Bronchoscopy: From Tool to Trouble

Written by Kaylee Stella Harris MBChB III and Mayuri Ramnarain MBChB IV

Bronchoscopy is routinely used in the diagnosis of lung infections, tumours and to find the cause of lung haemorrhage.⁽¹⁾ However, in the setting of the Covid-19 pandemic, this aerosol generating procedure poses a significant risk of viral transmission to healthcare workers. Interestingly, bronchoscopy may theoretically be used in the diagnosis of SARS-CoV-2.

Bronchoscopy to Diagnose SARS-CoV-2

The Real-Time Polymerase Chain Reaction (RT-PCR) test is the preferred diagnostic tool for SARS-CoV-2 due to its high specificity.⁽²⁾ The RT-PCR nasopharyngeal (NP) and oropharyngeal (OP) swab tests collect a sample of the saliva and mucus. The test is conducted 8 days after suspected exposure to the virus and may present a certain discomfort to the patient. Even though the RT-PCR provides a high level of specificity, NP and OP swabs only provide upper respiratory tract samples. This may result in false negatives as SARS-CoV-2 is a lower respiratory tract infection.⁽³⁾ Bronchoscopy could theoretically be used as an alternative means to diagnose SARS-CoV-2 as it provides vivid imaging of the bronchi of the lungs, and access to collect bronchoalveolar lavage fluid (BALF) tissue samples for RT-PCR via a stent.⁽²⁾  OP and NP swabs have sensitivities of 32% and 63% respectively, while BALF is positive in 93% of patients. Despite this, bronchoscopy should not be used to diagnose SARS-CoV-2 infection. This is due to the high risk of viral transmission to health care workers and the numerous risks involved in the procedure for the patient. Exceptions include use in immunocompromised patients, if superinfection or mucus plugging is suspected, or in life-saving conditions. ⁽⁴⁾

Figure 1: Congestion and mucus secretions in bronchial lumen⁽⁵⁾

Method of Bronchoscopy

During the procedure, a local anaesthetic is used as well as a sedative for the patient’s comfort. A bronchoscope is then inserted through the patient’s nose or mouth and guided at the back of the pharynx down into the trachea towards the bronchi. There are two types of bronchoscopes: flexible and rigid. Rigid bronchoscopes are used to view the larger airways. They are used to clear vast amounts of secretions or blood, insert stents, and remove foreign objects or lesions. Flexible bronchoscopes can be used to probe further into the lungs, reaching the bronchioles. They are also used to insert breathing tubes for oxygen delivery, the suctioning of secretions, biopsies and the transfer of medicine into the lungs.⁽⁶⁾

Patients are reported to feel a slight pressure or tugging sensation deep in their chest. Occasionally patient’s may gag or require oxygen to aid the procedure. Any instrument that the health care practitioner may require for biopsy or other procedures is inserted through a channel in the bronchoscope. Bronchoscopies average between 20 to 30 minutes.⁽³⁾

Figure 2:Bronchoscopy procedure⁽⁷⁾

Risks Associated with Bronchoscopy

Unfortunately, this excellent diagnostic instrument has turned into the Covid-19 virus’s best friend and the health care practitioner’s worse nightmare: from tool to trouble!

SARS-CoV-2 is transmitted through viral particles in an aerosol form. The bronchoscope invades an area of the body that typically contains a high viral load of SARS-CoV-2 when infected. The virus is then loosened and released into the patient’s surroundings which contaminates surfaces and poses a direct infection risk to the health care workers involved in the procedure. This has led to an increase in the number of patient to health care worker transmissions. The risk is also increased when rigid bronchoscopes are performed.⁽⁸⁾ Rigid bronchoscopy is used in severe airway obstruction as the scope can be pushed passed the site of obstruction and into the bronchus. Due to this, patients may require general anaesthetic and more virus is converted to an aerosol form, making the procedure even more hazardous.⁽⁹⁾

Measures to Prevent Viral Transmission During Bronchoscopy

In cases where bronchoscopy is unavoidable, especially in paediatric patients, additional precautions are taken to ensure the safety of the patient, their family and the health care workers involved. The Personal Protective Equipment (PPE) required includes a long-sleeved waterproof gown, non-sterile gloves, a filtering facepiece and a shield to protect the eyes and face. These guidelines are put in place by the European Resuscitation Council. Adapted scuba masks have also been used as protective gear. This includes SEAC® Libera snorkel mask that has been modified with a Intersurgical Clear-Guard filter and a viral/bacteria filter. These customisations were made possible with the use of 3D printing technology.⁽⁸⁾

Figure 3: A Scuba mask adapted for bronchoscopy PPE use⁽⁶⁾

Bronchoscopies should be conducted in negative pressure room or rooms that are well ventilated. Only essential practitioners should be granted access to this room. Once preparations are complete, the patient and caregiver (in paediatric cases) enter the room and anaesthesia is administered. This is done to limit contact between the health care workers and the patient.⁽⁶⁾ Below, the image depicts measures that are taken to reduce the risk of patient to health care practitioner transmission.

Figure 4:Recommmendations for PPE and safe procedures when performing a bronchoscopy⁽¹⁰⁾

A: Bronchoscope is introduced via an opening in the O2 mask. A plastic sheet covers the patient’s head.

B: Transnasal approach with O2 supplementation via nasal cannula. A surgical mask is placed over the patient’s mouth and the oral aspiration cannula.

C. Performed during ventilation, using a closed-circuit ventilation and non-ventilated masks with a dedicated bronchoscope entrance.

D. Transparent protective box restricts the spread of droplets.

E. Transparent protective box is placed over the patient’s head.

F. Rigid bronchoscopy with rubber caps on the ports of the scope and a plastic covering.(10)

Bronchoscopy remains a high-risk procedure especially during a global pandemic of an aerosol transmitted virus. Special precautions must be taken by health care practitioners to reduce the risk of transmission enabling the efficient and effective treatment to combat this unprecedented Covid-19 pandemic.

Full article is available from the UP library website: https://www-clinicalkey-com.uplib.idm.oclc.org/#!/content/journal/1-s2.0-S1526054221000014?scrollTo=%23hl0000139

References

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