Gastric Dilatation Volvulus
Marianne Alcan, DVM
GDV, or gastric dilatation volvulus, is a commonly seen condition in veterinary emergency medicine. Overall mortality for this condition is variably cited at 20-37%. Euthanasia at time of diagnosis represents a large majority of this patient loss. Thus, thee is significant research aimed at better understanding risk factors for this disease in order to improve our prevention tools.
Accepted risk factors include older age, pure breed, deep-chested conformation, an affected first-degree relative and a nervous temperament. Diet-related risk factors include feeding an exclusively dry food diet, eating one large meal per day and eating quickly.2 A recent study also found that presence of a gastric foreign body is a significant risk factor for developing GDV in at-risk breeds.3 Feeding from an elevated bowl position is no long recommended for prevention and in at least one study was found to be a risk factor for GDV. There are conflicting results in the literature for evaluation of splenectomy as a risk factor.
The most current research is focusing on learning more about gastric motility differences in patients with GDV and the genetic basis for the disease. In 2014, the AKC Canine Health Foundation Bloat Initiative began funding large, long-term studies in these areas to better understand, treat and prevent GDV.
With suspicion from history, signalment and exam, it is important to quickly establish the diagnosis via abdominal radiographs (two-view or often just a right lateral view) and start perioperative supportive care. Even if owners are deliberating how to proceed, it is ideal to start IV fluids (crystalloids +/- colloids) to correct hypovolemia as well as start a full mu agonist analgesic such as hydromorphone, methadone or morphine. Trocharization of the stomach is also important to provide decompression during this initial optimization time. Alternatively, some practitioners prefer to pass an orogastric tube prior to surgery for initial decompression.
Two studies published in 2007 and 2012 by the same research group evaluated lidocaine as a perioperative treatment. The first was a retrospective and did not find benefit to its use. The second paper was prospective and used a protocol of 2mg/kg lidocaine IV at initial treatment then a CRI at 0.05ug/kg/min for 24hrs. This second study found that dogs treated with lidocaine had decreased incidence of arrhythmias and AKI as well as shorter hospitalization times.4 There were several limitations (not blinded or randomized, use of historical controls) to this study, so adoption of a lidocaine protocol is not yet widespread. But further research is warranted.
Lactate was first established in 1999 as a GDV biomarker and prognostic indicator and has continued to be extensively studied. Hyperlactatemia is suspected to occur from many sources due to shock, hypovolemia and potentially also gastric necrosis. The initial study suggested increased mortality with a lactate value > 6.0 mmol/l. Subsequent studies have tested higher and lower thresholds, but the consistent important finding has been to emphasize the change of the lactate over time as the indicator of prognosis rather than focusing on any single value. Specifically, the failure to improve lactate during treatment is associated with worse outcomes. Because research in this area is ongoing, use of lactate in making decisions regarding euthanasia should be cautious in nature.
Minimum data base for a GDV patient after abdominal imaging is typically full bloodwork and three-view thoracic radiographs. The latter is offered due to evaluation of respiratory compromise that is often present with GDV, and as this patient population is older, also serves as a metastasis check. A recent study showed a very small number of these patients actually had pulmonary nodules (4%) or sternal lymphadenopathy (1%). However, 14% of patients were found to have aspiration pneumonia.5 This knowledge then allows for more aggressive antimicrobial care than used in standard GDV treatment and should also allow more informed anesthesia use for these patients. Other expected findings include a small vena cava, microcardia and esophageal dilation.
Once initial resuscitation is under way, immediate surgery to decompress, derotate and perform gastropexy is then indicated. The most common gastropexy procedure is the incisional form attaching the pyloric antrum to the right body wall. Standard postoperative care is performed along with monitoring of heart rate and rhythm due to the risk of cardiac arrhythmias associated with GDV. This monitoring is done most easily with telemetry but can also be done with monitoring for tachycardia and pulse deficits. Other potential postop complications include ileus, persistent hypotension, DIC, peritonitis and multiple organ dysfunction syndrome.
Overall, patients who undergo treatment for GDV have a good outcome with survival rate of 85%.
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