• Gastric necrosis signals an unfavourable prognosis
Introduction:Patients with GDV are considered critical care cases; every minute of presurgical treatment is vital to a successful outcome. Survival is generally determined by early and appropriate presurgical management; not surgery. Efficient presurgical treatment usually involves a minimum of two people. Gastric decompression and shock therapy should be done simultaneously. If this is not possible; decompression should be performed first. It is stated that gastric decompression is the single most important factor in reversing cardiovascular deficits in patients with GDV.
Decompression:Generally, orogastric intubation can successfully be performed in 80 - 90% of GDV patients. Decompression via flank needle puncture should be attempted in cases difficult to intubate or severly depressed metabolically deranged patients.
Technique: The stomach tube is measured to the last rib and marked with a piece of tape. A stiff foal or mare stomach tube with a smooth tip works best (having several diameter and stiffness tubes is ideal). Apply adequate lubrication to the tube. Place a functional mouth speculum; generally a roll of 2” tape secured in the mouth with tape encircling the muzzle. As the stomach tube is passed, you will generally meet resistance at the esophageal-stomach junction. Pass the tube firmly in a twisting manner to pass the lower esophageal sphincter.
If unsuccessful, place the patient in various positions and attempt to pass the tube (i.e., elevate animal at 45 degree angle with rear feet on floor and forefeet on table, right lateral recumbancy, and left lateral recumbancy). This movement may encourage the stomach to rotate enough to allow tube passage. Be careful not to position the patient in dorsal recumbancy as this will increase abdominal visceral pressure on the caudal vena cava and exacerbate signs of shock.
If still unsuccessful, try different diameter tubes; try a smaller diameter, more flexible tube and proceed as described above.
If still unsuccessful, attempt to remove some of the air in the stomach by placing a l6 or l8 gauge needle at the point of distention in the right flank region. Ping the area to make sure the spleen is not under the proposed trocarization site. After trocar decompression, attempt to pass the stomach tube as described above.
If still unsuccessful, sedate the dog with a narcotic (Oxymorphone .11 to .22 mg/kg IV) and try to pass the tube again. Mild sedation is recommended if the patient strongly resists physical restraint.
Success in passing a stomach tube depends on the skill of the operator and available assistants.
If you are successful at passing a stomach tube, but plan to refer the patient to a referral surgical center for gastropexy, transport the patient with the tube remaining in the stomach (i.e., taped to the mouth) or bring the tube out through a pharyngostomy incision or maintain it as a nasogastric tube.
If a stomach tube was successfully passed, stomach contents should be evaluated for color and presence or absence of necrotic gastric mucosa. This may give an impression of gastric viability.
;Fluids: Shock dosage of polyionic isotonic fluid is carefully administered to expand the vascular compartment. Patients are frequently monitored during fluid administration to help determine ultimate fluid rate and amount. For convenience, lactated Ringer's or Normosol-R is generally used. One or two indwelling cephalic catheters are placed.
Referral: If you are successful at passing a stomach tube, but plan to refer the patient to a referral surgical center for gastropexy, transport the patient with the tube remaining in the stomach (i.e., taped to the mouth) or bring the tube out through a pharyngostomy as described below.
a. Orally palpate the fossa lateral to the hyoid apparatus until a lateral bulge is seen
b. Make a small skin incision over the bulge and press a curved forceps (substitute for finger) through the soft tissues and skin incision.
c. Pull the stomach tube through the incision with curved forceps; then pass the tube over the arytenoid cartilages, down the esophagus, and into the stomach (measure to the 13th rib).
Disadvantages include: heavy sedation or general anesthesia is necessary for placement of tube.
Alternatively a temporary gastrostomy can be performed. The patient is placed in left lateral recumbancy with the right flank area clipped and surgically prepared. Heavy sedation and local infiltration of lidocaine or light general anesthesia is performed. A 4 - 5 cm incision is made in the skin over the point of greatest gastric distention (generally 1 - 2 cm caudal to the 13th rib and 2 - 3 cm distal to the transverse processes of the lumbar vertebrae). A grid technique is used to gain entrance into the peritoneal cavity. Due to severe gastric distention the stomach wall is pressed against the abdominal wall and easily identified through the flank incision. The stomach wall is sutured to the skin using a simple continuous pattern with 3-0 Maxon. This is done prior to incising into the stomach lumen. A #11 BP scalpel blade is used to puncture into the lumen of the stomach. Gas and stomach contents are expelled under pressure so stand back! The gastric mucosa is evaluated for viability. Disadvantages of gastrostomy include: the stomach is sutured in its rotated position and more time is required when definitive surgical treatment is performed due to the necessity of closing the gastrostomy.
Successful stomach tube placement: Once the stomach tube has been passed into the stomach or gastrostomy performed, the stomach is lavaged with warm water. If a stomach tube was successfully passed, the stomach contents should be evaluated for color and presence or absence of necrotic gastric mucosa. This may give an impression of gastric viability.
