A descriptive study of venous pressures and gradients while awake and both pre- and post-stent under anesthesia in patients with idiopathic intracranial hypertension.

BACKGROUND: This study aims to explore factors that affect venous sinus pressures and associated gradients while awake and under general anesthesia (GA) both before and after venous sinus stenting (VSS) in patients with idiopathic intracranial hypertension (IIH). METHODS: A retrospective analysis was performed examining pressures and gradients in patients with IIH having undergone awake venography followed by VSS under GA. RESULTS: 174 patients were included. Compared with awake, GA superior sagittal sinus (SSS) pressures were 2.6 mmHg lower (p=0.01) resulting in a total cranial gradient reduction of 2.5 mmHg (p=0.002). The transverse-sigmoid gradient, the most commonly stented segment, did not differ under the two conditions (p=0.30). Regression analyses demonstrated that body mass index, gender, blood pressure, and end-tidal carbon dioxide content significantly affected venous pressures (all p<0.05). After stenting, mean total cranial gradients decreased by 13.2 mmHg while skull base gradients increased by 0.8 mmHg. Stenting resulted in an 84% mean reduction in the target gradient and a mean decrease in SSS pressures by 78% of the target gradient. When cardiopulmonary and anesthetic factors were optimized, GA had a limited effect on the target gradient in most patients (p=0.88). CONCLUSIONS: This study is the largest series to date to report on cerebral venous pressure measurements and gradients recorded while awake and under GA both before and after VSS for IIH. In a well-controlled cardiorespiratory and anesthetic setting, GA venography may provide information that is not substantially inequivalent to that obtained while awake.

Sticks or Carrots? How an Easy-to-Implement Incentive Plan Improved Our Performance on the In-training Exam.

BACKGROUND: In-training examinations (ITEs) are commonly used by residency programs to measure competency in their respective fields. It has been demonstrated that success on the ITE is correlated to First Time Pass Rate (FTPR) on the boards. Therefore, it is important to motivate residents to perform well on these exams. Previous studies indicate positive incentivization may contribute to improvement on examinations. The objective of our study was to determine whether introduction of a positive incentive could improve resident performance on the ITE and/or FTPR on the advanced certifying exam. METHODS: A positive incentive was introduced in 2017 (certificate of commendation, curriculum vitae honor, public recognition, and $500 in their books/travel allowance) to residents who achieved the target score on the ITE (80th percentile). A survey was then provided to these residents to determine which incentives contributed most to their motivation. RESULTS: Before the incentivization, 21 (15.1%) of the previous 149 senior residents reached the target score on the annual ITE. After incentivization, this improved to 28 (30.9%) of 81 (P = .0056). The FTPR on the advanced certifying exam was 90% before incentivization and 97.6% after (P = .14). The survey found that the primary motivators were extra funding, honor on their curriculum vitae, and public recognition. CONCLUSIONS: We found that our residents had significant improvements on the annual ITE after the introduction of positive incentives. This incentivization may be easily implemented by program directors in their respective medical residencies to increase examination performance.

Changes in mean arterial pressure and end-tidal carbon dioxide content affect venous sinus pressures in patients with idiopathic intracranial hypertension: a randomized study.

INTRODUCTION: Little is known about how changes in physiologic parameters affect venous sinus pressure measurements, waveforms, or gradients associated with sinus stenosis. OBJECTIVE: To evaluate the effect of changes in cardiovascular and respiratory physiologic parameters on venous sinus pressure and caliber measurements in patients with idiopathic intracranial hypertension (IIH) undergoing venous sinus stenting. METHODS: In a prospective, randomized pilot study, eight patients with IIH undergoing venous sinus stenting were randomized to one of two groups. Under general anesthesia, patients underwent venous manometry and waveform recordings twice in succession based on assigned physiologic groups immediately before stenting. The mean arterial pressure (MAP) group maintained normocapnia but modified MAPs in two arms to control for temporal confounding: group A1 (MAP 60-80 mm Hg then 100-110 mm Hg) and group A2 (MAP 100-110 mm Hg then 60-80 mm Hg). The end-tidal carbon dioxide (EtCO2) group maintained a high-normal MAP similar to standard neuroanesthesia goals and modified EtCO2: group B1 (EtCO2 24-26 mm Hg then 38-40 mm Hg) and B2 (EtCO2 28-40 mm Hg then 24-26 mm Hg). RESULTS: In group A, superior sagittal sinus (SSS) pressures (ranging from 8 to 76 mm Hg) and trans-stenotic pressure gradients (TSPGs) (ranging from 2 to 67 mm Hg) were seen at MAP of 100-110 mm Hg compared with SSS pressures (4-38 mm Hg) and TSPGs (3-31 mm Hg) at 60-80 mm Hg. In group B, SSS pressures and TSPGs were considerably higher at EtCO2 levels of 38-40 mm Hg (15-57 mm Hg and 3-44 mm Hg, respectively) than at 24-26 mm Hg (8-26 mm Hg and 1-8 mm Hg, respectively). CONCLUSIONS: Despite the small sample size, this pilot study demonstrates a dramatic effect of both MAP and EtCO2 on venous sinus pressures obtained during venography. These findings underscore the importance of maintaining normal physiologic cardiovascular and respiratory parameters during venous sinus manometry.

