GI emergency patients (Proceedings)
Gastric dilation volvulus
Commonly affecting the large breed deep chested breeds gastric dilatation and volvulus syndrome has the potential to be a life threatening problem. Progressive gastric distension leads to pressure on the vascular system especially the venous system compromising venous return to the heart thus leading to inadequate preload and shock secondary to inadequate stroke volume. Pressure on the diaphragm caused by a progressively dilating stomach may compromise lung expansion and lead to ventilatory compromise. Vascular compromise of the circulation to the stomach itself may lead to tissue ischemia, release of endotoxins into the circulation and ultimately to the release of cytokines and SIRS.
CausesThere are many inciting events that can "cause" GDV. GDV is often associated with a disease processes that involves ilius, anxiety, anatomy of a large deep chest, and age enough to see the suspensory apparatus of the stomach be "streched " out. Most animals that have a GDV are middle aged (6year or greater). The disease of GDV was first described in humans.
Diagnosis is commonly made by observing a dog that is restless, attempting to retch nonproductively and perhaps has rapid abdominal distension. Due to the fact that the GDV mainly occurs in the deep chested dog the abdominal distension may not be evident until late in the disease. In early cases the gas distended stomach may be detectable on percussion of the cranial abdomen. On examination the dog may be in hyperdynamic shock or may be in a stage of decompensatory shock. As such findings are variable from tachycardia, tachypnea, bounding pules and injected mucous membranes to collapse, respiratory distress, weak thready pulses.
Immediate treatment should consist of oxygen if the dog is showing any signs of shock, and volume replacement with crystalloids and synthetic colloids started. Recent studies point to the value of hypertonic saline mixed with a colloid and given at 5 –7 ml/kg as a bolus and then reassessing. Hetastarch or Oxyglobin should be considered to maintain BP and flow. ECG should be monitored, as these dog are prone to ventricular arrhythmias. The stomach should only be decompressed after volume replacement has been started due to the potential for worsening the hypovolemic shock. Rapid onset corticosteroids are usually given at shock doses (dexamethesone sodiuum phosphate at 48 mg/kg iv or methylprednisolone sodium succinate at 1530 mg/kg iv) and broad spectrum antibiotics started. However there is NO good controlled randomized blind study of a significant number of patients that has been done to conclude that steroids of any kind make a significant difference in survival.
A right lateral radiograph should be taken. On occasion the volvulus will not be evident on the right lateral in which case if there is a high index of suspicion a left lateral radiograph should taken. A characteristic shelf sign with compartmentalization supports a diagnosis of a gastric volvulus. Barium placed by an NG tube may have to be administered to define the location of the stomach. Coagulation should be monitored as these patients are at risk for DIC. Blood pressure should be monitored.
The dog ideally is taken to surgery as rapidly as possible for derotation and a gastropexy. Gastric lavage can be performed prior to, or during surgery; however it should be remembered a stomach tube can bepassed on a twisted stomach. It is also possible to pass a stomach tube through the wall of an ischemic stomach and excessive force should not be used. Following gastric repositioning an incisional gastropexy is accomplished. A nasogastric tube is inserted to prevent re-dilation postoperatively. In cases that have much food material in the stomach the stomach is massaged and the food removed via a large orogastric stomach tube in which water is added to dilute the food material. In cases that have very thick or very large amounts of food material including "chuncks" the stomach is opened and all the food material is dumped out and into a basin. The stomach is closed routinely with two continuous closure patterns. An inverting pattern on the second closure can also be used and is recommended if peritonitis is also present or the stomach had previously ruptured. This is a "serosal patch" and helps prevent leakage of the gastric incision line.