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Pulmonary Embolism in Patients With COVID-19

Awareness of an Increased Prevalence
and Lille ICU Haemostasis COVID-19 Group
Originally published 2020;142:184–186

We report a case series of patients with coronavirus disease 2019 (COVID-19) with pulmonary embolism (PE) in our institution. Lille University Hospital is the tertiary care center for the North of France, the second greatest French region in population density (189 people per 1 km2), also considered a metabolic area with high number of overweight patients. The study was approved by the institutional data protection authority of Lille University Hospital.

Among the 107 first consecutive patients with confirmed COVID-19 admitted to the intensive care unit (ICU) for pneumonia from February 27 to March 31, we noticed an unexpectedly high number of PEs during their stay in the ICU: 22 (20.6%) at the time of analysis (April 9), within a median time from ICU admission of 6 days (range, 1–18 days). To determine whether this represents an increase in the expected incidence of PE over a similar time interval, we analyzed the files of 196 patients hospitalized in our ICU during the same time interval in 2019. Despite a similar severity score on admittance to the ICU, the frequency of PE in our COVID-19 series was twice as high as the frequency we found in this control period (20.6% versus 6.1%; absolute increased risk, 14.4% [95% CI, 6.1–22.8]). It was also twice as high as the 7.5% frequency of PE in the 40 patients with influenza admitted to the ICU between January 1 and December 30, 2019 (3 PEs; absolute increased risk, 13.1% [95% CI, 1.9–24.3]). A qualitative description of the main characteristics of the patients with PE in the different periods is given in the Table.

Table. Number of CTPAs Performed for Suspicion of PE and Number and Main Characteristics of PE Events in the ICU From the COVID-19 Pandemic Period Compared With the Same Period in 2019 and With Patients With Influenza in 2019

Study Period
February 27–March 31, 2019 (All ICU Patients*, n=196)January 1–December 31, 2019 (Patients With Influenza in the ICU [PCR+], n=40)February 27–March 31, 2020 (Patients With COVID-19 in the ICU [PCR+], n=107)
Chest CT scans, n (%)50 (25.5)20 (50.0)36 (33.6)
CTPAs, n (%)30 (15.3)17 (42.5)34 (31.8)
CTPAs performed for a PE diagnosis, n (%)20 (10.2)8 (20.0)34 (31.8)
PE cases, n (%)12 (6.1)3 (7.5)22 (20.6)
 Bilateral8 (66.6)08 (40.0)§
 Proximal2 (16.6)02 (10.0)§
 Segmental6 (50.0)011 (55.0)§
ARDS, n (%)14 (7.1)15 (37.5)67 (62.6)
Intubation, n (%)84 (42.9)17 (42.5)67 (62.6)
Doppler ultrasound, n (%)12 (6.1)2 (5.0)8 (7.5)
 DVT, n (%)9 (4.6)1 (2.5)5 (4.7)
Patients with PE
 Age, median (range), y66 (30–72)71 (57–72)57 (29–80)
 Men, n (%)8 (66.7)2 (66.7)13 (59.1)
 Body mass index, median (range), kg/m229 (18–42)26 (16–52)30 (22–53)
 SOFA score at admission, median (range)8 (1–16)2 (1–9)4 (0–14)
 SAPS II at admission, median (range)53 (23–69)41 (34–65)40 (18–78)
 ARDS, n (%)5 (41.7)2 (66.7)17 (77.3)
 Intubation, n (%)8 (66.7)3 (100.0)17 (77.3)
 DVT associated with PE, n (%)7 (58.3)1 (33.4)3 (13.6)

The SAPS II score provides an estimate of the risk of death without having to specify a primary diagnosis. It includes physiological variables, type of admission and underlying disease variables. Point score between 0 and 163 predicts mortality between 0% and 100%.; SOFA is a mortality prediction score that is based on the degree of dysfunction of six organ systems. The score is calculated on admission and every 24 hours, ranging from 0 (normal) to 4 (high degree of dysfunction/failure) for each organ failure. ARDS indicates acute respiratory distress syndrome; BMI, body mass index; COVID-19, coronavirus disease 2019; CT, computed tomography; CTPA, computed tomography pulmonary angiography; DVT, deep venous thrombosis ICU, intensive care unit; PCR, polymerase chain reaction; PE, pulmonary embolism; SAPS II, Simplified Acute Physiology Score; and SOFA, Sequential Organ Failure Assessment.

*Reasons for hospitalization in this group were acute respiratory failure (34%), sepsis/septic shock (19%), strokes and other neurological disorders (10%), nonseptic shock (6%), cardiac arrest (6%), intoxication (6%), metabolism disorders (4%), postoperative conditions (5%), microangiopathies (1.5%), acute kidney injury (1.5%), and others (7%: pancreatitis, self-hanging injury, severe trauma, gas embolism).

†Corresponding to an absolute increase of 14.4% (95% CI, 6.1–22.8%) vs control group of patients admitted to the ICU from February 27 to March 31, 2019, and 13.1% (95% CI, 1.9–24.3) vs control group of patients with influenza admitted to the ICU from January 1 to December 31, 2019.

