The Effect of Sedation on Cortical Activation: A Randomized Study Comparing the Effects of Sedation With Midazolam, Propofol, and Dexmedetomidine on Auditory Processing.

BACKGROUND: Every day, millions of people undergo surgical procedures facilitated by anesthesia. Yet, there is no clinically accepted measure to predict the effects of sedation or anesthesia on the central nervous system. Auditory brain activation may provide an objective and quantifiable method to measure of the effects of sedation on neuronal processing. METHODS: This is a randomized clinical trial. Forty-eight healthy volunteers were randomly assigned to receive 1 of 3 sedative drugs (midazolam [n = 11], propofol [n = 12], or dexmedetomidine [n = 12]) at a concentration adjusted to achieve mild sedation by self-rating, or to a no-drug control group (n = 13). Participants underwent functional magnetic resonance imaging while listening to music in a 5-minute block design experiment. We tested the hypothesis that mild sedation changes the magnitude or extent of cortical activation of an auditory stimulus. RESULTS: We observed a significant reduction in auditory activation in both the dexmedetomidine (P = .001) and midazolam (P = .029) but not the propofol group (P = .619) when compared with saline control. CONCLUSIONS: Our findings indicate that, compared with saline control, there is a significant reduction of brain activation in the auditory cortex in response to midazolam and dexmedetomidine but not propofol when given at mildly sedative doses. This method serves as a novel approach to quantify the effects of sedative agents in an objective fashion.

The Association Between Progesterone, Estradiol, and Oxytocin and Heat Pain Measures in Pregnancy: An Observational Cohort Study.

BACKGROUND: Hormonal action has been implicated as a possible mechanism for pregnancy-induced analgesia. Previous investigators have reported an increase in heat pain tolerance during labor compared with nonpregnant controls and postulated it was because of the hormonal changes during pregnancy. However, these previous reports did not include measurement of hormonal values. The purpose of our study was to quantitatively test if changes in pregnancy hormone concentrations correlated with changes in temperature ratings. METHODS: This was a prospective cohort study consisting of 32 women scheduled for elective cesarean delivery at term between July 2010 and January 2013. Heat pain threshold and tolerance, estrogen, progesterone, and oxytocin levels were measured twice in each patient at term and again 4 to 8 weeks postpartum. RESULTS: All hormone levels decreased significantly between term pregnancy and the postpartum visit (all P values < 0.029). However, there were no statistically significant differences between term and postpartum heat pain measurements. The mean baseline heat pain threshold was 40.9°C at term compared with 40.3°C °postpartum (P = 0.47; mean change, -0.6°C; 95% confidence interval of change, -1.8°C to +0.7°C). The mean baseline heat pain tolerance was 46.1°C at term and 46.0°C postpartum (P = 0.59; mean change, -0.1°C; 95% confidence interval of change, -0.8°C° to +0.6°C). CONCLUSIONS: Our findings show that amounts of estradiol and progesterone changed significantly between the term and the postpartum visit; however, the thermal pain tolerance did not significantly change. In summary, we did not observe an association between hormonal changes and changes in pain threshold measures. This finding argues against the concept of simple progesterone- or estrogen-induced analgesia in humans.

Why do pregnant women die? A review of maternal deaths from 1990 to 2010 at the University of Alabama at Birmingham.

BACKGROUND: The number of reported pregnancy-related deaths in the United States steadily increased from 7.2 deaths per 100,000 live births in 1987 to a high of 17.8 deaths per 100,000 live births in 2009. Compared to Caucasian women, African American women were nearly 4 times as likely to die from childbirth. To better understand the reason for this trend, we conducted a case-control study at University of Alabama at Birmingham (UAB) Hospital. Our primary study hypothesis was that women who died at UAB were more likely to be African American than women in a control group who delivered an infant at UAB and did not die. We expected to find a difference in race proportions and other patient characteristics that would further help to elucidate the cause of a racial disparity in maternal deaths. METHODS: We reviewed all maternal deaths (cases) at UAB Hospital from January 1990 through December 2010 identified based on electronic uniform billing data and ICD-9 codes. Each maternal death was matched 2:1 with women who delivered at a time that most closely coincided with the time of the maternal death in 2-step selection process (electronic identification and manual confirmation). Maternal variables obtained were comorbidities, duration of hospital stay, cause of death, race, distance from home to hospital, income, prenatal care, body mass index, parity, insurance type, mode of delivery, and marital status. The strength of univariate associations of maternal variables and case/control status was calculated. The association of case/control status and race was also examined after controlling for residential distance from the hospital. RESULTS: There was insufficient evidence to suggest racial disparity in maternal death. The proportion of African American women was 57% (42 of 77) in the maternal death group and 61% (94 of 154) in the control group (P = 0.23). The univariate odds ratio for maternal death for African American to Caucasian race was 0.66 (95% confidence interval [CI], 0.37-1.19); the adjusted odds ratio was 1.46 (95% CI, 0.73-3.01). Longer compared with shorter distance of residence to the hospital was a highly significant predictor (P < 0.001) of maternal death. CONCLUSIONS: We did not observe a racial disparity in maternal deaths at UAB Hospital. We suggest that the next step toward understanding racial differences in maternal deaths reported in the United States should be directed at the health care delivery outside the tertiary care hospital setting, particularly at eliminating access barriers to health care for all women.