270 Practice Guidelines for Obstetric Anesthesia: An Updated Report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia and the Society for Obstetric Anesthesia and Perinatology (Practice Parameters)

These Practice Guidelines for obstetric anesthesia update the “Practice Guidelines for Obstetric Anesthesia: An Updated Report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia," which were adopted by the American Society of Anesthesiologists in 2006 and were published in 2007. They provide basic recommendations that are supported by a synthesis and analysis of the current literature, expert and practitioner opinion, open forum commentary, and clinical feasibility data. The Guidelines focus on the anesthetic management of pregnant patients during labor, nonoperative delivery, operative delivery, and selected aspects of postpartum care and analgesia. The intended patient population includes, but is not limited to, intrapartum and postpartum patients with uncomplicated pregnancies or with common obstetric problems.

312 Cognitive Functioning after Surgery in Middle-aged and Elderly Danish Twins

The association between exposure to surgery and subsequent level of cognitive functioning assessed by a five-component test battery was examined in a sample of 8,503 middle-aged and elderly twins. Intrapair analyses of 87 monozygotic and 124 dizygotic same-sex twin pairs in whom one had a history of major surgery and the other had no surgery were performed to address genetic and shared environmental confounding and to take preoperative cognition into account. In the analysis of the 211 discordant pairs, the surgery-exposed twin had a lower cognitive score than the co-twin in 49% of the pairs. There was no association between major surgery/anesthesia and cognitive score and there was evidence of high correlation in cognitive scores among twins, suggesting long-term postoperative cognitive functioning is primarily determined by preoperative cognitive functioning. See the accompanying Editorial View on page 255.

353 Cerebrospinal Fluid Biomarker for Alzheimer Disease Predicts Postoperative Cognitive Dysfunction

The hypothesis that elderly patients with Alzheimer disease neuropathology, as determined by cerebrospinal fluid analysis, who undergo surgery under general anesthesia would have an increased risk for postoperative cognitive dysfunction (POCD) was tested in 57 patients at least 60 yr of age undergoing elective total hip joint replacement. Key cerebrospinal fluid biomarker characteristics of early Alzheimer disease neuropathology include a decrease in amyloid β1–42 concentrations. Preexisting cognitive impairment, in 25.4% of patients, was not associated with low cerebrospinal fluid amyloid β1–42 concentrations. Cerebrospinal fluid amyloid β1–42 concentrations were below the cut-point for Alzheimer disease neuropathology in 11 patients, 3 of whom were classified as having POCD (27.3%) 3 months postoperatively, while 2 of the 46 patients with concentrations above the cut-point were classified as having POCD (4.3%).

339 Platelet Counts, Acute Kidney Injury, and Mortality after Coronary Artery Bypass Grafting Surgery

Thrombocytopenia in critically ill patients is associated with an increased incidence of acute kidney injury (AKI) and reduced survival. Associations of decreased platelet count after coronary artery bypass grafting surgery with increased risk for postoperative AKI and mortality were evaluated in a retrospective study of 4,217 patients who underwent coronary artery bypass grafting surgery between 2001 and 2009. Patients were stratified according to postoperative platelet counts: the lowest 10th percentile (thrombocytopenic cohort) and the remaining patients. The incidences of stages I, II, and III postoperative AKI were 51%, 13%, and 7%, respectively, in the thrombocytopenic cohort and 46%, 4%, and 1%, respectively, in the remaining patients. After adjusting for differences in baseline and clinical characteristics, postoperative thrombocytopenia was strongly associated with AKI and with increased risk for mortality immediately after surgery. See the accompanying Editorial View on page 265.

396 Impact of Perioperative Epidural Placement on Postdischarge Opioid Use in Patients Undergoing Abdominal Surgery

The hypothesis that perioperative epidural placement will reduce opioid consumption after discharge and prevent their persistent use was tested in opioid naïve patients identified in the claims database of a nationwide health insurer as having undergone open abdominal surgery between January 2004 and December 2013. A propensity score calculated to predict the probability of epidural placement was used to match each of the 2,144 patients who had an epidural placed to two patients who did not. There was no effect of epidural placement on persistent opioid use, assessed as the time to discontinuation of opioids, which was defined as a period of 30 days without filling a prescription for opioids after discharge from the hospital. Total morphine equivalents dispensed within 90 days of discharge did not differ between the groups.

417 Inflammation Increases Neuronal Sensitivity to General Anesthetics

The hypothesis that inflammation increases anesthetic neurodepression by up-regulating γ-aminobutyric acid type A (GABAA) receptor activity was tested in vitro and in vivo. Hippocampal and cortical neurons were pretreated with either the inflammatory cytokine interleukin-1β or vehicle. Whole-cell currents were activated by a low concentration of GABA, in the absence or presence of either etomidate or isoflurane. Following treatment with interleukin-1β, low clinically relevant concentrations of etomidate and of isoflurane produced GABAergic inhibitory currents that were equivalent to those generated by much higher concentrations in control neurons. The hypnotic properties of both etomidate and isoflurane were enhanced in mice treated with a low dose of endotoxin lipopolysaccharide. Lipopolysaccharide enhanced the immobilizing properties of etomidate, but not isoflurane. The interaction between lipopolysaccharide and etomidate for impairment of contextual fear memory was not significant.

483 Differential Opioid Tolerance and Opioid-induced Hyperalgesia: A Clinical Reality (Clinical Concepts and Commentary)

It may be thought that the perioperative period is too short for significant opioid tolerance to develop and that tolerance can be overcome by administering larger doses of opioids if it develops. It may be further thought that tolerance to opioid analgesic effects is associated with tolerance to their side effects. However, not only can opioid tolerance develop within hours when patients are exposed to high doses of opioids but also patients using opioids for preoperative pain control may be tolerant before they enter the operating room. In addition, opioid-induced hyperalgesia (increased sensitivity to painful stimuli) may occur within the perioperative period. Furthermore, opioid tolerance development is fastest and most profound for analgesic effects, less for respiratory depressant effects, and least for peripheral effects.

489 Emerging Roles for MicroRNAs in Perioperative Medicine (Review Article)

MicroRNAs (miRNAs) are small, non–protein-coding, single-stranded RNAs that function as posttranscriptional regulators of gene expression. They interact with target messenger RNAs, thereby preventing their translation into functional proteins. The basic biology of miRNAs is first reviewed. Significant roles of miRNAs with aberrant expressions in the development and maintenance of cardiovascular disorders are subsequently considered as are their roles in controlling inflammation and immune responses and their interaction with invading pathogens. The potential use of significantly altered expression of circulating miRNAs in diagnosis and prognosis of various diseases is discussed. Pharmacologic functions of miRNAs are then reviewed, including the effects of miRNAs on drug metabolism and their role in mediating anesthetic toxicity, as are pharmacologic approaches targeting miRNAs, such as therapeutic inhibition of miRNAs and restoration of miRNA functions.