What does "brainstem death" mean? A review of international protocols.

PURPOSE: The term "brainstem death" is ambiguous; it can be used to refer either exclusively to loss of function of the brainstem or loss of function of the whole brain. We aimed to establish the term's intended meaning in national protocols for the determination of brain death/death by neurologic criteria (BD/DNC) from around the world. METHODS: Of 78 unique international protocols on determination of BD/DNC, we identified eight that referred exclusively to loss of function of the brainstem in the definition of death. Each protocol was reviewed to ascertain whether it 1) required assessment for loss of function of the whole brain, 2) required assessment only for loss of function of the brainstem, or 3) was ambiguous about whether loss of function of the higher brain was required to declare DNC. RESULTS: Of the eight protocols, two (25%) required assessment for loss of function of the whole brain, three (37.5%) only required assessment for loss of function of the brainstem, and three (37.5%) were ambiguous about whether loss of function of the higher brain was required to declare death. The overall agreement between raters was 94% (κ = 0.91). CONCLUSIONS: There is international variability in the intended meaning of the terms "brainstem death" and "whole brain death" resulting in ambiguity and potentially inaccurate or inconsistent diagnosis. Regardless of the nomenclature, we advocate for national protocols to be clear regarding any requirement for ancillary testing in cases of primary infratentorial brain injury who may fulfill clinical criteria for BD/DNC.

RéSUMé: OBJECTIF: Le terme « mort du tronc cérébral ¼ est ambigu; il peut être utilisé pour désigner soit la perte de fonction du tronc cérébral uniquement, soit la perte de fonction du cerveau entier. Nous avons cherché à établir la signification voulue du terme dans les protocoles nationaux utilisés pour la détermination de la mort cérébrale/du décès selon des critères neurologiques (MC/DCN) du monde entier. MéTHODE: Sur 78 protocoles internationaux uniques sur la détermination de la MC/DCN, nous en avons identifié huit qui faisaient exclusivement référence à la perte de fonction du tronc cérébral dans la définition de la mort. Chaque protocole a été examiné pour déterminer s'il 1) exigeait une évaluation de la perte de fonction du cerveau entier, 2) exigeait une évaluation uniquement pour la perte de fonction du tronc cérébral, ou 3) était ambigu quant à savoir si la perte de fonction du cerveau supérieur était requise pour déclarer un DCN. RéSULTATS: Sur les huit protocoles, deux (25 %) exigeaient une évaluation de la perte de fonction de l'ensemble du cerveau, trois (37,5 %) ne nécessitaient qu'une évaluation de la perte de fonction du tronc cérébral, et trois (37,5 %) étaient ambigus quant à savoir si la perte de fonction du cerveau supérieur était nécessaire pour déclarer le décès. L'accord global entre les évaluateurs était de 94 %, (κ = 0,91). CONCLUSION: Il existe une variabilité internationale quant au sens voulu des termes « mort du tronc cérébral ¼ et « mort cérébrale totale ¼ qui entraîne une ambiguïté et un diagnostic potentiellement inexact ou incohérent. Quelle que soit la nomenclature, nous préconisons que les protocoles nationaux soient clairs en ce qui concerne toute exigence d'examens auxiliaires dans les cas de lésion cérébrale infratentorielle primaire qui pourraient répondre aux critères cliniques de MC/DCN.

Effective Vaccination Policies.

We present a framework for modeling the spread of pathogens throughout a population and generating policies that minimize the impact of those pathogens on the population. This framework is used to study the spread of human viruses between cities via airplane travel. It combines agent-based simulation, mathematical analysis, and an Evolutionary Algorithm (EA) optimizer. The goal of this study is to develop tools that determine the optimal distribution of a vaccine supply in the model. Using plausible benchmark vaccine allocation policies of uniform and proportional distribution, we compared their effectiveness to policies found by the EA. We then designed and tested a new, more effective policy which increased the importance of vaccinating smaller cities that are flown to more often. This "importance factor" was validated using U.S. influenza data from the last four years.

The effects of income inequality and income level on mortality vary by population size in Texas counties.

