Amit Prabhakar

The role of analgesics in cancer propagation.

The treatment of cancer pain is paramount to both medical practitioner and patient in order to maximize quality of life. Cancer pain results from direct tumor effects as well as from surgical and medical treatments. Despite therapeutic advancements, morbidity and mortality in cancer care remains high, often from local recurrence or metastasis. Increasing evidence suggests analgesics affect the cellular milieu of malignant and nonmalignant cells and may influence cancer outcomes by directly stimulating tumor growth and inhibiting immune surveillance. Opioids have been shown to cause immunosuppression and stimulate malignant cells in vitro, though adjunct analgesics may additionally promote tumor cell growth. These results have led many to hypothesize that regional analgesic techniques may offer survival advantages to systemic analgesics. Thus far, the data do not support specific analgesic recommendations for the cancer patient, though ongoing prospective, randomized clinical trials are under way to better characterize the safest analgesic regimens for cancer patients.

Evolution of the transversus abdominis plane block and its role in postoperative analgesia.

Since it was first described by Rafi in 2001, the transversus abdominis plane (TAP) block can be best described as a peripheral nerve block to the anterior abdominal wall (T6 to L1). The TAP block is specifically a local anesthetic injection into the fascial plane superficial to the transversus abdominis muscle and deep to the internal oblique muscle. The TAP block has been a subject of controversy with regard to utility, to indications, and more fundamentally, how best to place the block and its precise mechanism of action. The evolution of thinking with regard to this block, or more correctly family of interrelated blocks, includes knowledge of underlying anatomy, as well as an appreciation of its varied approaches. The TAP block affords excellent analgesia for abdominal procedures. In summary, the TAP block affords effective analgesia with opioid sparing effects, technical simplicity, and long duration of action. Some disadvantages include the need for bilateral block for midline incisions and absence of effectiveness for visceral pain.

Perioperative analgesia outcomes and strategies

Despite an appreciation for many unwanted physiological effects from inadequate pain postoperative relief, moderate to severe postoperative pain remains commonplace. Though treatment options have evolved in recent years, including improvement in medications, multimodal regimens, and regional anesthetic techniques, including ultrasound and continuous catheters, outcomes data indicate that many of these strategies are associated with varying degrees of morbidity and mortality. This review focuses on the importance of effective postoperative analgesia and both short- and long-term effects associated with inadequate management. A careful literature review of emphasizing treatment options and potential pathogenesis associated with these strategies is emphasized in this review.

Propofol Infusion Syndrome: A Retrospective Analysis at a Level 1 Trauma Center

Objectives. The propofol infusion syndrome (PRIS), a rare, often fatal, condition of unknown etiology, is defined by development of lipemic serum, metabolic acidosis, rhabdomyolysis, hepatomegaly, cardiac arrhythmias, and acute renal failure. Methods. To identify risk factors for and biomarkers of PRIS, a retrospective chart review of all possible PRIS cases during a 1-year period was conducted at a level 1 trauma hospital in ICU patients over 18 years of age receiving continuous propofol infusions for ≥3 days. Additional study inclusion criteria included vasopressor support and monitoring of serum triglycerides and creatinine. Results. Seventy-two patients, 61 males (84.7%) and 11 females (15.3%), satisfied study inclusion criteria; and of these, 3 males met the study definition for PRIS, with 1 case fatality. PRIS incidence was 4.1% with a case-fatality rate of 33%. The mean duration of propofol infusion was 6.96 days. A positive linear correlation was observed between increasing triglyceride levels and infusion duration, but no correlation was observed between increasing creatinine levels and infusion duration. Conclusions. Risk factors for PRIS were confirmed as high dose infusions over prolonged periods. Increasing triglyceride levels may serve as reliable biomarkers of impending PRIS, if confirmed in future investigations with larger sample sizes.

Peripheral nerve catheters and local anesthetic infiltration in perioperative analgesia

Peripheral nerve catheters (PNCs) and local infiltration analgesia (LIA) represent valuable options for controlling perioperative pain. PNCs have been increasingly utilized to provide both surgical anesthesia and prolonged postoperative analgesia for a wide variety of procedures. PNCs can be more technically challenging to place than typical single-injection nerve blocks (SINB), and familiarity with the indications, contraindications, relevant anatomy, and appropriate technical skills is a prerequisite for the placement of any PNC. PNCs include risks of peripheral nerve injury, damage to adjacent anatomic structures, local anesthetic toxicity, intravascular injection, risks associated with motor block, risks of unnoticed injury to the insensate limb, and risks of sedation associated with PNC placement. In addition to these common risks, there are specific risks unique to each PNC insertion site. LIA strategies have emerged that seek to provide the benefit of targeted local anesthesia while minimizing collateral motor block and increasing the applicability of durable local anesthesia beyond the extremities. LIA involves the injection and/or infusion of a local anesthetic near the site of surgical incision to provide targeted analgesia. A wide variety of techniques have been described, including single-injection intraoperative wound infiltration, indwelling wound infusion catheters, and the recent high-volume LIA technique associated with joint replacement surgery. The efficacy of these techniques varies depending on specific procedures and anatomic locations. The recent incorporation of ultra-long-acting liposomal bupivacaine preparations has the potential to dramatically increase the utility of single-injection LIA. LIA represents a promising yet under-investigated method of postoperative pain control.