‡The 3 PEs identified in patients with influenza were unilateral and subsegmental.

§Two missing values.

‖One missing value.

Taking into account the ICU duration at time of analysis, we estimated the cumulative incidence of PE using the Kalbfleisch and Prentice method by taking into account death (n=15) and discharged alive (n=48) as competing events. The 22 patients still hospitalized in the ICU without PE at the time of analysis (median ICU length of stay, 15 days; range, 10–30 days) were treated as censored observations. At day 15 of ICU admission, the cumulative incidence of PE in patients with COVID-19 in the ICU was estimated to be 20.4% (95% CI, 13.1–28.7). In terms of the main data at ICU admission (using the univariable Fine and Gray model to estimate subhazard ratios of PE), D-dimers (estimate subhazard ratio per log-SD increase, 1.81 [95% CI, 1.03–3.16]), plasma factor VIII activity (estimate subhazard ratio per log-SD increase, 1.73 [95% CI, 1.10–2.72]), and von Willebrand factor antigen (estimate subhazard ratio per log-SD increase, 1.69 [95% CI, 1.12–2.56]) values seem to be associated with a greater PE risk.

At the time of PE diagnosis, 20 of 22 patients were receiving prophylactic antithrombotic treatment (unfractionated heparin or low-molecular-weight heparin) according to the current guidelines in critically ill patients.1,2 One patient with a history of deep venous thrombosis was receiving fluindione with an international normalized ratio in the therapeutic range, and 1 patient was receiving therapeutic unfractionated heparin because of atrial fibrillation. The criteria for deciding to perform computed tomography pulmonary angiography (CTPA) were suspicion of PE on admission and acute degradation of hemodynamic or respiratory status. All CTPAs were performed with multibar computed tomography with no difference in the injection protocol regardless of whether the CTPA was performed for PE diagnosis. The number of CTPAs was higher in patients with COVID-19 than in patients hospitalized in the ICU during the same time period in 2019. This historical control group reflects the global practice in our ICU. Because only 34% of patients from this group have respiratory failure requiring CTPA (Table), a potential bias of an increased detection of PE in patients with COVID-19 could have been generated. That is why we compared patients with COVID-19 and patients with influenza admitted to the ICU for respiratory failure in 2019. Even if the number of CTPAs performed in patients with influenza was higher than in patients with COVID-19, fewer PEs were identified, reinforcing the increased risk of PE in patients with COVID-19. The low number of associated deep venous thromboses in patients with COVID-19 may suggest that they have pulmonary thrombosis rather than embolism.

PE frequency has not yet been reported in the different series of patients with COVID-19. All our patients received thromboprophylaxis according to the current recommendations for critically ill medical patients. However, we suspect that the high obesity prevalence in our patient group contributes to the increased PE frequency.3 Because of the lack of specific studies in this population, the recommendations do not mention adaptation of the prophylaxis regimen in overweight patients or a need to monitor anti–factor Xa concentrations. Heparin could have benefic effects in COVID-19 through different mechanisms. However, the effective dose and monitoring are discussed, in particular in very high-risk patients and those with high body mass index.4 Indeed, during the H1N1 flu pandemic, some centers reported an increased thrombotic risk in patients with severe acute respiratory distress syndrome and suggested the use of higher doses of heparin.5

In conclusion, there is an urgent need for replication on a much larger scale of our data on PE frequency in COVID-19 infection in patients in the ICU. Failure to identify and accurately manage this risk could worsen the prognosis of patients with COVID-19.


The authors wish to thank the Lille COVID Research Network (LICORNE) and the i-site for their support during the COVID-19 pandemic.


For the Lille ICU Haemostasis COVID-19 Group

Nicolas Cousin, Arthur Durand, Ahmed El Kalioubie, Raphaël Favory, Patrick Girardie, Marion Houard, Emmanuelle Jaillette, Mercé Jourdain, Geoffrey Ledoux, Daniel Mathieu, Anne-Sophie Moreau, Christopher Niles, Saad Nseir, Thierry Onimus, Sébastien Préau, Laurent Robriquet, Anahita Rouzé, Arthur Simonnet, Sophie Six, Aurélia Toussaint, Annabelle Dupont, Anne Bauters, Christophe Zawadzki, Camille Paris, Nathalie Trillot, Bénédicte Wibaut, Audrey Hochart, Catherine Marichez, Vincent Dalibard, Sandrine Vanderziepe, Laureline Bourgeois, Anaïs Gaul, Aurélie Jospin, Nataliia Stepina, Bénédicte Pradines, Antoine Tournoys, Thierry Brousseau, Martine Rémy, Antoine Hutt


*A complete list of members of the Lille ICU Haemostasis COVID-19 Group is provided in the Appendix.

Data, analytical methods, and study materials are available to other researchers on request by email.

Julien Poissy, MD, PhD, Pôle de Réanimation, Hôpital Roger Salengro, Rue Emile Laine, CHU Lille, 59037 Lille Cedex, France; Email
Sophie Susen, MD, PhD, Institut Cœur-Poumon (Heart and Lung Institute), Hemostasis Department, Bd du Pr Leclercq, CHU Lille, 59037 Lille Cedex, France. Email


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