Geothermal convection through oceanic crust and sediments in the Indian ocean.

Closely spaced heat flow surveys at four sites on the flanks of the Central Indian Ridge and the Southeast Indian Ridge delineate a pattern of oscillatory heat flow which can only result from cellular convection of oceanic bottom water through the oceanic crust and overlying sediment. These cells have a wavelength of 5 to 10 kilometers and are presently active in sea floor 18 x 10(6), 25 x 10(6), and 45 x 10(6) years old of the Crozet Basin and in sea floor 55 x 10(6) years old of the Madagascar Basin. The precise measurement of nonlinear temperature profiles makes it possible to calculate the conductive and convective heat transfer components through the sea floor. Even in the oldest sites, geothermal convection is still a major component of heat transfer through both the crust and sedimentary layers. These observations coupled with the results of earlier oceanwide geothermal studies indicate that more than one-third of the entire surface area of the world's ocean floor contains presently active geothermal convection that is cellular in plan form.

A method for constructing complete annual U.S. life tables.

OBJECTIVES: This report describes a method for constructing complete annual U.S. life tables and for extending the age coverage of the life table to age 100. Previously, annual life tables were based on an abridged methodology and were closed with the age category 85 years and over. In the United States, approximately one-third of the population survives beyond age 85 years. This fact, coupled with improvements in age reporting and the availability of higher quality old-age mortality data, recommends that the life table be closed at an older age. METHODS: The method, similar to that used to construct the decennial life tables, uses vital statistics and census data to calculate death rates for ages under 85 years and Medicare data for ages 85 years and over. Previously, the annual life tables were abridged, and used only vital statistics and census data. CONCLUSIONS: The complete life table methodology described in this report produces estimates of life expectancy at ages 100 years and younger that are consistent with previously published life tables. Complete life tables based on 1996 mortality data compared favorably with published 1996 abridged life tables and with the 1989-91 decennial life tables. The methodology was implemented beginning with final mortality data for 1997.

Age-adjusted death rates: consequences of the Year 2000 standard.

PURPOSE: For nearly 60 years, official U.S. mortality statistics have been age-adjusted using the age distribution from the U.S. population for the year 1940. A new population standard, the projected Year 2000 U.S. standard, has been approved for use by the Department of Health and Human Services (DHHS). It will be implemented for official U.S. Government statistics published for deaths occurring in 1999. The new standard reflects the older age distribution of the population; 6.8% of the population was age 65 years or more in 1940, as compared to 12.6% projected for 2000. METHODS: This paper investigates the consequences of the new age distribution standard by comparing death rates by time, place, and population characteristics, adjusted to both the 1940 and projected 2000 population standards. RESULTS: The new standard changes the level of the age-adjusted death rate for total mortality and for many causes of death, as compared to the 1940 standard. For example, the 1995 death rate for diseases of the heart is 138 per 100,000 population when adjusted using the 1940 standard, but is 296 per 100,000 using the Year 2000 standard. The new standard may change the comparison of age-adjusted rates if there are substantial differences in the age-specific rates. For example, the ratio of age-adjusted death rates for ischemic heart disease in black relative to white males is 1.07 using the 1940 standard, but is 0.96 using the Year 2000 standard. CONCLUSIONS: The new Year 2000 age standard has the potential to change both levels and comparisons of age-adjusted rates. Age-adjustment is an averaging process, and consequently, has the potential to view the data effectively as a whole while possibly obscuring important age-specific details.

Differences in ventricular septal motion between subgroups of patients with heart failure.

BACKGROUND: Septal systolic motion is determined by the end-diastolic trans-septal pressure gradient, and hence is load dependent. OBJECTIVE: To explore septal contribution to left ventricular (LV) systolic function in patients with heart failure. DESIGN: Echocardiograms were identified post hoc from normal subjects and a cohort of patients with heart failure. PATIENTS: Twelve normal subjects and 69 patients with heart failure and normal conduction or left bundle brance block (LBBB) were studied. METHODS: Parasternal short axis LV end-diastolic and end-systolic areas were traced. Using a floating centroid, 32 radial chords were constructed, and perecentage shortening from end-diastole to end-systole was calculated for each chord. MAIN RESULTS: Comparing heart failure with normal conduction and LBBB, LV end-diastolic area was similar (43+/-10 versus 45+/-12 cm(2) not significant), but stroke area was higher in normal conduction (7+/-4 versus 4+/-4cm(2), P<0.05) as was area ejection fraction (0.17+/-0.11 versus 0.10+/- 0.08, P<0.01). In normal subjects, the summed percentage shortening of 10 midseptal chords was similar to that of 10 midfreewall chords (256+/-16% versus 235+/-32%, not significant). In contrast, patients with heart failure and normal conduction had greater midseptal than midfreewall sum med chord shortening (113+/-18% versus 60+/-12%, P<0.05); patients with heart failure and LBBB had paradoxical septal motion (3+/-28, P<0.05 compared with normal conduction). CONCLUSIONS: Patients with heart failure and normal conduction have an enhanced septal contribution to LV systolic function compared with normal subjects. In heart failure with LBBB, this is lost and the area ejection fraction is lower. Strategies to optimize septal function in heart failure warrant further study.

