Role of microcirculatory impairment in delayed cerebral ischemia and outcome after aneurysmal subarachnoid hemorrhage

Early brain injury (EBI) is considered an important cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). As a factor in EBI, microcirculatory dysfunction has become a focus of interest, but whether microcirculatory dysfunction is more important than angiographic vasospasm (aVS) remains unclear. Using data from 128 cases, we measured the time to peak (TTP) in several regions of interest on digital subtraction angiography. The intracerebral circulation time (iCCT) was obtained between the TTP in the ultra-early phase (the baseline iCCT) and in the subacute phase and/or at delayed cerebral ischemia (DCI) onset (the follow-up iCCT). In addition, the difference in the iCCT was calculated by subtracting the baseline iCCT from the follow-up iCCT. Univariate analysis showed that DCI was significantly increased in those patients with a prolonged baseline iCCT, prolonged follow-up iCCT, increased differences in the iCCT, and with severe aVS. Poor outcome was significantly increased in patients with prolonged follow-up iCCT and increased differences in the iCCT. Multivariate analysis revealed that increased differences in the iCCT were a significant risk factor that increased DCI and poor outcome. The results suggest that the increasing microcirculatory dysfunction over time, not aVS, causes DCI and poor outcome after aneurysmal aSAH.

Coronary Microcirculatory Dysfunction and Acute Cellular Rejection After Heart Transplantation

Background: Acute cellular rejection is a major determinant of mortality and re-transplantation after heart transplantation. We sought to evaluate prognostic implications of coronary microcirculatory dysfunction assessed by index of microcirculatory resistance (IMR) for risk of acute cellular rejection after heart transplantation. Methods: The current study prospectively enrolled 154 heart transplant recipients who underwent scheduled coronary angiography and invasive coronary physiologic assessment 1 month after transplantation. IMR is microcirculatory resistance under maximal hyperemia. By measuring hyperemic mean transit time using 3 injections (4 mL each) of room-temperature saline under maximal hyperemia, IMR was calculated as hyperemic distal coronary pressure × hyperemic mean transit time. The primary endpoint was biopsy-proven acute cellular rejection of grade ≥2R during 2 years of follow-up after transplantation and was compared using multivariable Cox proportional hazard regression according to IMR. The incremental prognostic value of IMR, in addition to the model with clinical factors, was evaluated by comparison of c-index, net reclassification index (NRI), and integrated discrimination index (IDI). Results: Mean age of recipients was 51.2±13.1 years (81.2% male), and cumulative incidence of acute cellular rejection was 19.0% at 2 years. Patients with acute cellular rejection had significantly higher IMR values at 1 month than those without acute cellular rejection (23.1±8.6 vs. 16.8±11.1, P=0.002). IMR was significantly associated with the risk of acute cellular rejection (per 5-unit increase: adjusted HR 1.18, 95% CI 1.04-1.34, P=0.011) and the optimal cut-off value of IMR to predict acute cellular rejection was 15. Patients with IMR≥15 showed significantly higher risk of acute cellular rejection than those with IMR<15 (34.4% vs. 3.8%, adjusted HR 15.3, 95% CI 3.6-65.7, P<0.001). Addition of IMR to clinical variables showed significantly higher discriminant and reclassification ability for risk of acute cellular rejection (C-index 0.87 vs. 0.74, P<0.001; NRI 1.05, P<0.001, IDI 0.20, P<0.001). Conclusions: Coronary microcirculatory dysfunction assessed by IMR measured early after heart transplantation showed significant association with the risk of acute cellular rejection. In addition to surveillance endomyocardial biopsy, early stratification using IMR could be a clinically useful tool to identify patients at higher risk of future acute cellular rejection after heart transplantation. Clinical Trial Registration: URL: https://clinicaltrials.gov Unique Identifier: NCT02798731

State of plasma hemostasis in newborn infants

Aim. To study the features of the plasma hemostasis in newborns with congenital IUI.Material and methods. The observation of 52 newborns with intrauterine infections was conducted. All the children were divided into two groups. The first group included 36 (69, 2%) patients with a severe IUI and the second - 16 (30,8) patients with a very slow course of the pathological process.Results and discussion. The results of the study showed that IUI in children has a generalized form of the course, with symptoms of microcirculatory dysfunction of the internal organs and systems.Conclusion. The study of the plasma component of hemostasis showed multidirectional changes in it in the form of activation of plasma clotting factors, at the same time there was an increase in the duration and time of blood clotting, indicating the development of consumption coagulopathy in this category of patients, whose severity depends on the course of fetal infections and tropism of the pathogen to the organs and tissues. Identified changes in the plasma component in children with intrauterine infections dictate the need for timely adequate corrective therapy.

