'Lactate washout' following circulatory arrest

Area of Science:

• Cardiovascular Science
• Critical Care Medicine
• Biochemistry

Background:

• Arterial blood lactate concentration is used to estimate acute perfusion failure severity.
• Concerns exist regarding "lactate washout" invalidating measurements post-resuscitation.
• Lactate washout could confound the interpretation of increasing lactate levels as a sign of ongoing anaerobiosis.

Purpose of the Study:

• To investigate the phenomenon of lactate washout in a porcine model of cardiac arrest.
• To determine if lactate measurements are invalidated by washout following resuscitation from cardiac arrest.

Main Methods:

• A porcine model of electromechanical dissociation-induced cardiac arrest was used.
• Cardiopulmonary resuscitation (CPR) was administered for up to 30 minutes or until spontaneous circulation returned.
• Arterial blood lactate concentrations were monitored during and after resuscitation efforts.

Main Results:

• In successfully resuscitated animals (n=14, 25 trials), arterial lactate decreased within 4 minutes post-resuscitation.
• In animals with failed resuscitation (n=24), arterial lactate concentrations increased throughout the observation period.
• The observed lactate washout occurred rapidly, within a mean interval of 2.6 +/- 0.3 minutes.

Conclusions:

• Lactate washout does not invalidate arterial blood lactate measurements under the extreme conditions of cardiac arrest.
• Lactate levels remain a valid indicator of perfusion status even immediately following resuscitation.
• These findings support the continued use of arterial lactate concentration in assessing critical care patients.