Neuraxial Anesthesia in Parturients with Thrombocytopenia: A Multisite Retrospective Cohort Study.

BACKGROUND: The primary aim of this study was to estimate the risk of neuraxial hematoma associated with neuraxial anesthetic procedures in thrombocytopenic parturients. METHODS: A multicenter retrospective cohort study design was used to estimate the risk for spinal-epidural hematoma in parturients with a platelet count of <100,000/mm receiving neuraxial anesthesia and the risk of complications in thrombocytopenic parturients who receive general anesthesia. RESULTS: No cases of spinal hematoma were observed in 102 thrombocytopenic parturients receiving epidural analgesia or 71 receiving spinal anesthesia. Including data from the previous published series (total n = 499), the exact binomial 95% confidence interval for the risk of spinal-epidural hematoma was 0% to 0.6%. Given the small number of patients at each specific platelet count, the theoretical risks at individual platelet count strata are presented. Overall aggregate serious morbidity rate in women who received general anesthesia secondary to thrombocytopenia was 6.5% (95% confidence interval, 2.1%-14.5%). CONCLUSIONS: Our work supports the relative maternal safety of neuraxial anesthesia in parturients with mild thrombocytopenia and estimates the maternal complication rate associated with the avoidance of neuraxial anesthesia. Remaining uncertainties at lower platelet counts make a national "low platelet" registry critical to a more accurate assessment of the risk of epidural hematoma and would aid in standardization of anesthesia practice.

Critical action procedures testing: a novel method for test-enhanced learning.

CONTEXT: Human error is a leading cause of adverse events in anaesthesia. Residents' knowledge of how to respond to rare, yet potentially life-threatening events has been shown to deteriorate over time and thus cost-effective educational interventions are indicated. Previous research has shown that test-enhanced learning has the potential to strengthen both clinical knowledge and performance. We hypothesised that critical action procedures (CAPs) tests, similar to those employed by high-performance aircraft pilots, would help improve resident knowledge about how to respond to rare and potentially catastrophic events encountered during the perioperative period. METHODS: Knowledge assessments were administered to 29 first-year anaesthesiology residents over the course of 9 months. Five-minute closed-book tests were administered with fill-in-the-blank questions regarding the American Society of Anesthesiologists' difficult airway guideline, advanced cardiac life support protocols, an institutional airway fire protocol and drug dosing for malignant hyperthermia. Inter-group comparisons were evaluated using the Kruskal-Wallis test. The difference between the pre-test and final test scores for each subsection was determined with the Mann-Whitney U-test for independent samples. RESULTS: Composite subtest scores, when compared with baseline pre-test scores and subsequent scores, and when adjusted for attrition, significantly improved over the course of 9 months (20.5% versus 80%; P < or = 0.001). Likert-based survey data indicated a positive report for attainment of knowledge. CONCLUSIONS: In this longitudinal observational study of first-year anaesthesiology residents, CAPs testing helped improve knowledge about critical events. Although the study was limited by its small number of subjects, a significant attrition rate and the lack of a control group, it demonstrates a cost-effective educational intervention that improved resident knowledge. This intervention may enable residents to transfer learned skills from theoretical testing situations to real-life scenarios. We propose the use and further study of CAPs testing as a cost-effective modality to augment both simulated and actual experiential learning.

Dexmedetomidine and ketamine show distinct patterns of cell degeneration and apoptosis in the developing rat neonatal brain.

OBJECTIVE: Early exposure to common anesthetic and sedative agents causes widespread brain cell degeneration and apoptosis in the developing rat brain, associated with persistent learning deficits in rats. This study was designed to determine whether the α2 adrenergic receptor agonist, dexmedetomidine, produces brain cell degeneration and apoptosis in postnatal day-7 rats in the same brain areas when compared to ketamine. METHODS: Systemic saline, ketamine 20 mg/kg, or dexmedetomidine at 30 or 45 µg/kg were given six times to postnatal day 7 rats (n = 6/group) every 90 min. Twenty-four hours after the initial injection, brain regions were processed and analyzed for cell degeneration using the silver stain and for apoptosis using activated caspase-3 immunohistochemistry. RESULTS: Exposure to ketamine resulted in significant cellular degeneration and apoptosis in limbic brain regions, but nonsignificant changes in primary sensory brain regions. In contrast, dexmedetomidine produced significant cellular degeneration and apoptosis in primary sensory brain regions, but nonsignificant changes in limbic regions. CONCLUSIONS: These data show that ketamine and dexmedetomidine result in anatomically distinct patterns of cell degeneration and apoptosis in the brains of 7-day-old rat pups. The meaning and the clinical significance of these findings remain to be established.

The association between epidural labor analgesia and maternal fever.

The association between epidural labor analgesia and maternal fever is complex and controversial. Observational, retrospective, before-and-after, and randomized controlled trials all support the association, with the most current evidence supporting the mechanistic involvement of noninfectious inflammation. Considering the clinically significant neonatal consequences that have been previously demonstrated, and the possibility of more common subclinical fetal brain injury that animal models imply, the avoidance of maternal fever during labor is imperative. With the current popularity of epidural analgesia in labor, it is important that clinicians delineate how epidurals cause maternal fever and how to block the noninfectious inflammatory response that seems to warm a subset of women laboring with epidurals.