Endothelial-Dependent Vasomotor Dysfunction in Infants After Cardiopulmonary Bypass.

OBJECTIVES: Cardiopulmonary bypass-induced endothelial dysfunction has been inferred by changes in pulmonary vascular resistance, alterations in circulating biomarkers, and postoperative capillary leak. Endothelial-dependent vasomotor dysfunction of the systemic vasculature has never been quantified in this setting. The objective of the present study was to quantify acute effects of cardiopulmonary bypass on endothelial vasomotor control and attempt to correlate these effects with postoperative cytokines, tissue edema, and clinical outcomes in infants. DESIGN: Single-center prospective observational cohort pilot study. SETTING: Pediatric cardiac ICU at a tertiary children's hospital. PATIENTS: Children less than 1 year old requiring cardiopulmonary bypass for repair of a congenital heart lesion. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Laser Doppler perfusion monitoring was coupled with local iontophoresis of acetylcholine (endothelium-dependent vasodilator) or sodium nitroprusside (endothelium-independent vasodilator) to quantify endothelial-dependent vasomotor function in the cutaneous microcirculation. Measurements were obtained preoperatively, 2-4 hours, and 24 hours after separation from cardiopulmonary bypass. Fifteen patients completed all laser Doppler perfusion monitor (Perimed, Järfälla, Sweden) measurements. Comparing prebypass with 2-4 hours postbypass responses, there was a decrease in both peak perfusion (p = 0.0006) and area under the dose-response curve (p = 0.005) following acetylcholine, but no change in responses to sodium nitroprusside. Twenty-four hours after bypass responsiveness to acetylcholine improved, but typically remained depressed from baseline. Conserved endothelial function was associated with higher urine output during the first 48 postoperative hours (R = 0.43; p = 0.008). CONCLUSIONS: Cutaneous endothelial dysfunction is present in infants immediately following cardiopulmonary bypass and recovers significantly in some patients within 24 hours postoperatively. Confirmation of an association between persistent endothelial-dependent vasomotor dysfunction and decreased urine output could have important clinical implications. Ongoing research will explore the pattern of endothelial-dependent vasomotor dysfunction after cardiopulmonary bypass and its relationship with biochemical markers of inflammation and clinical outcomes.

Endothelial-Dependent Vascular Reactivity After Cardiopulmonary Bypass is Associated with Unique Metabolomic Signatures.

ABSTRACT: Cardiopulmonary bypass (CPB), an extracorporeal method necessary for the surgical correction of complex congenital heart defects, incites significant inflammation that affects vascular function. These changes are associated with alterations in cellular metabolism that promote energy production to deal with this stress. Utilizing laser-doppler perfusion monitoring coupled with iontophoresis (LDPMI) in patients undergoing corrective heart surgery, we hypothesized that temporal, untargeted metabolomics could be performed to assess the link between metabolism and vascular function. Globally, we found 2404 unique features in the plasma of patients undergoing CPB. Metabolites related to arginine biosynthesis were the most altered by CPB. Correlation of metabolic profiles with endothelial-dependent (acetylcholine, ACh) or endothelial-independent (sodium nitroprusside, SNP) vascular reactivity identified purine metabolism being most consistently associated with either vascular response. Concerning ACh-mediated responses, acetylcarnitine levels were most strongly associated, while glutamine levels were associated with both ACh and SNP responsiveness. These data provide insight into the metabolic landscape of children undergoing CPB for corrective heart surgery and provide detail into how these metabolites relate to physiological aberrations in vascular function.

The Inverse Relationship Between Endothelium-Dependent Vasodilation and Blood Pressure is Lost After Cardiopulmonary Bypass.

Cardiopulmonary bypass (CPB) is required for the surgical correction of congenital heart defects and incites an acute inflammatory response that impairs endothelial function post-operatively. Therefore, we hypothesized that the pre-operative relationship between endothelial function and blood pressure would be impaired after CPB-mediated inflammation. Using laser Doppler perfusion monitoring coupled with iontophoresis, we found that while there was a significant inverse correlation between endothelium-dependent vascular reactivity to acetylcholine (ACh) stimulation and systolic blood pressure (SBP), this relationship was lost after CPB. No relationship was observed between endothelium-independent vascular reactivity using sodium nitroprusside (SNP) and SBP either pre-CPB or any point thereafter. Additionally, neither CPB time nor inflammatory cytokines correlated with the degree of responsiveness to ACh. These data suggest that the measurement of endothelium impairment after CPB may be more reflective of cardiovascular health than SBP alone.

Late immune consequences of combat trauma: a review of trauma-related immune dysfunction and potential therapies.

With improvements in personnel and vehicular body armor, robust casualty evacuation capabilities, and damage control resuscitation strategies, more combat casualties are surviving to reach higher levels of care throughout the casualty evacuation system. As such, medical centers are becoming more accustomed to managing the deleterious late consequences of combat trauma related to the dysregulation of the immune system. In this review, we aim to highlight these late consequences and identify areas for future research and therapeutic strategies. Trauma leads to the dysregulation of both the innate and adaptive immune responses, which places the injured at risk for several late consequences, including delayed wound healing, late onset sepsis and infection, multi-organ dysfunction syndrome, and acute respiratory distress syndrome, which are significant for their association with the increased morbidity and mortality of wounded personnel. The mechanisms by which these consequences develop are complex but include an imbalance of the immune system leading to robust inflammatory responses, triggered by the presence of damage-associated molecules and other immune-modifying agents following trauma. Treatment strategies to improve outcomes have been difficult to develop as the immunophenotype of injured personnel following trauma is variable, fluid and difficult to determine. As more information regarding the triggers that lead to immune dysfunction following trauma is elucidated, it may be possible to identify the immunophenotype of injured personnel and provide targeted treatments to reduce the late consequences of trauma, which are known to lead to significant morbidity and mortality.