The measurement of blood lactate levels is becoming more common in emergency patients.
Where oxygen delivery is reduced to tissues, the cells switch to anaerobic respiration to produce energy. One of the waste products of this inefficient form of energy production is lactate. Therefore lactate levels give us an indication of reduced perfusion to cells.
Why are lactate levels relevant in patients with hypovolaemic shock – what are they telling us?
In hypovolaemic patients, there is a reduced circulating volume. Tissues in the body will be receiving a reduced blood supply, and therefore reduced oxygen delivery. The worse the hypovolaemic shock, the higher we can expect lactate levels to be. Normal levels in dogs are less than 2mmol/litre of blood. In the GDV case pictured, the hand-held lactate monitor indicates a reading of 14.7mmol/litre; a very large elevation that indicates very poor perfusion.
How can blood lactate levels be used to assess the effectiveness of treatment with intravenous fluids in these patients?
When treating hypovolaemic shock, we usually look for an improvement in physical parameters that reflect perfusion (heart rate, pulse quality, mucous membrane colour, capillary refill time). By monitoring blood lactate levels, we can also look at what is happening at a cellular level; we expect to see a rapid reduction in lactate levels if we are adequately resuscitating the patient
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