Anesthesiology and Perioperative Outcomes Research: Where Should We Focus?

Since 2012, the American Society of Anesthesiologists has promoted the Perioperative Surgical Home model in which anesthesiologists function as leaders in the coordination of perioperative care for surgical patients to improve outcomes (1,2). While anesthesiologists globally have had similar interests over the years, the unifying challenge continues to be the selection of outcomes and demonstration of improvement due to the anesthesiologist’s role and/or choice of anesthetic or analgesic technique. Since the types of outcomes and frequency of occurrence vary widely, a comprehensive discussion of perioperative outcomes is beyond the scope of this summary. Therefore, this review will focus on select anesthesiologist-driven factors related to acute pain management and anesthetic technique on perioperative outcomes and potential research directions.

Rare Outcomes and Big Data

For anesthesiologists, avoiding adverse events of the lowest frequency (death, recall, and nerve injury) receives highest priority with death ranking first among complications to avoid (3). Studies involving rare outcomes, positive or negative, will invariably require accumulation of “big data.” Such studies must either involve multiple institutions over a long study period (if prospective) or access data involving a large cohort of patients for retrospective studies; these study designs involving longitudinal data may also require advanced statistical methods (4). For example, Memtsoudis and colleagues sought to evaluate postoperative morbidity and mortality for lower extremity joint arthroplasty patients in a recent study (5). They utilized a large nationwide administrative database maintained by Premier Perspective, Inc. (Charlotte, NC, USA); the study data were gathered from 382,236 patients in approximately 400 acute care hospitals throughout the United States over 4 years (5). Other retrospective cohort studies comparing the occurrence of perioperative complications such as surgical site infections, cardiopulmonary morbidity, and mortality have used the American College of Surgeons National Surgical Quality Improvement Project (NSQIP) (6-8). NSQIP originally started within the Veterans Health Administration (VHA) system in the 1980s with a small sample of hospitals; this project, which included public reporting of outcomes data, eventually expanded to include all VHA surgical facilities and others outside the VHA system (9). Multi-center prospective registries such as the SOS Regional Anesthesia Hotline (10, 11) and AURORA (12, 13) have been developed for outcomes research and have reported the occurrence rates of rare complications related to regional anesthesia. The disadvantages to these data-driven studies include lack or randomization introducing potential bias, missing or incorrectly coded data, inability to draw conclusions regarding causation, and restrictions to access such as information security issues and/or cost (e.g., the Premier database). However, these retrospective cohort database studies may offer large samples sizes and administrative data from actual “real world” patients over a longer period of time and may identify important associations that influence clinical practice and generate hypotheses for future prospective studies.

Anesthesia Type and Perioperative Mortality

Based on the study by Memtsoudis and colleagues, overall 30-day mortality for lower extremity arthroplasty patients is lower for patients who receive neuraxial and combined neuraxial-general anesthesia compared to general anesthesia alone (5). In most categories, the rates of occurrence of in-hospital complications are also lower for the neuraxial and combined neuraxial-general anesthesia groups vs. the general anesthesia group, and transfusion requirements are lowest for the neuraxial group compared to all other groups (5). Studies using NSQIP have reported no difference in 30-day mortality for carotid endarterectomy patients associated with anesthetic technique although regional anesthesia patients are more likely to have a shorter operative time and next-day discharge (8); similarly, there is no difference in 30-day mortality for endovascular aortic aneurysm repair although general anesthesia patients are more likely to have longer length of stay and pulmonary complications (14).

Perioperative Analgesia and Cancer Recurrence

In a relatively-small matched retrospective study, Exadaktylos and colleagues have reported lower rates of recurrence and metastasis for breast cancer surgery patients who receive paravertebral analgesia vs. conventional systemic opioids (15). Although the exact mechanism was not well-understood at that time (regional anesthesia vs. reduction in the use of anesthetic agents and opioids), clinical and basic science research in this area has grown rapidly and has demonstrated mixed results. A follow-up study involving 503 patients who underwent abdominal surgery for cancer and were previously enrolled in a large multi-center clinical trial (16) and a retrospective database study of 424 colorectal cancer patients who underwent laparoscopic resection (17) have not shown a difference in recurrence-free survival or mortality. A recent meta-analysis including 14 prospective and retrospective studies involving cancer patients (colorectal, ovarian, breast, prostate, and hepatocellular) demonstrates a positive association between epidural analgesia and overall survival but no difference in recurrence-free survival compared to general anesthesia with opioid analgesia (18).

Analgesic Technique and Persistent Postsurgical Pain

Chronic pain may develop after many common operations including breast surgery, hernia repair, thoracic surgery, and amputation and is associated with severe acute pain in the postoperative period (19). While regional analgesic techniques are effective for acute pain management, currently-available data are inconclusive with regard to their ability to prevent the development of persistent postsurgical pain (20-22). There is an opportunity to use larger databases to investigate this issue further.

Ultrasound and Patient Safety

In 2010, the American Society of Regional Anesthesia and Pain Medicine published a series of articles presenting the evidence basis for ultrasound in regional anesthesia (23). According to the article focused on patient safety, evidence at the time suggested that ultrasound may decrease the incidence of minor adverse events (e.g., hemidiaphragmatic paresis from interscalene block or inadvertent vascular puncture), but serious complications such as local anesthetic systemic toxicity (LAST) and nerve injury did not occur at different rates based on the nerve localization technique (24). Since then, a large prospective multi-center registry study has shown that the use of ultrasound in regional anesthesia does reduce the incidence of LAST compared to traditional techniques (13). Similar methodology may be applied to other rare complications associated with anesthetic interventions.

Perioperative Medicine and Health Care Costs

Approximately 31% of costs related to inpatient perioperative care is attributable to the ward admission (25). Anesthesiologists as perioperative physicians have an opportunity to influence the cost of surgical care by decreasing hospital length of stay through effective pain management and by developing coordinated multi-disciplinary clinical pathways (26, 27).


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