Role of Preoperative Testing and Duration of Viral Shedding
COVID-19 testing is accomplished via detection of SARS-CoV-2 in a
nasopharyngeal specimen or bronchoalveolar lavage (BAL) using reverse
transcriptase-polymerase chain reaction (RT-PCR).11The role of preoperative testing in ascertaining the COVID-19 status of
asymptomatic individuals has emerged as a point of discussion, as the
prevalence of asymptomatic SARS-CoV-2 infection is unknown but assumed
to be meaningful given high rates of community
transmission.12,13
At the time of this writing, due in large part to the relative lack of
available testing supplies, there is not a standard protocol for
preoperative testing of asymptomatic patients planned for tracheostomy
or other AGPs. Patients who do not have respiratory symptoms suggestive
of COVID-19 have an unknown risk of being asymptomatic carriers of
disease. If resource availability permits, preoperative testing prior to
surgical intervention is preferred, as a positive test would alert the
healthcare team to the increased risk, and surgery may be deferred to
maximize safety if clinically appropriate.
Importantly, for patient with some conditions, including head and neck
cancer, airway compromise may be imminent and necessitate urgent
treatment with tracheostomy.14 Acute airway
compromise, or inability to intubate, as can occur in patients with head
and neck cancer, could necessitate an awake tracheotomy. In this
scenario, the patient is breathing orally and potentially seeding the
room with aerosolized viral particles. All precautions with appropriate
PPE should be taken by the surgical team in cases where potential airway
manipulation is anticipated. Currently, specialized hoods to cover the
patient and prevent aerosolization have been proposed but are not widely
available.15
Preoperative testing is significant in determining the appropriate
timing of tracheostomy for patients with COVID-19 infection. For
patients with known disease, testing is a reasonable surrogate for viral
clearance. BAL is the most sensitive means of testing and is recommended
in intubated patients.11 These tests will be important
in enacting de-isolation protocols, whereby hospitalized patients with
recent infection may be removed from an isolation environment. One such
proposed de-isolation protocol calls for two consecutive negative PCR
tests 24 hours apart.16 Due to constraints on the
availability of testing and the turnaround time for results,
preoperative testing may not be universally feasible.
In the absence of a standard preoperative testing protocol, we have
proposed not pursuing early tracheotomy, but rather delaying for
COVID-19 positive patients in order to reduce exposure to higher viral
loads, which are expected to peak in the first few days of symptom
onset.16 The duration of viral shedding is estimated
to be between 20-24 days from symptom onset, based on laboratory testing
of nasopharyngeal swabs. The longest observed duration of shedding
reported in one study was 37 days.5,16 Importantly,
viral loads in asymptomatic and symptomatic patients are believed to be
similar13, highlighting the need for proper PPE and
surgical protocols in all cases of tracheostomy. The optimal timing of
tracheostomy for asymptomatic patients without ARDS is not clear. At
UCSF, we have elected to maintain standard timing of 10-14 days
post-intubation for this group.
The clinical course of the COVID-19 infected patient is well described
by Zhou et al. who found the median time from illness onset to dyspnea
was 13 days and dyspnea to invasive mechanical ventilation was 10
days.5 In pre-pandemic conditions, we typically aim to
perform tracheostomy for patients requiring prolonged mechanical
ventilation by 10-14 days post-intubation. In the current pandemic, we
propose when resources are available, that an additional week of
mechanical ventilation be permitted to reduce viral load and thereby
limit risk to healthcare personnel.