Monthly Update
Issue Contributors: Shana O'Marra, DVM, DACVECC             
Editor: William B. Henry DVM, DACVS  
February 2014

Using Lactate as an Endpoint of Shock Resuscitation 

Shana O'Marra, DVM, DACVECC


When treating shock, many practitioners use traditional markers such as blood pressure to determine if a patient is in shock. While a low blood pressure is certainly a good indicator that your patient is experiencing shock, hypotension only occurs when compensatory mechanisms fail. Looking for earlier indicators of shock such as an elevation in blood lactate help us to not only identify shock sooner, but to make sure we are actually resolving shock with our treatment rather than simply reverting back to a compensated state.

Lactate is an easy to measure value that gives us a lot of information about what is happening at the cellular level. Lactate is produced during anaerobic metabolism in order to provide cells with ATP as an energy source. Anaerobic metabolism occurs when there is not enough oxygen for the mitochondria to participate in aerobic metabolism. In a healthy patient, lactate is produced by the mitochondria during periods of intense exercise when the enormous energy needs of the muscle outpace the rate of oxygen delivery. This excess lactate is rapidly cleared by the liver and kidneys. In a patient in shock, the amount of oxygen that is delivered to cells is so low that anaerobic metabolism is necessary to produce the energy needed for those cells to survive.

Long before hypotension occurs, lactate levels in the blood begin to rise as cells are starved of oxygen. This makes lactate a great tool for identifying the early stages of shock. Once shock has occurred, a normalization of the blood lactate level is an indicator that shock has completely resolved. Resolution of hyperlactatemia is a powerful predictor of survival in human patients with shock, and has been shown to predict survival from GDV in our canine patients. Many patients will have an elevated lactate even after their blood pressure has come back up into the normal range. This is a sign that these patients are still suffering from shock and need further resuscitative efforts.

Measuring lactate in your practice is easy! A hand-held lactatometer like the Nova Lactate Plus (Figure 1) retails for about $300 and will pay for itself many times over. The handheldlactatometers function just like glucometers, with individual test strips that require only a drop of blood. This makes it easy on your technical staff and easy on your patients. 


When interpreting your lactate value, it is important to remember that excess lactate can be produced after heavy exercise such as struggle during restraint, seizures or muscle tremors. There are also instances of type B lactic acidosis, where lactate is produced inappropriately from aberrant metabolism or decreased clearance. These disorders are very rare but should be considered in patients with persistently elevated lactate levels. The vast majority of patients with a high lactate are suffering from inadequate oxygen delivery.

Early goal-directed therapy (EGDT) is a strategy of rapidly achieving goal lactate, blood pressure and central venous oxygen saturation that is associated with increased survival in humans. Although measuring central venous oxygen saturation may be out of reach for manygeneral practitioners, blood pressure and lactate are easily measured. One example of early goal-directed therapy in veterinary medicine is the RECOVER CPR post-cardiac arrest hemodynamic optimization flow chart. This chart gives instructions based on mean arterial blood pressure, central venous pressure and central venous oxygen saturation (click here to see Figure 2). While this chart requires a central line to measure central venous blood pressure and central venous oxygen saturation, general practices can use a similar strategy to achieve end goals of a normal mean arterial pressure, CRT and lactate. Using lactate will allow you to intervene before your patients develop overt hypotension and subsequent organ damage. If you do not have the capability to measure lactate, you can substitute endpoints of normalizing HR, blood pressure and capillary refill time (CRT). The important thing is to reassess your patient and continue intervening until you have reached your goals. Implementing goal-directed therapy requires nothing more than a shift in mindset.

So what does this look like in real life? When you start to treat shock, you will choose an intervention (eg: IV fluids in hypovolemic shock), then immediately reassess your endpoints (blood pressure, mucous membrane color and CRT, lactate) and repeat as needed until you achieve those endpoints. Once you have reached your endpoints of resuscitation, you can transition to a longer term plan for support that does not require constant reassessment. If you fail to reach your endpoints you may need to consider a different strategy such as pressors for patients that are no longer volume-responsive, or an inotrope for a patient with systolic cardiacfailure. These are patients that will require ongoing intensive care and may need to be transferred to a specialty facility.    
Tech Tip
This article provides objective data for a more selective IM injection site of Dexdomitor. We use a lot of dexmedetomidine (Dexdomitor) for our out patient radiographs. When reversed with antisedan the dog recovers quickly. We have found, subjectively, that when the Antisedan is injected it must be directly into muscle. We found the Triceps muscle to be ideal because there are no major nerves caudally and minimal subcutaneous fat. Grasping the muscle between your thumb and fore finger cranially pushing/pinching the triceps caudally provided a good IM target. 
Now, based on this paper in the JAVMA we will instruct or Techs to grasp the thigh muscle cranially, as they do with the Triceps muscle, and inject cranially (not laterally because of the sciatic nerve) into the Semitendenosis / Semimembranosis  muscles. We used to inject the lumbar muscles and found in obese dogs the onset sometimes was very slow because it was entering fat or fascia and not vascular muscle.  