OBJECTIVES: This study uses the counties of Texas to empirically test the predictions of Wilkinson's theory on the role of income and inequality in explaining health differentials in populations. Wilkinson predicts (1) that health is affected more by income inequality than average income in areas with large population, and (2) that health is affected more by average income than income inequality in areas with small population. We investigate how large the population of a unit must be for income inequality within the unit to affect mortality. METHODS: Measures of income inequality were computed from the 1990 U.S. census data and mortality was computed from Vital Statistics data. Poisson regressions estimated the age-adjusted relative risk of the top quintile relative to the bottom quintile for equality and for income among selections of Texas counties based on population size. County ethnic composition, educational level, and health care access were controlled for. RESULTS: Among counties with populations greater than 150,000, the risk of death was lower in counties with more equal income distribution than in counties with less equal income distribution. Among counties with population less than 150,000, median income affected relative risk in counties with less than 30 percent Hispanics, but not in those with more than 30 percent Hispanics. CONCLUSIONS: This study provides some support for the predictions of Wilkinson's theory.

Assessing number-specific error in the recall of onset of last menstrual period.

The goal of this investigation was to determine whether women who did not report preferred numbers for their last menstrual period (LMP) may be a group of women who are particularly careful in keeping track of their menstrual cycles and therefore have more accurate LMP dating--based on a comparison with ultrasound examinations. We also sought to estimate the frequency with which preferred numbers are reported in different sources of data and for different subgroups of women. First, we examined the 1987 California birth certificates in which LMP was collected at the time of birth (n = 504853). We also examined the records of 43880 women participating in the California Alpha-fetoprotein (AFP) Screening Program between 1986 and 1987, for whom gestational ages based on both early ultrasound examination and LMP were collected before 20 weeks of gestation. In the 1987 California birth certificates, seven numbers--1, 5, 10, 15, 20, 25 and 28--were recorded more frequently than expected. An estimated 12.9% of these records had preferred numbers. The most frequently recorded number was 15, occurring 2.5 times more often than expected (P < 0.01). In the data of the AFP Screening Program, the same seven numbers were preferred, and approximately 7.9% of records were affected by number preference. Comparisons with measurements of gestational age based on ultrasound demonstrated that LMP-based gestational ages in which non-preferred numbers are reported for the LMP are slightly more accurate than those in which preferred numbers are reported (P < 0.01). In most cases, number preference appears to introduce small errors into measurements of gestational age, probably as a result of rounding. Thus, the effect of number preference may be primarily of interest to research studies in which small errors in the measurement of gestational age will have a significant impact on findings.

Cost-effectiveness of childhood immunization reminder/recall systems in urban private practices.

OBJECTIVE: To assess cost and cost-effectiveness of immunization reminder/recall systems in the private sector. METHODS: A manual postcard system (mail) was compared with a computer-based telephone system (autodialer) and control. Costs included time costs and the cost of equipment and supplies. The cost per child and the incremental cost of the intervention relative to control were computed. Cost-effectiveness ratios were computed for return visits and for immunizations delivered. RESULTS: The average cost per child was $2.28 for the mail group and $1.47 for the autodialer group. The incremental visit cost relative to the control was higher for the mail group ($9.52) than for the autodialer group ($3.48). The autodialer was more cost-effective in delivering immunizations: $4. 06 per extra immunization (autodialer) versus $12.82 (mail). CONCLUSIONS: Excluding start-up costs, the autodialer system was most cost-effective. Including autodialer equipment costs, the autodialer system is more cost-effective only for larger practices.

Public health workforce information: a state-level study.

A two-stage sample survey was used to estimate the size of Texas' professional public health workforce and to describe its composition in terms of employment settings, job characteristics, and individual characteristics. The estimated 17,700 public health professionals employed in 1995 represented approximately three percent of the state's total health workforce. About 55 percent of all these professionals worked in agencies that provide population-based public health services. An estimated seven percent had formal public health education. These findings raise issues concerning the numerical adequacy of the state's supply of public health professionals, the adequacy of their educational preparation, and the human resources capacity of the state's official public health agencies.

Searching for preventable causes of child mortality in Texas: trends in the major causes from 1987 through 1996.

