Get the most value out of your IDEXX VetLab® System                    Fall 2005 Issue

Lactate measurement is making a resurgence in clinical veterinary medicine
Kristen Hibbetts, DVM, DACVIM, DACVECC

The ability to measure lactate concentrations in plasma has been around for decades. However, the clinical usefulness for measuring lactate levels has been limited because patient lactate levels change rapidly and older technologies for measuring lactate were slow. Now that lactate measurement is available as an in-house test, we can fully utilize it to help us resuscitate our critical patients.

Lactate is the result of anaerobic metabolism and is a normal physiologic process that occurs to some degree in all animals. When cells lose their normal oxygen supply, they revert to a form of energy production called anaerobic glycolysis. One end-product of anaerobic glycolysis is the production of lactate. A healthy animal can convert small amounts of lactate back into usable substances. Lactate levels rise when its production exceeds its utilization/elimination. While its presence does not indicate any particular disease, elevated amounts of lactate are an indicator of significant metabolic derangement.

One very significant cause for an imbalance between lactate production and lactate elimination is hypoperfusion. For example, a patient may present in hypovolemic shock with decreased blood flow to many organs. Those organs revert to anaerobic metabolism and large amounts of lactate are produced. The elevated levels of lactate result in acidosis, which further destabilizes the patient.

"The ability to measure lactate levels gives us a quantitative assessment of perfusion, versus more subjective methods. Measuring serial blood lactate concentrations can be clinically useful in any disease state that causes hypoperfusion, including hypovolemic shock, septic shock, cardiogenic shock and gastric-dilitation volvulus."

Fortunately, lactate levels can be lowered with aggressive fluid therapy, which restores blood flow to the tissues, returns the cells to aerobic metabolism, and reverses the lactic acidosis. Measuring sequentially declining levels of lactate during shock therapy in these patients has been correlated with an improved prognosis. The ability to measure lactate levels gives us a quantitative assessment of perfusion, versus more subjective methods. Measuring serial blood lactate concentrations can be clinically useful in any disease state that causes hypoperfusion, including hypovolemic shock, septic shock, cardiogenic shock and gastric-dilitation volvulus.

Lactate levels may be elevated in some patients for reasons other than hypoperfusion. For example, severe anemia, very severe hypoxemia, seizures and very heavy exercise can cause excessive lactate production. Certain drugs or toxins, and some diseases, such as diabetes mellitus, liver disease, sepsis and some cancers, also either increase the production of lactate or diminish its elimination. While these patients may benefit from fluid administration, the focus in these situations is on treating the underlying disease.

*Not available in all countries. Check with your distributor or IDEXX representative.

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Meet Michael Williams

Michael has been with IDEXX for two-and-a-half years and is the division vice president and general manager of IDEXX’s instrument business, which covers the IDEXX VetLab® suite of diagnostic instruments. He has always been "nuts about animals," and after considering pursuing a career as a veterinarian, decided to take the science and research route. Michael has a PhD in biochemistry from the University of Oxford and was a research associate at the Oxford Center for Molecular Sciences before completing four years of post-doctoral work with the Scripps Research Institute in San Diego. Prior to joining IDEXX, Michael worked with several major healthcare companies in the U.S., Europe and Japan.

Michael was drawn to IDEXX by the opportunity to have a global impact on animal health. He notes (in his wonderful British accent), "There is a recognition in the veterinary community of the importance of diagnostic testing for animals. They can’t tell us how they’re feeling, so anything we can do to enhance diagnostics—giving us the information we need to help them—is a good thing."

Michael and his wife have two horses—Phebe, a four-year-old thoroughbred, and Macy Grey, an eight-year-old paint-quarter horse mix—and a golden retriever aptly named Merlin due to his many disappearing acts.

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did you know? by Michelle Kahn, MS, DVM

Lactate Basics
Have you ever worked out and felt sore the next day? Chances are, you’ve experienced lactic acidosis at some point. While lactic acid is the end-product of both aerobic and anaerobic glucose metabolism, clinically significant levels are due to excessive anaerobic glycolysis. Lactate levels are usually increased because of hypoxia or hypoperfusion. Moreover, the degree of increase can help assess the degree of tissue hypoxia and hypoperfusion for the patient, and serves as an important prognostic indicator since persistently high lactate levels are often associated with poor prognoses.

