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AbstractConscious perception relies on interactions between spatially and functionally distinct modules of the brain at various spatiotemporal scales. These interactions are altered by anesthesia, an intervention that leads to fading consciousness. Relatively little is known about brain functional connectivity and its anesthetic modulation at a fine spatial scale. Here, we used functional imaging to examine propofol-induced changes in functional connectivity in brain networks defined at a fine-grained parcellation based on a combination of anatomical and functional features. Fifteen healthy volunteers underwent resting-state functional imaging in wakeful baseline, mild sedation, deep sedation, and recovery of consciousness. Compared with wakeful baseline, propofol produced widespread, dose-dependent functional connectivity changes that scaled with the extent to which consciousness was altered. The dominant changes in connectivity were associated with the frontal lobes. By examining node pairs that demonstrated a trend of functional connectivity change between wakefulness and deep sedation, quadratic discriminant analysis differentiated the states of consciousness in individual participants more accurately at a fine-grained parcellation (e.g., 2000 nodes) than at a coarse-grained parcellation (e.g., 116 anatomical nodes). Our study suggests that defining brain networks at a high granularity may provide a superior imaging-based distinction of the graded effect of anesthesia on consciousness.

Standardization and accreditation of fellowship training have been considered in the field of neuroanesthesiology. A prior survey of members of the Society for Neuroscience in Anesthesiology and Critical Care (SNACC) suggested strong support for accreditation and standardization. In response, SNACC created a Task Force that developed curricular guidelines for neuroanesthesiology fellowship training programs. These guidelines represent a first step toward standards for neuroanesthesiology training and will be useful if accreditation is pursued in the future.

The question of accreditation and standardization of neuroanesthesia fellowship training programs in the U.S. has been discussed extensively within the field. Although numerous opinion pieces have been published, there are no data indicating the level of support or opposition for accreditation of subspecialty training among specialists in the field of neuroanesthesia. To address this gap in knowledge, a web-based survey was designed and electronically distributed to members of the Society of Neurosurgical Anesthesia and Critical Care (SNACC) that were practicing in the United States (n339). The primary question assessed support for subspecialty accreditation. In addition, the participants were asked to rate the importance of various curricular elements for a neuroanesthesia fellowship training program. Over a 1-month period, there were 134 responses in total (40 of the sample). Ninety percent of the respondents identified themselves as having a university affiliation. Of the respondents, 64 indicated support for accreditation, 20 indicated opposition, and the remainder was equivocal. Career development, neurocritical care, and intraoperative neuromonitoring were the top 3 subjects thought to be essential to a neuroanesthesia fellowship. The majority supported a 1-year fellowship training program. These data indicate measurable support among members of SNACC for a process toward the accreditation of neuroanesthesia fellowship training programs.

Abstract: Objective. To quantify the effect of an induction dose of midazolam on median nerve somatosensory evoked potentials.Methods. We studied 10 patients undergoing lumbar spine surgery. After an induction dose of intravenous midazolam was given, MNEPs were collected for ten minutes. After ten minutes the patients were intubated and their anesthetic was supplemented with 0.5% isoflurane, narcotic, and N2O.Results. We found a clinically significant decrease in amplitude and an insignificant delay in latency.Conclusion. When midazolam is used as an anesthetic induction agent, a decrease in amplitude can be expected.

The usual method of substantiating collateral circulation of the hand is with Allen's test. We used the pulse-detecting capability of the pulse oximeter to assess the presence of collateral circulation of the hand. Thirty-one patients undergoing radial artery cannulation for intraoperative monitoring were evaluated before cannulation with a modified Allen's test and by pulse oximetry. After the collateral circulation of the hand was tested by the modified Allen's test, a pulse oximeter probe was placed on the index finger. Both radial and ulnar arteries were occluded until no perfusion was detected by the pulse oximeter. The test was repeated twice on each hand, once for each artery. The time to reperfusion after arterial release was recorded. Reperfusion times greater than 15 seconds were considered abnormal. This sequence was repeated postoperatively after the radial artery cannulae were removed. A total of 68 tests were performed before cannulation; 3 showed an abnormal Allen's test, a finding confirmed by pulse oximetry evaluation. The Allen's test was indeterminate 13 times. In all of these cases, pulse oximetry demonstrated collateral blood flow. When collateral circulation was determined to be present by Allen's test, it was also found to be present with pulse oximetry. Three days after cannulation was discontinued, 8 patients had abnormal Allen's test results, a finding again confirmed by pulse oximetry evaluation. Of 15 patients with indeterminate Allen's test results, 12 had collateral blood flow determined by pulse oximetry and 3 had abnormal results. The ability of pulse oximetry to detect collateral circulation was significantly different (P<0.001) when compared with Allen's test both before and after radial artery cannulation. Using the photoplethysmographic component of the pulse oximeter may improve the assessment of collateral circulation of the hand in which arterial cannulation is being contemplated.