[Losing consciousness: role of the venous lactate levels in the diagnosis of convulsive crises].
OBJECTIVE
This prospective study was conducted to evaluate the usefulness of venous lactate assay in the diagnosis of generalized seizures.


METHODS
Over a three month period, 78 consecutive adults admitted to the emergency unit for unconsciousness were included in the study. Three study groups were defined: patients with generalized seizures (n = 22), unconscious patients without seizure (n = 34) and known epileptic patients with unexplained malaises (n = 22). Patients with a disease susceptible of increasing lactate levels were excluded. Peripheral venous blood was drawn to determine lactates, bicarbonates and pH on a blood gas analyzer. All determinations were performed within 5 minutes of blood withdrawal. CPK level was also determined with an enzymatic method.


RESULTS
In patients who had seizures, venous lactate levels were higher than those in patients who had no seizures: 4.3 +/- 0.5 mmol/l in generalized seizure patients versus 1.64 +/- 0.1 and 2.2 +/- 1.39 in unconscious patients without seizure and known epileptic patients with unexplained malaise respectively. The threshold lactate level of 2.5 mmol/l given by ROC curves gave a 0.97 specificity and a 0.73 sensitivity.


CONCLUSIONS
The acidosis observed in patients with generalized seizures results from the combined effects of respiratory and metabolic acidosis. High lactate level would be a consequence of hypoxemia, per seizure rise in catecholamines, and aerobic and anaerobic metabolism in muscles during the tonic-clonic phase. In patients presenting in an unconscious state, increased lactate levels, even when determined up to 2 hours after venous blood withdrawal, could be a useful parameter for the diagnosis of epileptic seizure.
Service de Réanimation médicale, CHU Bretonneau, Tours.
E
E
Hazouard
P F
PF
Dequin
R
R
Lanotte
A
A
Legras
M
M
Ferrandière
D
D
Perrotin
D000328:Adult; D000368:Aged; D001639:Bicarbonates / Q000097:blood; D003937:Diagnosis, Differential; D004630:Emergencies; D004827:Epilepsy / Q000097:blood* / Q000175:diagnosis; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013575:Syncope / Q000097:blood* / Q000175:diagnosis; D014474:Unconsciousness / Q000097:blood* / Q000175:diagnosis
D001639:Bicarbonates; D007773:Lactates
Perte de connaissance: intérêt du dosage des lactates veineux pour le diagnostic de crise convulsive.