A is for airway: needle techniques to the neck.

The purpose of this article is only to introduce these procedures. More extensive review of the procedures and instruction by a qualified professional are mandatory before proceeding further. The three procedures are very similar, using the same anatomic location and many of the same techniques. They allow you to establish a secure airway rapidly; however, the skills needed to do them must be practiced on a regular basis and performed by people who are familiar with ACLS procedures, are intimately aware of airway anatomy and are skilled at doing endotracheal intubation. Since these techniques are probably used infrequently, a regular training schedule should be established, along with competency testing. Whichever procedure is used will enable appropriately trained and competent personnel to get a patient through a life-threatening situation quickly.

A is for airway: alternative airway devices.

There are many alternative airway devices available on today's market. The type of device that your department uses will depend on your medical control, as well as local protocols and regulations. These devices all require practice, refresher training and on-going skill maintenance. Endotracheal intubation remains the gold standard for airway control; however, proper usage of an alternative airway device can allow patients to be ventilated and oxygenated, even if they cannot be immediately intubated.

Proportion of injury deaths with unspecified external cause codes: a comparison of Australia, Sweden, Taiwan and the US.

BACKGROUND: The proportion of injury deaths with unspecified external cause codes has been used as an indicator of the level of comprehensiveness and specificity of information on death certificates provided by certifiers. OBJECTIVE: To compare the proportion of unspecified external cause codes across countries. METHODS: Multiple-cause-of-death mortality data for people who died in 2001 due to external causes in Australia, Sweden, Taiwan and the USA were used for this international comparison study. The proportion of injury deaths coded as due to an unspecified external cause (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, ICD-10, chapter XX) to all injury deaths in each block was calculated. RESULTS: Sweden (33%) had the highest proportion of use of the least specific code (ICD-10 code X59 exposure to unspecified factor), followed by Australia (17%), Taiwan (13%) and the USA (7%). More than two-thirds of the deceased for whom an ICD-10 code X59 was assigned in Sweden and Australia were those aged > or =65 years, and more than half of them had femoral fractures. The percentage of use of the unspecified codes within specific groups of external causes was relatively high for falls and unintentional drowning. CONCLUSIONS: Caution should be used in examining the compensatory effects of the unspecified external event code (ICD-10 code X59) on specific external causes (especially falls) when making international comparisons. Efforts are needed to educate certifiers to report sufficient information for specific coding so as to provide more useful information for injury prevention.

Certifying diabetes-related cause-of-death: a comparison of inappropriate certification statements in Sweden, Taiwan and the USA.

AIMS/HYPOTHESIS: The aim of this study was to assess differences in the certification practices of physicians in Sweden, Taiwan and the USA with regard to diabetes-related cause-of-death (COD) statements. METHODS: Multiple-cause-of-death data from Sweden (2000), Taiwan (2001) and the USA (2001) were used for this study. All deaths with mention of diabetes anywhere on the death certificate were extracted for analysis. Two types of inappropriate COD statements were: (1) reporting two or more diagnoses per line; and (2) entering an incorrect causal sequence among reported diagnoses. RESULTS: Of those deaths in which diabetes was reported in Part I of the death certificate, American physicians (19%) were less likely to report two or more diagnoses per line than physicians in Sweden (46%) and Taiwan (56%). On the other hand, Swedish physicians (5%) were less likely to report incorrect causal sequences than were their counterparts in Taiwan (21%) and the USA (28%). CONCLUSIONS/INTERPRETATION: These findings reveal substantial differences in diabetes-related COD statements among physicians in Sweden, Taiwan and the USA, implying that caution should be used when interpreting differences in mortality statistics between these countries.

United States life tables, 1998.

The life tables in this report are current life tables for the United States based on age-specific death rates in 1998. Data used to prepare these life tables are 1998 final mortality statistics; July 1, 1998, population estimates; and data from the Medicare program. Presented are complete life tables by age, race, and sex. In 1998 the overall expectation of life at birth was 76.7 years, an increase of 0.2 years compared with life expectancy in 1997. Life expectancy increased from 1997 to 1998 for each of the four race-sex groups for which life expectancy is reported. Life expectancy increased for black males by 0.4 year (from 67.2 to 67.6), for black females by 0.1 year (from 74.7 to 74.8), for white males by 0.2 year (from 74.3 to 74.5), and for white females by 0.1 year (from 79.9 to 80.0).

Deaths: leading causes for 1999.

