Coronavirus disease 2019 (COVID-19) is a pandemic respiratory disease caused by the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first identified in Wuhan, China, in December 2019. SARS-CoV-2 is believed to infect others via contact and droplet transmission1,2. Patients commonly present with fever, cough, and ground-glass opacification on chest computed tomography (CT)3. It has been reported that up to 6.1% of patients require intensive care or mechanical ventilation with a mortality rate of 1.4%1. To date, we have limited information on the operations performed on these patients. We report our experience of a relatively asymptomatic elderly patient who underwent surgery for a hip fracture and was subsequently confirmed postoperatively to have COVID-19.
The patient was informed that data concerning the case would be submitted for publication, and she provided consent.
An 83-year-old woman with a history of dementia, diabetes, hyperlipidemia, and ischemic heart disease suffered a fall on February 15, 2020. Radiographs showed a fracture of the neck of right femur. She had no fever, cough, or respiratory symptoms on admission. Chest radiographs did not show lung consolidation (Fig. 1). There was no travel history or known contact with a confirmed patient with coronavirus in the past 14 days before admission. Her husband is her main carer, providing assistance for her activities of daily living. She was admitted to the general orthopaedic ward and was given a surgical mask, but she was uncooperative because of her dementia. Right hip cemented hemiarthroplasty was performed under spinal anesthesia on February 16, 2020, under standard precautions and usual operating theater settings. The surgical staff wore eye protection, surgical masks, gowns, and gloves. Monopolar diathermy and pneumatic oscillating saw were used to cut the femoral neck. A handheld reamer was used to prepare the femoral canal. No pulsatile lavage was used.
Postoperatively, she remained afebrile and did not have any respiratory symptoms. Her husband was contacted by our occupational therapist to further understand her home environment to plan her future care. At that time, her husband revealed that their son-in-law and daughter had been diagnosed with COVID-19 on February 16 and 17, respectively. The patient's last contact with them was on January 27, 2020 (19 days before our patient's admission). The patient herself did not have any recent travel history. The husband noted that the patient had a mild runny nose on February 14, 2020, but this was not noted during her admission. In view of her contact with the confirmed patients with COVID-19, she was sent for SARS-CoV-2 testing and was confirmed positive on February 18, 2020, with an initial cycle threshold (Ct) value of 27.6. Ct value reflects the number of polymerase chain reaction (PCR) cycles required for the fluorescent signal to cross the threshold and is inversely proportional to the viral load.
In the isolation ward, she remained afebrile and did not have any cough or respiratory symptoms. Serial chest radiographs also did not show any lung consolidation (Fig. 1). Repeated PCR of throat swabs and stool specimens tested positive for SARS-CoV-2 untill March 7, 2020, with the last positive specimen having a Ct value of >40 (reflecting a low viral load). At 19 days after the initial diagnosis, she tested negative for SARS-CoV-2 on PCR. The postoperative course was uneventful, and she did not exhibit any symptoms of COVID-19. She was eventually discharged home on April 2, 2020 (47 days after admission), and she was able to walk using a frame with assistance.
After our patient was confirmed to have COVID-19, further questioning revealed that her husband had multiple visits to Mainland China in late January 2020 and had already recovered from a period of cough. This information was obscured initially and was only obtained in retrospect. He had ground-glass changes typical of COVID-19 in his chest CT1,3 and later tested positive for antibody against SARS-CoV-2 but negative for the viral RNA suggesting before infection and recovery. In actual practice, obtaining a reliable travel history is not always feasible, as was the case with our patient with dementia and her elderly husband. All the 22 hospital staff who had close contact with our patient, including 10 staff present during the operation, and 6 patients who shared the same cubicle tested negative for SARS-CoV-2. A small proportion of our operative theater staff were not tested because they were asymptomatic and did not fulfill the testing criteria used at our hospital, which includes exposure to the patient for more than 15 minutes without a surgical mask and personal protective equipment (PPE), or 2 hours with a surgical mask and PPE. All staff and patients completed 28 days of medical surveillance without infection.
Asymptomatic or pauci-symptomatic patients with COVID-19 are a constant threat to healthcare workers and public health. In a large cohort involving 3,063 subjects tested for SARS-CoV-2 on a cruise ship, there were 634 subjects who tested positive, of which 17.9% of infected subjects were asymptomatic4. It has also been documented that asymptomatic patients can still transmit SARS-CoV-2 to others5. We report a case of asymptomatic COVID-19 infection, which was diagnosed postoperatively with 3 days under standard hospital precaution only.
A meta-analysis performed by MacIntyre showed that the use of surgical masks or N95 respirators along with hand hygiene was effective in reducing transmission of influenza and SARS-CoV6 (close relative of SARS-CoV-2). Moreover, if the infected subject wore a surgical mask or a respirator, there was an additional 3-fold reduction in the infection rate of others. Other authors also supported the use of additional eye protection, gowns, gloves, and handwashing to prevent droplet transmission7. These standard precautions were universally adopted by medical staff, as supported by previous literature and hospital guidelines.
In the operative room, the situation is compounded by prolonged close contact with the patient during anesthesia, preoperative positioning, and during invasive interventions. SARS-CoV-2 is known to be present in the serum of patients with severe disease5, but the infectivity of SARS-CoV-2 in this situation is unknown. During surgery, the patient's potentially infected serum may be aerosolized via the use of diathermy, pulsatile lavage, power tools, or intramedullary reaming6-8, resulting in high risk of airborne transmission of pathogens which normally only transmit via droplets (i.e., SARS-CoV-2). In clinical situations where there is a risk of airborne transmission, it is recommended that healthcare workers should use N95 respirators.6,8
In our case with potential aerosolization, no staff was infected despite the use of standard surgical attire only (Fig. 2). We theorized this could primarily be because of the patient having mild disease, thus the serum likely had negligible or absent levels of SARS-CoV-2. Therefore, even if aerosolization occurred, it did not infect the surgical staff. Second, in view of the mild disease, the patient likely had a low viral load in her respiratory tract, thus the surgical mask prevented droplet spread of SARS-CoV-2. Third, the patient underwent spinal anesthesia with no aerosol-generating intubation2. Currently, there is no robust evidence for the optimal mode of anesthesia in patients with COVID-19 because our information on the disease is still rapidly evolving. However, intubation for general anesthesia is a known aerosol-generating procedure, which may potentially increase the risk of aerosol transmission of the virus. A systematic review by Tran et al. suggested that aerosol-generating procedures were associated with increased risk of SARS transmission to healthcare workers9. In our patient, fortunately, the standard surgical attire prevented infection of the medical staff.
With the progression of the COVID-19 pandemic, it is inevitable that medical workers will encounter asymptomatic but infected patients. Meticulous hand hygiene and use of surgical mask in daily practice is crucial to protect against asymptomatic and undiagnosed patients2,8. High index of suspicion against SARS-CoV-2 is warranted. When it is practical clinically, we should exclude SARS-CoV-2 before operation. In both suspected and confirmed patients, anesthesia and surgery should be performed by experienced doctors to reduce the duration of exposure2,8, aerosol-generating procedures should be avoided2,8,9, and surgeons should use N95 respirators with a powered air-purifying respirator in addition to the standard surgical attire.2,6-8
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