VOLUME 30, ISSUE 1
Kristina L. Goff, MD
Assistant Professor, Department of Anesthesiology & Pain Medicine
The University of Texas Southwestern Medical Center
Dallas, TX
Understanding the Literature: A Summary of Recent Publications
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 2017 Texas Society of Anesthesiologists annual conference in San Antonio, TX.
Each year at the Texas Society of Anesthesiologists annual conference, Girish P. Joshi presents a talk highlighting publications from the past year that he believes may have a significant impact on the practice of anesthesiology. This year, he covered a wide spectrum of controversial topics in our field, from a discussion on the validity of perioperative fasting protocols to the risks and benefits of the use of high intraoperative inspired fraction of oxygen in reducing surgical site infection. Here I have summarized the most salient points from each of these publications.
Lambert E, Carey S. Practice Guideline Recommendations on Perioperative Fasting: A Systematic Review. J Parenter Enteral Nutr. 2016; 40: 1158-65.
In recent years, the practice of prolonged perioperative fasting has come under scrutiny with the development of enhanced recovery protocols demonstrating better outcomes in surgical patients who experienced shorter preoperative NPO duration and expedited reinstitution of oral intake postoperatively. A number of proposed revisions to the traditional fasting guidelines have been published, leading to significant variability in hospital protocols and uncertainty amongst many physician anesthesiologists. Hoping to address this, Dr. Joshi selected a literature review by Eva Lambert and Sharon Carey in the Journal of Parenteral and Enteral Nutrition focusing on perioperative fasting guidelines as his first featured article. Their review investigates nineteen sets of guidelines on perioperative fasting, evaluating their quality using the Appraisal of Guidelines Research and Evaluation (AGREE) tool and generating a consensus on several high-level recommendations. In particular, the evidence for minimizing preoperative fasting times was felt to be quite strong, even in patients with gastro-esophageal reflux disease, obesity and/or diabetes. Clear liquids should be freely permitted up to 2 hours prior to anesthetic administration. Solids should be held 6 hours prior to an elective anesthetic, unless the meal contains meat or is high in fat, in which case a longer fasting time (e.g. 8 hours) is still recommended. Chewing gum and eating hard candy should not be causes for delay. Early oral intake of both solids and liquids postoperatively was also well supported by the current evidence.
Chung F, Memtsoudis SG, Ramachandran SK, et al. Society of Anesthesia and Sleep Medicine Guidelines on Preoperative Screening and Assessment of Adult Patients With Obstructive Sleep Apnea. Anesth Analg. 2016; 123: 452-73.
The Society of Anesthesia and Sleep Medicine (SASM) published guidelines for the perioperative evaluation of patients with obstructive sleep apnea. These guidelines emphasize the value of standardized preoperative OSA screening in order to allow for tailored anesthetic management in high-risk patients. Additional evaluation should be considered if there is evidence of associated comorbidities such as pulmonary hypertension or hypoventilation syndromes. The use of previously prescribed positive airway pressure devices should be continued throughout the perioperative period when the patient is asleep. The SASM guidelines confirm the recommendations of the SAMBA guidelines published in 2012 (Joshi GP, Ankichetty S, Chung F, Gan TJ. Society for Ambulatory Anesthesia (SAMBA) consensus statement on preoperative selection of patients with obstructive sleep apnea scheduled for ambulatory surgery. Anesth Analg 2012; 115: 1060-8).
Duceppe E, Parlow J, MacDonald P, et al. Canadian Cardiovascular Society Guidelines on perioperative cardiac risk assessment and management for patients who undergo noncardiac surgery. Can J Cardiol 2017; 33: 17-32.
The Canadian Cardiovascular Society published an updated set of guidelines this year for the preoperative assessment and management of cardiac disease in patients undergoing non-cardiac surgery. Their recommendations featured several notable deviations from the latest ACC/AHA guidelines. These guidelines are specifically for hospitalized patients and thus, may not apply to ambulatory surgery population. They do away with preoperative exercise or pharmacologic stress testing as a means of further evaluating potentially high-risk patients, instead suggesting that BNP or NT-proBNP be checked to help with risk stratification. They recommend measurement of BNP or NT-proBNP before surgery in patients >65 years or 45-64 years of age with significant cardiovascular disease, or have a Revised Cardiac Risk Index (RCRI) score >1. In patients with an elevated BNP level preoperatively, they recommend an ECG be obtained in PACU, and the patient’s troponin level be trended for 48-72 hours postoperatively. Further, this update addresses perioperative medication management, recommending against the prophylactic initiation or continuation of aspirin in the perioperative period, except in patients with a recent coronary stent placement or who are undergoing carotid endarterectomy. Similarly, they recommend against the prophylactic initiation of beta-blockers prior to surgery. ACE inhibitors and ARBs should be held 24 hours prior to surgery. Attempts to facilitate smoking cessation should be encouraged and aspirin and statin therapy should be initiated in any patient with evidence of myocardial injury in the postoperative period. These guidelines are largely based on the findings of the POISE 1, POISE 2, and VISION trials. The data in these trials has been called into question due to the inability to control for patient comorbidities, variability in anesthetic techniques and postoperative care, and the heterogeneity of the surgical populations.
Levine GN, Bates ER, Bittl JA, et al. 2016 ACC/AHA Guideline Focused Update on Duration of Dual Antiplatelet Therapy in Patients With Coronary Artery Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol 2016; 68: 1082-115.
