Minimising risk to thoracic surgical teams in an era of COVID-19: exploring possible preventative measures

The demands of curtailing the impact of the coronavirus disease 2019 (COVID-19) global pandemic have disrupted the world’s ability to care for patients with thoracic pathologies. Those who undergo thoracic surgical therapeutic procedures are a high-risk category, likely to have impaired lung function but also high risk for exposing clinical teams to aerosolised viral loads. In light of this global pandemic, thorough pre-procedural planning, adequate personal protective equipment (PPE), experienced personnel and judicious anaesthetic and intra-operative measures will serve to be instrumental in ensuring positive patient outcomes whilst still protecting the safety of healthcare workers.


Introduction
The novel coronavirus, now termed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a significant global impact in the space of 4 months. This has had resounding effects on the ability to deliver adequate healthcare to all those who require it. The demands of curtailing the impact of the pandemic have disrupted the world's ability to care for patients with thoracic pathologies. The ever increasing burden of the coronavirus disease 2019 (COVID-19) pandemic coupled with the finite amount of hospital resources has forced surgeons to prioritise cases and protect patients. At the same time, however, careful consideration must also be given to the hospital policies and procedures that need to be implemented in order to protect the healthcare teams from viral transmission. Numerous bodies from multiple cancer, surgical and research organisations have come together to form consensus statements on how we can mitigate the risk of transmission through optimisation of pre-operative, intra-operative and post-operative procedures [1]. This brief article seeks to provide an overview of the current guidance on how intraoperative precautions can be employed to make thoracic surgical procedures safer for all healthcare personnel involved.