Multimodal Approaches to Analgesia in Enhanced Recovery After Surgery Pathways

Enhanced Recovery After Surgery (ERAS) is a multimodal perioperative care pathway designed to decrease morbidity, length of stay, and promote faster postoperative recovery. Surgery is associated with many undesirable potential consequences, including pain, cardiopulmonary sequelae, thromboembolic events, nausea/vomiting, ileus, and fatigue. The surgical stress response related to inflammatory mediators and neurohumoral responses combined with postoperative pain, nothing by mouth status, anxiety, hypovolemia, fatigue, and sleep disturbances is primarily responsible for many of the aforementioned potential consequences after a surgical procedure. The implementation of ERAS protocols, therefore, is aimed to attenuate these processes. Current ERAS protocols involvemany techniques to promote early mobilization and attenuate the surgical stress response, and involve a collaborative effort between anesthesiologists, surgeons, the

Techniques to Optimize Multimodal Analgesia in Ambulatory Surgery

Purpose of ReviewAmbulatory surgery has grown in popularity in recent decades due to the advancement in both surgical and anesthetic techniques resulting in quicker recovery times, fewer complications, higher patient satisfaction, and reduced costs of care. We review common approaches to multimodal analgesia.Recent FindingsA multimodal approach can help reduce perioperative opioid requirements and improve patient recovery. Analgesic options may include NSAIDs, acetaminophen, gabapentinoids, corticosteroids, alpha-2 agonists, local anesthetics, and the use of regional anesthesia.SummaryWe highlight important aspects related to pain management in the ambulatory surgery setting. A coordinated approach is required by the entire healthcare team to help expedite patient recovery and facilitate a resumption of normal activity following surgery. Implementation and development of standardized analgesic protocols will further improve patient care and outcomes.

Drug Formulation Advances in Extended-Release Medications for Pain Control

Prescription opioid abusers frequently tamper with opioid tablets in order to either accelerate the delivery of the euphoria-inducing agent or to alter the route of delivery, such that it may be delivered intranasally or intravenously. As one strategy to combat the opioid epidemic in the USA, drug manufacturers have begun to explore formulations which resist such tampering by abusers. Techniques to prevent tampering consist of physical barriers to crushing, chewing, and drug extraction, or aversive or antagonistic agents, incorporated within the formulation itself. Recent years have seen the development of numerous extended-release opioid agents, which are described in this review. This article provides a comprehensive summary of the pharmacology, benefits, risks, and processes behind the development of currently available extended-release opioid drugs, as well as a glimpse into promising future formulations.

Preoperative Assessment for Ambulatory Surgery

Purpose of ReviewAmbulatory surgery has grown in recent decades in volume and represents a significant number of anesthetics delivered throughout the USA. Preoperative anesthetic assessment in the ambulatory setting has become important because patients with numerous complex comorbidities are now commonplace in this arena. Disease states involving the lungs, the heart, the kidneys, and subpopulations including those who are obese and the elderly commonly receive anesthetics in an ambulatory setting.Recent FindingsThis review presents key aspects of current thinking with regard to preoperative assessment and considerations for different critical disease states and subpopulations that are now being managed under ambulatory surgery. Same day surgery centers require patient safety, and expectations are high for patient satisfaction. Advancements in surgical and anesthetic technique have allowed for more complex patients to partake in ambulatory surgery.SummaryAnesthesiologists must be familiar with guidelines, state-of-the-art pain management, and standards of preoperative patient evaluation to accurately stratify patient risk and to advocate for patient safety.

Preemptive Analgesia, Regional Anesthesia, and Prevention of Chronic Postoperative Pain

Preemptive analgesia is focused on both the prevention and treatment of postoperative pain. There are several factors at play related to postoperative pain and the individual patient. Furthermore, sensitization is an important aspect to consider when determining an appropriate analgesic plan for patients. Similarly, exposure to noxious stimuli for prolonged periods or of high frequency in the periphery can lead to changes in the central nervous system pain processing centers, which can affect the appropriate analgesic plan for patients. Pain can be controlled in several phases of perioperative care including pre-, peri-, and postoperative periods, and many agents can be used as preemptive analgesic treatments such as NSAIDs, local anesthetics, opioids, and NMDA receptor antagonists. Local wound infiltration is being used in conjunction with nerve blocks and is becoming an efficient method of postoperative pain control. Regional anesthesia is also continuing to grow and is used for a wide variety of procedures in the treatment of chronic pain. Several complex pain syndromes are discussed in this chapter, as well as the diagnostic criteria and how to treat them. Overall, the value of comprehensive pain control for surgical patients should not be underestimated and is likely to be best addressed with a multimodal, patient-specific approach.