Brain glucose and lactate levels during ventilator-induced hypo- and hypercapnia

Authors: Hulst R.A.; Lameris T.W.¹; Haitsma J.J.²; Klein J.²; Lachmann B.²

Source: Clinical Physiology and Functional Imaging, Volume 24, Number 4, July 2004 , pp. 243-248(6)

Publisher: Wiley-Blackwell

Abstract:

Summary Objective:

Levels of glucose and lactate were measured in the brain by means of microdialysis in order to evaluate the effects of ventilator-induced hypocapnia and hypercapnia on brain metabolism in healthy non-brain-traumatized animals. Design and setting:

Prospective animal study in a university laboratory. Subjects:

Eight adult Landrace/Yorkshire pigs. Interventions:

The microdialysis probe was inserted in the brain along with a multiparameter sensor and intracranial pressure (ICP) probe. The animals were ventilated in a pressure-controlled mode according to the open lung concept with an inspired oxygen fraction of 0·4/1·0. Starting at normoventilation (PaCO₂ ±40 mmHg) two steps of both hypercapnia (PCO₂ ± 70 and 100 mmHg) and hypocapnia (PaCO₂ ± 20 and 30 mmHg) were performed. Under these conditions, brain glucose and lactate levels as well as brain oxygen (PbrO₂), brain carbon dioxide (PbrCO₂), brain pH (brpH), brain temperature and ICP were measured. Results:

At hypercapnia (PaCO₂ = 102·7 mmHg) there were no significant changes in brain glucose and lactate but there was a significant increase in PbrCO₂, PbrO₂ and ICP. In contrast, at hypocapnia (PCO₂ = 19·8 mmHg) there was a significant increase in brain lactate and a significant decrease in both brain glucose and PbrCO₂. Conclusions:

Hypocapnia decreases brain glucose and increases brain lactate concentration, indicating anaerobic metabolism, whereas hypercapnia has no influence on levels of brain glucose and brain lactate.

Keywords: animal model; brain glucose; brain lactate; hypercapnia; hypocapnia; microdialysis

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1475-097X.2004.00557.x

Affiliations: 1: Departments of Anesthesiology and Internal Medicine, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands 2: Department of Anesthesiology

Publication date: 2004-07-01

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• In this Subject: Anatomy & Physiology ,  Radiology & Imaging
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