Electrochemistry Provides Insight Into Gastric Dilatation-Volvulus

January 13, 2018
JoAnna Pendergrass, DVM

Dr. Pendergrass received her DVM degree from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory Universitys Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner ofJPen Communications, a medical communications company.

Cyclic voltammetry, an electrochemical technique, can measure oxidative stress and predict survival in dogs with GDV.

Canine gastric dilatation-volvulus (GDV) is rapidly progressive and causes life-threatening hemodynamic and breathing disruptions. Surgical treatment for GDV—gastric decompression and repositioning—allows for hypoxic tissue reperfusion, which subsequently causes ischemic reperfusion injury (IRI) and reactive oxygen species (ROS) production. ROS production leads to such GDV complications as systemic inflammatory response syndrome (SIRS).

GDV has a relatively high mortality rate, necessitating a multipronged therapeutic approach that includes prevention and treatment of IRI and oxidative stress, according to authors of a recent study on GDV.

Previous studies have reported lidocaine’s ability to decrease IRI and SIRS and improve clinical outcome by reducing inflammation and oxidative stress. To date, though, “direct measurement of inflammatory mediators, antioxidants, or indicators of oxidative stress has not been thoroughly evaluated,” wrote the authors.

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Cyclic voltammetry (CV) can quantify a substance’s total reducing power (TRP), an indication of antioxidant activity. The current study’s authors sought to evaluate TRP in dogs with GDV and determine how well lidocaine improves TRP capacity.

Analyses

The investigators recruited 30 adult dogs diagnosed with GDV at the Hebrew University Veterinary Teaching Hospital’s emergency service and divided them into 2 groups:

  • Treatment: IV lidocaine followed by lidocaine constant-rate infusion (CRI)
  • Placebo: IV saline followed by saline CRI

Dogs received immediate treatment according to group classification, crystalloid or colloid administration as needed, and surgical treatment. Eleven healthy dogs were recruited as controls.

Blood samples were collected from each dog to evaluate CBC, lactate levels, and oxidative status. Using CV to assess oxidative status, the investigators placed 3 electrodes in a well with heparinized plasma and applied a constant electric potential. Several CV parameters were measured:

  • Ep: indicates types of low-molecular-weight antioxidants (LMWA)
  • Ah: indicates LMWA concentrations

Results

The 30 dogs with GDV were hospitalized for a median of 24 hours. Four of these dogs did not survive (mortality rate, 13%); their deaths occurred naturally after surgery. Lactate levels were higher among nonsurvivors than survivors. Gastric wall necrosis (GWN) was present in 5 dogs with GDV and significantly increased GDV mortality risk.

Overall, median Ep was similar between dogs with GDV and healthy dogs. However, among dogs with GDV at presentation, Ep was significantly higher among nonsurvivors than survivors, possibly because nonsurvivors had greater oxidative stress and subsequently fewer potent antioxidants, which have lower Eps. Ep was determined to be a strong predictor of survival.

At presentation, median Ah was similar between dogs with GDV and healthy dogs. After 24 hours, Ah significantly decreased in dogs with GDV, indicating disease progression and decreased antioxidant concentration. This decrease was greatest in dogs treated with saline, suggesting that lidocaine can maintain higher antioxidant concentrations.

Ah and lactate levels were positively correlated, potentially indicating recruitment of antioxidants to combat oxidative stress. Notably, Ah levels were highest in dogs with GWN, suggesting that necrosis increases oxidative stress and the subsequent need for antioxidants.

Bringing it Together

The investigators concluded that CV can effectively measure oxidative stress in dogs with GDV and predict survival. In addition, lidocaine’s demonstrated ability to counteract oxidative stress supports its inclusion in GDV treatment. The authors emphasized that larger-scale studies are needed to further investigate the diagnostic usefulness of CV in veterinary medicine and explore the role of oxidative stress in other diseases.

Dr. JoAnna Pendergrass received her Doctor of Veterinary Medicine degree from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, a medical communications company.