Simulating nirs and mrs measurements during cerebral hypoxia-ischaemia in piglets using a computational model

Abstract

We present a group analysis of the changes in cerebral haemodynamics, and the oxidation state of cytochrome-c-oxidase measured using broadband nearinfrared spectroscopy (NIRS) and intracellular pH measured by phosphorous (31 P) magnetic resonance spectroscopy (MRS) during and after cerebral hypoxiaischaemia (HI) in 15 piglets. We use a previously published computational model of cerebral metabolism in the piglet [1] to integrate these measurements and simulate HI. We successfully simulate changes in cellular metabolism including shifts in intracellular pH observed in the piglet brain during HI. In this process, we optimise physiological parameters in the model identifi ed through sensitivity analysis (such as the rate of glucose metabolism and intracellular lactate concentration), to fi t simulated and measured data. The model fi ts the data reasonably and suggests a 20% drop in glucose consumption, a ~65% increase in lactate concentration and ~35% drop in the cerebral metabolic rate of oxygen (CMRO 2) during HI.