Monitoring of cerebral oxygenation during hypoxic gas management in congenital heart disease with increased pulmonary blood flow

Presurgical Use of Hypoxic Mixture for Systemic Perfusion Improvement in Neonates With Complex Congenital Heart Disease: A Systematic Review and Meta-Analysis

Oxygen therapy is essential for the survival of preterm babies and critically ill newborns; however, it has the potential to cause harm through hypoxemia or hyperoxemia. Newborns with complex congenital heart diseases (CHD) suffer from oxygen fluctuations due to the disease and its treatments, altering pre and postnatal development. The objective of this study is to evaluate the evidence for using a hypoxic mixture to decrease pulmonary over-circulation and improve systemic perfusion before surgical interventions in newborns with complex CHD that course with pulmonary over-circulation and systemic hypoperfusion. A search was conducted in PubMed, EMBASE, LILACS, Scielo, Taylor and Francis, SAGE, and Science Direct databases from 2000 to 2022 by two independent authors, including articles with hypoxic mixture treatment in observational studies or trials, with pre-treatment and post-treatment measurements in the same patient, or two groups or more comparisons. Six articles were selected, with a total of 75 patients. The primary outcome was improved systemic circulation and decreased pulmonary over-circulation measured directly with Qp/Qs and indirectly with oxygen saturation and cerebral near-infrared spectroscopy (NIRS). In addition, we performed a meta-analysis for oxygen saturation and cerebral NIRS. Oxygen saturation was the value uniformly reported; three studies reported a significantly lower oxygen saturation after the hypoxic mixture. The cerebral NIRS was measured in 4 studies, with inconsistent results. After using the hypoxic mixture, the Qp/Qs calculation was lower in the two studies but was not statistically significant. The meta-analysis for oxygen saturation showed a fixed effect post-hypoxic therapy of -0.7 (-1.06; -0.35), p < 0.001. The meta-analysis of two studies that measured cerebral NIRS did not show a statistically significant difference at 12 and 24 hours. In conclusion, this is the first systematic review and meta-analysis regarding the pre-operative use of hypoxic gas mixtures for newborns with complex congenital heart disease. Treatment results in lower oxygen saturations, but there is a lack of evidence of improvement in systemic perfusion. The utilization of this therapy is controversial, and better evidence is necessary.

Umbilical cord milking stabilizes cerebral oxygenation and perfusion in infants born before 29 weeks of gestation

OBJECTIVE

To investigate the effects of umbilical cord milking at birth on cerebral perfusion and systemic perfusion in very low birth weight (VLBW) infants.

STUDY DESIGN

Cerebral tissue oxygenation index and cerebral fractional tissue oxygen extraction were monitored in 50 stable VLBW infants (gestational age <29 weeks, birth weight <1250 g), with 26 allocated to the milked group and 24 to the control group. We used near-infrared spectroscopy 3-6, 12, 18, 24, 36, 48, and 72 hours after birth. Left ventricular end-diastolic dimension, left ventricular ejection fraction, left ventricle (LV) Tei index (measurement of left ventricular systolic and diastolic function), left ventricular cardiac output, and superior vena cava flow were measured concurrently using echocardiography.

RESULTS

There were no significant differences in gestational age and birth weight between the 2 groups. Hematocrit, left ventricular end-diastolic dimension, left ventricular cardiac output, and superior vena cava flow were higher in the milked group than in the control group, with improvement in the LV Tei index despite the absence of left ventricular ejection fraction changes within 24 hours after birth. Tissue oxygenation index increased and cerebral fractional tissue oxygen extraction decreased in the milked group within 24 hours after birth.

CONCLUSION

Umbilical cord milking stabilized cerebral oxygenation and perfusion in VLBW infants by improving LV diastolic function by increasing LV preload.

