6 research outputs found
A practical approach to cerebral near-infrared spectroscopy (NIRS) directed hemodynamic management in noncardiac pediatric anesthesia
Safeguarding cerebral function is of major importance during pediatric anesthesia.
Premature, exâpremature, and fullâterm neonates can be vulnerable to physiologiâ
cal changes that occur during anesthesia and surgery. Data from studies performed
during pediatric cardiac surgery and in neonatal/pediatric intensive care units have
shown the benefits of nearâinfrared spectroscopy (NIRS) monitoring of regional cerâ
ebral oxygenation (cârSO2). However, NIRS monitoring is seldom used during nonâ
cardiac pediatric anesthesia. Despite compelling evidence that blood pressure does
not reflect endâorgan perfusion, it is still regarded as the most important determiâ
nant of cerebral perfusion and the most relevant hemodynamic management target
parameter by most (pediatric) anesthetists. The principle of NIRS monitoring is not
selfâexplanatory and sometimes seems even counterintuitive, which may explain why
many anesthesiologists are reserved regarding its use. The first part of this paper is
dedicated to a clinical introduction to NIRS monitoring. Despite scientific efforts,
it has not yet been possible to define individual lower limit cârSO2 values and it is
unlikely this will succeed in the near future. Nonetheless, published treatment algoâ
rithms usually specify cârSO2 values which may be associated with cerebral hypoxia.
Our treatment guideline for maintaining sufficient cerebral oxygenation differs funâ
damentally from all previously published approaches. We define a baseline cârSO2
value, registered in the awake child prior to anesthesia induction, as the lowest acâ
ceptable limit during anesthesia and surgery. The cerebral rSO2 is the single target
parameter, while blood pressure, heart rate, PaCO2, and SaO2 are major parameters
that determine the cârSO2. Cerebral NIRS monitoring, interpreted together with its
continuously available contributing parameters, may help avoid potentially harmful
episodes of cerebral desaturation in anesthetized pediatric patients
Electrical Control of Optical Emitter Relaxation Pathways enabled by Graphene
Controlling the energy flow processes and the associated energy relaxation
rates of a light emitter is of high fundamental interest, and has many
applications in the fields of quantum optics, photovoltaics, photodetection,
biosensing and light emission. While advanced dielectric and metallic systems
have been developed to tailor the interaction between an emitter and its
environment, active control of the energy flow has remained challenging. Here,
we demonstrate in-situ electrical control of the relaxation pathways of excited
erbium ions, which emit light at the technologically relevant telecommunication
wavelength of 1.5 m. By placing the erbium at a few nanometres distance
from graphene, we modify the relaxation rate by more than a factor of three,
and control whether the emitter decays into either electron-hole pairs, emitted
photons or graphene near-infrared plasmons, confined to 15 nm to the sheet.
These capabilities to dictate optical energy transfer processes through
electrical control of the local density of optical states constitute a new
paradigm for active (quantum) photonics.Comment: 9 pages, 4 figure