Surgical Treatment;: Surgical procedures utilized in the treatment of gastric dilatation volvulus can be divided into two categories; 1) immediate decompression and 2) therapeutic gastropexy. Immediate decompression is performed with a successfully passed stomach tube secured to the patient or temporary gastrostomy as described above. Therapeutic or prophylactic gastropexy techniques are described below.
Gastric repositioning: Anatomic repositioning of the stomach is necessary to perform prior to permanent gastropexy. Repositioning occasionally occurs spontaneously at the time of gastric decompression. Knowledge of normal anatomy is necessary to understand how repositioning is performed. In each case the same manoeuvre is performed to derotate the stomach. The pylorus, located near the cardia of the stomach, is grasped by one hand and elevated as the other hand presses down on the fundus and body of the stomach. Reduction is generally easily performed if the stomach has been adequately decompressed. The spleen is generally returned to its normal location once the stomach has been successfully derotated. In patients that are difficult to derotate exteriorizing the spleen may facilitate gastric derotation. Splenectomy is rarely performed but may be necessary if splenic vessels are infarcted. The greater curvature and fundus of the stomach are examined for areas of necrosis. If necrosis is present, the prognosis is unfavorable to grave.
Incisional gastropexy: This technique is based on the construction of a seromuscular antral flap attached to a scarified segment of transversus abdominus muscle. A 2-3 cm incision is made in the antral portion of the stomach. The bleeding surface of the antrum is brought to the right body wall. With the stomach in a normal position, the bleeding antral surface is touched to the peritoneal wall to create a blood mark on the peritoneum. This is the location of the gastropexy. The peritoneum and transverses abdominus muscle are incised creating a mirror image defect of the stomach flap. The stomach flap incisional defect is sutured to the abdominal wall incisional defect with simple continuous or simple interrupted synthetic absorbable suture.
Belt Loop Gastropexy:This technique is based on the construction of a sero-muscular antral flap attached around a segment of transversus abdominus muscle. A horseshoe shaped incision is made in the serosal layer of the antral portion of the stomach with its base at the greater curvature. The sero-muscular portion of the stomach is identified by grasping full thickness antral wall between the thumb and index finger and “slipping” the mucosal and submucosal layers away so only the sero-muscular portion of the wall remains between thumb and finger. The sero-muscular layer is incised with scissors and the horseshoe shaped sero-muscular antral flap is dissected and elevated of the submucosal layer. The stomach is replaced in the abdominal cavity in normal position and the sero-muscular flap lined up with the transversus abdominus muscle. Once this optimal location is discovered, two longitudinal incisions (along the fibers of the transversus m.) are made in the transversus abdominus m. The segment of muscle between the incisions is undermined. The sero-muscular flap from the stomach (i.e., belt) is passed through the transversus abdominus m. (i.e., loop) and sutured to itself to complete the “Belt-Loop” gastropexy. 2-0 or 3-0 monofilament absorbable synthetic suture in a simple interrupted or continuous pattern is used to secure the flap in place. Advantages of belt loop gastropexy include: it is relatively easy to perform alone and in the middle of the night, it can be performed quickly, and it is an effective means of permanent gastropexy.
In most cases 3 to 4 days of intensive monitoring is necessary for the successful management of GDV patients. Postoperative considerations are listed below:
a. Shock is a postoperative possibility and the patient should be monitored and treated accordingly.
b. Patients are generally held off food and water for 24 hours following surgery. During this time maintenance fluids should be supplied using polyionic isotonic crystalloid fluid. Vomiting may occur following surgery; the NPO period should be extended accordingly. Gastritis and gastric motility disorder are common sequelae to GDV.
c. After 24 hours of no vomiting, oral alimentation should begin gradually with
a sequence of ice cubes, water, baby food and finally canned dog food. This should occur over a 2-3 day period.
d. Antibiotics should be continued for 7 - 10 days.
e. Routine surgical complications such as infection, dehiscence, seroma, etc. should be watched for and treated accordingly.
f. EKG monitoring: the most common severe postoperative complication is cardiac arrhythmia. Approximately 75% of GDV patients will develop severe arrhythmia’s in the immediate postoperative period. Arrhythmia’s can be present at the initial time of presentation but most often occur within 24 - 72 hours after surgery. Ventricular premature contractions, progressing to ventricular tachycardia is most common. Etiology is unknown but shock, hypoxia, acid base alterations, endotoxins, myocardial depressant factor (MDF), reperfusion injury, release of free radicals, and hypokalemia have been associated. A total body potassium deficit has been proposed. Etiology of the hypokalemia includes anorexia, vomiting, tremendous outpouring of potassium rich fluids into a dilated stomach, and use of potassium poor fluids in treatment of shock. For this reason, adding 20-30 mEq of potassium chloride per liter of maintenance fluids during and after surgery are recommended.
g. Gastric motility: occasionally GDV patients with develop postoperatove gastric motility abnormalities. Patients with gastric hypomotility or gastric stasis should be treated with a motility modifier (i.e., metaclopramide, erythromycin, etc).