VOLUME 31, ISSUE 1

Based on the lecture “From Print to Practice: Recent Publications and their Possible Impact on Anesthesia Care” given by Dr. Girish P. Joshi at the 2018 Texas Society of Anesthesiologists annual conference in Bastrop, TX.

Each September at the Texas Society of Anesthesiologists annual conference, Girish P. Joshi, MBBS, MD, FFARCSI, Professor of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center, Dallas gives a presentation highlighting publications from the past year that he believes may have an impact on the practice of anesthesiology. In this article, we seek to summarize the most salient points of his talk, touching on the key studies he mentioned and their potential influences on our clinical practice. This year, Dr. Joshi covered a spectrum of important topics in our field, from the use of patient frailty as a predictor of morbidity in ambulatory surgery to the impact intraoperative medications such as opioids and neuromuscular blocking agents may have on readmission rates.

Seib CD, Rochefort H, Chomsky-Higgins K, et al. Association of patient frailty with increased morbidity after common ambulatory general surgery operations. JAMA Surg 2018;153:160-8.

Over the past several decades, the field of ambulatory surgery has grown tremendously, and the patient population undergoing ambulatory surgery has become significantly more complex. In order to provide safe care in the ambulatory setting, patient risk stratification is of critical importance, and a number of tools have been developed and implemented in recent years in an attempt to improve our ability to identify patients who are at high risk of doing poorly after surgery.

The modified frailty index was developed by the American College of Surgeons National Surgical Quality Improvement Program (NSQUIP) to provide an estimate of a patient’s frailty, independent of his or her age. This index considers a number of variables, centering on the presence of comorbid conditions of particular significance for the risk of cardiovascular and neurologic complications and the patient’s overall functional status. This tool has been validated as a predictor of morbidity and mortality in major elective and emergency general surgeries, but to this point, it had not been tested in the ambulatory setting.

In this retrospective study, analysis was performed looking at over 140,000 patients in the NSQUIP Participant Use File who underwent ambulatory or 23-hour stay surgery between 2007 and 2010. A statistically significant stepwise association was found between an increased modified frailty index and the occurrence of postoperative complications. This relationship remained, even after adjustment for age, sex, race/ethnicity, anesthesia type, presence of renal failure and tobacco use.

Clinical Take Away: This study suggests that the modified frailty index, already a valuable tool used in assessing a variety of non-ambulatory surgical patients, can be similarly useful in the ambulatory setting, and is recommended for use in the patient selection process for ambulatory surgical patients.

Long DR, Lihn AL, Friedrich S, et al. Association between intraoperative opioid administration and 30-day readmission: a pre-specified analysis of registry data from a healthcare network in New England. Br J Anaesth. 2018;120:1090-102.

The perioperative use of opioid pain medications has been the focus of much attention recently as the United States government seeks to understand and address the now well-recognized opioid epidemic we are facing. Opioid use is a highly variable aspect of anesthetic practice, and the significance of intraoperative use as a contributor to the opioid crisis has been quite controversial.

In this study, published in the British Journal of Anaesthesia, a retrospective analysis of over 150,000 surgical cases, all performed under general anesthesia, examined the relationship between intraoperative opioid use and readmission rate. High doses of intraoperative opioids were found to be an independent predictor of 30-day readmission. This was particularly true for ambulatory surgical patients, who showed a dose dependent increase in readmission based on intraoperative opioid use. The class of opioid drug used also seemed to matter, with longer acting opioids showing a stronger effect than shorter acting medications.

Clinical Take Away: Intraoperative opioid use varies significantly in individual practice and is a technique with potentially negative unintended consequences that should be taken into consideration. This is particularly true in the ambulatory setting. Using a conservative strategy with regard to intraoperative opioids may reduce the risk of readmission in surgical patients.

Thevathasan T, Shih SL, Safavi KC, et al. Association between intraoperative non-depolarising neuromuscular blocking agent dose and 30-day readmission after abdominal surgery. Br J Anaesth. 2017;119:595-605.

