Anest. intenziv. Med. 2026;37(1):8-15 | DOI: 10.36290/aim.2026.001

Comparison of unfractionated heparin and low­‑molecular­‑weight heparin for thromboprophylaxis in critically ill patients with covid-19 pneumonia: A retrospective cohort studyOriginal Article

Romanová T.^1-4, Gumulec J.^{5, 6}, Buffa D.⁵, Lečbychová K.^{1, 2}, Káňová M.^{1, 2, 4}, Burša F.^{1, 2}, Sklienka P.^{1, 2, 4}, Pulcer M.⁷, Burda M.⁸, Máca J.^{1, 2, 4}

¹ Klinika anesteziologie, resuscitace a intenzivní medicíny, Lékařská fakulta, Ostravská univerzita, Ostrava

² Klinika anesteziologie, resuscitace a intenzivní medicíny, Fakultní nemocnice Ostrava

³ Oddělení urgentního příjmu, Fakultní nemocnice Ostrava

⁴ Ústav fyziologie a patofyziologie, Lékařská fakulta, Ostravská univerzita, Ostrava

⁵ Klinika hematoonkologie, Fakultní nemocnice Ostrava

⁶ Klinika hematoonkologie, Lékařská fakulta, Ostravská univerzita, Ostrava

⁷ Ústav laboratorních metod, Fakultní nemocnice Ostrava

⁸ IT4Innovations národní superpočítačové centrum, Ostrava

Objective: Covid-19 is associated with a significantly increased risk of macrovascular and microvascular thrombotic complications, especially in critically ill patients with a severe form of the disease. Antithrombotic prophylaxis is an important part of treatment and was being applied using different drugs and dosing schemes during the pandemic. Data comparing various possibilities of antithrombotic therapy in these patients is lacking. The primary endpoint of this study was a retrospective assessment of ICU-free days, hospital-free days, and bleeding or thrombotic complications in critically ill patients with covid-19 pneumonia, who initially received higher doses of anticoagulation therapy either using subcutaneous (s. c.) application of low molecular weight heparin (LMWH) or continuous intravenous (i. v.) infusion of unfractionated heparin (UFH). The secondary endpoint was to compare 30-day mortality.

Design: Retrospective cohort study. Setting: Intensive Care Unit (ICU) of a university hospital.

Material and methods: A retrospective analysis of medical records of critically ill patients with covid-19 associated pneumonia and acute respiratory failure was performed. Patients were admitted to the ICU from 1. 3. 2020 to 31. 3. 2022 and received higher doses of anticoagulation using s. c. nadroparine or i. v. infusion of UFH at least from the second to eighth day of admission.

Results: A total of 153 patients were included in the analysis. Median of ICU-free days at 30 days was 15 days for LMWH group and 12 days for UFH group (p = 0.1932). Median of hospital-free days at 60 days and 90 days was 5,5 days for LMWH group and 0 days pro UFH group (p = 0.5511), 26 days and 23 days (p = 0.6590) respectively. The difference in incidence of thromboembolic complications was not significant (1.96% in LMWH group and 7.84% in UFH group (p = 0.2732)). Minor bleeding complications were more frequent in LMWH group (11.76% vs. 0.98%, p = 0.0058). Logistic regression model found no significant effect of anticoagulation therapy on 30-day mortality.

Conclusion: No statistically significant difference was found between both groups in the incidence of thromboembolic complications, the number of ICU-free days, the number of hospital-free days. Logistic regression model proved no effect of anticoagulation type on 30day mortality. In the LMWH group, a higher frequency of minor bleeding complications was observed, while the frequency of major bleeding complications did not increase.

Keywords: covid-19, heparin, pneumonia, intensive care.

Received: October 26, 2025; Revised: December 20, 2025; Accepted: January 2, 2026; Prepublished online: March 9, 2026; Published: April 9, 2026  Show citation