Tissue oxygenation and vascular reactivity as measured with Near-Infrared Spectroscopy in (perioperative) patients

Many processes surrounding surgery can influence the oxygen supply or consumption of organs. This thesis aimed to gain insight into a measurement method that can non-invasively measure oxygen levels in tissue: near-infrared spectroscopy (NIRS). Early detection of oxygen deficiency in the kidney or brain of patients during surgery might prevent damage to these organs.In literature, lower kidney NIRS values were associated with kidney damage after surgery in approximately 63% of the cases. Unfortunately, we cannot recommend kidney NIRS measurements for evaluating the oxygen content in the kidney, as we discovered in healthy volunteers that kidney NIRS measurements underestimate the directly measured oxygen content in the kidney's blood vessels. We found that lower brain NIRS values (72 hours after cooling) in children born with oxygen deprivation are associated with adverse neurological development later in life. Low brain NIRS values directly after intubation in pediatric cardiac surgery are associated with increased mortality 30 days after surgery.The dynamics of small blood vessels influence the oxygen supply to the organs and can be objectified by adding a short blood vessel occlusion test to the NIRS measurements. Literature has described that the dynamics of small blood vessels decrease during surgery, possibly due to the (sterile) inflammatory reaction. Different oxygen or carbon dioxide concentrations in the inhaled air in healthy volunteers did not influence these dynamics

Tissue oxygenation and vascular reactivity as measured with Near-Infrared Spectroscopy in (perioperative) patients

Many processes surrounding surgery can influence the oxygen supply or consumption of organs. This thesis aimed to gain insight into a measurement method that can non-invasively measure oxygen levels in tissue: near-infrared spectroscopy (NIRS). Early detection of oxygen deficiency in the kidney or brain of patients during surgery might prevent damage to these organs.In literature, lower kidney NIRS values were associated with kidney damage after surgery in approximately 63% of the cases. Unfortunately, we cannot recommend kidney NIRS measurements for evaluating the oxygen content in the kidney, as we discovered in healthy volunteers that kidney NIRS measurements underestimate the directly measured oxygen content in the kidney's blood vessels. We found that lower brain NIRS values (72 hours after cooling) in children born with oxygen deprivation are associated with adverse neurological development later in life. Low brain NIRS values directly after intubation in pediatric cardiac surgery are associated with increased mortality 30 days after surgery.The dynamics of small blood vessels influence the oxygen supply to the organs and can be objectified by adding a short blood vessel occlusion test to the NIRS measurements. Literature has described that the dynamics of small blood vessels decrease during surgery, possibly due to the (sterile) inflammatory reaction. Different oxygen or carbon dioxide concentrations in the inhaled air in healthy volunteers did not influence these dynamics