Clinical practice is also highly variable with regard to the approach toward non-depolarizing neuromuscular blocking drugs (NMBA)and reversal agents. Many anesthesiologists believe that avoidance of these medications, when appropriate, may decrease postoperative morbidity. This topic has been looked at with renewed vigor after the recent introduction of sugammadex to the American market.

In this retrospective study of over 13,000 patients undergoing abdominal surgery under general anesthesia, also published in the British Journal of Anaesthesia, the intraoperative use of neuromuscular blocking agents was found to be associated in a dose-dependent fashion with an increased risk of 30-day hospital readmission. This was again particularly true in the ambulatory surgery population, where high dose NMBAs conferred a 2.61 adjusted odds ratio for readmission as compared to low dose NMBA use. The dose of neostigmine used intraoperatively was also associated significantly with an increased risk of readmission. Sugammadex use was not analyzed in this study.

Clinical Take Away: Data supports a strategy of conservative use of non-depolarizing neuromuscular blocking agents, particularly in the ambulatory setting, to minimize the risk for readmission.

Myles PS, Bellomo R, Corcoran T, et al. Restrictive versus liberal fluid therapy for major abdominal surgery. N Engl J Med. 2018 May 9. doi: 10.1056/NEJMoa1801601. [Epub ahead of print]

Fluid resuscitation strategies have shifted dramatically in the last 50 years, and the once liberal use of crystalloids in the operating room has now fallen by the wayside, as goal-directed fluid administration has become more en vogue. Unfortunately, the data to support this more restrictive approach to intraoperative fluid management has not been as robust as we might hope. Although we recognize the benefits of decreased intraoperative fluids with respect to wound healing and postoperative ileus, many concerns remain about the maintenance of adequate end-organ perfusion and the risk for postoperative morbidity with this strategy.

In this randomized controlled trial of 3000 patients undergoing major abdominal surgery, published in the New England Journal of Medicine, restrictive and liberal fluid administration strategies were compared, evaluating the rate of disability-free survival at one year as a primary outcome, with acute kidney injury, need for renal replacement therapy at 90 days, and a composite of other septic complications including surgical site infection as secondary outcomes. The restrictive group received an average of 3.7L of IV fluid as compared to 6.1L in the liberal group. No significant difference with regard to disability-free survival was found between the two groups, but the rate of acute kidney injury at 30 days and the need for renal replacement therapy at 90 days were slightly higher in the restrictive group. However, this study has significant limitations including the pragmatic study design as well as the definitions of restrictive and liberal fluid administration.

Clinical Take Away: Given the significant flaws in the study design, the impact of this study on current clinical practice with regards to perioperative fluid management is negligible.

Pei L, Huang Y, Xu Y, Zheng Y, et al. Effects of ambient temperature and forced-air warming on intraoperative core temperature: a factorial randomized trial. Anesthesiology. 2018;128:903-11.

The Surgical Care Improvement Project (SCIP) included body temperature as one of its key measures for the quality of perioperative care in 2003, recognizing that inadvertent perioperative hypothermia is associated with an increased rate of postoperative complications such as surgical site infection and coagulopathy. Recognizing the significant risk for hypothermia during surgery, anesthesiologists and surgeons have developed a number of strategies to maintain patient body temperature while under anesthesia. Forced-air warming has quickly become standard of care in the operating room, begging the question – Do we still need to argue over the thermostat?

In this unblinded, randomized, factorial trial, the effect of ambient temperature, both with and without forced air warming, was examined on 292 patients under anesthesia. Although patients who were passively insulated without forced air warming did have a small increase in body temperature with increasing room temperature, this effect was negligible in patients with forced air warming.

Clinical Take Away: Using a forced-air warming device obviates the need for adjusting ambient temperature to keep patients warm. The room temperature can safely be adjusted for staff comfort without detriment to the patient in most cases.