We ranked the underlying causes of child deaths in Texas from 1989 through 1991 for the groups aged 1 through 4, 5 through 9, 10 through 14, and 15 through 19 years. External causes (injuries) accounted for 66% of child deaths, and 5 accounted for at least 100 deaths each: motor vehicle accidents, homicide, suicide, drowning, and burns. Of the deaths that had potential for primary prevention, more than 95% involved accidents, suicide, and homicide. Of the smaller number of deaths that had potential for secondary prevention, treatment of infectious conditions had the greatest potential. From 1987 through 1996, child deaths from all causes averaged 2498 per year. Natural causes averaged 871 per year; external causes averaged 1627 per year. Among the external causes, annual averages for accidents were 1089 deaths; for motor vehicle accidents, 703; for homicide, 334; and for suicide, 187. We used linear regression analyses to estimate trends in deaths and mortality rates. The only categories that experienced an increased number of deaths, despite a 12% increase in the population, were deaths from all causes in the adolescent age groups; from natural causes in all but the group aged 1 through 4 years; from external causes in the adolescent age groups; from suicide in all but the group aged 1 through 4 years; and from homicide in all age groups. The increased number of deaths was often lower than the increase in the population, resulting in lower mortality rates. The only mortality rates that increased were those from all causes in the group aged 15 through 19 years; from natural causes, in both adolescent age groups; from suicide, in the group aged 10 through 14 years; and from homicide, in all but the group aged 5 through 9 years. These trends suggest that primary prevention of child deaths in Texas should focus on external causes, particularly motor vehicle accidents, homicides, and suicides.

A triethnic comparison of intracerebral hemorrhage mortality in Texas.

Intracerebral hemorrhage (ICH) is a significant cause of stroke death. Little is known about the relative risk of Hispanic Americans (HAs), African Americans (AAs), and non-Hispanic whites (NHWs) for ICH mortality. Based on the high prevalence of hypertension in AAs and the low prevalence of hypertension in HAs, we expected AAs to have the highest ICH mortality rates and HAs the lowest. Race/ethnic age-specific ICH mortality rates were calculated from Texas vital statistics for the years 1980 through 1995. Rate ratios (RRs) are reported with NHWs as the referent group. There were 15,042 deaths due to ICH in Texas during this time. In the 45- to 59-year age group, AAs had an RR of 4. The RR for HAs was 1.9. In the 60- to 74-year age range, AAs had an RR of 1.7 and HAs had an RR of 1.3. In the 75+ age group, the rates were similar among all three race/ethnic groups. We conclude that there is a significant interaction of age and race/ethnicity for ICH. At younger ages, AAs and HAs have the highest ICH mortality rates. Access to care and socioeconomic status may play a role in the unexpectedly high ICH mortality rates in HAs.

Searching for preventable causes of infant mortality in Texas.

Texas' health objectives include reducing the infant mortality rate from 8.1 per 1000 live births in 1990 to no more than 7 per 1000 by the year 2000. To help target potentially preventable causes of infant mortality, we examined the underlying cause of each of the 2545 infant deaths that occurred in Texas during 1990. Potential existed for primary prevention of the underlying cause of at least some of 778 infant deaths and for secondary prevention by treating the underlying causes of 1127. The following appear to be the most promising targets and strategies for prevention: causes of neonatal mortality by improving the clinical care of high-risk newborns; sudden infant death syndrome by having infants sleep in the supine position; respiratory complications of preterm birth by preventive and therapeutic surfactant; death from bacterial infections by optimal antibiotic therapy; injuries and accidents by optimal parental supervision; preterm birth and adverse pregnancy outcomes by optimal prenatal, obstetric, and neonatal care; and neural tube defects by adequate paraconceptual folic acid.

African Americans and women have the highest stroke mortality in Texas.

BACKGROUND AND PURPOSE: Hispanic American (HA), African American (AA), and non-Hispanic white (NHW) populations are well represented in Texas. The Texas HA population is 95% Mexican American, affording comparison with other Hispanic populations. From risk factor profiles we expected stroke mortality to be highest in AAs and HAs. We also expected stroke mortality to be considerably higher for men than for women based on previous data. METHODS: We used International Classification of Diseases, 9th Revision, codes 430 to 438 to search Texas vital statistics data for the 5-year period from 1988 through 1992. Race/ethnic differences are presented in age- and sex-specific format to avoid masking the important interaction of age and sex with stroke mortality. RESULTS: Women constituted 61% of the 40,346 stroke deaths in Texas during this period. The ratio of stroke deaths for women versus men approximates the ratio of women to men in the population. AAs had a threefold to fourfold increased stroke mortality relative to NHWs at young ages. At older ages, when stroke mortality is the highest, the stroke mortality rate in NHWs approached the stroke mortality rate of AAs. HAs had a significantly higher rate of stroke mortality at younger ages relative to NHWs but a significantly lower rate at older ages. CONCLUSIONS: Measures to prevent stroke mortality should emphasize its predilection for young AAs and women. A rigorous surveillance project is needed to determine whether stroke mortality is underestimated in the HA population.

