This Month in: Anesthesiology

Pediatric patients undergoing cardiac surgery are vulnerable to pulmonary complications. The hypothesis that perioperative lung ultrasound examinations followed by interventions according to the lung ultrasound findings would benefit pediatric patients undergoing cardiac surgery with cardiopulmonary bypass and improve clinical outcomes was tested in a randomized controlled trial of 120 patients. Among the three primary outcomes, the incidence of postoperative desaturation was higher in the control group than it was in the intervention group (64% vs. 27%). However, the incidences of intraoperative desaturation (36% vs. 19%) and postoperative pulmonary complications (12% vs. 3%) in the groups were similar. Neither the incidence of desaturation during transfer to pediatric intensive care unit nor the length of pediatric intensive care unit stay differed between the groups, but the duration of mechanical ventilation was significantly shorter in the intervention group than it was in the control group.

Long-term catheter use increases the risk of catheter-related infections. The hypothesis that each additional day of catheter use is associated with an increased risk of catheter-related infection was tested by evaluating how peripheral nerve and epidural catheter-related infections increased over time in adult cases acquired between 2007 and 2014 in a prospective voluntary national multicenter registry in Germany. The incidence of peripheral catheter-related infections was 2.9% in 24,103 patients. With adjusted Cox regression analysis, the probability of peripheral infection-free catheter use was 99% at day 4 of catheter duration, 96% at day 7, and 73% at day 15. The incidence of epidural catheter-related infections was 3.9% in 20,452 patients. With adjusted Cox regression analysis, the probability of epidural infection-free catheter use was 99% at day 4 of catheter duration, 95% at day 7, and 73% at day 15.

Renal ischemia-reperfusion injury induced by extracorporeal circulation is at least partially responsible for acute kidney injury after coronary artery bypass grafting with extracorporeal circulation, which occurs in approximately one third of patients. A single pretreatment dose of cyclosporine has been reported to have renoprotective effects against ischemia-reperfusion injury in the experimental setting. The hypothesis that cyclosporine, administered as a single dose intravenously before coronary artery bypass graft surgery, may reduce the level of postoperative renal injury was tested in a randomized placebo-controlled trial of 154 patients. The primary endpoint was relative plasma cystatin C concentration change from preoperative concentrations to day 3 after surgery. Administration of 2.5 mg/kg cyclosporine before coronary artery bypass surgery with extracorporeal circulation resulted in decreased renal function postoperatively according to all measured renal parameters, as compared with placebo. No renal protective effects of cyclosporine were found.

Up to half of patients undergoing cardiac surgery may experience postoperative cognitive dysfunction at the time of hospital discharge. Perioperative inflammation could stimulate or accelerate β-amyloid-mediated neurologic degeneration, which could contribute to postoperative cognitive dysfunction. The novel positron emission tomography tracer, ¹⁸F-florbetapir, binds with high affinity to β-amyloid fibrils. The hypothesis tested in 40 patients aged at least 60 yr and undergoing cardiac surgery with cardiopulmonary bypass was that the 6-week ¹⁸F-florbetapir cortical amyloid burden would be greater in patients manifesting postoperative cognitive dysfunction and that the amyloid deposition pattern in patients with cognitive dysfunction would be similar to that seen in individuals with mild cognitive impairment. There was no association between 6-week global cortical amyloid burden and cognitive dysfunction at 6 weeks, and amyloid deposition in the surgical cohort was not different from that in normal subjects.

High-rate epidural boluses increase delivery pressure at the catheter orifice and could result in more spread of local anesthetic within the epidural space. The hypothesis that patients whose labor analgesia is maintained using high-rate (300 ml/h) programmed-intermittent and patient-controlled epidural analgesia boluses will have less breakthrough pain requiring a provider-administered supplemental bolus than women maintained with low-rate (100 ml/h) programmed-intermittent and patient-controlled epidural analgesia boluses was tested in a double-blind, randomized controlled trial of 210 term, nulliparous patients with singleton pregnancies and cervical dilation of no more than 5 cm. There was no difference in the frequency of requests for supplemental provider-administered analgesia when providing labor analgesia with high-rate epidural boluses compared with the low-rate epidural boluses. In addition, bupivacaine consumption, patient request for epidural boluses and deliveries, and the ratio of requests to boluses were not different.

Corticosteroids mainly mediate their antiinflammatory and immunomodulatory effects via cytosolic receptors and genomic mechanisms, a process that usually takes several hours or days. There is emerging evidence of rapid nongenomic effects of corticosteroids that are mediated by membrane-bound receptors. The hypothesis that persistent nociceptive stimulation leads to changes in glucocorticoid receptor and mineralocorticoid receptor expression in spinal and dorsal root ganglia neurons as well as glia cells and astrocytes was tested in rats with Freund’s complete adjuvant-induced hind paw inflammation. Hind paw inflammation resulted in significant increases in neuronal glucocorticoid and mineralocorticoid membrane receptors in both the spinal cord and the dorsal root ganglia ipsilateral to the inflammation; receptors in microglia and astrocytes were upregulated only to a minor extent. The enhanced mechanical sensitivity of inflamed hind paws was attenuated immediately after glucocorticoid receptor agonist and mineralocorticoid receptor antagonist administration, suggesting acute nongenomic effects consistent with membrane-bound glucocorticoid receptors and mineralocorticoid receptors.

The U.S. Food and Drug Administration has issued a warning that exposure to anesthetics in children in utero and up to 3 yr of age may have deleterious effects on the brain. This article reviews and summarizes the large body of scientific evidence from animal studies showing the potential etiologies with a special focus on nonhuman primates because of their similarities to humans. The author concludes that the preponderance of animal and in vitro experiments find overwhelming evidence that young neurons and glia exhibit morphologic and functional impairments from anesthetic drugs, including volatile agents, propofol and ketamine. While much attention in the past has focused on apoptosis, or cell death, more recent studies show synaptic dysfunction and impaired formation of neuronal circuits. Studies in rodents as well as infant monkeys suggest that timing of anesthesia exposure is more important than duration or type of anesthesia. See the accompanying Editorial Views on pages 693 and 697.

There is great uncertainty over how studies of the effects of anesthetic agents on the developing brain in animal models translate to clinically relevant human scenarios. Human studies have found mixed evidence for an association between anesthesia exposure in early childhood and later deficits in a range of neurodevelopmental outcomes due to confounders, such as comorbidity and the inflammatory response induced by surgery, and insensitive or variable definitions of outcomes. Prospective randomized or carefully matched cohort studies have not found evidence of any adverse neurodevelopment outcomes in children younger than 3 yr who received anesthesia. While there is only weak human evidence to drive a choice of age, duration, and number of exposures that is safe or unsafe, there is strong evidence that a single brief anesthetic exposure in a healthy infant is not associated with poorer neurodevelopment outcome. See the accompanying Editorial Views on pages 693 and 700.