The American College of Cardiologists together with the American Heart Association published updated guidelines on the duration of antiplatelet therapy after percutaneous coronary intervention. The management of bare metal stents has not changed significantly: patients should remain on dual antiplatelet therapy (DAPT) for one month after stent placement. After one month, DAPT can safely be discontinued. However, the recommendations for the management of second generation drug eluting stents have been modified to allow for discontinuation of DAPT at 3-6 months in cases where the risk of delaying surgery is felt to be greater than the risk of in-stent thrombosis. After 6 months, DAPT may be safely discontinued for surgery.
Roshanov PS, Rochwerg B, Patel A, et al. Withholding versus Continuing Angiotensin-converting Enzyme Inhibitors or Angiotensin II Receptor Blockers before Noncardiac Surgery: An Analysis of the Vascular events In noncardiac Surgery patients cohort evaluation Prospective Cohort. Anesthesiology 2017; 126: 16-27.
How to best advise patients taking angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARBs) in the perioperative period has been the subject of much recent controversy. Because of the concern for refractory intraoperative hypotension, many physician anesthesiologists recommend holding ACE inhibitors and ARBs for 24 hours preoperatively, but there is limited data to support this practice. In fact, one study published two years ago in Anesthesiology by Lee and Takemoto found a strong association between holding ACEi/ARBs and mortality, particularly in young patients. To further muddy the waters, this year, Roshanov and colleagues published a secondary analysis of vascular events in the 2012 VISION trial, looking at a cohort of patients who chronically used ACE inhibitors or ARBs, which found a significant decrease in death, stroke and myocardial infarction in those patients whose ACE inhibitors and ARBs were withheld prior to surgery. Given the limitations of the current evidence, Dr. Joshi suggests an approach that continues ACE inhibitors and ARBs in most patients, withholding only if the risk for stroke or the potential for significant blood loss is high or if the patient is taking both an ACEi and an ARB. He emphasizes that when caring for patients on ACE inhibitors and ARBs, we must adjust our drug dosing, including opioids and propofol, at induction of anesthesia as well as titrate our inhaled anesthetics carefully to minimize sympatholytic effects.
Allegranzi B, Zayed B, Bischoff P, et al, and the WHO Guidelines Development Group. Surgical site infections 2: New WHO recommendations on intraoperative and postoperative measures for surgical site infection prevention: an evidence-based global perspective. Lancet Infect Dis 2016; 16: e288–303.
Several recent publications, including a new set of guidelines published by the World Health Organization in the Lancet, advocate for the use of a high inspired fraction of oxygen as a means of reducing the rate of surgical site infections. However, these recommendations are focused solely on preventing wound infections, and neglect to consider the detrimental effects of hyperoxia on other organ systems. High FiO2 promotes atelectasis and may lead to impaired oxygenation up to several days in the postoperative period. Further, high levels of oxygen favor the production of free radicals that may cause tissue injury in the lungs and elsewhere in the body. The risk of increased postoperative pulmonary complications associated with the use of high intraoperative FiO2 likely outweighs the benefits observed with regard to surgical site infections, and these recommendations should be considered carefully.
Salmasi V, Maheshwari K, Yang D, et al. Relationship between Intraoperative Hypotension, Defined by Either Reduction from Baseline or Absolute Thresholds, and Acute Kidney and Myocardial Injury after Noncardiac Surgery: A Retrospective Cohort Analysis. Anesthesiology 2017; 126: 47-65.
Appropriate thresholds in the management of hypotension are subject to recent debate. Traditional practice recommends the maintenance of intraoperative blood pressure within 20% of the patient’s baseline. Dr. Joshi highlights Salmasi and colleagues 2017 study published in Anesthesiology, which investigates the relationship between intraoperative blood pressure management and acute kidney and myocardial injury. This retrospective study found no difference in the incidence of renal or myocardial injury when the mean arterial pressure was maintained >65mmHg as compared to maintaining the MAP within 20% of the patient’s preoperative baseline. Based on this data, it may be reasonable to target a goal MAP of 65mmHg in supine patients, without consideration of the preoperative blood pressure. Dr. Joshi emphasized that in patients undergoing surgical procedures in the sitting position, the MAP should be maintained at a higher value (e.g. 80mmHg).
Joshi GP, Desai MS, Gayer S, Vila H Jr; Society for Ambulatory Anesthesia (SAMBA). Succinylcholine for Emergency Airway Rescue in Class B Ambulatory Facilities: The Society for Ambulatory Anesthesia Position Statement. Anesth Analg 2017; 124: 1447-9.
In light of recent concerns, the Society for Ambulatory Anesthesia (SAMBA) released a position statement on the availability of succinylcholine in Class B Ambulatory facilities for the purpose of airway rescue. As the risk of life-threatening laryngospasm significantly outweighs the likelihood of developing malignant hyperthermia after a single dose of succinylcholine, SAMBA believes it is appropriate for Class B facilities to stock succinylcholine for emergency use, without requiring the facility to keep a supply of dantrolene. Facilities should have a relationship with a nearby health care center that stocks dantrolene, and employees should be familiar with the signs and symptoms of malignant hyperthermia. Patients who are susceptible to malignant hyperthermia should undergo procedures only in facilities that have dantrolene.
