Thromboelastography clot strength profiles and effect of systemic anticoagulation in COVID-19 acute respiratory distress syndrome: a prospective, observational study

OBJECTIVE

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) infection may yield a hypercoagulable state with fibrinolysis impairment. We conducted a single-center observational study with the aim of analyzing the coagulation patterns of intensive care unit (ICU) COVID-19 patients with both standard laboratory and viscoelastic tests. The presence of coagulopathy at the onset of the infection and after seven days of systemic anticoagulant therapy was investigated.

PATIENTS AND METHODS

Forty consecutive SARS-CoV-2 patients, admitted to the ICU of a University hospital in Italy between 29th February and 30th March 2020 were enrolled in the study, providing they fulfilled the acute respiratory distress syndrome criteria. They received full-dose anticoagulation, including Enoxaparin 0.5 mg·kg-1 subcutaneously twice a day, unfractionated Heparin 7500 units subcutaneously three times daily, or low-intensity Heparin infusion. Thromboelastographic (TEG) and laboratory parameters were measured at admission and after seven days.

RESULTS

At baseline, patients showed elevated fibrinogen activity [rTEG-Ang 80.5° (78.7 to 81.5); TEG-ACT 78.5 sec (69.2 to 87.9)] and an increase in the maximum amplitude of clot strength [FF-MA 42.2 mm (30.9 to 49.2)]. No alterations in time of the enzymatic phase of coagulation [CKH-K and CKH-R, 1.1 min (0.85 to 1.3) and 6.6 min (5.2 to 7.5), respectively] were observed. Absent lysis of the clot at 30 minutes (LY30) was observed in all the studied population. Standard coagulation parameters were within the physiological range: [INR 1.09 (1.01 to 1.20), aPTT 34.5 sec (29.7 to 42.2), antithrombin 97.5% (89.5 to 115)]. However, plasma fibrinogen [512.5 mg·dl-1 (303.5 to 605)], and D-dimer levels [1752.5 ng·ml-1 (698.5 to 4434.5)], were persistently increased above the reference range. After seven days of full-dose anticoagulation, average TEG parameters were not different from baseline (rTEG-Ang p = 0.13, TEG-ACT p = 0.58, FF-MA p = 0.24, CK-R p = 0.19, CKH-R p  = 0.35), and a persistent increase in white blood cell count, platelet count and D-dimer was observed (white blood cell count p < 0.01, neutrophil count p = 0.02, lymphocyte count p < 0.01, platelet count p = 0.13 < 0.01, D-dimer levels p= 0.02).

CONCLUSIONS

SARS-CoV-2 patients with acute respiratory distress syndrome show elevated fibrinogen activity, high D-dimer levels and maximum amplitude of clot strength. Platelet count, fibrinogen, and standard coagulation tests do not indicate a disseminated intravascular coagulation. At seven days, thromboelastographic abnormalities persist despite full-dose anticoagulation.

In vitro pharmacologic activity of congener derivatives and model conjugates of propranolol and practolol

Previous studies in our laboratory suggested that synthetized derivatives of isoproterenol and histamine could create agonists more potent and receptor and/or tissue selective than the parent compound. In the present study we have evaluated the hypothesis that our results with isoproterenol and histamine derivatives could be extended to include beta-adrenergic antagonists. With this purpose in mind, fourteen derivatives of propranolol and practolol were synthesized and tested in four in vitro systems. The congeners and conjugates were tested using biologic assays (blocking of cAMP accumulation) and/or radioligand binding assays in S-49 lymphoma cells and in rat adipocytes, heart and lung which contain beta 1 and/or beta 2 receptors. Our results indicate that structural modifications distant from the pharmacophore alter the pharmacologic profile of the parent compound. The relative potencies of the derivatives were dependent upon several key factors including the length of the methylene spacer chain and the nature of the substituents on the aromatic ring. The presence of a spacer group with four methylenes resulted in the most active compound in each series when tested on S-49 cells. The derivatives with a paramethyl toluidide group were more potent than the derivatives with a trifluoromethyl toluidide group. The dipeptide derivatives were more potent on adipocyte than S-49 cells, suggesting a preference for beta 1 receptors. Some of the same modifications that led to altered potency and which resulted in an increased receptor and/or tissue selectivity using the progenitors isoproterenol or histamine did extrapolate to the beta blockers. Our data suggest that alterations in receptor and/or tissue selectivity must be imparted by the carrier moiety of the drug and may be related to the biochemical microenvironment of the receptors.