Pulmonary Hemodynamics and Ventilation in Patients With COVID-19-Related Respiratory Failure and ARDS

Background: It has been suggested that COVID-19-associated severe respiratory failure (CARDS) might differ from usual acute respiratory distress syndrome (ARDS) due to failing autoregulation of pulmonary vessels and higher shunt. We sought to investigate pulmonary hemodynamics and ventilation properties in patients with CARDS compared to patients with ARDS of pulmonary origin. Methods: This was a retrospective analysis of prospectively collected data from consecutive adults with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 patients treated in our ICU in 04/2020 and a comparison of the data to matched controls with ARDS due to respiratory infections treated in our ICU from 01/2014 to 08/2019 for whom pulmonary artery catheter data were available. Results: CARDS patients (n = 10) had ventilation characteristics similar to those of ARDS (n = 10) patients. Nevertheless, mechanical power applied by ventilation was significantly higher in CARDS patients (23.4 ± 8.9 J/min) than in ARDS (15.9 ± 4.3 J/min; P < 0.05). COVID-19 patients had similar pulmonary artery pressure but significantly lower pulmonary vascular resistance, as cardiac output was higher in CARDS vs. ARDS patients ( P < 0.05). Shunt fraction and dead space were similar in CARDS compared to ARDS ( P > 0.05) and were correlated with hypoxemia in both groups. The arteriovenous pCO2 difference (▵pCO2) was elevated (CARDS 5.5 ± 2.8 mmHg vs. ARDS 4.7 ± 1.1 mmHg; P > 0.05), as was the P(v-a)CO2/C(a-v)O2 ratio (CARDS mean 2.2 ± 1.5 vs. ARDS 1.7 ± 0.8; P > 0.05). Conclusions: Respiratory failure in COVID-19 patients seems to differ only slightly from ARDS regarding ventilation characteristics and pulmonary hemodynamics. Our data indicate microcirculatory dysfunction. More data need to be collected to assure these findings and gain more pathophysiological insights into COVID-19 and respiratory failure.

Role of endothelial nitric oxide synthase for early brain injury after subarachnoid hemorrhage in mice

The first few hours and days after subarachnoid hemorrhage (SAH) are characterized by cerebral ischemia, spasms of pial arterioles, and a significant reduction of cerebral microperfusion, however, the mechanisms of this early microcirculatory dysfunction are still unknown. Endothelial nitric oxide production is reduced after SAH and exogenous application of NO reduces post-hemorrhagic microvasospasm. Therefore, we hypothesize that the endothelial NO-synthase (eNOS) may be involved in the formation of microvasospasms, microcirculatory dysfunction, and unfavorable outcome after SAH. SAH was induced in male eNOS deficient (eNOS–/–) mice by endovascular MCA perforation. Three hours later, the cerebral microcirculation was visualized using in vivo 2-photon-microscopy. eNOS–/– mice had more severe SAHs, more severe ischemia, three time more rebleedings, and a massively increased mortality (50 vs. 0%) as compared to wild type (WT) littermate controls. Three hours after SAH eNOS–/– mice had fewer perfused microvessels and 40% more microvasospasms than WT mice. The current study indicates that a proper function of eNOS plays a key role for a favorable outcome after SAH and helps to explain why patients suffering from hypertension or other conditions associated with impaired eNOS function, have a higher risk of unfavorable outcome after SAH.

Discrepancy between RFR and FFR based decision on revascularization – is coronary microcirculatory dysfunction responsible?

