Read the German translation: Intraoperative Entscheidungen beim Hund mit Magendrehung

Read the French translation: Décisions Intra-Opératoires Lors d'une Torsion d'Estomac chez le Chien

Surgical Preparation of Abdomen, Ventral Thorax, and Inguinal Area

Standard clipping and aseptic preparation of the abdomen from cranial to the xyphoid to caudal to the pubis should be performed. Assuming that clipping does not injuriously prolong anaesthesia time it is best to clip and prep a liberal field. A wide clip will be appreciated if during surgery it is decided to place a jejunostomy tube. Clipping around the genitalia and anus will allow easier care of soiling due to loose stools and leaky urine which are sometimes encountered in animals after GDV surgery.

During preparation proper patient positioning is important. In fact, improper positioning can occasionally be life threatening. Standard positioning is dorsal recumbency with the limbs extended; however, this positioning will increase compression of the vena cava and decrease venous return and resultant drop in cardiac output. Therefore, for unstable patients standard positioning should be abandoned. These patients can be positioned obliquely to minimise pressure on the vena cava. Patients are returned to dorsal recumbency immediately prior to surgery. Prompt entry into the abdomen is warranted in such cases so that the vena cava can be decompressed.

Anesthetic Induction, Intubation, and Assisted/Controlled Ventilation is Initiated. Intraoperative Monitoring to Include ECG, Blood Pressure, End-Tidal CO₂, Pulse Oximetry, Arterial Gases and PCV/TS

Rapid intravenous anesthetic induction is performed so that immediate control of the airway can be taken. Numerous anaesthetic protocols have been described for dogs with GDV. The lowest amount of cardiovascular depressant drugs should be used.

The following is a protocol adapted from the Section of Anesthesia of the Vetsuisse Faculty in Bern (Courtesy of Dr. Shannon Axiak and Dr Helen Rohrbach)

Appropriate intraoperative monitoring includes constant ECG for arrhythmia monitoring. Blood pressure monitoring is important, especially when the stomach is decompressed completely, and the pressure on the central vein is released. A sudden decrease in preload can produce acute hypotension. In addition, many anesthetic agents augment hypotension (iso-, sevoflurane) or potentiate arrhythmias (halothane). End-tidal CO₂ helps monitor for adequate ventilation. Pulse oximetry monitors trends of change in hemoglobin oxygen saturation.

Arterial blood gas analysis confirms that the instruments are working adequately and allow an assessment of the pH status. PCV/TS are essential in assessing the need for red blood cell and/or plasma transfusions, especially in the actively hemorrhaging patient. A PCV<25% (hemoglobin<8 g/dL) indicates the need for red cells/hemoglobin to provide oxygen carrying capabilities, and a TS<3.5 g/dL indicates a need for plasma to provide albumin and other proteins.

Surgical Approach to the Abdomen, Followed by Decompression and Derotation

A long incision is performed from the xyphoid past the umbilicus. The abdominal cavity is entered with extreme caution not to damage the underlying stomach. The first thing that a surgeon encounters in a GDV surgery after opening of the linea alba normally is the dilated stomach covered by omentum. Most of the time the stomach is so dilated that other organ structures are not visible. First the stomach needs to be decompressed and derotated. Assessment of perfusion and viability of tissue is the next step followed by a gastropexy and a thorough abdominal exploration.

Do not try to derotate a dilated stomach. The risk of vascular disruption, especially from the spleen is too high. Once the abdomen is open a 20G needle attached to a suction system is introduced in the stomach in an area without large vessels. Dilation can be reduced by suctioning to an amount that allows derotation or orogastric tube placement to continue evacuation of stomach contents.

The stomach once less dilated is derotated as follows. The surgeon standing on the right side of the animal pushes with the fist of the left hand the fundus in a dorsal (towards the surgical table) direction and pulls the pylorus from the left ventral side towards the midline and right side with his right hand. Using this approach it is almost never necessary to perform a gastrotomy to remove gastric contents before derotation. In the authors experience a gastrotomy will only be necessary if impacted hard stomach contents are present.

Hemostasis, Final Decompression, Evaluation and Repair of Gastric Wall Integrity

Visualization of a potential seriously bleeding vessel is the next step. Decompression of the stomach is necessary in order to evaluate the fundus and the splenic vessel for vascular tears. If a tear is visualised then the vessel should be immediately ligated. In case of a splenic tear it might be necessary to perform a partial or total splenectomy. We see in our hospital increased postoperative complications with partial splenectomies compared to total splenectomies and tend therefore to perform total splenectomise if necessary.

Control of gastric integrity is the next step in GDV surgery. Perforations need to be controlled soon after derotation to minimize gastric spillage. Perforations are most commonly located in the fundus region, which has to be visualised even before total decompression has been achieved. Gastric perforations in GDV dogs are most of the time a consequence of poor gastric blood flow. After derotation and decompression the gastric wall will change its colour to a more normal pink to hyperaemic red. Some areas however might stay grey or black indicating permanent damage to the gastric wall. We prefer to wait a certain time (15-20 min) in surgery before the perforation is closed by partial gastric wall resection and suture. During this time the gastric wall in the region of the perforation might potentially normalize in color and structure which might help to better define the line of gastric resection in healthy actively bleeding tissue.