Changes in cerebral perfusion in extremely LBW infants during the first 72 h after birth

Cerebral perfusion and its relation with systemic circulation in extremely LBW (ELBW) infants in the early neonatal period are not well understood. The cerebral tissue oxygenation index (TOI) and cerebral fractional tissue oxygen extraction (FTOE) were monitored in stable 16 ELBW infants (GA <29 wk) using near-infrared spectroscopy (NIRS) at 3-6, 12, 18, 24, 36, 48, and 72 h after birth. The left ventricular end-systolic wall stress (ESWS), left ventricular ejection fraction (LVEF), left ventricular cardiac output (LVCO), and superior vena cava (SVC) flow were also measured simultaneously using echocardiography. The ESWS increased till 18 h and then decreased; LVEF, LVCO, and SVC flow decreased till 12 h and increased thereafter. The TOI decreased till 12 h and correlated with SVC flow; FTOE increased until 12 h and then decreased. These changes in variables of NIRS and echocardiographic measurements contrasted to changes in mean arterial blood pressure (MABP), which showed trends of continuous and gradual increase after birth. We conclude that even stable ELBW infants undergo evident transitional changes in cerebral oxygenation and perfusion in the early postnatal period, which may reflect changes in cardiac function and cardiac output.

Near infrared spectroscopy (NIRS) should not be standard of care for postoperative management

Neurologic dysfunction is a problem in patients with congenital heart disease. Near infrared spectroscopy (NIRS) may provide a real-time window into cerebral oxygenation. Enthusiasm for NIRS has increased in hopes of reducing neurologic dysfunction. However, potential gains need to be evaluated relative to cost and potential detriment of intervention before routine implementation. Responding to data in ways that seem intuitively beneficial can be risky when the long-term impact is unknown. Many centers, and even entire countries, have adopted NIRS as standard of care. Available data suggest that multimodality monitoring, including NIRS, may be a useful adjunct. However, the current literature on the use of NIRS alone does not demonstrate improvement in neurologic outcome. Data correlating NIRS findings with indirect measures of neurologic outcome or mortality are limited. Although NIRS has promise for measuring regional tissue oxygen saturation, the lack of data demonstrating improved outcomes limits the support for wide-spread implementation.

Optical measurement of cerebral hemodynamics and oxygen metabolism in neonates with congenital heart defects

We employ a hybrid diffuse correlation spectroscopy (DCS) and near-infrared spectroscopy (NIRS) monitor for neonates with congenital heart disease (n=33). The NIRS-DCS device measured changes during hypercapnia of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations; cerebral blood flow (rCBF(DCS)); and oxygen metabolism (rCMRO(2)). Concurrent measurements with arterial spin-labeled magnetic resonance imaging (rCBF(ASL-MRI), n=12) cross-validate rCBF(DCS) against rCBF(ASL-MRI), showing good agreement (R=0.7, p=0.01). The study demonstrates use of NIRS-DCS on a critically ill neonatal population, and the results indicate that the optical technology is a promising clinical method for monitoring this population.

Advances in cardiac intensive care

PURPOSE OF REVIEW

As surgical survival in children with congenital heart disease, particularly those with univentricular hearts, has improved in recent years, focus has shifted to reducing the morbidity of congenital cardiac malformations and their treatment. This review will focus on emerging therapies aimed at reducing these morbidities in the intensive care unit.

RECENT FINDINGS

A protracted stay in the intensive care unit after cardiac surgery is a risk factor for developing various morbidities. Therapies or interventions that may hasten postoperative recovery and minimize the length of stay are thus important to evaluate. Fluid overload, renal dysfunction, low cardiac output and neurological dysfunction remain major contributors to morbidity after cardiac surgery. In addition, the treatment of these adverse states can potentially compound the injury.

SUMMARY

The reduction in morbidity after cardiac surgery remains challenging. Recent insights have allowed us to recognize the impact of factors beyond the intraoperative period as significant contributors to morbidity. As our field continues to evolve, future studies should focus on emerging technologies and therapies that facilitate the prevention of physiological states that compound congenital morbidities.

Near-infrared spectroscopy in the fetus and neonate

Near-infrared spectroscopy allows for real-time, noninvasive measurement of cerebral hemodynamics and oxygenation at the bed-side. This article describes animal and clinical research using near-infrared spectroscopy to study cerebral hemodynamic function in the fetus, neonate, and child.