Introduction
Antegrade selective cerebral perfusion (ASCP) has a widespread use today
for cerebral protection during aortic arch surgery with increasing
incorporation of moderate hypothermia (28°C) during lower body
circulatory arrest (LBCA). Although a considerable amount of
contribution has been made literally addressing the favorable effects of
this technique questions remain regarding the protection of distal
abdominal viscera and neuronal structures-namely the spinal cord- during
lower body circulatory arrest with moderate hypothermia. The nervous
tissue is very sensitive to ischemia and ensuing spinal cord
complications can be devastating with a wide spectrum ranging from
clinically undetected sensory loss to permanent paraplegia. Animal
models of arch surgery at moderate hypothermia revealed insufficient
spinal cord blood flow below thoracic 8 and 9 segment to sustain its
viability with ASCP only 1. If distal perfusion is not
included during arch surgery, concerns about the margins of the safe
period for spinal cord ischemia during distal circulatory arrest exist.
Considering that a real time information system may help raise awareness
of the team about ischemic insult of the spinal cord during
thoracoabdominal interventions where there is a considerably high risk
of paraplegia, pioneering experimental works with near infrared
spectrometry (NIRS) yielded acceptable results 2-4.
NIRS could reveal both ischemic and reperfusion related changes below
midthoracic level (T7) in procedures involving the proximal descending
thoracic aorta in a large animal model 5. In the
clinical setting, after the feasibility of NIRS monitoring in both open,
endovascular and hybrid thoracoabdominal interventions has been
confirmed and the Leipzig group have reported upgrading their monitoring
system to bilateral thoracic and lumbar paravertebral NIRS monitoring
today it is used in both open and endovascular thoracoabdominal
procedures 4,6,7. Regarding arch surgery, Kinoshita et
al. were the first to use NIRS monitoring in a pilot study and reported
that lower part of the spinal cord was not perfused sufficiently during
ASCP 8. We use routine cerebral NIRS monitoring in
arch surgery and had experience with spinal cord NIRS monitoring in
patients with type B aortic dissection in our hospital previously9,10. We therefore planned to monitor spinal cord
oxygenation with NIRS in our patients undergoing arch surgery to detect
a warning sign regarding spinal cord ischemic insult and looked for a
correlation between blood lactate, s100β values and NIRS levels.