After derotation and the control of serious bleeding and gastric wall perforations the stomach should be decompressed and emptied. A large orogastric tube is used. It is not necessary to empty the stomach totally. The tube can be connected to the surgical suction unit to evacuate gastric content. This manoeuvre is not without a certain risk. The tube has to be held by the surgeon in the middle of the stomach lumen to avoid sucking in stomach wall. Immediate disconnection of the suction unit is necessary if this happens. To remove "impacted" material it can be helpful to pass tap water into the stomach through the tube and to knead by hand the contents into smaller pieces. Sometimes it is not possible to evacuate the majority of the stomach contents and it might be necessary to perform a gastrotomy. The line of incision should be in a healthy part of the stomach. Spillage of gastric contents should be minimized by using gastric stay sutures and packing of the abdominal cavity with abdominal towels or sponges. Gastric wall is closed in two layers with absorbable suture material (i.e., 3.0 polydioxanon, PDS). The first layer includes submucosa and muscularis using a continuous appositional pattern and the second layer should include the submucosa, the muscularis and the serosa using an inverting pattern.

Gastrotomy should be avoided whenever possible. In addition to the risk of spillage, healing may be delayed increasing the possibility of suture line leakage.

Viability of the stomach wall can be theoretically assessed by pulse oximetry, Doppler blood flow measurements and fluorescin dye evaluation. These tests are only assessing vascularity and not mucosal integrity. During surgery the visual inspection and palpation of the stomach wall are still standard and used to decide if resection of parts of the stomach is indicated. Serosal color can be black, blue, grey or brick red. Usually if the serosal colour stays dark after derotation and decompression a resection of this area should be envisaged. If small cuts into the muscularis of these regions do not bleed, then resection should be definitively performed. Vascular patency and gastric wall thickness are other criteria used frequently. The mucosal color should not be used as an indication for resection. In GDV patients it is not uncommon to see black gastric mucosa. Mucosal haemorrhage or vascular obstruction are not correlated with survival of gastric tissue however they predispose to gastric ulceration.

Once viability of a region is questioned and gastric resection becomes an option, the surgeon needs to decide if the affected region can be resected easily. The fundus region is usually the affected area in GDV patients. This region can be easily resected by ligating the vessels from the gastroepiploic artery and the short gastric vessels as needed. Resection is performed in viable bleeding areas and a two-layer closure is performed. Alternatively a stapling device can be used to resect the stomach part. If the necrotized area includes parts of the cardia, the pylorus or is so large that the lesser curvature is compromised, then resection becomes more than a challenge. Prognosis in our hands is very poor in such a situation and the euthanasia option is suggested to the owner.

The spleen is often engorged with blood in GDV patients. Thrombosis of the splenic vessels and vessel avulsions resulting in splenic necrosis require splenectomy. In most GDV patients however the spleen is viable. Splenic torsion has been described together with GDV but is rarely encountered. Derotation of the splenic pedicle should not be attempted in case of already present splenic necrosis but splenectomy should be performed directly.

Abdominal Inspection and Gastropexy

After the assessment of viability a routine inspection of the abdominal cavity should be performed followed by a gastropexy procedure. There are multiple different techniques that can be used to produce a permanent adhesion between the stomach and the abdominal wall. Recently several minimally invasive techniques have been described in the surgical literature. These techniques are only indicated as elective procedures to prevent GDV. During classical GDV surgery one of the easiest and quickest procedures is the incisional gastropexy of the gastric antrum to the right ventrolateral abdominal wall. A 5 cm long incision is made through the gastric serosa into the muscularis over the parietal surface of the pyloric antrum equidistant from the attachments of the greater and lesser omenta. The incision should not be in the pylorus itself. A second incision is made in the peritoneum and internal fascia of the rectus abdominus muscle or transversus abdominus muscle adjacent to the incision of the pyloric antrum. The edges of the incision in the abdominal wall are then sutured to the edges of the gastric incision using a Nr 1 polyglactin 910 (Vicryl) in a continuous pattern.

Another option used in our hospital is a gastropexy where the pyloric antrum is included in the cranial 5 cm of the abdominal closure. This technique has been shown to produce permanent adhesions similar to the incisional technique. The potential for gastric perforation could arise with this technique when another laparotomy has to be performed later. Therefore the author uses it only in unstable patients in which surgery time has to be kept to an absolute minimum.

Need of Feeding Tube Placement

It is recommended that a jejunostomy tube be placed if any gastric resection or pancreatic trauma occurs. Placed appropriately, intestinal feeding tubes provide immediate intestinal feeding postoperatively. It allows home care if gastric feeding is not possible once the animal is ready to be discharged. It also reduces the cost of parenteral nutrition because caloric requirements can usually be supplied within a few days. Gastrojejunostomy tubes can be used with the advantage to have a permanent gastropexy, a possibility to evacuate gastric contents and to perform intestinal feeding all at the same time. In the authors experience it is hardly necessary to use tube feeding. If short term nutrition cannot be given by the stomach it is advised to use total parenteral nutrition as an alternative.

Lavage and Suction, Routine Closure

Copious saline lavage and suction of the abdomen is necessary. A routine 3-layer closure is performed and placement of dressing over the incision site and ostomy tube sites.