Immunization prevalence rates for infants in a large urban center: Houston/Harris County, 1993.

Immunization prevalence rates in Houston/Harris County for children 18 to 24 months were determined by a prospective immunization survey conducted from January through May 1993. Rates for immunization series were very low for 2-year old children regardless of infant gender, maternal age, maternal education, or immunization provider (public verus private). African-American infants had the lowest likelihood of completing their immunization series. Infants who had received their first immunization within the scheduled time frame were most likely to complete the series. More than 57% of caregivers could not state accurately the immunization status of their children. Barriers to immunizations perceived by caregivers were identified as medical barriers, vaccine cost, and transportation. New goals for infant immunization delivery have been established by the national Comprehensive Children's Immunization Initiative. To meet these goals, large urban centers like Houston/Harris County must use resources through both public and private sectors, ie, networked, confidential immunization tracking system; enhanced and sustained educational efforts; and expansion of vaccine availability.

Ethnic differences in causes of infant mortality: Texas births, 1989 through 1991.

The mortality rate of African-American infants in Texas is about twice those of Anglo and Hispanic infants, due at least partly to their increased risk of preterm and low-weight birth. We examined the underlying causes of infant deaths from 1989 through 1991 for specific causes that accounted for the racial difference and for those that were associated with those adverse pregnancy outcomes. The overall infant mortality rate was 8.27 per 1000 live births (6.80 for Anglo, 7.72 for Hispanic, and 15.32 for African-American infants). About 37% of all infant deaths (but 48% of African-American deaths) were associated with adverse pregnancy outcomes; excluding these deaths reduced the overall rate to 5.20 per 1000 (4.59 for Anglo, 5.03 for Hispanic, and 8.05 for African-American infants). Accordingly, reducing adverse pregnancy outcomes in African-American women will reduce but not resolve the discrepancy in racial infant mortality rates. Infant mortality rates for 30 of the top 59 causes of death were at least 1.5 times higher in African-American than in Anglo and Hispanic infants, while a comparable excess in Hispanic infants was noted only for anencephaly; Anglo infants did not have an excessive mortality rate for any of the 59 causes. Reduction of the racial infant mortality rate discrepancy in Texas will require clarification and correction of factors that place pregnancies of African-American women at increased risk for adverse pregnancy outcomes and those that place their infants at increased risk for death from a wide range of causes.

Proportional differences in births and infant mortality rates among the triethnic population in Texas from 1984 through 1986.

Birth at preterm gestation and/or with low birth weight is a major predictor of the infant mortality rate, which is twice as high in African-American as in Anglo and Hispanic infants in Texas. This study examined the relative proportions of Anglo, African-American, and Hispanic births that occurred in Texas at specific gestational ages and birth weights, and the neonatal, postneonatal, and infant mortality rates associated with those births. African-American infants showed a systematic tendency to be born at earlier gestational ages and with lower birth weights than did Anglo infants, while Hispanic-Anglo differences were limited to a small excess of preterm but not low weight Hispanic births. Preterm and low-birth-weight African-American infants had neonatal and infant mortality rates that were lower than those of Anglo infants, but that benefit was inadequate to compensate for the greater proportion of African-American births that were at risk. No consistent difference could be identified between Hispanic and Anglo infant mortality rates. We conclude that the birth weight and gestational age predictors of infant mortality reflect the combined effects of two ethnic-specific factors: the mortality rates at specific birth weights and gestational ages, and the proportions of births that are at risk. The biological and/or sociological causes for these ethnic differences in pregnancy outcomes and mortality risk need to be identified if the mortality rate of African-American infants in Texas is to be reduced.

Supply and distribution of primary care physicians and medical school enrollments in Texas.

The search for policy options to contain health-care costs has sparked renewed national interest in reducing medical school enrollments. Concurrently, the goals of improving the specialty and geographic distribution of physicians have proved elusive both at the state and national levels. This study reexamines and reaffirms the conclusions of an earlier study that suggested enrollment reductions in Texas might decrease rather than increase the supply of primary care and rural physicians.

Patterns of infant mortality in relation to birth weight, gestational and maternal age, parity, and prenatal care in Texas' triethnic population, 1984 through 1986.

