Premedication, Monitoring, and Multimodal Analgesia
Rebecca L. Johnson
Michael F. Mulroy
KEY POINTS
1. Preoperative optimization of the patient’s perioperative pain management with the use of multimodal analgesia has emerged as a standard tactic to reduce opioid use (1).
2. Multimodal analgesia can be defined as the use of different analgesic agents administered to target various sites along nociceptive pathways.
3. Periprocedural sedation remains a key component for regional anesthesia and analgesia success. Careful titration of sedative agents improves patient cooperation, analgesia, and may promote desirable amnesia.
4. Patients receiving regional anesthesia require the same American Society of Anesthesiologists (ASA) standards of monitoring as those undergoing general anesthesia, including electrocardiogram, blood pressure device, and pulse oximetry.
5. Patients undergoing regional anesthesia must be closely monitored during and after local anesthetic injection for signs and symptoms of local anesthetic systemic toxicity (LAST). The American Society of Regional Anesthesia and Pain Medicine (ASRA) has issued a practice advisory on the prevention, diagnosis, and treatment of LAST (2).
MULTIMODAL ANALGESIA INCORPORATES the use of different analgesic agents that work at targeted sites along the nociceptive pathways (3). The concept of preemptive oral pain management has emerged as a strategy to significantly decrease postoperative pain and reduce reliance on opioids. Incorporation of regional anesthesia into a comprehensive, multimodal analgesic clinical pathway promotes early mobilization, shorter hospital stay, and decreased reliance on opioids (4,5). Patients who participate in clinical pathways that include regional anesthesia techniques often report improved pain control and higher overall satisfaction.
Premedication and intraoperative sedation are important components of regional techniques. “Pure” regional anesthesia can be performed without supplementation, especially in ambulatory surgery, but patient acceptance is often enhanced with sedation. Omission of sedation is appropriate in the obstetric suite, where systemic medications must be carefully limited.
The preoperative visit is extremely effective in reducing patient anxiety. Kind attention to the patient’s concerns and situation will curtail the need for escalating premedication. Often small gestures, such as comfortable positioning of the bed, a warm blanket, and the practitioner sitting rather than standing while providing tailored patient education, lead to perceptions of more time spent and higher levels of patient satisfaction (6). Music also displays sedative properties. The use of headphones may actually muffle anxiety-provoking sounds and conversations in the induction and operating rooms (7).
In the operating room, successful regional anesthesia for nonobstetric surgery is facilitated by the skillful use of adjuvants to ensure cooperation and acceptance. This may include sedation and analgesia for the performance of the block, as well as sedation during prolonged surgical procedures even in the presence of an adequate block.
I. Multimodal therapy
A. Goals. Multimodal analgesia clinical pathways—the perioperative use of medications and regional anesthesia techniques using local anesthetics to facilitate the recovery process strives to achieve the following goals:
1. To inhibit the stress response to surgery
2. To improve antinociception through the synergistic/additive effects of individual components (Fig. 4.1).
3. To reduce pharmacologic side effects by decreasing the overall dose of any individual medication agent, such as opioids.
 FIGURE 4.1 Targeted sites along nociceptive pathways for multimodal analgesic agents. |
B. Selective components of multimodal therapy (Table 4.1)
1. Nonselective and selective cyclooxygenase (COX) nonsteroidal anti-inflammatory drugs (NSAIDs)
a. Renowned for their antipyretic, analgesic, and anti-inflammatory properties, NSAIDs provide significant pain relief for moderate and severe pain and can reduce the opioid dose required to treat severe pain. They provide an advantage over opioids by decreasing swelling; curtailing the perioperative stress response; and decreasing morbidity, mortality, and resource utilization (3,8).
b. Inhibit the COX enzymes responsible for catalyzing the conversion of arachidonic acid to prostaglandins and thromboxanes.
c. NSAIDs are categorized by their selectivity in inhibiting the two main isoforms of COX-1 (e.g., aspirin, ketorolac) and COX-2 (e.g., celecoxib).
d. Consider celecoxib, 400 mg, in single or divided doses for patients >50 kg, who have adequate renal function (creatinine clearance > 50 mL/min) and who are 18 to 64 years of age. Consider reducing the dose to 200 mg or avoiding its use altogether in patients at extremes of age (pediatric or older adults), patients with gastrointestinal bleeding within the past 6 months, or patients afflicted with acute or chronic renal insufficiency (creatinine clearance <30 mL/min).
TABLE 4.1 Common components of multimodal analgesic pathways | ||||||||||||||||||||||||||||||
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e. All NSAIDs display a ceiling effect for analgesia but not for side effects. NSAIDs (more COX-1 than COX-2 inhibitors) use may result in gastrointestinal erosions, decreased renal blood flow, and impaired platelet function. Nonselective NSAIDs have been associated with increased blood loss in some surgical procedures. The cause of cardiovascular complications seen with certain selective COX-2 inhibitors became, and remains, a subject of intensive research (9). NSAIDs exposure during orthopedic surgery has further been the subject of intense debate among surgeons and anesthesiologists. High doses of NSAIDs for prolonged periods can increase the risk of bone nonunion. However, there exists no clear contraindication to NSAIDs (e.g., in terms of bone healing) if the latter are dosed appropriately and used during a discrete perioperative episode of care (10).
2. Acetaminophen
a. Centrally acting antipyretic and analgesic properties with no anti-inflammatory or peripheral activity.
b. Commonly used as an oral premedication in doses ranging from 650 to 1,000 mg every 6 hours to a maximum of 3,500 to 4,000 mg/day based on age. Oral acetaminophen possesses a bioavailability of 80% to 90%; however, in the early postoperative period, individual absorption can be unpredictable because of delayed gastric emptying and may warrant intravenous (IV) administration in special circumstances. Rectal administration results in poor and unpredictable absorption.
c. Published trials evaluating acetaminophen have demonstrated opioid-sparing effects that are 20% inferior to those of NSAIDs.
3. Gabapentanoids/alpha-2 delta ligands
a. Gabapentanoids, such as gabapentin and pregabalin, bind to the alpha-2 delta subunit of voltage-gated calcium channels, preventing the release of nociceptive neurotransmitters. Both gabapentin (300 to 600 mg once preoperatively) and pregabalin (50 to 100 mg once preoperatively) have been shown to decrease postoperative pain and narcotic requirements.
b. Dose-dependent side effects (e.g., sedation, dizziness, and nausea) are often more pronounced among older adults undergoing general anesthesia (11). Moreover, emerging evidence suggests caution when combining preoperative use of pregabalin with infusions of remifentanil for sedation. Although the combination provides an additive analgesic effect, it seems to result in more pronounced respiratory depression and cognitive decline when compared with that of either agent alone among volunteers (12).
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