Hyperchloremic acidosis during grand mal seizure lactic acidosis.

OBJECTIVE

To evaluate the prevalence and the mechanism of hyperchloremic acidosis component (HClA) during lactic acidosis secondary to grand mal seizures.

DESIGN

Retrospective study.

SETTING

Medical intensive care unit in a university hospital.

PATIENTS

35 patients admitted for grand mal seizures with lactic acidosis (pH < 7.35, TCO2 < 20 mmol/l and PaCO2 < 8 kPa).

MEASUREMENTS

HClA was defined by the ratio: excess anion gap/HCO3 deficit (delta AG/delta TCO2) < 0.8. A difference in the distribution space of protons and their accompanying anion, i.e., a displacement of chloride from cells by the entering lactate, was evaluated by the ratio natremia/chloremia (Na+/Cl-).

RESULTS

Immediately after seizures, a profound lactic acidosis was observed (pH = 7.22 +/- 0.17 (mean +/- SD), AG: 23.8 +/- 7.1 mmol/l, TCO2 = 14.5 +/- 5.3 mmol/l, lactate: 14.6 +/- 6.9 mmol/. HClA was present on admission in 11 patients (31.5%). Its prevalence increased to 73% after recovery. delta AG/delta TCO2 ratios were unrelated to creatinine, level and PaCO2, but dependent on the ratio Na+/Cl- (r = 0.803; p < 0.001, delta AG/delta TCO2 = 6.4 x (Na+/Cl-)-7.9). These data demonstrate that HClA is not a respiratory or renal phenomenon and suggest differences in the distribution spaces of hydrogen ions and their accompanying anions.

CONCLUSION

HClA component may be associated with lactic acidosis in grand mal seizures and appears to be secondary to a lactate antiport. This phenomenon could be an immediate physiological response to a sudden metabolic acidosis.