With the onset and explosive spread of the COVID-19 pandemic, healthcare professionals have come under a lot of scrutiny as well as stress, as they are on the frontline of the battle. One area, discussed in a recent paper by Northwestern University researchers and published on the preprint server medRxiv* in August 2020, is the viral exposure suffered by healthcare workers during bronchoalveolar lavage (BAL). BAL is a diagnostic method of the lower respiratory system in which a bronchoscope is passed through the mouth or nose into an appropriate airway in the lungs, with a measured amount of fluid introduced and then collected for examination.
Aerosols and Viral Spread
The pandemic is thought to be most commonly spread by aerosols containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). One classic aerosol-generating procedure is BAL. As a result, many professional societies have issued guidelines specifying that this should be carried out only when strictly required. However, this overlooks one fundamental flaw: the risk of infection during such procedures is unknown.
BALs for Better Outcomes
The current study exploits the fact that over 450 BALs were carried out on intubated patients with COVID-19 disease, using a modified protocol, to examine the actual risk to the healthcare providers. BALs are typically performed in these situations to diagnose bacterial superinfections in the presence of viral pneumonia, as have been known to occur commonly during influenza pandemics, pushing up mortality rates. The very high rate of death in COVID-19 pneumonia patients with such bacterial co-infections indicates the need for the proper identification and treatment of the latter.
Early studies by the current researchers indicate that bacterial infections are common in these patients, especially when they require mechanical ventilation. BAL and quantitative culture is, therefore, a helpful test for such diagnoses, and has long been part of the protocol in the center that this study focuses on. Here, healthcare providers perform BAL and rapid diagnostic tests to detect and treat severe pneumonia. This also allows them to evaluate the lung microenvironment in this condition.
Protocols for Safety
The standard procedure here is non bronchoscopic BAL, which is carried out by respiratory therapists, with the bronchoscopic variant reserved for difficult cases. The concern with the advent of COVID-19 was the generation of respiratory aerosols, which led to a lower rate of BAL. However, endotracheal aspiration failed to return the same satisfactory results and requires the ventilator to be disconnected for an extended period, which is unacceptable in this clinical setting, leaving bronchoscopic BAL as the only safe option
Little information has trickled down about the safety of these procedures in this scenario, some studies showing the infection rate to be low, while guidelines by professional organizations discourage its routine use in these patients based solely on expert opinion. To help settle the debate, the researchers first set up and then tested out a safety protocol for bronchoscopic BALs in intubated patients with respiratory failure and who have or are suspected of having COVID-19.
The study included 52 staff involved in lung and critical care at a tertiary-level hospital. All the bronchoscopies were carried out by attending pulmonary ICU physicians, or interventional pulmonary physicians or fellows. There were no nurses or respiratory therapists present during the bronchoscopy itself.
All participants wore PPE and used disposable bronchoscopes. The use of a short-acting muscle paralyzing agent cisatracurium was encouraged to discourage coughing during the procedure. Short clamping of the endotracheal tube and brief interruption of the inspiratory limb of the ventilator circuit was recommended to allow proper placement of the bronchoscope. The participants also rated the difficulty of the procedure on a score of 1 to 10.
The researchers received a 90% response rate, with over 40% having spent five weeks on ICU service with patients known or suspected to have COVID-19. The highest number of BALs performed by any single provider on these patients was over 60, and the lowest zero. Approximately 80% had performed one or more bronchoscopies, with the median range being 10-30.
Twelve of the providers reported that they could not follow the modified protocol fully, and two could not don full PPE, the respondents reported. Over 40% spent five or more weeks in ICUs caring for COVID-19 patients, which correlated well with the number of bronchoscopies.
Overall, the difficulty was not significantly greater with this protocol than for a routine BAL in an ICU patient, with the median score being 6. This was not related to the number of bronchoscopies or the time on ICU service.
The respondents perceived these to be safe procedures in their setting, with full precautions and PPE available as required. Almost half of the providers (27) who did these providers had been tested at least once by nasopharyngeal swab (NPS) for the infection, but none were positive, while serology was positive in one of 27. In this case, the individual had been tested twice by serology, and the other test returned a negative test. No symptoms of fever and respiratory illness were present.
Though small and single-center, the study indicates that with proper safety precautions, the risk of COVID-19 transmission to healthcare providers during bronchoscopic BALs is low. The protocol used by providers in this study includes:
- Excluding unnecessary staff from the room during the procedure
- Preventing aerosol generation by shutting off parts of the ventilator circuit during manipulation
- Using appropriate drugs to minimize the risk of coughing
- Using single-use scopes
Also, the protocol was largely adhered to because the providers in most cases came from a small group of highly skilled professionals and because the difficulty was not significantly greater compared to routine bronchoscopies in an ICU setting.
The researchers say that since other similar centers are likely to have the same type of protocols, a more systematic exploration of the procedure would help to codify its efficacy in preventing infection. This could lead to the development of medical care protocols in line with scientific evidence and not only medical opinion.
The researchers show that the priority of keeping medical staff safe required them to rule out the previous standard of care non bronchoscopic BAL performed by respiratory therapists. Instead, the providers who already did this procedure as part of their critical care were trusted to do it safely, using PPE and adopting precautions to avoid excessive aerosol generation. This proved to be a valid line of action, they say.
Conclusion and Future Directions
They point out, “Our group has supported adhering to evidence-based critical care during the COVID-19 pandemic rather than making practice changes solely in response to uncertainties associated with the COVID pandemic.”
The study is limited by its retrospective and recall-based design. Protocol adherence was not monitored. Serology testing was not mandatory, and NPS testing was also based on the likelihood of exposure or symptoms. Asymptomatic infection may have been missed as a result.
However, this report fills a necessary slot as the first in-depth report on the real-time risk of BAL in a large center handling multiple such procedures on COVID-19 patients. More research will be required to shape the best protective protocol and its indications in this pandemic, so as to achieve the best outcomes. However, the current findings suggest, they say, that “BAL can be routinely incorporated into the ICU care of these patients with minimal infectious risk to providers.”
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.