What are the recommendations for anesthesia in morbidly obese patients?

From the Guidelines

Anesthesia management for morbidly obese patients should prioritize a multimodal, opioid-sparing approach, with careful planning and specific modifications to standard protocols, as recommended by the most recent guidelines 1.

Key Considerations

• Pre-operatively, thorough assessment of airway, cardiopulmonary status, and comorbidities like obstructive sleep apnea, diabetes, and hypertension is essential.
• Medication dosing should be based on ideal body weight (IBW) for lipophilic drugs like propofol and fentanyl, while hydrophilic drugs like succinylcholine and neuromuscular blockers should be dosed using total body weight.
• Intraoperatively, positioning is critical—ramped position with elevation of the head, shoulders, and upper body improves laryngoscopy and ventilation.
• Regional anesthesia should be considered when appropriate to reduce opioid requirements, as it has been demonstrated to be highly efficient in reducing opioid requirements 1.
• Postoperatively, extended monitoring is recommended due to increased risk of respiratory depression, with judicious use of opioids and consideration of multimodal analgesia including NSAIDs, acetaminophen, and regional techniques.

Regional Anesthesia

• Regional anesthesia is recommended as desirable but is often technically difficult and may be impossible to achieve 1.
• The use of ultrasound-guided techniques and extra-long spinal or epidural needles can facilitate regional anesthesia in morbidly obese patients 1.
• A plan for airway management is still mandatory when using regional anesthesia, and sedation should be kept to a minimum 1.

Airway Management

• The ramped position with the tragus of the ear level with the sternum and the arms away from the chest can improve lung mechanics and maximize safe apnoea time 1.
• The use of positive end-expiratory pressure (PEEP) and recruitment maneuvers can further facilitate pre-oxygenation and improve ventilation 1.
• Supraglottic airway devices should be reserved for highly selected patients undergoing short procedures, and tracheal intubation with controlled ventilation is the airway management technique of choice 1.

From the Research

Challenges of Regional Anesthesia in Morbidly Obese Patients

• Morbid obesity is associated with physiological derangements, difficult airway management, and biological augmentation in pharmacokinetics, making anesthesia administration and maintenance challenging 2.
• The risk of pulmonary complications such as respiratory failure, hypoxia, and apnea is higher in morbidly obese patients, especially those with obstructive sleep apnea 3.
• Regional anesthesia can be difficult to achieve in obese patients, with an increased incidence of failed blocks compared to normal weight patients 4.
• Obesity is associated with increased morbidity and mortality, and patients with super-super obesity (BMI > 60 kg/m2) are at even greater risk for complications 5.

Guidelines for Overcoming Difficulties

• A preoperative assessment and risk stratification are crucial in the anesthesiological care of morbidly obese patients 3.
• The selection of the anesthesia technique, drugs, and dosage should be thoughtful, taking into account the pathophysiological changes and comorbidities of morbid obesity 3.
• Short-acting, less lipophilic anesthetic drugs are recommended, as well as multimodal pain therapy to avoid high opiate doses 3.
• Regional anesthetic techniques should be used whenever possible, and anesthesiologists should be experienced in regional techniques and knowledgeable about the unique challenges presented by obese patients 4.
• Improvements in technology, such as ultrasound-guided nerve blocks and advanced airway devices, can enhance safety in patients with obesity 5.
• Newer drugs and monitors have been developed for perioperative use to enhance safety in patients with obesity 5.

Recommendations for Anesthesia in Morbidly Obese Patients

• Regional anesthesia offers advantages, including minimal airway intervention, less cardiopulmonary depression, excellent postoperative analgesia, and shorter recovery room and hospital stays 6.
• A thorough understanding of the pathophysiological changes and comorbidities of morbid obesity is essential for providing adequate care to this patient group 3.
• Clinical anesthesiologists must utilize careful assessment and consultation in developing safe anesthesia plans for morbidly obese patients 5.
• The indication for intensified postoperative monitoring depends on the patient's preexisting illnesses, the type of anesthesia, and the type of surgical procedure 3.