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.