How to Manage Acute Pain in Morbidly Obese Patients
Naveen Eipe, MBBS, MD, Associate Professor of Anesthesiology at University of Ottawa, gave an impressive review course on acute pain management in morbid obesity, sponsored by the International Society for the Perioperative Care of the Obese Patient, “Acute Pain Management in Morbid Obesity: Controversies and Conundrums.” During his presentation, held on May 16 at the IARS 2021 Annual Meeting, he tackled how to prepare and optimize acute pain management, the rationale behind acute pain pharmacology and perioperative strategies for treating patients who are morbidly obese and suffer from acute pain.
Giving opioids to a patient who is morbidly obese or has obstructive sleep apnea (OSA) can accentuate the effects of hypoventilation, central respiratory and level of consciousness depression, he explained. Hence, it is important to educate patients perioperatively on their comorbidities and engage them in the evaluation and optimization of their treatment. This includes providing education on smoke and alcohol cessation, diet and exercise but also engagement of the patients in perioperative care with consistent messaging and empowerment with functional prehabilitation.
Dr. Eipe then highlighted multimodal analgesia using the World Health Organization (WHO) Analgesic Ladder, “the new Ottawa ladder in acute pain.” He explained that pain can be managed in an opioid sparing stepwise severity-based approach. He described the ladder as follows: on the left side of the ladder: step 1. foundational analgesia with acetaminophen, step 2. weak opioids using tramadol or tapentadol, step 3. opioid analgesics like morphine and hydromorphone. Whereas non-opioid adjuvants are located on the right side of the ladder and include pregabalin, lidocaine, ketamine and dexmedetomidine. These last drugs are analgesic/antihyperalgesia and are most suitable for moderate to severe pain in patients with morbid obesity ± OSA.
The big takeaway message is to be able to identify patients who would benefit from antihyperalgesics, using a DN4 4-question pain questionnaire. This questionnaire helps estimate the probability of neuropathic pain and its association with burning, tingling, numbness, etc. A score of 4 indicated the necessity of usage of antihyperalgesics (ketamine, lidocaine, dexmedetomidine), in order to better control the pain and avoid usage of opioids.
Dr. Eipe also mentioned the presence of an alternative way to manage pain in morbidly obese patients. It involves usage of standardized anesthetics and acute pain protocols with regional techniques, which remains the main way to stay away from opioids in this patient population and decrease risks of opioid side effects.
At the end of the review course, Dr. Eipe established the controversies and conundrums associated with acute pain management in morbid obesity. There is an increased chance of causing respiratory depression and sedation after giving opioids to morbidly obese patients. It is then important to find better ways to monitor them and optimize their condition, for example, using telemetry and checking their CO2 in the postoperative period.