Ketamine and Treatment-Resistant Depression.

Major depressive disorder affects tens of millions of people each year. One-third of those affected have depression that is resistant to conventional pharmacologic, psychologic, or somatic treatments. Patients with treatment-resistant depression have few remedies other than electroconvulsive therapy or transcranial magnetic stimulation. Recent research has highlighted the promising antidepressant effects of subanesthetic ketamine infusions. This journal course examines the efficacy of ketamine for treatment-resistant depression. Evidence from 10 systematic reviews and randomized controlled trials suggest that most of the researchers concluded ketamine significantly decreased depression severity ratings at short-term assessment intervals, whereas evidence examining the long-term effects is lacking. Ketamine infusion therapy was generally well tolerated, with minimal untoward effects. Large, randomized controlled trials are needed to discern the longer-term efficacy, tolerance, and dependence profiles of ketamine infusions. Optimal dosing schedules to best prolong the antidepressant effects of ketamine have yet to be determined.

Pharmacologic Methods for Preventing Pruritus in Patients Receiving Intrathecal Opioids for Cesarean Delivery.

Neuraxial anesthesia with the addition of opioids is the preferred technique for cesarean delivery because of the safety and efficacy of the technique compared with general anesthesia. However, pruritus associated with neuraxial opioids is reported by patients to be one of the most distressing side effects and is a source of patient dissatisfaction. The incidence of pruritus has been reported to be as high as 100%. This review examines the efficacy of different medications for the prevention of pruritus. An online database search of PubMed, Cochrane Database of Systemic Reviews, Cumulative Index to Nursing and Allied Health Literature, and Google Scholar revealed 127 potential evidence sources. Fifteen randomized controlled studies met the inclusion criteria. Mixed opioid agonist-antagonists and dopaminer-gic receptor antagonists were found to be effective. Antihistamines, opioid antagonists, corticosteroids, and nonsteroidal anti-inflammatory drugs were found to be ineffective for the prevention of pruritus. Results conflicted regarding the efficacy of serotonin receptor antagonists and γ-aminobutyric acid receptor agonists for the prevention of pruritus caused by intrathecal opioid administration. The most promising evidence supported the use of nalbuphine and perhaps ondansetron. Findings of this review were incorporated into protocols for pain management for patients undergoing cesarean delivery and receiving intrathecal opioids.

Usefulness of Cerebral Oximetry in Preventing Postoperative Cognitive Dysfunction in Patients Undergoing Coronary Artery Bypass Grafting.

Postoperative cognitive dysfunction (POCD) following coronary artery bypass grafting has a negative impact on patients physically and psychologically. Of increasing interest is the role that cerebral autoregulation plays in postoperative neurologic outcomes. We sought evidence examining the usefulness of cerebral oximetry data in preventing POCD. Three hundred eighty potential evidence sources were located. Twelve evidence sources (8 randomized controlled trials, 2 retrospective reviews, and 2 prospective cohort studies with a retrospective cohort control) met inclusion criteria. Although the neurologic assessment tools, desaturation definitions, and interventional protocols varied, strong statistical significance links the use of cerebral oximetry information to the prevention of POCD.

Effects of Ondansetron on Attenuating Spinal Anesthesia­Induced Hypotension and Bradycardia in Obstetric and Nonobstetric Subjects: A Systematic Review and Meta-Analysis.

Hypotension and bradycardia are common adverse effects following spinal anesthesia. Ondansetron has been studied in the attenuation of spinal anesthesia­ induced hypotension (SIH) and bradycardia because of its antagonistic effect on the Bezold-Jarisch reflex. The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to determine the efficacy of intravenous (IV) ondansetron in reducing the incidence of SIH and bradycardia. Thirteen RCTs were included in this analysis, totaling 1,225 subjects. Hypotension and bradycardia were summarized using a risk ratio (RR) with 95% confidence interval (CI). Heterogeneity was summarized using randomeffects model for I(2) greater than 50%; otherwise, a fixed-effects model was performed. Intravenous ondansetron reduced the incidence of hypotension in both the all-procedure analysis group (RR, 0.64; CI, 0.45-0.90) and cesarean delivery group (RR, 0.63; CI, 0.45-0.88). For bradycardia, IV ondansetron resulted in reduced risk (RR, 0.31; CI, 0.19-0.50). Findings of our meta-analysis suggest that IV ondansetron may mitigate the risks of SIH and bradycardia following spinal anesthesia.

Prolongation of Subarachnoid Block With Concomitant Use of Intravenous Dexmedetomidine: An Evidence-based Review.

A failed subarachnoid block due to prolonged surgical duration continues to be a challenging problem for anesthesia providers. This evidence-based review updates a 2013 systematic review describing the use of intravenous dexmedetomidine as an extrathecal spinal adjunct capable of extending the duration of a subarachnoid block. Eight randomized controlled trials published after the 2013 systematic review met the inclusion criteria. The evidence continues to support the use of intravenous dexmedetomidine as an effective method for prolonging the duration of motor and sensory blockade and postoperative analgesia in a subarachnoid block, with minimal side effects. This updated review reported a more consistent use of assessment tools measuring motor and sensory recovery, expanded the volume of evidence related to postoperative analgesia, and further validated the safe and efficacious use of intravenous dexmedetomidine in extending the duration of a subarachnoid block. Future studies are needed to evaluate the rescue benefit of intravenous dexmedetomidine in failed subarachnoid blocks converted to general anesthesia resulting from prolonged surgical times.