Lactic acid kinetics in respiratory alkalosis.

Abstract

OBJECTIVE:

To evaluate the impact of respiratory alkalosis on the elimination of intravenously infused lactate.

DESIGN:

Prospective, randomized, crossover study.

SETTING:

Medical ICU of a university hospital.

PATIENTS:

Eight patients treated by ventilatory support for neurologic or neuromuscular diseases.

INTERVENTIONS:

Patients were investigated on two occasions: during normoventilation (pH 7.42 +/- 0.1, PCO2 41 +/- 2 torr [5.5 +/- 0.2 kPa]) and during respiratory alkalosis (pH 7.59 +/- 0.1, PCO2 27 +/- 2 torr [3.6 +/- 0.2 kPa]) induced by controlled hyperventilation. To evaluate lactate elimination kinetics, 1 mmol/kg body weight of L-lactic acid was infused over 5 mins.

MEASUREMENTS AND MAIN RESULTS:

Arterial lactate concentrations and blood gas values were determined before and repeatedly after the infusion. Lactate elimination variables were calculated from the plasma curve by using a two-compartment model. Respiratory alkalosis increased plasma lactate from 1.56 +/- 0.1 to 2.49 +/- 0.2 mmol/L (p less than .001). The lactate elimination half-life increased from 4.57 +/- 0.2 mins at pH 7.42, to 9.96 +/- 1.1 mins during pH 7.59 (p less than .01), and beta half-life increased from 12.2 +/- 1.9 to 44.1 +/- 1 mins (p less than .01). Whole-body clearance decreased 40% from 24.2 +/- 2.9 to 14.3 +/- 2.0 mL/kg body weight-min (p less than .01).

CONCLUSIONS:

Respiratory alkalosis increases the basal concentration of plasma lactate and decreases clearance of infused lactic acid. These findings provide further evidence of the adverse effects of alkalosis.

• Authors: W Druml, G Grimm, A N Laggner, K Lenz, B Schneeweiss
• Journal: Critical care medicine (Crit Care Med) Vol. 19 Issue 9 Pg. 1120-4 (Sep 1991) ISSN: 0090-3493 [Print] United States
• PMID: 1884611 (Publication Type: Clinical Trial, Comparative Study, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Lactates
• Lactic Acid

Topics

• Aged
• Alkalosis, Respiratory (blood, therapy)
• Female
• Half-Life
• Humans
• Hydrogen-Ion Concentration
• Hyperventilation (blood)
• Infusions, Intravenous
• Lactates (administration & dosage, blood, pharmacokinetics)
• Lactic Acid
• Male
• Middle Aged
• Respiration, Artificial
• Time Factors