This Month in: Anesthesiology

The incidence of acute kidney injury after cardiac surgery with cardiopulmonary bypass (CPB) ranges from 15 to 30%. Renal ischemia has been considered an important pathway in the development of acute kidney injury after cardiac surgery. The hypothesis that normothermic CPB induces impaired renal oxygen delivery, causing a renal oxygen supply/demand mismatch, was tested in 18 patients undergoing cardiac surgery. Despite a 33% increase in systemic perfusion flow during CPB, renal blood flow remained unchanged and a renal oxygen supply/demand mismatch developed due to decreased renal oxygen delivery at a maintained level of renal oxygen consumption. This was most likely caused by renal vasoconstriction, which, together with hemodilution, decreased renal oxygen delivery by 20% during CPB. Impaired renal oxygenation was accompanied by release of a tubular injury marker and was further aggravated after weaning from CPB. See the accompanying Editorial View onpage 199.

The isolated forearm technique (IFT) allows assessment of consciousness of the external world (connected consciousness) through a verbal command to move the hand (of a tourniquet-isolated arm) during intended general anesthesia. An international, multicenter, pragmatic study was conducted to establish the incidence of IFT responsiveness after intubation in routine practice. Of 260 patients enrolled, 12 (4.6%) were IFT responsive after intubation, five of whom reported pain through a second hand squeeze (42% of IFT responders). There were no reports of explicit awareness of intraoperative events by either responders or nonresponders when asked within 24 h of the operation. Despite responders being younger than nonresponders on average, the data do not suggest how to identify those at risk. After adjusting for age in those patients undergoing inhalational anesthesia, nonexposure to volatile anesthetic before laryngoscopy was associated with increased odds of responsiveness. See the accompanying Editorial View onpage 202.

Based on the improved analgesia and accelerated recovery associated with peripheral nerve block (PNB) for total knee arthroplasty (TKA), the hypothesis that receipt of a PNB for TKA would decrease resource utilization and improve outcomes after surgery, including decreased hospital length of stay, decreased rates of hospital readmission, and fewer emergency department visits, was tested in a population-based cohort study of adults having their first primary TKA between 2002 and 2014. Provision of a PNB for TKA was associated with a small but significantly decreased postoperative hospital length of stay and a significantly decreased risk of 30-day hospital readmission. This finding was consistent over time for single-shot PNBs, but the positive effect of continuous catheter techniques on outcomes was less clear. There was no consistent signal toward a decrease in emergency department visits.

Hemodynamic optimization in the perioperative period can reduce morbidity and sometimes mortality. The hypothesis that the degree of stroke volume reduction induced by a lung recruitment maneuver could represent a functional test to suggest preload responsiveness and therefore predict fluid responsiveness and guide fluid therapy was tested in 28 patients mechanically ventilated with low tidal volume under general anesthesia. Sixteen (57%) patients were responders to volume expansion. A 30% decrease in stroke volume during lung recruitment maneuver predicted fluid responsiveness with a sensitivity of 88% (95% CI, 62 to 98%) and a specificity of 92% (95% CI, 62 to 99%). The area under the receiver operating characteristic curve generated for changes in stroke volume induced by lung recruitment maneuver was 0.96 (95% CI, 0.81 to 0.99).

The perioperative use of glucocorticoids for an expanding number of indications is growing, with the principal anesthesia indication being the prevention of postoperative nausea and vomiting. The hypothesis that important adverse outcomes, including the occurrence of postoperative wound infection and hyperglycemia, are related to the perioperative use of glucocorticoids and these relationships are dose-dependent was tested with meta-analysis. Fifty-six randomized controlled trials using perioperative glucocorticoids, having one or more of the outcomes of interest and including 5,607 patients undergoing noncardiac surgery, were identified and subjected to meta-analysis. Perioperative glucocorticoid administration did not result in an increased incidence of any wound infection, deep wound infection, anastomotic leak, impaired wound healing, or bleeding. Glucocorticoids did not influence the length of stay but were associated with a clinically unimportant increase in blood glucose concentrations and a decrease in C-reactive protein concentrations.

Cardiac surgery with cardiopulmonary bypass is associated with a ubiquitous inflammatory response that may, in turn, be associated with adverse postoperative outcomes. The primary hypothesis that high-dose methylprednisolone improves the quality of recovery compared to placebo was tested in this substudy of the Steroids in Cardiac Surgery trial, a double-blinded, placebo-controlled, multicenter randomized controlled trial in which either 250 mg methylprednisolone or placebo was given at anesthetic induction and again just before starting cardiopulmonary bypass. The primary outcome was the quality of recovery over a 6-month period, measured using PostopQRS scale. Recovery improved over time for both the 236 patients in the methylprednisolone group and the 246 patients in the placebo group, but steroids did not alter either the primary endpoint of overall recovery or any of the individual recovery domains.

Widespread neurodegeneration has been observed in rodents following exposure to general anesthetics during the first postnatal week, but anesthesia during the critical synaptogenic period induces dendritic spine formation rather than widespread neuroapoptosis. Dendritic spines are postsynaptic actin-based protrusions that regulate the structure, function, and plasticity of excitatory synapses. To determine whether early anesthesia may lead to changes in synaptic transmission following dendritic spine formation and induce long-term neurodevelopmental behavior impairments, the effects of sevoflurane were evaluated in postnatal day 16 to 17 mice. In addition, to better understand the mechanism underlying anesthesia-induced spinogenesis, the effects of sevoflurane exposure on mitochondrial function were analyzed. Exposure to sevoflurane (2.5% for 2 h) during the critical synaptogenic period altered mitochondrial function and induced a sex-dependent transient imbalance of excitatory/inhibitory synaptic transmission but did not induce long-term behavioral changes.

Patients with liver diseases frequently have abnormal routine diagnostic hemostasis tests. It has been a common practice to attempt to correct these abnormalities by transfusion of blood products before invasive procedures, but recent insights in the hemostatic status of patients with liver disease cast doubt on this policy. Specifically, routine laboratory values in patients with liver disease may not accurately reflect the hemostatic status of these patients, and there is little evidence that routine preoperative hemostasis tests predict the risk for procedural bleeding in patients with liver disease. In this Clinical Concepts and Commentary, evidence is provided that, in contrast to what is suggested by the Practice Advisory for Preanesthesia Evaluation by the American Society of Anesthesiologists, the role of preoperative hemostasis screening for any patient with liver disease undergoing surgery is limited, which has important consequences for perioperative hemostatic management.