Changes in End-Tidal Carbon Dioxide Partial Pressure Alter Venous Sinus Pressure Measurements in Idiopathic Intracranial Hypertension.

BACKGROUND: In the diagnosis of venous stenosis associated with idiopathic intracranial hypertension, previous studies have identified significant differences when venous pressures are measured under conscious sedation versus general anesthesia. No previous reports have investigated the effect that respiratory parameters may have on cerebral venous sinus pressure and the associated trans-stenosis pressure gradient. CASE DESCRIPTION: Two patients with idiopathic intracranial hypertension were retrospectively identified from a prospective database wherein venous manometry was performed as part of a venous stenting procedure with waveform recording during changes in end-tidal carbon dioxide level (EtCO2). Upon microcatheterization of the superior sagittal sinus after induction of general anesthesia, both patients were noted to have an EtCO2 of 29 mm Hg. After EtCO2 was corrected to 40 mm Hg, repeat venous manometry was conducted, which demonstrated increased SSS venous pressures from 12.6 to 21.1 mm Hg and 18.4 to 30.3 mm Hg in patients 1 and 2, respectively. In addition, the waveform amplitude increased in both patients after EtCO2 correction. CONCLUSIONS: This series demonstrates that EtCO2 changes have an immediate and pronounced effect on venous sinus pressure measurements with waveform changes that may correlate to increased intracranial pressure. These findings underscore the need to perform measurements of venous sinus pressure gradients under normal awake conditions.

Venous waveform morphological changes associated with treatment of symptomatic venous sinus stenosis.

INTRODUCTION: Venous outflow obstruction is recognized as a contributing factor in a subset of patients with idiopathic intracranial hypertension (IIH). Little is known about venous sinus waveform morphology or how it changes after stenting. METHODS: Fifteen patients with IIH underwent waveform recording during catheter venography and manometry. Ten patients (Group A) with venous sinus stenosis and pressure gradient ≥7 mm Hg underwent waveform recording during awake venography and during stenting under general anesthesia. Five control IIH patients (Group B) without a gradient underwent awake recording only. RESULTS: Group A patients underwent successful stenting with reduction of their gradient from 15.1±6.19 mm Hg to 1.2±0.60 mm Hg. This resulted in an amplitude reduction from 8.3 mm Hg to 2.8 mm Hg (P=0.02). Qualitative evaluation of the waveform yielded a number of novel findings. In Group A before stenting, the observed waveform progressed from an intracranial pressure (ICP)-dominated to central venous pressure (CVP)-dominated waveform. Stenting abolished the high amplitude waveform and smoothed the transition from the intracranial to central venous measurement points. Group B displayed primarily CVP-influenced waveforms distal and proximal to the transverse-sigmoid junction along with respiratory variability of the waveform, absent in 8/10 Group A patients. General anesthesia appeared to blunt the waveform in 5/10 Group A patients. CONCLUSION: The cerebral venous waveform appears to be influenced by both the ICP and CVP waveforms. As measurement moves proximally, the waveform progressively changes to mirror the CVP waveform. Venous sinus stenosis results in a high amplitude waveform which improves with treatment of the stenosis.

$1.8 Million and counting: how volatile agent education has decreased our spending $1000 per day.

STUDY OBJECTIVE: Volatile anesthetic agents comprise a substantial portion of every hospital's pharmacy budget. Challenged with an initiative to lower anesthetic drug expenditures, we developed an education-based intervention focused on reducing volatile anesthetic costs while preserving access to all available volatile anesthetics. When postintervention evaluation demonstrated a dramatic year-over-year reduction in volatile agent acquisition costs, we undertook a retrospective analysis of volatile anesthetic purchasing data using time series analysis to determine the impact of our educational initiative. DESIGN/SETTING: We obtained detailed volatile anesthetic purchasing data from the Central Supply of Wake Forest Baptist Health from 2007 to 2014 and integrated these data with the time course of our educational intervention. PATIENTS: Aggregate volatile anesthetic purchasing data were analyzed for 7 consecutive fiscal years. INTERVENTION: The educational initiative emphasized tissue partition coefficients of volatile anesthetics in adipose tissue and muscle and their impact on case management. MEASUREMENTS: We used an interrupted time series analysis of monthly cost per unit data using autoregressive integrated moving average modeling, with the monthly cost per unit being the amount spent per bottle of anesthetic agent per month. MAIN RESULTS: The cost per unit decreased significantly after the intervention (t=-6.73, P<.001). The autoregressive integrated moving average model predicted that the average cost per unit decreased $48 after the intervention, with 95% confidence interval of $34 to $62. As evident from the data, the purchasing of desflurane and sevoflurane decreased, whereas that of isoflurane increased. CONCLUSIONS: An educational initiative focused solely on the selection of volatile anesthetic agent per case significantly reduced volatile anesthetic expense at a tertiary medical center. This approach appears promising for application in other hospitals in the rapidly evolving, value-added health care environment. We were able to accomplish this with instruction on tissue partition coefficients and each agent's individual cost per MAC-hour delivered.