Discussion
Venous thromboembolism (VTE), comprising deep venous thrombosis (DVT)
and pulmonary embolism (PE), is a common and serious complication
predominantly occurring in hospitalized patients. The estimated
incidence of a first acute VTE is 0.7 to 1.4 per 1000 person-years and
is mostly observed in patients older than 55 years8.
Marik et al. reported an 11.7% incidence of DVT in a group of medical
ICU patients9. The lack of resources limited our
ability to systematically perform US screening for each COVID-19 patient
with a VTE risk factor. The real morbidity and mortality of VTE in
COVID-19 patients needs to be investigated further.
The treatment of DVT and PE is nonspecific. Anticoagulant and
thrombolytic therapies are essential strategies. However, for
hemorrhagic or preoperative patients who are suffering from DVT
simultaneously, IVC filter insertion could be an effective intervention
for preventing lethal PE.
Our report describes three severe COVID-19 patients also presenting with
DVT disease. All of them had reached IVCF implantation intervention
criteria to prevent acute PE. There are however no recommendations on
the best IVCF implantation strategy in the latest COVID-19 practice
guidelines. ICVF implantation is normally performed under digital
subtraction angiography (DSA) guidance, as presented in case 1. Severe
COVID-19 patients however often present with hypoxaemia, requiring
continuous HFNC and ECG monitoring. These unstable features would not
allow transfer of these patients to the DSA room. Transferring patients
from isolation wards would also increase the likelihood of
cross-infection in the hospital. Disinfection of the DSA room would have
a significant impact on medical and non-medical resources, together with
manpower. The team thus opted for US guided IVCF implantation for both
remaining cases.
Up to the point of submission, we believe that this is the first bedside
US-guided IVCF implantation reported case in severe COVID-19 patients on
the isolation ward. We would like to summarise our experience pertaining
to thrombosis prevention and treatment in severe and critical COVID-19
patients as follows:
1. More attention should be paid to the prevention and treatment of DVT
and PE, in spite of the current shortage of critical medical resources;
2. For severe and critically ill patients, primary preventive strategies
with stockings and/or drugs should be encouraged. Physicians should
closely monitor biomarkers of hypercoagulation. There should also be
increased awareness about the possibility of neurovascular compromise in
the extremities. Routine colour US scans may be necessary for COVID-19
inpatients;
3. During the current COVID-19 epidemic, an US-guided IVCF implantation
on the isolation ward may be considered in patients who fulfil criteria
for implantation;
4. Full preparation is needed to achieve bedside IVCF implantation:
pre-assessment of the feasibility of a percutaneous approach via the
femoral vein; assessment of whether the inferior vena cava is
unobstructed; evaluation of whether there is vena cava variation;
fasting for 12 hours before surgery (giving an ordinary enema 1 hour
before surgery is another alternative choice). Vascular surgeons need to
take level 3 protective measures before entering the isolation ward and
strictly follow protective protocol to avoid contamination.
In conclusion, COVID-19 positive patients with abnormal signs and
symptoms in the extremities should be monitored closely. A colour US
scan is recommended for severe and critical COVID-19 patients with a
high PADUA index and/or Caprini index. If the patients have reached an
IVCF implantation indication, we strongly recommend opting for an
US-guided bedside IVCF implantation strategy on the isolation ward
instead of the conventional DSA method.