Comments
Therapeutic procedures on the lung during the era of COVID-19 automatically place clinical teams to a high risk of exposure from aerosolised viral loads. Procedures such as bronchoscopy, tracheostomy, double-lumen endotracheal tube placement, airway surgery, laparoscopy and lung surgery with post-operative parenchymal air leaks all pose a risk. Multidisciplinary strategies should initially be put in place to triage patients to treatment pathways that are often alternative to surgery. These should be balanced against the COVID-19 status of the hospital, the level of hospital resources available and the COVID-19 trajectory of the hospital (i.e. not in rapid escalation phase) [1]. Those patients who do undergo surgery or allied thoracic surgical procedures must be carried out after judicious evaluation of the 'patient benefit' to 'healthcare worker risk' ratio.
Tracheostomy and bronchoscopy both have a continuing role in managing weaning from extended periods of mechanical ventilation during this pandemic. Working groups have determined that for tracheostomy, patient selection and timing of procedure are paramount [2]. The procedure be delayed until at least day 10 of mechanical ventilation and when there are signs of clinical improvement. Use of enhanced personal protective equipment (PPE) should be carried whenever possible in an appropriate location. Minimal use of diathermy is advocated with use of a smoke evacuator in the case of an open surgical technique. Pre-oxygenation, followed by a trial of apnoea in the intensive care unit (ICU), with an FiO 2 of 1.0 and positive end-expiratory pressure of 5 cm H 2 O, in patients who are supine before tracheostomy to show physiological readiness to tolerate the procedure, with strategies to mitigate aerosolisation is also advised [2]. Little exists in the way of objective evidence to see if there is a tangible transmission impact from the implementation of these added precautions; however, Angel and colleagues [3] reported on the outcomes of 98 COVID-19-positive patients on mechanical ventilation undergoing a novel percutaneous dilational tracheostomy (PDT) procedure. The concurrent use of rigid bronchoscopy adjacent to the endotracheal tube provided good visualisation whilst reducing the risk of virus aerosolisation. The procedure was deemed safe and feasible with a low overall procedural complication rate (5.1%). At the time of reporting, 33% of patients had been weaned from mechanical support, 19% had their tracheostomy tube downsized and 8% were de-cannulated. Forty patients remained on full ventilator support. An 8-person healthcare team was involved in performing PDT on all the patients in this series; of these, 4 were formally tested for SARS-CoV-2, and none was positive. No person in the entire healthcare team developed any coronavirus-related symptoms. Furthermore, Mecham and colleagues [4] reviewed the literature for evidence on how to best perform tracheostomy in patients with potential COVID-19 infection. They concluded that adequate peri-procedural planning, enhanced provisions of PPE and careful anaesthesia are key to good patient outcome and ensuring the safety of all involved. Furthermore, timely execution of the procedure at the bedside would help to limit the number of personnel exposed. Wahidi and colleagues [5] provided six guiding statements on the role of bronchoscopy during the COVID-19 pandemic. Of these, one statement was evidence based (level 2C); the use of bronchoscopy to diagnose, stage or characterise known or suspected lung cancer in an area where COVID-19 transmission is present, should be carried out in a timely and safe manner. The remaining five consensus-based statements relate to preprocedural COVID-19 patient testing and the provision and use of full PPE throughout.
During the conduct of thoracic surgery and elective lung resection, multiple guidance documents have been produced. Rakovich and colleagues [6] assimilated a multi-disciplinary working group in order to guide the conduct of elective lung cancer resections to reduce the risk of viral transmission through aerosolisation. Six time points were devised; strategies were devised to reduce the risk for aerosol at each time point (these are all detailed in Table 1). These strategies can help to revise and guide operating theatre protocols for the purposes of this pandemic and indeed similar situations in the future. Thornton and colleagues [7] developed a set of practicebased recommendations for airway management and lung isolation during thoracic surgery to mitigate against the risk of aerosolisation. Guidance is provided around tracheal intubation and extubation, conduct of lung isolation and single-lung ventilation as well as flexible bronchoscopy. When dealing with hypoxic episodes during singlelung ventilation, the authors recommend two-lung ventilation for critical hypoxia. However shunt-driven hypoxia can be overcome by administering oxygen to the dependent lung which is advised to be via a continuous positive pressure circuit with a built-in high-efficiency particulate air (HEPA) filter. Soma and colleagues [8] designed an 8step operative checklist to reduce aerosolisation of secretions. The checklist was based on an example of paediatric laryngo-bronchoscopy for diagnostic and therapeutic purposes (foreign body removal). The steps start with notifying the surgical booking centre and on-call anaesthetist all the way through to surgical and anaesthetic completion and debrief. Measures are described at each step to reduce risk of aerosolisation. Intra-procedural measures include lowest acceptable gas flows for oxygenation and glass screens to protect surgical teams during visualisation through rigid bronchoscopy.
In the world of Minimally Invasive and Robotic Surgery, similar working groups have been formed. Porter and colleagues [9] conducted a pan-specialty review in an effort to provide guidance on how to mitigate against the transmission of COVID-19 in minimally invasive surgery. The risk of COVID-19 transmission through CO 2 insufflation during these procedures remains unclear; however, precautions should be undertaken to decrease exposure to surgical smoke, decrease production of surgical plume and filter any gaseous products (e.g. CO 2 ) through pre-approved filters. Van den Eynde and colleagues [10] described guidance on the conduct of robot-assisted cardiothoracic surgical procedures in COVID-19 patients. Whilst the conduct of the surgery may be beneficial over traditional open methods in terms of length of post-operative stay and recovery, these must be balanced against the risk of viral aerosolisation which should be managed by judicious use of CO 2 insufflation as well as highenergy electrocautery and ultrasonic devices.

Conclusion
The COVID-19 pandemic has dramatically affected the conduct of healthcare practices globally. This has sparked the development of various guidelines to reduce the risk of viral transmission during thoracic surgery and allied specialties. In light of this global pandemic, there is a growing body of evidence, which is largely guideline, expert opinion and consensus driven, yet still represents the current best platform from which we can inform our precautions in the management of this uncertain threat. Thorough pre-procedural planning, adequate PPE, experienced personnel and judicious anaesthetic and intra-operative measures will serve to be instrumental in ensuring positive patient outcomes whilst still protecting the safety of healthcare workers.
Authors' contributions AJP, SM and EC designed and constructed the manuscript together with data accrual. BN provided supervisorial support and critique in manuscript revisions. All authors have read and approved the manuscript.
Funding None.
Data availability All data and material are publicly available.

Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of interest.
Ethics approval and consent to participate Not applicable.

Consent for publication Not applicable.
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