Successful stabilization of the patient with gastric dilatation-volvulus (Proceedings)
Background information, risk factors, and pathophysiology
Gastric dilatation and volvulus syndrome (GDV) is a life-threatening condition primarily affecting large breed dogs. Distension and rotation of the stomach leads to compromised gastric perfusion and obstruction of the caudal vena cava. Sequestration of blood in the splanchic and skeletal muscle beds as well as hemorrhage from torn gastric vessels leads to a state of hypovolemic shock. Without aggressive medical and surgical intervention, the condition is generally fatal. GDV is a very common condition affecting approximately 60,000 dogs per year in the US with mortality rates ranging from 10-60% (overall mortality is much closer to the 10% range).1 Much research interest has focused on identification of risk factors for GDV such that prophylactic measures may be instituted to try to prevent the occurrence of the problem. Presently, the following factors have been identified:
Overall, risk of developing GDV is likely a result of a complex interplay between age, genetic, conformational, environmental, and behavioral factors.Initial stabilization
Initial stabilization of the dog presenting with suspected GDV should focus on the treatment of hypovolemic shock (decreased oxygen delivery to the tissues due to inadequate circulating volume). Oxygen therapy should be administered initially by mask or flow-by techniques while venous access (14-18g) is acquired via the cephalic veins. Hind-limb catheters should be avoided due to the decreased venous return from the caudal vena cava seen in dogs with GDV. From the catheter, a PCV / TS / Blood Glucose / Venous Blood Gas (Emergency Database) should be collected. If possible, an entire CBC and Serum Biochemical Profile should be drawn prior to fluid therapy. Baseline physiologic data in addition to those gained through major body systems assessment should be collected. These include blood pressure, ECG, and pulse oximetry reading (SpO2).
Assuming that there is no contraindication to aggressive fluid support, (such as history of cardiomyopathy) volume resuscitation should commence with isotonic crystalloid solutions (LRS, Normosol-R, Saline). A shock rate of fluids (90 ml/kg/hr) should be calculated and then administered to effect. The authors prefer administer shock rates of fluids in increments of approximately ¼ of the calculated dose, reassessing major body systems after each bolus. It is important to remember that the endpoint of fluid therapy should be the normalization of vital signs, not the administration of some arbitrary volume. Some dogs may not need the entire 90ml/Kg, while others will need significantly more.
When rapid or small-volume resuscitation is needed, colloids and/or hypertonic saline may be considered. Colloids have the advantage of being retained in the vascular space for longer than crystalloids, allowing for smaller administered volumes. Hetastarch, a synthetic colloid, may be administered for this purpose at a dose of 10-20 ml/kg. Alternately, the following technique may be utilized. In a 60ml syringe, draw up 43ml of synthetic colloid and 17ml of 23% hypertonic saline. Administer at a dose of 5ml/Kg no faster than 1ml/Kg/min. This resuscitation option has the main advantage of speed. The osmotic effect of the hypertonic saline and the oncotic effect of the synthetic colloid will restore intravascular volume extremely rapidly. Additional crystalloid fluids may then be continued as needed.
Gastric decompression should be considered once volume resuscitation is underway. The authors prefer a combination of trocharization and orogastric intubation. Trocharization is performed using an 18g needle or 16-18g over-the-needle intravenous catheter placed transabdominally into the stomach. Anatomically in GDV, the fundus will most often be located on the right side. Palpation for gas distention, will help identify the optimal location for trochar placement. It is important to avoid the often-distended spleen while placing the trochar catheter. Trocharization has the advantage of being quick and easy to perform with minimal risks. It is not stressful and does not require sedation. Disadvantages of trocharization are the risk of puncturing another abdominal structure of importance (spleen), and inability to evacuate liquid and food material from the stomach.
Orogastric intubation is indicated once the patient is more stable. Orogastric intubation has the advantages of being able to completely decompress the stomach and to lavage out any food material within. The primary disadvantages of this technique are the high degree of stress associated with orogastric intubation (often requiring sedation) and the risk of esophageal or gastric injury. During lavage, aspiration pneumonia is a significant risk. Orogastric intubation should be performed using a tube appropriate for the size of the patient, well-lubricated, and measured from the mouth to the last rib. A piece of tape as a marker will ensure that the tube is not advanced too far into the patient. A mouth gag is required (2-3inch PVC tubing works well) to prevent trauma to your orogastric tube. Once the stomach is entered and the gas decompressed, lavage of the stomach with warm water is indicated. For patient safety, the authors prefer to endotracheally intubate the patient if gastric lavage is to be performed. This makes sense logistically as well, since the patient will be proceeding directly to surgery following decompression.
A dose of broad spectrum antibiotics is indicated early in the course of therapy and should be continues through surgical intervention and beyond if specific indications exist.