Postoperative assessment and management of complications after Y-shaped gastric bypass surgery

**Postoperative assessment, record management and follow-up after Y-type gastric bypass**

Edward C. Mun, Vivian M. Sanchez, and Daniel B. Jones

Bariatric surgery is a complex procedure, often involving patients with multiple comorbidities, making the surgery high-risk. Detailed postoperative assessment and management can prevent preventable complications, early identification and treatment of postoperative complications can save lives, and establishing patient records and long-term follow-up can prevent complications and monitor surgical outcomes. For these reasons, the American Society for Bariatric Surgery (ASBS) has developed strict guidelines for medical centers performing bariatric surgery, including the following three main requirements: ① The center should have a comprehensive protocol involving a multidisciplinary team of medical professionals, including surgeons, bariatric internists, nurses, psychologists, physical therapists, nutritionists, and other specialists, to collaboratively monitor patients before and after surgery; ② Postoperative medical records should be documented and retained for at least 5 years, with strict follow-up procedures required for at least 50% of patients (those undergoing procedures primarily focused on restricting food intake) and 75% of patients (those undergoing procedures primarily focused on reducing nutrient absorption); ③ New surgeons must evaluate the clinical outcomes of their bariatric surgeries within the first 6 months. Postoperative clinical pathway management protocols may further improve the quality of care while shortening length of stay (LOS) and reducing costs. This chapter will primarily discuss issues related to postoperative assessment and management.

**Postoperative assessment during hospitalization**

Patients with obstructive sleep apnea (OSA) require immediate postoperative nasal continuous positive airway pressure (CPAP) or combined CPAP, which has been shown to reduce the need for tracheotomy. Patients suspected of having severe obstructive sleep apnea should undergo a sleep study preoperatively and be equipped with appropriate devices before surgery so that a properly sized mask is available postoperatively. Although it is positive pressure, CPAP does not increase the probability of postoperative anastomotic leakage. Patients with a history of asthma should receive bronchodilator therapy for an adequate duration during and after surgery to reduce postoperative pulmonary complications, and frequent lung auscultation should begin in the recovery room.

Few patients require a transition to the intensive care unit (ICU) after bariatric surgery, but ICU facilities should be available to monitor such patients. Patients with severe cardiopulmonary abnormalities, such as valvular heart disease, coronary artery disease, and heart failure, may require postoperative electrocardiography and hemodynamic monitoring via a Swan-Ganz catheter. For patients with severe obstructive and restrictive lung disease, retaining the endotracheal tube and delaying extubation may be more beneficial. However, most patients can be safely extubated in the operating room after surgery and require close monitoring of respiratory and hemodynamic parameters, such as vital signs, oxygen saturation, and urine output, in the postoperative recovery room before being transferred to a general ward.

If any signs of acute bleeding or respiratory failure are observed immediately postoperatively, re-exploration or re-intubation is necessary. Closely monitor for signs of hypovolemia by observing blood pressure, heart rate, urine output, and skin capillary refill. If a drainage tube or stoma (such as a gastrostomy) is placed, closely observe the amount and nature of the drainage fluid (bloody or serous). If blood loss is significant, continuously monitor hematocrit. For patients with active bleeding, coagulation function should be checked, and appropriate clotting factors should be administered to control bleeding. Close monitoring of oxygen saturation, respiratory rate, peripheral cyanosis, and respiratory function is required to determine adequacy of spontaneous breathing. If hypoxemia or hypercapnia is suspected, arterial blood gas analysis should be performed. Because many morbidly obese patients already have hypoxia and hypercapnia, recording preoperative values ​​in these high-risk patients can help determine the extent of postoperative respiratory failure.

The administration of morphine or other anesthetics in patient-controlled analgesia (PCA) can begin in the postoperative recovery room. After bariatric surgery, PCA appears to be safer and superior to intramuscular injection (IM) in terms of analgesia and sedation. Using ketorolac as an anesthetic for patients undergoing bariatric surgery can help reduce the incidence of nausea and vomiting and promote rapid recovery from anesthesia postoperatively. Unless specific contraindications exist, ketorolac can be used as an adjunct to PCA to reduce postoperative pain.

Many surgeons remove the nasogastric tube (NGT) early after surgery or even avoid its use altogether. For patients after laparotomy, indwelling NGTs are associated with discomfort, atelectasis, pneumonia, and may increase gastroesophageal reflux. In one study, routine NGT decompression after Y-type gastric bypass (RYGB) did not provide any benefit in preventing postoperative complications. When intestinal obstruction occurs after gastric bypass, NGTs should be avoided as much as possible, as changes in postoperative gastrointestinal anatomy can increase the risk of gastrointestinal perforation and do not effectively achieve adequate gastrointestinal decompression.

Once transferred from the ICU or postoperative recovery room, most patients can be discharged after 2-3 days of observation in the ward. Serious complications can occur during this period, so caution is needed to detect any signs of potential complications as early as possible.

