The Sublingual Microcirculation Throughout Neonatal and Pediatric Extracorporeal Membrane Oxygenation Treatment: Is It Altered by Systemic Extracorporeal Support?

End organ perfusion and pediatric microcirculation assessment

Cardiovascular instability and reduced oxygenation are regular perioperative critical events associated with anesthesia requiring intervention in neonates and young infants. This review article addresses the current modalities of assessing this population's adequate end-organ perfusion in the perioperative period. Assuring adequate tissue oxygenation in critically ill infants is based on parameters that measure acceptable macrocirculatory hemodynamic parameters such as vital signs (mean arterial blood pressure, heart rate, urinary output) and chemical parameters (lactic acidosis, mixed venous oxygen saturation, base deficit). Microcirculation assessment represents a promising candidate for assessing and improving hemodynamic management strategies in perioperative and critically ill populations. Evaluation of the functional state of the microcirculation can parallel improvement in tissue perfusion, a term coined as "hemodynamic coherence". Less information is available to assess microcirculatory disturbances related to higher mortality risk in critically ill adults and pediatric patients with septic shock. Techniques for measuring microcirculation have substantially improved in the past decade and have evolved from methods that are limited in scope, such as velocity-based laser Doppler and near-infrared spectroscopy, to handheld vital microscopy (HVM), also referred to as videomicroscopy. Available technologies to assess microcirculation include sublingual incident dark field (IDF) and sublingual sidestream dark field (SDF) devices. This chapter addresses (1) the physiological basis of microcirculation and its relevance to the neonatal and pediatric populations, (2) the pathophysiology associated with altered microcirculation and endothelium, and (3) the current literature reviewing modalities to detect and quantify the presence of microcirculatory alterations.

The Disconnect Between Extracorporeal Circulation and the Microcirculation: A Review

Extracorporeal circulation (ECC) procedures, such as cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO), take over the function of one or more organs, providing clinicians time to treat underlying pathophysiological conditions. ECMO and CPB carry significant mortality rates for patients, despite prior decades of research focused on the resulting failure of critical organs. Since the focus of these procedures is to support blood flow and provide oxygen-rich blood to tissues, a shift in research toward the effects of ECMO and CPB on the microcirculation is warranted. Along with provoking systemic responses, both procedures disrupt the integrity of red blood cells, causing release of hemoglobin (Hb) from excessive foreign surface contact and mechanical stresses. The effects of hemolysis are especially pronounced in the microcirculation, where plasma Hb leads to nitric oxide scavenging, oxidization, formation of reactive oxygen species, and inflammatory responses. A limited number of studies have investigated the implications of ECMO in the microcirculation, but more work is needed to minimize ECMO-induced reduction of microcirculatory perfusion and consequently oxygenation. The following review presents existing information on the implications of ECMO and CPB on microvascular function and proposes future studies to understand and leverage key mechanisms to improve patient outcomes.

Circular RNA UBAP2 (hsa_circ_0007367) Correlates with Microcirculatory Perfusion and Predicts Outcomes of Cardiogenic Shock Patients Undergoing Extracorporeal Membrane Oxygenation Support

BACKGROUND

Severe microcirculatory disturbance is common in patients with cardiogenic shock necessitating extracorporeal membrane oxygenation (ECMO), however, biomarkers linked to microcirculation and clinical outcome are scarce. Herein we identified a circular RNA, hsa_circ_0007367, rooted from the ubiquitin-associated protein 2 (UBAP2) gene, namely circUBAP2, and evaluated its biological function and the associations with microcirculation and the prognosis.

METHODS

Patients on ECMO with cardiogenic shock were included if qualified sublingual microcirculation parameters could be obtained and were categorized into the survivor group or non-survivor group. Macro-circulatory, microcirculatory data, cytokine levels, and relative circUBAP2 expressions were collected before, at 24 h, and at ECMO weaning off, respectively. The effects of circUBAP2 on the migration, polarization, cytokine productions, and inflammatory pathways in macrophage NR8383 cells were investigated using in vitro methods.

RESULTS

Thirty-three patients with an average age of 58.0 years were enrolled, including 19 survivors and 14 non-survivors. The survivors had higher small vessel density, perfused small vessel density (PSVD), and microvascular flow index (MFI) throughout the ECMO course than did the non-survivors. Relative expression of circUBAP2 (hsa_circ_0007367) correlated with the microcirculatory parameters and satisfactorily predicted the 30-day in-hospital mortality. A multivariable logistic model was developed, showing following four predictors: age (odds ratio [OR] 1.06, 95% confidence interval [CI] 1.00-1.12), time from shock to ECMO (OR 1.10, 95% CI 1.01-1.20), PVSD (OR 0.14, 95% CI 0.02-0.89), and the circUBAP2 expression (OR 0.25, 95% CI 0.08-0.78). In addition, circUBAP2 inhibited the migratory activity and promoted M2 polarization in macrophages, declining the productions of cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-1β, and monocyte chemotactic protein [MCP]-1) and the PI3K/Akt/mTOR pathway.

CONCLUSION

The expression of circUBAP2 correlates with microcirculatory perfusion and has the potential in predicting outcomes for on-ECMO patients with cardiogenic shock.

Microvascular dysfunction in pediatric patients with SARS-COV-2 pneumonia: Report of three severe cases

The coronavirus 19 (COVID-19) pandemic has affected hundreds of millions of people worldwide: in most of cases children and young people developed asymptomatic or pauci-symptomatic clinical pictures. However authors have showed that there are some categories of childhood more vulnerable to COVID-19 infection such as newborns or children with comorbidities. We report for the first time to the best of our knowledge about microvascular dysfunction in three pediatric clinical cases who developed COVID-19 infections with need of pediatric critical care. We found that sublingual microcirculation is altered in children with severe COVID-19 infection.

Our findings confirmed most of data already observed by other authors in adult population affected by severe COVID-19 infection, but with distinct characteristics than microcirculation alterations previous observed in a clinical case of MIS-C.

However we cannot establish direct correlation between microcirculation analysis and clinical or laboratory parameters in our series, by our experience we have found that sublingual microcirculation analysis allow clinicians to report directly about microcirculation dysfunction in COVID-19 patients and it could be a valuable bedside technique to monitor thrombosis complication in this population.