Perioperative Pain Management

Until recently, parenteral opioids were the mainstay of postoperative pain management after Cardiac Surgery (CS). Opioids are associated with multiple adverse effects, including sedation, respiratory depression, nausea, vomiting, and ileus. There is growing evidence that multimodal opioid-sparing approaches can adequately address pain through the additive or synergistic effects of different types of analgesics, permitting lower opioid doses in the population receiving CS.

Nonsteroidal anti-inflammatory drugs are associated with renal dysfunction after CS. Selective COX-2 inhibition is associated with a significant risk of thromboembolic events after CS. The safest nonopioid analgesic may be acetaminophen. Intravenous acetaminophen may be better absorbed until gut function has recovered postoperatively. Per a medium-quality meta-analysis, when added to opioids, acetaminophen produces superior analgesia, an opioid-sparing effect, and independent antiemetic actions. Acetaminophen dosing is 1 g every 8 hours. Combination acetaminophen preparations with opioids should be discontinued.

Tramadol has dual opioid and nonopioid effects but with a high delirium risk. Tramadol produces a 25% decrease in morphine consumption, decreased pain scores, and improved patient comfort postoperatively. Pregabalin also decreases opioid consumption and is used in postoperative multimodal analgesia. Pregabalin given 1 hour before surgery and for 2 postoperative days improves pain scores compared with placebo. A 600-mg gabapentin dose, 2 hours before CS, lowers pain scores, opioid requirements, and postoperative nausea and vomiting.

Dexmedetomidine, an intravenous α-2 agonist, reduces opioid requirements. A medium-quality meta-analysis of dexmedetomidine infusion reduced all-cause mortality at 30 days with a lower incidence of postoperative delirium and shorter intubation times. Dexmedetomidine may reduce AKI after CS. Ketamine has potential uses in CS owing to its favorable hemodynamic profile, minimal respiratory depression, analgesic properties, and reduced delirium incidence; further studies are needed in the CS setting.

Patients should receive preoperative counseling to establish appropriate expectations of perioperative analgesia targets. Pain assessments must be made in the intubated patient to ensure the lowest effective opioid dose. The Critical Care Pain Observation Tool, Behavioral Pain Scale, and Bispectral Index monitoring may have a role in this setting. Although no single pathway exists for multimodal opioid-sparing pain management, there is sufficient evidence to recommend that CS programs use acetaminophen, Tramadol, dexmedetomidine, and pregabalin (or gabapentin) based on formulary availability (class I, level B-NR).

Source: Jama

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