Perioperative Care in Bariatric Surgery: 2021 ERAS Society Guideline

Recommendations for preadmission care in bariatric surgery

• Preoperative information and education, adapted to the individual requirements, should be given to all patients.
• Indications for bariatric surgery should follow updated global and national guidelines.
• All patients should be screened for alcohol and tobacco use. Tobacco smoking should be stopped at least 4 weeks before surgery. For patients with alcohol abuse, abstinence should be strictly adhered to for 1–2 years. Moreover, the risk for relapse after bariatric surgery should be acknowledged.
• Preoperative weight loss using a very low or low-calorie diet prior to bariatric surgery should be recommended.
• While feasible, patients with diabetes and treatment with glucose-lowering drugs should closely monitor treatment effects, and be aware of the risk for hypoglycemia. A very low-calorie diet improves insulin sensitivity in patients with diabetes.
• Although prehabilitation may improve general fitness and respiratory capacity, there is insufficient data to recommend prehabilitation before bariatric surgery. 

Recommendations for preoperative care in bariatric surgery

• 8 mg intravenous dexamethasone should be administered preferably 90 min prior to induction of anesthesia for reduction of PONV as well as inflammatory response.
• There is insufficient evidence to support perioperative statins for statin-naive patients in bariatric surgery. Patients on statins can safely continue the treatment during the perioperative phase.
• The beta-adrenergic blockade does not influence the risk for adverse outcomes in bariatric surgery but can be safely continued during the perioperative phase for patients at high risk of cardiovascular events.
• Solids until 6 h before induction and clear liquids until 2 h before induction for elective bariatric surgery assuming no contraindications (e.g., gastroparesis, bowel obstruction).
• Patients with diabetes should follow these recommendations, but further studies are needed for patients with additional risk factors such as gastroparesis.
• There is insufficient evidence to make a recommendation about preoperative carbohydrate loading in bariatric surgery.
• A multimodal approach to PONV prophylaxis should be adopted in all patients. 

Recommendations for intraoperative care in bariatric surgery

• The goal of perioperative fluid management is to maintain normovolemia and optimize tissue perfusion and oxygenation. Individual goal-directed fluid therapy is the most effective strategy, avoiding both restrictive and liberal strategies.
• Colloid fluids do not improve intra- and postoperative tissue oxygen tension compared with crystalloid fluids and do not reduce postoperative complications.
• The current evidence does not allow the recommendation of specific anesthetic agents or techniques.
• Opioid-sparing anesthesia using a multimodal approach, including local anesthetics, should be used in order to improve postoperative recovery.
• Whenever possible, regional anesthetic techniques should be performed to reduce opioid requirements. Thoracic epidural analgesia should be considered in laparotomy.
• BIS monitoring of anesthetic depth should be considered where ETAG monitoring is not employed.
• Anesthetists should recognize and be prepared to handle the specific challenges in airways in patients with obesity.
• Endotracheal intubation remains the main technique for intraoperative airway management.
• Lung protective ventilation should be adopted for all patients undergoing elective bariatric surgery with the avoidance of high PEEP values.
• Increases in driving pressure resulting from adjustments in PEEP should ideally be avoided.
• PCV or VCV can be used for patients with obesity with an inverse respiratory ratio (1.5:1).
• Positioning in a reverse Trendelenburg, flexed hips, reverse- or beach chair positioning, particularly in the presence of pneumoperitoneum, improves pulmonary mechanics and gas exchange.
• Deep neuromuscular blockade improves surgical performance.
• Ensuring full reversal of neuromuscular blockade improves patient recovery.
• Objective qualitative monitoring of neuromuscular blockade improves patient recovery.
• Laparoscopic approach whenever possible.
• During the learning curve phase, all operations should be supervised by a senior surgeon with significant experience in bariatric surgery.
• There is a strong association between hospital volume and surgical outcomes at least up to a threshold value.
• Nasogastric tubes and abdominal drains should not be used routinely in bariatric surgery.

• Patients without OSA or with uncomplicated OSA should be supplemented with oxygen prophylactically in a head-elevated or semi-sitting position. Both groups can be safely monitored in a surgical ward after the initial PACU stay. A low threshold for non-invasive positive pressure ventilation should be maintained in the presence of signs of respiratory distress.
• Patients with OSA on home CPAP therapy should use their equipment in the immediate postoperative period.
• Patients with obesity hypoventilation syndrome (OHS) are at higher risk of respiratory adverse events. Postoperative BiPAP/NIV should be considered liberally during the immediate postoperative period, in particular in the presence of hypoxemia.
• Thromboprophylaxis should involve mechanical and pharmacological measures. Doses and duration of treatment should be individualized.
• A clear liquid meal regimen can usually be initiated several hours after surgery.
• All patients should have access to comprehensive nutrition and dietetic assessment with counseling on the macronutrient and micronutrient content of the diet based on the surgical procedure and the patient's nutritional status.
• Patients and healthcare professionals should be aware of the risks of thiamine deficiency, especially in the early postoperative periods.
• A regimen of life-long vitamin and mineral supplementation and nutritional biochemical monitoring is necessary.
• PPI prophylaxis should be considered for at least 30 days after Roux-en-Y gastric bypass surgery.
• There is not enough evidence to provide a recommendation of PPI prophylaxis for sleeve gastrectomy, but given the high numbers of patients with gastroesophageal reflux after this procedure, it may be considered for at least 30 days after surgery.
• Ursodeoxycholic acid should be considered for 6 months after bariatric surgery for patients without gallstones at the time of surgery.