Neonatal, postneonatal, and infant mortality rates were determined in Texas' triethnic populations from 1984 through 1986 with relation to gestational age, birth weight, maternal age, parity, and prenatal care. All mortality rates were increased in the black population. Preterm birth and low birth weight were both strong predictors of mortality. The neonatal mortality rate of preterm black infants was actually lower than those of the other ethnic groups, but the increased proportion of black pregnancies that resulted in preterm and low-birth-weight births, together with their elevated postneonatal mortality rates, produced an infant mortality rate that was twice as high in black as in Anglo and Hispanic infants. The infant mortality rate was highest in infants born to mothers younger than 18 years, of high multiparity, and with inadequate or no prenatal care. Recognition of these associations should enable improved planning of care for all Texas women and their infants.

Patterns of birth weight in relation to gestational age, maternal age, parity, and prenatal care in Texas' triethnic population, 1984 through 1986.

This study investigated the distribution of birth weights in Texas' triethnic populations for the years 1984 through 1986 (more than 900,000 births) with regard to gestational age, maternal age, parity, and visits for prenatal care. African-American infants had a systematic tendency to be born earlier and smaller than Anglo and Hispanic infants. Among the maternal age categories, mothers younger than 18 years had the highest rates of preterm birth (less than 37 completed weeks), very low birth weight (less than 1500 g), and low birth weight (less than 2500 g). High multiparity and inadequate visits for prenatal care were associated with increased rates for the same adverse pregnancy outcomes, and the risks were always much higher in African-American than in Anglo and Hispanic women of the same age, parity, and prenatal care categories. The predictive values of these associations for individual pregnancies were limited, but their recognition may improve the planning of prenatal care for Texas women and of the anticipatory care for their infants.

Brain metastases and testicular tumors: long-term survival.

In this updated and expanded retrospective analysis, the treatment records of 24 patients with brain metastases from nonseminomatous germ cell testicular tumors (NSGCT's) treated at the Indiana University Department of Radiation Oncology from 1975 through 1988 were reviewed. All patients received standard cisplatin-based induction chemotherapy. These patients were divided into three groups. Group 1 (n = 10) consisted of patients who presented initially with brain metastases and had no prior systemic treatment. Group 2 (n = 4) consisted of those patients who, after achieving a complete response (CR) with cisplatin, vinblastine, and bleomycin (PVB) +/- doxorubicin, developed a relapse confined to the brain. Group 3 (n = 10) consisted of those patients who were initially treated with PVB +/- doxorubicin or bleomycin, etoposide, and cisplatin (BEP) and eventually developed progressive disease and brain metastases. Group 1 was treated with whole brain irradiation (WBRT) and PVB +/- doxorubicin or BEP. Group 2 was treated with WBRT, cisplatin-based chemotherapy +/- surgical excision. Group 3 was usually treated with WBRT palliatively. Six patients, three in Group 1 and three in Group 2, are alive and disease-free with follow-up of 5+ years from beginning WBRT. Two additional patients in Group 1 survived 5+ years from beginning WBRT before dying with disease. No patient in Group 3 survived. Patients with brain metastases who have potentially controllable systemic disease should be treated curatively with WBRT (5000 cGy/25 fractions) +/- surgical excision and concomitant chemotherapy.

Estimating the impact of state manpower policy: a case study of reducing medical school enrollments.

Perceptions of an impending oversupply of physicians have prompted proposals to reduce medical school enrollments in a number of states. Most of these states are also concerned with improving the specialty and geographic distribution of their medical manpower. The present study provides estimates of the effects of reduced numbers of in-state medical school graduates upon the future supply of physicians in Texas, and examines the medical school origin, medical specialty, and practice location of selected groups of Texas physicians. The results suggest that in Texas enrollment reductions would have no significant impact on physician supply over the next 15 years, and might actually prove counterproductive in altering physician distribution. The analysis of Texas data illuminates the unintended consequences likely to accompany a policy option that has been widely embraced by state officials largely on the basis of its intuitive appeal.

Flight-skill decay and recurrent training.

This article addresses the problem of flight-skill decay. The complexity of the problem is outlined with regard to identifying the nature and extent of decayed skills. It is suggested that cognitive/procedural skills are more prone than control-oriented skills to decay over periods of disuse. Effective recurrent training methods offer the most promise in forestalling loss of proficiency. Several such methods are described, and the importance of cognitive training is emphasized. Finally, criteria are noted for evaluating the utility of recurrent training media. The theories and practical measures discussed apply to many skills other than those of flying.