1. Lactate – the most objective marker of “shock”
In anaerobic conditions, pyruvate does not enter TCA (Krebs) cycle but is converted to lactate
Lactate diffuses rapidly out of cell and can be measured in systemic circulation

2. Restoration of perfusion
As perfusion is restored, lactate is metabolised in liver with regeneration of glucose (Cori cycle)
Rapid process
Lactate provides “real-time” marker of perfusion status

3. Has been recognised as a prognostic marker in people since 1970’s
Circulation 41: 989, 1970
Experimental and clinical studies on lactate and pyruvate as indicators of the severity of acute circulatory failure

4. Lactate interpretation
Objective measure of severity of “shock”
Change in lactate following therapy may be more prognostically useful than a single lactate measurement
Severity of shock
Mild
Moderate
Severe
Lactate value (mmol/L)
2.5-5
5-7
>7
{Amanda has seen a living dog with a lactate of 17.3 but it was dead soon after
....anything over 12 is very very bad}

5. Clinical use of lactate
Serial measurements invariably preferable to single point measurement
Pre and post fluid bolus – how effective has your treatment been?
Ideally normalise or near normalise lactate pre-GA/sedation
To confirm if hypoperfusion present if unsure
Tachycardic RTA – is it early shock/is it pain?

6. Red herrings
Lactate will be high but not represent hypoperfusion in....
Animals which have had a recent seizure
Immediately post-exercise
Animals that are trembling a lot
Some other VERY uncommon scenarios
Very severe anaemia
Some neoplasia
Rare drugs/toxins

7. Lactate....a really useful tool
Pricing set up to encourage monitoring of trends
Much more valuable than single measures
Consider as part of baseline in all critically ill admissions
As with all tests, care not to over interpret if the patient physical exam tells you differently