the use of exhausted trocars. Current protection against gas leakage may not be sufficient and new surgical safety measures and device development may be needed in the future.

Development of an emergency airway response system for COVID-19 at a tertiary care hospital in resource limited country.

The ongoing coronavirus (COVID-19) infection causes severe respiratory dysfunction and has become an emergent issue for worldwide healthcare due to highly transmissible and contagious nature. Aerosol generating procedures such as tracheal intubation is of particularly high risk. This mandates some advice on processes and techniques required to protect staff and uniform approach during airway management. We hereby share our experience in development of an emergency response system to deal with COVID airway management at a frontline hospital which particularly consider the local demands and resources. This includes a change in working dynamics with 24/7 consultant coverage for emergent or urgent tracheal intubation of COVID patients at non-operating room locations. Other steps include prepackaging intubation baskets, availability of videolaryngoscope, standard personal protective equipment including powered air purifying respirator, and use of modified intubation checklist.

Quantitative evaluation of aerosol generation during manual facemask ventilation.

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.

COVID-VU - ENT-UK national survey of flexible nasendoscopy in the upper aerodigestive tract amidst the COVID-19 pandemic.

BACKGROUND: Flexible nasendoscopy (FNE) is an invaluable multi-disciplinary tool for upper aerodigestive tract (UADT) examination. During the COVID-19 pandemic concerns were raised that FNE had the potential of generating aerosols resulting in human cross-contamination when performed on SARS-COV2 carriers. In the UK, and other European countries, national guidelines were issued restricting FNE to essential cases. We surveyed ENT-UK members and Royal College of Speech and Language Therapists (RCSLT) members to determine the impact of the COVID-19 pandemic (first peak) on FNE practice in the UK. METHODS: An observational internet-based survey constructed in accordance to the CHERRIES checklist and setup in SurveyMonkey of FNE practice amongst UK-based ENT surgeons and speech and language therapists in community clinics, the outpatient department, inpatient wards, ICU, emergency department and operating theatres (through the NHS and private sector) prior to, during and following the first COVID-19 wave in the UK. RESULTS: 314 responses collected (24% response rate), 82% from ENT clinicians, 17% from SLTs and 1% from other allied healthcare professionals. Overall, there has been a large reduction in the volume and indications for FNE during the first peak of the COVID-19 pandemic with limited recovery by mid-August 2020. Cancer and airway assessments were impacted less. A wide range of FNE protocols influenced by local factors are reported, varying in endoscope preference, Personal Protective Equipment (PPE) and sterilization methods. Where dedicated Aerosol Generating Procedure (AGP) rooms were unavailable, clinicians resorted to window opening and variable room "down-time" between patients. Endoscope preference reflected availability and user familiarity, ENT trainees favoring the use of single-use video endoscopes. CONCLUSION: Despite national guidance, local practice of FNE remains interrupted and highly variable in the UK. A collaborative inter-disciplinary approach is required to re-introduce FNE safely in volume across healthcare settings, re-establishing timely endoscopic diagnosis and pre-pandemic levels of patient care.