647 Nondepolarizing Neuromuscular Blocking Agents, Reversal, and Risk of Postoperative Pneumonia
The effects of nondepolarizing neuromuscular blocking agents (NMBAs) can last beyond the time the patient leaves the operating room despite monitoring neuromuscular transmission and reversing neuromuscular blockade with acetylcholinesterase inhibitors. Postoperative residual neuromuscular block is associated with symptoms that may lead to impaired breathing or diminished protective airway reflexes. Intraoperative NMBA use and NMBA reversal were evaluated as risk factors for postoperative pneumonia using validated retrospective data from surgical cases that received general anesthesia between 2005 and 2013. The incidence of pneumonia in 1,455 cases that received an intermediate-acting nondepolarizing NMBA was 1.79 times that of 1,455 propensity score–matched cases that did not. The incidence of pneumonia in 1,320 cases that received an NMBA without reversal of neuromuscular blockade with neostigmine was 2.26 times that of 1,320 propensity score–matched cases that received reversal with neostigmine. See the accompanying Editorial View on page 611.
667 Neurodevelopmental Assessment in Kindergarten in Children Exposed to General Anesthesia before the Age of 4 Years: A Retrospective Matched Cohort Study
A large retrospective matched cohort study assessed the effect of general anesthesia on specific neurodevelopmental domains of children exposed to general anesthesia and surgery before 4 yr of age using the Early Development Instrument assessment, which was administered in kindergarten. A total of 18,056 children were studied: 3,850 exposed to one general anesthetic, 620 exposed to at least two general anesthetics, and 13,586 matched nonexposed children. When analyzed as a single cohort, the results corroborated earlier studies that suggested a single anesthetic exposure before age 4 yr is associated with small, statistically significant neurodevelopmental deficits. When the analysis was stratified by age, the negative neurodevelopmental findings were accounted for by children exposed to general anesthesia between 2 and 4 yr of age. An increased risk with multiple general anesthetic exposure was not confirmed.
724 Anesthesia Technique and Mortality after Total Hip or Knee Arthroplasty: A Retrospective, Propensity Score–matched Cohort Study
A propensity score–matched cohort study of all patients undergoing total hip or knee arthroplasty from 2003 to 2014 was conducted to determine whether spinal (intrathecal) anesthesia is associated with a reduction in 30-day mortality after elective total hip or knee arthroplasty compared to general anesthesia. To correct for possible confounders, 92% (n = 2,135) of the patients who had general anesthesia were matched to a similar patient who had spinal anesthesia. Within the matched cohort, the 30-day mortality rate was 0.19% (n = 4) for those who had spinal anesthesia and 0.8% (n = 17) for those who had general anesthesia (relative risk, 0.42; 95% CI, 0.21 to 0.83). This difference corresponds to a relative risk reduction of 58%, an absolute risk reduction of 0.61%, and a number needed to treat of 164 patients.
793 Raman Spectroscopy Differentiates Each Tissue from the Skin to the Spinal Cord: A Novel Method for Epidural Needle Placement?
A technique to aid with epidural needle placement may be beneficial if it can identify each tissue in the path of the needle, potentially preventing wrong site needle insertion and drug injection. The ability of diffuse reflectance spectroscopy, fluorescence spectroscopy, and Raman spectroscopy to characterize each tissue encountered during neuraxial anesthesia and epidural steroid injection techniques was tested in ex vivo porcine neuraxial and paravertebral tissues. Raman spectroscopy had better prediction accuracy in identifying and differentiating dissected individual tissues than diffuse reflectance spectroscopy and fluorescence spectroscopy because the Raman spectrum of each tissue was unique and could be identified based on the relative amount of albumin, actin, collagen, triolein, and phosphatidylcholine. This identification also held for the Raman spectra collected during in situ probe in needle insertion in a stepwise manner from dermis to spinal cord.
700 Sedation with Dexmedetomidine or Propofol Impairs Hypoxic Control of Breathing in Healthy Male Volunteers: A Nonblinded, Randomized Crossover Study
Regulation of breathing is controlled in part by chemoreflexes: carbon dioxide dependent for central chemoreceptors in the brain stem and oxygen dependent for peripheral receptors in the carotid body. Propofol impairs both central and peripheral regulation of breathing. The purpose of this randomized crossover trial in 10 healthy male volunteers was to determine whether dexmedetomidine-induced sedation reduces hypoxic ventilation and to compare its effect to that of sedation with propofol. Sedation was titrated to a target value of 2 to 4 (light to moderate sedation) on the 5-point Observer´s Assessment of Alertness/Sedation Scale. Sedation with dexmedetomidine and propofol reduced the hypoxia-induced increase in minute ventilation to 59% and 53% of baseline and also reduced the 5% CO2–induced increase in minute ventilation by 18% and 13% compared to baseline, respectively.
656 Success of Intubation Rescue Techniques after Failed Direct Laryngoscopy in Adults: A Retrospective Comparative Analysis from the Multicenter Perioperative Outcomes Group
The hypothesis that video laryngoscopy is associated with a higher success rate than other intubation rescue techniques recommended by the American Society of Anesthesiologists Difficult Airway Algorithm was tested by analyzing a large database of perioperative medical records from seven large tertiary care centers. Between 2004 and 2013, 1,427 cases met inclusion criteria of an initial unsuccessful direct laryngoscopy attempt followed by rescue intervention using some other means. There were 1,619 attempts at intubation rescue. Providers most frequently chose video laryngoscopy to rescue the airway (n = 1,122/1,619; 69%). Using video laryngoscopy resulted in a success rate (92%) that was significantly higher than those for the other four primarily studied rescue techniques: supraglottic airway conduit (78%); flexible fiberoptic intubation (78%); lighted stylet (77%); and optical stylet (67%). See the accompanying Editorial View on page 615.
690 Intraoperative Care Transitions Are Not Associated with Postoperative Adverse Outcomes
Transfer of responsibility and information about patients from one set of caregivers to another can result in a loss of important information, potentially affecting patient safety. The hypothesis that handovers would have no effect on patient outcomes was tested in a retrospective assessment of the relationship between intraoperative anesthesia transitions of care and postoperative outcomes. Factors associated with increased odds of postoperative adverse outcomes for 140,754 anesthetics administered between 2005 and 2014 included American Society of Anesthesiologists physical status, diagnosis severity, procedure severity, age, sex, and start time of surgery. The number of anesthesia handovers was not associated with increased odds of postoperative mortality and serious complications, as measured by the collapsed composite, with odds ratio (95% CI) for a one-unit increase in handovers of 0.957 (0.895 to 1.022), when controlled for potential confounding variables.
755 Opioid-induced Loss of Local Anesthetic Potency in the Rat Sciatic Nerve
Postoperative pain management in opioid-tolerant patients can be difficult due to not only a decrease in the analgesic efficacy of opioids but also a decrease in the potency of local anesthetics. The effect of systemic morphine on the potency of lidocaine-induced block of the compound action potential in the isolated rat sciatic nerve was assessed to determine whether the apparent loss of local anesthetic potency in opioid-tolerant patients is due to intrinsic changes in peripheral nerves. Acute morphine administration had no detectable effect on lidocaine potency. Repeated systemic morphine administration resulted in a decrease in lidocaine potency that was correlated with the development of tolerance to morphine-induced analgesia and persisted beyond the recovery of tolerance. The loss of lidocaine potency was blocked by naloxone, but not naloxone methiodide, which blocks only peripheral opioid receptors. See the accompanying Editorial View on page 625.