Cerebral and Peripheral Tissue Oxygenation in Children Supported on ECMO for Cardio-Respiratory Failure

Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for patients with cardio-respiratory failure. Establishing, maintaining and weaning from ECMO may increase the risk for intracranial injury. We used a dual channel near infrared system to monitor cerebral and peripheral tissue oxygenation in 3 venoarterial (VA) and 1 venovenous (VV) ECMO patients undergoing manipulations in the ECMO circuit flows. Spectral analysis was performed on the oxyhaemoglobin data collected from these patients with the aim of comparing oscillations at range of frequencies appearing in the two measurement sites

Multichannel near infrared spectroscopy indicates regional variations in cerebral autoregulation in infants supported on extracorporeal membrane oxygenation

Assessing noninvasively cerebral autoregulation, the protective mechanism of the brain to maintain constant cerebral blood flow despite changes in blood pressure, is challenging. Infants on life support system (ECMO) for cardiorespiratory failure are at risk of cerebral autoregulation impairment and consequent neurological problems. We measured oxyhaemoglobin concentration (HbO(2)) by multichannel (12 channels) near-infrared spectroscopy (NIRS) in six infants during sequential changes in ECMO flow. Wavelet cross-correlation (WCC) between mean arterial pressure (MAP) and HbO(2) was used to construct a time-frequency representation of the concordance between the two signals to assess the nonstationary aspect of cerebral autoregulation and investigate regional variations. Group data showed that WCC increases with decreasing ECMO flow indicating higher concordance between MAP and HbO(2) and demonstrating loss of cerebral autoregulation at low ECMO flows. Statistically significant differences in WCC were observed between channels placed on the right and left scalp with channels on the right exhibiting higher values of WCC suggesting that the right hemisphere was more susceptible to disruption of cerebral autoregulation. Multichannel NIRS in conjunction with wavelet analysis methods can be used to assess regional variations in dynamic cerebral autoregulation with important clinical application in the management of critically ill children on life support systems

Optical topography to measure variations in regional cerebral oxygenation in an infant supported on veno-arterial extra-corporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for patients with cardio-respiratory failure which exposes the patient to the risk for in-tracranial injury. We used a 12-channel optical topography system to monitor ce-rebral oxygenation in a venoarterial (VA) ECMO patient during alterations in the ECMO flows. Changes in oxy-(HbO2), deoxy-(HHb) and total-(HbT) haemoglo-bin concentrations were measured simultaneously with systemic and ECMO cir-cuit parameters. Decreasing the flows resulted in a decrease in venous (SvO2) and arterial (SpO2) saturations. These were reflected in the haemoglobin data by a sig-nificant increase in HHb of varying magnitude across the 12 channels and mod-erate changes in HbO2 suggestive of cerebral arterial dilation to compensate for the lack of oxygen delivery. In the patient studied here ECMO flows appear to present a significant haemodynamic challenge to cerebral circulation

Canonical correlation analysis in the study of cerebral and peripheral haemodynamics interrelations with systemic variables in neonates supported on ECMO.

Neonates supported on extracorporeal membrane oxygenation (ECMO) are at high risk of brain injury due to haemodynamic instability. In order to monitor cerebral and peripheral (muscle) haemodynamic and oxygenation changes in this population we used a dual-channel near-infrared spectroscopy (NIRS) system. In addition, to assess interrelations between NIRS and systemic variables, collected simultaneously, canonical correlation analysis (CCA) was employed. CCA can quantify the relationship between a set of variables and assess levels of dependency. In four out of five patients, systemic variables were found to be less inter-related with cerebral rather than peripheral NIRS measurements. Moreover, during ECMO flow manipulations, we found that the interrelation between the systemic and the NIRS cerebral/peripheral variables changed. The CCA method presented here can be used to assess differences between NIRS cerebral and NIRS peripheral responses due to systemic variations which may be indicative of physiological differences in the mechanisms that regulate oxygenation and/or haemodynamics of the brain and the muscle

