Abstract
There are a variety of devices that quantify biological properties of cerebral tissue. Installing such device will cause a local insertion trauma, which will affect early measurements. Current literature proposes minimum one hour of observation before acquiring first measurements when using microdialysis. It is unknown whether this applies to other intracerebral devices. We therefore aimed to investigate time needed to reach steady state when using microdialysis and two intracerebral probes in a piglet model. Ten newborn piglets less than 24 hours of age were anaesthetized. Two probes (Codman and OxyLite/OxyFlo) and a microdialysis catheter (CMA Microdialysis) were installed 10 mm into the left hemisphere. Probes measured intracranial pressure, cerebral blood flow, and oxygen tension. The microdialysis catheter measured lactate, glucose, glycerol, and pyruvate. Measurements were acquired hourly for 20 hours. Lactate and glycerol peaked immediately after insertion and reached steady state after approximately four hours. Glucose, pyruvate, cerebral blood flow, and intracranial pressure reached steady state immediately. Oxygen tension reached steady state after 12 hours. With time, interindividual variability decreased for the majority of measurements. Consequently, time to stabilization after insertion depends on the choice of device and is crucial to obtain valid baseline values with high degree of precision.
Highlights
To quantify biological properties of cerebral tissue, microdialysis and intracerebral probes are used[1]
Except for one animal with an initially very high intracerebral glucose concentration, steady state was reached after one hour of observation for both glucose and pyruvate (Fig. 2)
The www.nature.com/scientificreports interindividual variation of lactate and glycerol decreased during the first four and seven hours, respectively, while glucose and pyruvate remained constant throughout the observation period (Supplementary Data S1)
Summary
To quantify biological properties of cerebral tissue, microdialysis and intracerebral probes are used[1] In paediatric research, these devices are used in experimental animal studies to investigate the intracerebral consequence of perinatal hypoxia and ischemia and specific treatments[2,3]. Mellergård et al investigated the impact of microdialysis-catheter placement in patients with severe brain injury[12]. They found stable values of glycerol, lactate and pyruvate immediately after insertion; but substantial changes in glutamate and several cytokines and chemokines up to 48 hours after insertion[12]. There is a lack of data on the consequence of insertion trauma for other devices used in cerebral tissue The aim of this newborn-piglet study was to determine www.nature.com/scientificreports/. Whether one hour of observation after insertion of two intracerebral probes, and a microdialysis catheter was sufficient to reach steady state
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