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Clinical Implications of Delayed Lactate Analysis

Søren R. Boysen, DVM, DACVECC, University of Calgary

Emergency Medicine & Critical Care

|November/December 2021

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In the Literature

Rizzo KN, Rozanski EA, DeLaforcade AM. Effect of time until sample analysis on lactate in dogs with shock. Vet Clin Pathol. 2020;49(4):614-617.


FROM THE PAGE …

Lactate concentration is widely used as a point-of-care diagnostic indicator to rapidly assess the severity of shock and response to treatment in patients with clinical signs of hypoperfusion. Confounding factors (eg, prolonged vessel occlusion, certain medications, patient stress, time delays between blood collection and analysis) can falsely increase lactate concentrations and complicate interpretation of baseline and serial lactate values in critically ill patients.1,2

This study used a handheld point-of-care lactate meter to assess the impact of time between whole blood collection and lactate analysis in clinically ill dogs at an emergency clinic. In prior studies of healthy dogs, lactate concentrations increased up to 34% from baseline within 15 to 25 minutes when blood was stored at room temperature.3 The current study reported significantly increased lactate concentrations when whole blood samples from ill dogs were stored at room temperature, with increases observed in as few as 7.5 minutes. The greatest increases occurred in dogs with lower presenting lactate concentrations. 

Within 7.5 minutes of sampling, average increase above baseline was 11% in dogs with initial lactate values <4 mmol/L and 4% in dogs with initial lactate values >4 mmol/L. Although a 4% increase is unlikely to influence clinical decision-making when baseline lactate is already ≥4 mmol/L, after 30 minutes of sampling, the percentage increase above baseline grew to 39% and 15% in dogs with initial lactate concentrations <4 mmol/L and ≥4 mmol/L, respectively, which could influence clinical management.

This study emphasized the importance of standardizing blood collection and analysis for lactate concentration in small animal patients and suggested that caution should be used when interpreting blood lactate results from room temperature samples analyzed >7.5 minutes after collection.


… TO YOUR PATIENTS

Key pearls to put into practice:

1

There are multiple causes of increased lactate in dogs and cats, with hypoperfusion being the most common. Serial lactate measurement is often recommended to guide treatment for patients in shock.

2

Confounding factors—such as those that result in type B lactic acidosis (eg, strenuous exercise, prednisone administration, seizures, decreased clearance) and sampling errors (eg, prolonged vessel occlusion, delayed analysis of whole blood samples)—should be considered when interpreting baseline and serial lactate concentrations.

3

When using point-of-care handheld lactate meters, whole blood samples should be analyzed within 7.5 minutes of collection to avoid misinterpretation of lactate concentration.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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