Adrenergic Alpha-1 Pathway Is Associated with Hypertension among Nigerians in a Pathway-focused Analysis

The pathway-focused association approach offers a hypothesis driven alternative to the agnostic genome-wide association study. Here we apply the pathway-focused approach to an association study of hypertension, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in 1614 Nigerians with genome-wide data.Testing of 28 pathways with biological relevance to hypertension, selected a priori, containing a total of 101 unique genes and 4,349 unique single-nucleotide polymorphisms (SNPs) showed an association for the adrenergic alpha 1 (ADRA1) receptor pathway with hypertension (p<0.0009) and diastolic blood pressure (p<0.0007). Within the ADRA1 pathway, the genes PNMT (hypertension P(gene)<0.004, DBP P(gene)<0.004, and SBP P(gene)<0.009, and ADRA1B (hypertension P(gene)<0.005, DBP P(gene)<0.02, and SBP P(gene)<0.02) displayed the strongest associations. Neither ADRA1B nor PNMT could be the sole mediator of the observed pathway association as the ADRA1 pathway remained significant after removing ADRA1B, and other pathways involving PNMT did not reach pathway significance.We conclude that multiple variants in several genes in the ADRA1 pathway led to associations with hypertension and DBP. SNPs in ADRA1B and PNMT have not previously been linked to hypertension in a genome-wide association study, but both genes have shown associations with hypertension through linkage or model organism studies. The identification of moderately significant (10(-2)>p>10(-5)) SNPs offers a novel method for detecting the "missing heritability" of hypertension. These findings warrant further studies in similar and other populations to assess the generalizability of our results, and illustrate the potential of the pathway-focused approach to investigate genetic variation in hypertension

Decoupling the influence of systemic variables in the peripheral and cerebral haemodynamics during ECMO procedure by means of oblique and orthogonal subspace projections

Extra-Corporeal Membrane Oxygenation (ECMO) is a life support system for infants and children with cardio-respiratory failure. During ECMO it is possible to have unstable cerebral haemodynamics, due to strong oscillations in the systemic variables, among other factors, which may lead to brain damage in the patients. Therefore, monitoring the coupling between cerebral haemodynamics and systemic signals might alert us of possible imminent brain damage. In this study we explore the use of orthogonal and oblique subspace projections in the decoupling of these variables, by assessing the ratio between the projections of the haemodynamic variables, onto the subspace spanned by the systemic variables, and the original signals. The coupling of these two systems may differ as different protection mechanisms protect the peripheral system and the brain. Subspace projection was able to decompose the heamodynamic variables as a sum of components related to each systemic variable, separately. As expected, stronger coupling was found between the peripheral haemodynamic and the systemic variables.status: publishe

Análisis de correlación canónica en el estudio de las interrelaciones de la hemodinámica cerebral y periférica con variables sistémicas en recién nacidos admitidos en ECMO

Neonates supported on extracorporeal membrane oxygenation (ECMO) are at high risk of brain injury due to haemodynamic instability. In order to monitor cerebral and peripheral (muscle) haemodynamic and oxygenation changes in this population we used a dual-channel near-infrared spectroscopy (NIRS) system. In addition, to assess interrelations between NIRS and systemic variables, collected simultaneously, canonical correlation analysis (CCA) was employed. CCA can quantify the relationship between a set of variables and assess levels of dependency. In four out of five patients, systemic variables were found to be less inter-related with cerebral rather than peripheral NIRS measurements. Moreover, during ECMO flow manipulations, we found that the interrelation between the systemic and the NIRS cerebral/peripheral variables changed. The CCA method presented here can be used to assess differences between NIRS cerebral and NIRS peripheral responses due to systemic variations which may be indicative of physiological differences in the mechanisms that regulate oxygenation and/or haemodynamics of the brain and the muscle