Agreement Between the TEG 6s and TEG 5000 Analyzers in Extracorporeal Membrane Oxygenation.

Thromboelastography (TEG) evaluates viscoelastic properties of blood clot formation. The TEG 5000 analyzer is commonly used but prone to errors related to vibration or operator error. The TEG 6s was developed to overcome these limitations. Performance of TEG 6s compared with TEG 5000 has not been reported in extracorporeal membrane oxygenation (ECMO). We compared the agreement between devices via a single-center prospective observational study in hospitalized adult patients on ECMO. Data for both devices were collected daily for 3 days after ECMO initiation. Standard tests for method comparison were used. Thirty-four matching samples were available for analysis. Minimal bias was noted; however, the limit of agreement was wide for TEG parameters. Visually, agreement was better for values within the reference ranges of the tests. Lin's coefficients demonstrated moderate correlation for reaction time and alpha angle (0.58; 95% confidence interval [CI], 0.31-0.76 and 0.63; 95% CI, 0.40-0.78, respectively). Excellent correlation was demonstrated for kinetic time and maximum amplitude (0.88; 95% CI, 0.79-0.94 and 0.89; 95% CI, 0.79-0.94). The TEG 6s device may represent an acceptable surrogate for the TEG 5000 in patients on ECMO. However, limitations in reliability were noted, and the devices may not be interchangeable when results fall outside of the reference values.

Inhaled Nitric Oxide via High-Flow Nasal Cannula in Patients with Acute Respiratory Failure Related to COVID-19.

INTRODUCTION: Limited evidence exists regarding use of inhaled nitric oxide (iNO) in spontaneously breathing patients. We evaluated the effectiveness of continuous iNO via high-flow nasal cannula (HFNC) in COVID-19 respiratory failure. METHODS: We performed a multicenter cohort study of patients with respiratory failure from COVID-19 managed with HFNC. Patients were stratified by administration of iNO via HFNC. Regression analysis was used to compare the need for mechanical ventilation and secondary endpoints including hospital mortality, length of stay, acute kidney injury, need for renal replacement therapy, and need for extracorporeal life support. RESULTS: A total of 272 patients were identified and 66 (24.3%) of these patients received iNO via HFNC for a median of 88 h (interquartile range: 44, 135). After 12 h of iNO, supplemental oxygen requirement was unchanged or increased in 52.7% of patients. Twenty-nine (43.9%) patients treated with iNO compared to 79 (38.3%) patients without iNO therapy required endotracheal intubation (P = .47). After multivariable adjustment, there was no difference in need for mechanical ventilation between groups (odds ratio: 1.53; 95% confidence interval [CI]: 0.74-3.17), however, iNO administration was associated with longer hospital length of stay (incidence rate ratio: 1.41; 95% CI: 1.31-1.51). No difference was found for mortality, acute kidney injury, need for renal replacement therapy, or need for extracorporeal life support. CONCLUSION: In patients with COVID-19 respiratory failure, iNO delivered via HFNC did not reduce oxygen requirements in the majority of patients or improve clinical outcomes. Given the observed association with increased length of stay, judicious selection of those likely to benefit from this therapy is warranted.

Association of D-dimer and Fibrinogen With Hypercoagulability in COVID-19 Requiring Extracorporeal Membrane Oxygenation.

BACKGROUND: D-dimer concentration has been used by institutions to identify candidates for intensified anticoagulant treatment for venous thromboembolism prevention and for the mitigation of the microthrombotic complications associated with COVID-19. Thromboelastography (TEG) maximum amplitude (MA) has been validated as a marker of hypercoagulability and MA ≥68 mm has been utilized as a marker of hypercoagulability in other conditions. METHODS: The goal of this study was to evaluate the relationship between coagulation, inflammatory, and TEG parameters in patients with COVID-19 on extracorporeal membrane oxygenation (ECMO). We performed a single-center retrospective analysis of consecutive patients that received ECMO for the treatment of COVID-19. TEG, inflammatory, and coagulation markers were compared in patients with and without a thrombotic complication. Correlation tests were performed to identify the coagulation and inflammatory markers that best predict hypercoagulability as defined by an elevated TEG MA. RESULTS: A total of 168 TEGs were available in 24 patients. C-reactive protein and fibrinogen were significantly higher in patients that developed a thrombotic event versus those that did not (P = 0.04 and P = 0.04 respectively). D-dimer was negatively correlated with TEG MA (P < 0.01), while fibrinogen was positively correlated (P < 0.01). A fibrinogen >441 mg/dL was found to have a sensitivity of 91.2% and specificity of 85.7% for the detection of MA ≥68 mm. CONCLUSIONS: In critically ill patients with COVID-19 treated with ECMO, D-dimer concentration had an inverse relationship with degree of hypercoagulability as measured by TEG MA. D-dimer elevation may potentially reflect hemostatic perturbation in patients on ECMO or the severity of COVID-19 related sepsis rather than designate patients likely to benefit from anticoagulation. Fibrinogen concentration may represent a more useful marker of hypercoagulability in this population.

High-Flow Nasal Cannula Therapy in COVID-19: Using the ROX Index to Predict Success.

BACKGROUND: Optimal timing of mechanical ventilation in COVID-19 is uncertain. We sought to evaluate outcomes of delayed intubation and examine the ROX index (ie, [[Formula: see text]]/breathing frequency) to predict weaning from high-flow nasal cannula (HFNC) in patients with COVID-19. METHODS: We performed a multicenter, retrospective, observational cohort study of subjects with respiratory failure due to COVID-19 and managed with HFNC. The ROX index was applied to predict HFNC success. Subjects that failed HFNC were divided into early HFNC failure (≤ 48 h of HFNC therapy prior to mechanical ventilation) and late failure (> 48 h). Standard statistical comparisons and regression analyses were used to compare overall hospital mortality and secondary end points, including time-specific mortality, need for extracorporeal membrane oxygenation, and ICU length of stay between early and late failure groups. RESULTS: 272 subjects with COVID-19 were managed with HFNC. One hundred sixty-four (60.3%) were successfully weaned from HFNC, and 111 (67.7%) of those weaned were managed solely in non-ICU settings. ROX index >3.0 at 2, 6, and 12 hours after initiation of HFNC was 85.3% sensitive for identifying subsequent HFNC success. One hundred eight subjects were intubated for failure of HFNC (61 early failures and 47 late failures). Mortality after HFNC failure was high (45.4%). There was no statistical difference in hospital mortality (39.3% vs 53.2%, P = .18) or any of the secondary end points between early and late HFNC failure groups. This remained true even when adjusted for covariates. CONCLUSIONS: In this retrospective review, HFNC was a viable strategy and mechanical ventilation was unecessary in the majority of subjects. In the minority that progressed to mechanical ventilation, duration of HFNC did not differentiate subjects with worse clinical outcomes. The ROX index was sensitive for the identification of subjects successfully weaned from HFNC. Prospective studies in COVID-19 are warranted to confirm these findings and to optimize patient selection for use of HFNC in this disease.