NIRS monitoring of brain and spinal cord — detection of adverse intraoperative events

Abstract

Near infrared spectroscopy (NIRS) monitors changes in oxygenated haemoglobin (HbO2), and redox status of cytochromeaa3(cyt) continuously and non-invasively in living tissue. We present examples where clinically relevant changes in HbO2and/or cyt were detected in real time, allowing intervention to avert potentially harmful hypoxic-ischaemic damage to the brain and/or spinal cord.Brain monitoring: In children undergoing surgery on cardiopulmonary bypass, observations include that: atrial fibrillation (cardiac arrhythmia) lowered cerebral HbO2concentration; concealed haemorrhage decreased cerebral HbO2concentration; inadequate level of anaesthetic resulted in spikes of changes in volume with interventions such as suturing; circulatory arrest reduced brain HbO2and cyt redox status; and bypass pump problems compromised cerebral blood flow.Spinal cord monitoring: In the experimental animal, we observed that NIRS detected ischaemic change immediately following aortic compression, spinal column distraction (instrumentation to separate the vertebrae), and hypoxia. In an infant requiring release of a congenitally tethered spinal cord, we observed that traction on the spinal cord of the infant resulted in decreased total haemoglobin concentration.Summary: NIRS brain monitoring probably represents the “standard of care” during cardiac surgery because adverse events can be detected and quantified. Similarly, spinal cord monitoring could reduce ischaemic spinal cord damage in spinal cord surgery and aortic aneurysm repair.

Wireless near-infrared spectroscopy of skeletal muscle oxygenation and hemodynamics during exercise and ischemia

“…The effects of ischemia on the patterns of change in O 2 Hb and HHb in our subjects are also consistent with those observed in other tissue such as the brain, spinal cord and bladder [17,26,27]. The changes in muscle TSI (%) observed differed in response to 10, 30 and 50% of MVC and during induced ischemia, declining most during 30 and 50% of MVC.…”

Near-Infrared Spectroscopy for Monitoring Spinal Cord Ischemia During Hybrid Thoracoabdominal Aortic Aneurysm Repair

“…Macnab et al 6 used NIRS in an infant requiring release of a congenitally tethered spinal cord. Subsequently, in a series of 9 patients undergoing TAAA repair, Edmonds and Ganzel 7 observed a greater decline in spinal saturation measured at T10 in patients who experienced lower limb motor deficit compared to patients without deficit.…”

“…To date, research on the use of NIRS to monitor spinal cord oxygenation is scarce: only animal studies 4,5 and 3 clinical reports [6][7][8] have examined the feasibility of NIRS to monitor spinal cord perfusion. We present a case where tissue oxygen saturation (S s O 2 ) at the level of the spinal cord decreased significantly after aortic endograft deployment and became strongly related to arterial blood pressure.…”

The evolution of near infrared spectroscopy in urology

“…11) [122,124]. CCO drives >95% of O 2 consumption and adenosine triphosphate (ATP) synthesis, and its redox status has principally been monitored in the brain [28,74,119]. The incentive to monitor CCO redox status is that while the O 2 Hb/HHb relationship indicates whether oxygen has been delivered and/or depleted, CCO changes reflect more intricate physiologic interplay such as the presence or absence of oxygen uptake, cellular transition from oxidative to substrate dependent phosphorylation, and whether or not glucose is available or ATP synthesis impaired [75].…”