Introduction Confirmation of significant ischemia is crucial for proper management of coronary artery disease. Non-hypaeremic indices along with fractional flow reserve are endorsed by current guidelines to prove ischemia. However some discrepancies between hyperaemic and non-hyperaemic decision on revascularisation is present in significant percentage of cases. Aim Aim of our study was to determine frequency of coronary microcirculatory dysfunction in patients with discrepant RFR and FFR measurements compared to concordant group. Methods Resting full cycle ratio (RFR) was measured in 69 left anterior descending arteries, all patients had symptoms of chronic coronary syndromes (CCS II-III). Cut-off values for ischemia detection were ≤0.80 for FFR and ≤0.89 for RFR. Coronary microcirculatory dysfunction (CMD) was defined as CFR &lt;2.0 or IMR ≥25 according to current guideline. Results Discrepancy between FFR and RFR decision on revascularisation was present in 18 (26.1%) of cases. Mean age of patients was 65 (SD=8.5), all patients were similar in terms of diabetes, prior MI or hypertension and statin use (p=NS for all comparisons). Group with discordant RFR and FFR results had higher prevalence of CMD compared to patients with concordant result (44.4% vs 21.6% respectively, p=0.004), however median values of CFR and IMR were similar (see table). Conclusions • Patients with discrepant results have more frequently coronary microcirculatory dysfunction. • Coronary microcirculatory dysfunction should be further investigated as it could explain discrepancies between RFR and FFR based decision on revascularisation. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Jagiellonian University statutory grant

Pulmonary Hemodynamics and Ventilation in Patients With COVID-19-related Respiratory Failure and ARDS

Background: It has been suggested that COVID-19-associated severe respiratory failure (CARDS) might differ from usual acute respiratory distress syndrome (ARDS) due to failing auto-regulation of pulmonary vessels and higher shunt. We sought to investigate pulmonary hemodynamics and ventilation properties in patients with CARDS compared to patients with ARDS of pulmonary origin. Methods: Retrospective analysis of prospectively collected data of consecutive adults with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 patients treated on our ICU in 04/2020 and comparison of the data to matched controls with ARDS due to respiratory infections treated on our ICU from 01/2014 to 08/2019 and for whom pulmonary artery catheter data were available. Results: CARDS patients (n = 10) had similar ventilation characteristics as compared to ARDS (n = 10) patients. Still, mechanical power applied by ventilation was significantly higher in CARDS patients (23.4 ± 8.9 J/min) than in ARDS (15.9 ± 4.3 J/min; p<0.05). COVID-19 patients had similar pulmonary artery pressure but significantly lower pulmonary vascular resistance, as cardiac output was higher in CARDS vs. ARDS patients (p<0.05). Shunt fraction and dead space were similar in CARDS compared to ARDS (p>0.05) and was in both groups correlated with hypoxemia. The arterio-venous pCO2 difference (DpCO2) was elevated (CARDS 5.5±2.8 mmHg vs. ARDS 4.7±1.1 mmHg; p>0.05) as was P(v-a)CO2/C(a-v)O2 ratio (CARDS mean 2.2±1.5 vs. ARDS 1.7±0.8; p>0.05). Conclusions: Respiratory failure in COVID-19 patients seems to differ only slightly from ARDS regarding ventilation characteristics and pulmonary hemodynamics. Differences are mainly due to increased CO2 production in CARDS patients. Our data indicate microcirculatory dysfunction. More data needs to be collected to assure these findings and gain more pathophysiological insights in COVID-19 and respiratory failure.

2-Chlorofatty acids are biomarkers of sepsis mortality and mediators of barrier dysfunction in rats

Sepsis is defined as the systemic, dysregulated host immune response to an infection that leads to injury to host organ systems and, often, death. Complex interactions between pathogens and their hosts elicit microcirculatory dysfunction. Neutrophil myeloperoxidase (MPO) is critical for combating pathogens, but MPO-derived hypochlorous acid (HOCl) can react with host molecular species as well. Plasmalogens are targeted by HOCl, leading to the production of 2-chlorofatty acids (2-CLFAs). 2-CLFAs are associated with human sepsis mortality, decrease in vitro endothelial barrier function, and activate human neutrophil extracellular trap formation. Here, we sought to examine 2-CLFAs in an in vivo rat sepsis model. Intraperitoneal cecal slurry sepsis with clinically relevant rescue therapies led to ∼73% mortality and evidence of microcirculatory dysfunction. Plasma concentrations of 2-CLFAs assessed 8 h after sepsis induction were lower in rats that survived sepsis than in nonsurvivors. 2-CLFA levels were elevated in kidney, liver, spleen, lung, colon, and ileum in septic animals. In vivo, exogenous 2-CLFA treatments increased kidney permeability, and in in vitro experiments, 2-CLFA also increased epithelial surface expression of vascular cell adhesion molecule 1 and decreased epithelial barrier function. Collectively, these studies support a role of free 2-CLFAs as biomarkers of sepsis mortality, potentially mediated, in part, by 2-CLFA-elicited endothelial and epithelial barrier dysfunction.