Pulmonary embolism remains the leading cause of death after gastric bypass surgery; therefore, patients should be encouraged to ambulate as early as possible on the evening of surgery. While there is no consensus on perioperative prevention of pulmonary embolism, many physicians use pneumoboots and subcutaneous heparin. Low molecular weight heparin may be more effective than unfractionated heparin; however, high doses increase the risk of bleeding. Comparing laparoscopic surgery with traditional open surgery, venous stasis is more severe in laparoscopic surgery due to the head-up, feet-down position and the need for pneumoperitoneum; however, the incidence of pulmonary embolism is not different between the two procedures. There is no evidence-based literature recommending a single best method for preventing deep vein thrombosis (DVT) or pulmonary embolism (PE).

Patients presenting with low oxygen saturation, shortness of breath, chest pain, difficulty breathing, and leg swelling and pain should be investigated for pulmonary embolism (PE) and deep vein thrombosis (DVT). Diagnosis can be made using CT angiography (CTA), pulmonary angiography, or bilateral lower extremity scans; however, lung scans are not highly specific. Some patients may be unable to undergo these diagnostic tests due to their large size. If pulmonary embolism or deep vein thrombosis is confirmed by examination or is clinically highly suspected, heparin anticoagulation therapy should be initiated immediately, followed by warfarin. For a small number of patients with contraindications to anticoagulation therapy, an inferior vena cava filter can be used to prevent clot embolism. Patients with a history of thromboembolic disease, venous stasis, or mobility impairment (such as requiring a wheelchair) are at high risk of pulmonary embolism, and therefore, heparin use may need to be continued for some time after discharge.

While focusing on pulmonary embolism, gastrointestinal fistula may be overlooked, leading to delayed diagnosis. Gastric bypass surgery requires anastomosis and reconstruction of the digestive tract at multiple sites; inadequate suturing or staples at any site can potentially cause gastrointestinal fistula. Peritonitis secondary to gastrointestinal fistula can cause serious conditions and even death. In recent reports of laparoscopic surgery, the incidence of gastrointestinal fistula ranged from 0% to 5.1%, similar to that of open surgery. Because the symptoms and signs of gastrointestinal fistula are highly nonspecific in patients receiving sedation to suppress postoperative pain, clues and symptoms of anastomotic leakage should be monitored early postoperatively. Some of the most sensitive signs associated with gastrointestinal fistula are tachycardia and respiratory limitation. The presence of unexplained tachycardia (especially a heart rate greater than 120 beats/min), respiratory distress, fever, severe pain or tenderness, oliguria, and hypotension should raise early suspicion of gastrointestinal fistula. Upper gastrointestinal contrast radiography (UGI) or enhanced CT scans are helpful in diagnosing gastrointestinal fistula. Even if the test result is negative, but there is a high clinical suspicion of a gastrointestinal fistula, it does not prevent the surgeon from exploring the abdomen.

If a gastrointestinal fistula leads to hemodynamic instability or sepsis, immediate surgery (open or laparoscopic) should be performed to flush the contaminated peritoneum, adequately drain the infected area, locate and repair the intra-abdominal defect, administer broad-spectrum antibiotics, and perform a gastrostomy to place a drainage and feeding tube. In patients with mild symptoms and no hemodynamic instability, gastrointestinal fistulas can be managed with percutaneous drainage, antibiotic treatment, parenteral nutrition (TPN), and/or a gastrostomy to place a feeding tube. Furthermore, placing a closed drainage tube, such as a Jackson-Pratt tube, during the initial surgery can help control small gastrointestinal fistulas, thus avoiding secondary surgery.

Acute gastric dilatation is a rare but potentially devastating complication. If paralytic ileus and peripheral mechanical obstruction occur postoperatively, the distal gastric remnant will become a blind pocket and may become distended. Iatrogenic damage to the vagus nerve fibers running along the lesser curvature of the stomach can lead to impaired gastric emptying. Further distension of the remnant stomach may eventually lead to rupture, spilling large amounts of gastric contents. This contaminated contents, mixed with acid, bile, pancreatic enzymes, and bacteria, can cause severe peritonitis. The toxic contents combined with large amounts of culture medium make this complication more serious than gastrojejunostomy leakage. Early postoperatively, symptoms such as upper abdominal fullness, distension, thumping, and belching should be carefully monitored, and X-rays or CT scans of the kidneys, ureters, and bladder (KUB) should be performed to check for large gastric bubbles. Although the creation of a stoma in the residual stomach is not routinely performed in the initial gastric bypass surgery for most surgeons, drainage of the residual stomach can prevent this rare but sometimes fatal complication. Residual stomach drainage should be considered for elderly patients, patients with advanced diabetes, patients whose vagal nerve function is uncertain after corrective surgery, and patients with slowed gastric emptying.