OBJECTIVES: This report presents final 1999 data on the 10 leading causes of death in the United States by age, race, sex, and Hispanic origin. Leading causes of infant, neonatal, and postneonatal death are also presented. This report supplements the annual report of final mortality statistics and responds to an increasing volume of requests by data users for leading-cause tables with more age and race detail than previously published. METHODS: Data in this report are based on information from all death certificates filed in the 50 States and the District of Columbia in 1999. Causes of death classified by the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) are ranked according to the number of deaths assigned to rankable causes. Age categories used to present leading causes of death in this report represent a substantial expansion from the age categories previously used to present leading-cause data in the annual report of final mortality statistics. RESULTS: In 1999 the 10 leading causes of death were (in rank order) Diseases of heart; Malignant neoplasms; Cerebrovascular diseases; Chronic lower respiratory diseases; Accidents; Diabetes mellitus; Influenza and pneumonia; Alzheimer's disease; Nephritis, nephrotic syndrome, and nephrosis; and Septicemia and accounted for nearly 80 percent of all deaths occurring in the United States. Differences in the rankings are evident by age, sex, race, and Hispanic origin. Leading causes of infant death for 1999 were (in rank order) Congenital malformations, deformations and chromosomal abnormalities; Disorders related to short gestation and low birthweight, not elsewhere classified; Sudden infant death syndrome; newborn affected by maternal complications of pregnancy; Respiratory distress of newborn; Newborn affected by complications of placenta, cord, and membranes; Accidents; Bacterial sepsis of newborn; Diseases of the circulatory system; and Atelectasis. Important variation in the leading causes of infant death is noted for the neonatal and postneonatal periods.

United States life tables, 1997.

The life tables in this report are current life tables for the United States based on age-specific death rates in 1997. Beginning with 1997 mortality data, complete U.S. life tables were constructed using a new methodology that replaces the abridged life table methodology used previously. The methodology is similar to that used in the decennial life tables. Also, life expectancy and other life table values are shown for ages 85 to 100 years for the first time as part of the annual U.S. life tables. Data used to prepare these life tables are 1997 final mortality statistics; July 1, 1997, population estimates; and data from the Medicare program. Presented are complete life tables by age, race, and sex. In 1997 the overall expectation of life at birth was 76.5 years, an increase of 0.4 years compared with life expectancy in 1996. Life expectancy increased from 1996 to 1997 for each of the four race-sex groups for which life expectancy is reported. Life expectancy increased for black males by 1.1 year (from 66.1 to 67.2), for black females by 0.5 year (from 74.2 to 74.7), for white males by 0.4 year (from 73.9 to 74.3), and for white females by 0.2 year (from 79.7 to 79.9).

United States abridged life tables, 1996.

The life tables in this report are current abridged life tables for the United States based on age-specific death rates in 1996. The data used to prepare these abridged life tables are 1996 final mortality statistics and July 1, 1996, population estimates. Presented are tables showing life expectancy and survivorship by age, race, and sex. In 1996 the overall expectation of life at birth was 76.1 years, an increase of 0.3 years compared with life expectancy in 1995. Life expectancy increased from 1995 to 1996 for each of the four race-sex groups for which life expectancy is reported. Life expectancy increased for white males by 0.5 year (from 73.4 to 73.9), for black males by 0.9 year (from 65.2 to 66.1), for white females by 0.1 year (from 79.6 to 79.7), and for black females by 0.3 year (from 73.9 to 74.2).

Why IFR (instrument flight rules)?

INTRODUCTION: Air medical services can use aircraft equipped to fly under visual flight rules (VFR) or instrument flight rules (IFR). IFR allows the pilot to fly safely into lower weather minimums, potentially increasing the number of EMS flights that can be completed. We examined the advantages and disadvantages of both methods of helicopter flight, the potential service gain with IFR capability, and the financial feasibility of using IFR in an urban air medical program. METHODS: Retrospective data were collected on the number of missed flights for Vanderbilt LifeFlight during a 6-year period. Focusing on 2 recent years, we examined the number of flights missed because of weather. Data were prospectively obtained on missed flights that could have been completed with IFR from April 1997 to March 1998. Financial estimates were calculated to determine the revenue potential of an IFR program. RESULTS: An average of 24% of flights were missed from 1991 to 1997. In 1996-97, primary reasons for missed flights included poor visibility and low clouds, conditions in which IFR capable helicopters could fly. Prospective data from 1997-98 indicated an average of 6.7 missed flights per month potentially could have been completed with IFR. Analysis of expenses and revenue suggest that converting a ship from VFR to IFR, which involves both equipment purchases and pilot training, is economically feasible given the potential revenue gained by the number of flights completed during marginal weather conditions. CONCLUSION: Implementing an IFR program increases the safety margin and allows better EMS service to the community.

Age-adjusted death rates: trend data based on the year 2000 standard population.

Age-adjusted death rates are routine mortality risk measures used to compare rates over time or between groups such as those living in different geographic areas. This type of measure eliminates differences that would be caused because one population is older than another. Beginning with mortality data for 1999, the standard population used by the Centers for Disease Control and Prevention's National Center for Health Statistics (NCHS) to calculate age-adjusted death rates based on the Year 2000 estimated population distribution replacing that of 1940 used previously. Comparisons of 1999 mortality data with that of 1998 and earlier years cannot be made unless age-adjusted death rates are based on the same standard population. Changing the standard population generally changes the magnitude of an age-adjusted death rate and may change the magnitude of the differential between two groups. Typically, the change in standard makes relatively little difference in the mortality trend but it can when age-specific rates have divergent patterns. This publication provides age-adjusted death rates by race and sex based on the year 2000 population standard and directs readers to the NCHS Web site for age-adjusted death rates by selected causes.