Hyperlactatemia is not uncommon, so why don’t we test for it more often? Well, we need a test that is available in-house since it is usually most necessary in emergency and critical care situations, and that is highly accurate because it is used to help assess prognoses. And since serial lactate measurements are more valuable than a single lactate level, the test must be available individually for cost-effective serial monitoring. These were the reasons most commonly cited by IDEXX customers who requested that we include a lactate test in the VetTest® analyzer’s menu.

And now that lactate will soon be available for the VetTest analyzer, we will be better able to assess the large number of common disorders that cause hyperlactatemia in the dog and cat.

Lactate is not just for emergency clinics—it’s a valuable test in all critical and injured patients, and every veterinarian unfortunately sees too many of these patients. The following is a list of potential causes of hyperlactatemia where the measurement of lactate would be particularly beneficial:

• Shock (hypovolemic, cardiogenic and septic)
• Cardiovascular insult
• GDV (gastric dilatation/volvulus)
• Hit by car
• Ischemia of the spleen
• Diabetes mellitus
• Aortic thromboembolism
• Cancer
• Primary hypoxemia
• Sepsis
• Severe anemia
• Asthma
• Excessive muscular activity, especially seizures
• Adverse drug reactions
• Carbon monoxide poisoning
• Potential toxin exposure

To contact Dr. Kahn, e-mail
Didyouknow@idexx.com.

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frequently asked questions
"What steps are necessary to ensure optimum performance of my IDEXX VetLyte® Electrolyte Analyzer?"

Answer: The following schedule will keep your VetLyte analyzer running smoothly and prevent any unexpected downtime. Your VetLyte operator's guide provides you with full instructions for each step, but here's a quick review to ensure that your VetLyte analyzer is receiving the proper preventive care.

After Each Sample Run

• Wipe the sample probe using a lint-free wipe.

• Run the electrode conditioning solution to prepare the sodium electrode to react properly with your samples.

• Pick a day of the week to run your cleaning solution to guarantee a balanced reaction with your sample. This step will strip away extra protein that has built up over the week from all of the electrodes and the sample sensor.

• Clean the reference housing and its aperture to keep them free from build-up.
• Run the VetTrol™ quality-control fluid once a month to verify your VetLyte analyzer's performance. This is the same quality-control material used for the IDEXX VetTest Chemistry Analyzer.

• Replace the peristaltic pump tubing every six months and replace the complete tubing every two years.
• Keep the sample probe and sample fill port clean to keep them free of bacteria and other build-up.

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NEW from IDEXX—A quality-control (QC) panel for the VetTest® analyzer

This fall, quality-control testing will become easier and more cost-effective with the new VetTest® Quality Control Panel. The new QC panel eliminates the need to take slides out of other prepackaged panels or pull single slides from your inventory.

The QC panel will be packaged with four panels per box, giving you a four-month supply of quality-control slides. Each panel will consist of all of the chemistries you need to efficiently perform quality control on your VetTest analyzer.

As part of our ongoing commitment to ensure that you are receiving the most accurate test results, IDEXX recommends that you perform quality control monthly on your VetTest analyzer. It’s easy to forget in your busy practice, however, it is a critical part of maintaining your in-house analyzers. In addition to offering a panel to make quality control easier and more cost-effective, IDEXX has also added a new quality-control reminder to your 8.05 software. Please refer to the VetTest feature guide for details. (1.3 MB)

It's easy to run QC on your VetTest analyzer:

1. Prepare your VetTrol Control following the instructions on the VetTrol package insert.
2. Remove one QC panel from your freezer and allow it to warm for 10 minutes.
3. At the VetTest main menu, press 1 for "New Sample."
4. Press 6 for "Controls."
5. Select the applicable lot number for the VetTrol Control you are running.
6. Load the six QC panel slides into the VetTest analyzer.
7. Run the VetTrol Control as if you were running a patient sample.

It is important to use all six slides included in the QC panel to ensure optimal performance of each of the six VetTest internal lamps.

For more information on the availability of the QC panel and other IDEXX VetLab® products, call IDEXX at 1-800-355-2896, or register for the IDEXX Diagnostic Edge online newsletter at www.idexx.com/diagnosticedge.

*Not available in all countries. Check with your distributor or IDEXX representative.

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Our world-class customer support is now available 24 hours a day, 7 days a week.

IDEXX is pleased to announce that we have extended our overnight customer support service for in-house diagnostic products. Now you can speak with, or receive a callback from, one of our customer support specialists around the clock. For more detailed information, visit idexx.com/customersupport.

Toll-free: 1-800-248-2483

Fax: 1-800-248-3010

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