Journal of the American Veterinary Medical Association 
December 1, 2013, Vol. 243, No. 11, Pages 1569-1572 
doi: 10.2460/javma.243.11.1569

Onset and quality of sedation after intramuscular administration of dexmedetomidine and hydromorphone in various muscle groups in dogs 
Jennifer E. Carter, DVM, DACVAA; Crace Lewis; Thierry Beths, DVM, PhD 
Department of Clinical Sciences, School of Veterinary Medicine, Ross University, Basseterre, Saint Kitts, West Indies. (Carter, Lewis, Beths) 
Drs. Carter and Beths' present address is Faculty of Veterinary Science, University of Melbourne, Werribee, VIC 3030, Australia. 
Supported by an internal research grant from Ross University School of Veterinary Medicine. 
The authors thank Crispin Worrell and Shakima Connor for contributions to the study. 
Address correspondence to Dr. Carter: 
Objective -To compare onset time and quality of sedation achieved by IM injection of hydromorphone and dexmedetomidine into either the semimembranosus, cervical, gluteal, or lumbar muscle groups in dogs. 
Design - Prospective, randomized, crossover study. 
Animals - 7 dogs. 
Procedures - Each dog was assigned to receive each treatment in random order, and at least 1 week elapsed between treatments. Dogs were sedated with dexmedetomidine and hydromorphone combined and injected IM into the assigned muscle group. An observer unaware of group assignments assessed physiologic variables every 5 minutes for 30 minutes, and a videographic recording was obtained. Recordings were evaluated by 16 individuals who were unaware of group assignments; these reviewers assessed time to onset of sedation and assigned a sedation score to each dog every 5 minutes. 
Results - Resting pulse and respiratory rates did not differ among injection site groups. The semimembranosus site had a significantly higher sedation score than all other sites, and the cervical site had a significantly higher sedation score than the lumbar and gluteal sites. The semimembranosus and cervical sites had significantly shorter time to onset of sedation than did the gluteal and lumbar sites. 
Conclusions and Clinical Relevance - When the combination of dexmedetomidine and hydromorphone was used to induce sedation in dogs, rapid and profound sedation was achieved with IM injection into the semimembranosus muscle.

In This Issue
Using Lactate as an Endpoint of Shock Resuscitation
Tech Tip
CT Scan Diagnostics
Business Tip
Continuing Education
Wellness Practice Educational Tips
Previous Tech Tips
Newsletter Archive
CT Scan Diagnostic 

CCVS CT Scan Hours: 


8:00 AM-6:00PM 7 days a week.  1-800-457-4900  

The breakdown of CT charges are as follows:

1. CT Scan, In patient $905.00 (case already hospitalized at CCVS or referred to CCVS for work up and treatment and has a CT scan)  
2. CT Scan, Additional image (if you add an additional scan site $300.00)  
3. CT Scan, Out patient $985.00 **(case sent to CCVS exclusively for a CT; this includes charges for doctor overseeing case, IV catheter, and fluids post CT).  
4. CT "Met Check" $590.00  
5. CT STAT fee, $50.00 (on top of whatever you are doing). 

These charges cover the CT, the contrast, radiologists read, rapid infuser, sevo anesthesia, and technician fee if we need to call someone in for the CT. It does not cover injectable drugs, if needed for IV anesthesia; estimated additional cost $50.00-$75.00. 



This month's CT Scan Diagnostics demonstrates the superior value of the CT alone or combination of myelogram/CT diagnostic value over radiography or myelography alone, in pre-operative diagnosis of lumbo-sacral disease ie. degenerative lumbosacral stenosis. One realizes how un-prepared we were in the past, when using radiographs or myelograms alone, for diagnostics or pre-operative preparation. Pre-operative CT/myelograms have become standard of care in veterinary neurosurgery. They are very quick scans (5 minutes), very diagnostic, and much less expensive than high field (1.5 Tesla) MRI scans. There are very few high field MRI units ie. high quality imagery, very fast scan (25-30 minutes), in veterinary medicine, because of their initial cost and annual maintenance cost. 




Business Tip

We joined Veterinary Purchasing Group (VPG) three years ago when they began their business. It is owned by a veterinary colleague, Dr. Scott Crawford. They now have 330 hospitals across the USA and growing rapidly. They save us THOUSANDS OF DOLLARS EVERY MONTH!!

IT IS SIMPLE MATH..... If you have a net profit of 10% and you can save $1000.00 you would have to earn $10,000 gross dollars to net a $1000.00. 





Continuing Education Opportunies

All our lectures provide 2 hours of Continuing Education Credits. You can register online through our websites, Boston Veterinary Specialists and

Cape Cod Veterinary Specialists. A meal is provided during each lecture. Your technicians are welcome as well.  
Tuesday, March 25, 2014: 
Dr. Karie Walton

Tuesday, April 29, 2014:
Dr. Virginia Sinnott, "Antibiotics: The Brave New World"

Tuesday, May 20, 2014: 
Dr. Daniel Beaver, "Surgery on the Head"

Wellness Practice Newsletters
Editors note:
Dr. Beverly Mason, Medical Director for our two general practices, writes a monthly newsletter that is emailed to our clients and printed for a handout to clients coming into the practices. They have been copied, pasted and passed around on the Internet. They are very concise, informative, and seasonally appropriate topics. Our general practice technicians find them helpful to educate their clients in the office and the email version gets very positive feedback on our Facebook and Yelp  accounts. We thought you might like to use them in your own practices and will provide them to you each month.      
This Month's Wellness Practice Newsletter: 
Previous Tech Tips 

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