Cerebral metabolic effects of exogenous lactate supplementation on the injured human brain.
OBJECTIVE
Experimental evidence suggests that lactate is neuroprotective after acute brain injury; however, data in humans are lacking. We examined whether exogenous lactate supplementation improves cerebral energy metabolism in humans with traumatic brain injury (TBI).


METHODS
We prospectively studied 15 consecutive patients with severe TBI monitored with cerebral microdialysis (CMD), brain tissue PO2 (PbtO2), and intracranial pressure (ICP). Intervention consisted of a 3-h intravenous infusion of hypertonic sodium lactate (aiming to increase systemic lactate to ca. 5 mmol/L), administered in the early phase following TBI. We examined the effect of sodium lactate on neurochemistry (CMD lactate, pyruvate, glucose, and glutamate), PbtO2, and ICP.


RESULTS
Treatment was started on average 33 ± 16 h after TBI. A mixed-effects multilevel regression model revealed that sodium lactate therapy was associated with a significant increase in CMD concentrations of lactate [coefficient 0.47 mmol/L, 95% confidence interval (CI) 0.31-0.63 mmol/L], pyruvate [13.1 (8.78-17.4) μmol/L], and glucose [0.1 (0.04-0.16) mmol/L; all p < 0.01]. A concomitant reduction of CMD glutamate [-0.95 (-1.94 to 0.06) mmol/L, p = 0.06] and ICP [-0.86 (-1.47 to -0.24) mmHg, p < 0.01] was also observed.


CONCLUSIONS
Exogenous supplemental lactate can be utilized aerobically as a preferential energy substrate by the injured human brain, with sparing of cerebral glucose. Increased availability of cerebral extracellular pyruvate and glucose, coupled with a reduction of brain glutamate and ICP, suggests that hypertonic lactate therapy has beneficial cerebral metabolic and hemodynamic effects after TBI.
Department of Intensive Care Medicine, Neuroscience Critical Care Research Group, Faculty of Biology and Medicine, University Hospital of Lausanne, Rue du Bugnon 46, 1011, Lausanne, Switzerland, PBouzat@chu-grenoble.fr.
Pierre
P
Bouzat
Nathalie
N
Sala
Tamarah
T
Suys
Jean-Baptiste
JB
Zerlauth
Pedro
P
Marques-Vidal
François
F
Feihl
Jocelyne
J
Bloch
Mahmoud
M
Messerer
Marc
M
Levivier
Reto
R
Meuli
Pierre J
PJ
Magistretti
Mauro
M
Oddo
D000328:Adult; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D000070642:Brain Injuries, Traumatic / Q000188:drug therapy* / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects*; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007262:Infusions, Intravenous; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis / Q000379:methods; D008875:Middle Aged; D000066829:Neuroprotection; D011446:Prospective Studies; D019289:Pyruvic Acid / Q000378:metabolism; D012121:Respiration, Artificial; D019354:Sodium Lactate / Q000008:administration & dosage* / Q000494:pharmacology; D013997:Time Factors
D019344:Lactic Acid; D019289:Pyruvic Acid; D005947:Glucose; D019354:Sodium Lactate