Highlights

**Veterans Health Administration**

April 12, 2002

New Device Measures Heart's Pumping Ability from Inside Windpipe

Patients in the operating room or ambulance will be able to have their
heart monitored more safely with a new device developed at the San
Francisco VA Medical Center (SFVAMC) that measures the heart's pumping
ability with sensors placed on the surface of the patient's windpipe.

To diagnose problems such as shock or cardiac arrest, doctors need to
measure the heart's ability to pump blood, or cardiac output. Until now,
the only option for an accurate measurement was to insert a catheter
into a major vein and risk damaging the heart or blood vessels.

"The new device provides real-time monitoring of cardiac output, which
allows you to detect and diagnose a whole range of problems," said Art
Wallace, MD, PhD, an anesthesiologist at SFVAMC and a University of
California, San Francisco associate professor of anesthesiology. "It is
safer and less invasive than other options," he added.

The device uses a network of electrodes to measure the heart's output.
The electrodes are attached to the endotracheal tube inserted into the
patient's windpipe, or trachea. "It sends an electrical signal into the
trachea, and since the aorta is right nearby, the electrodes can detect
changes in the signal caused by the flow of blood," Wallace said. These
variations are used to calculate cardiac output, he said.

"If a patient's having surgery, they are already going to be intubated.
So this device simply takes advantage of that tube's proximity to the
heart to collect some very valuable data for following the patient's
condition," Dr. Wallace said.

Dr. Wallace and his colleagues developed and tested the device at
SFVAMC, and have demonstrated its accuracy in more than 150 patients
there and elsewhere. Their device, known as an Endotracheal Cardiac
Output Monitor (ECOM), will be undergoing review by the FDA for approval
as a commercial product.

Once the ECOM has received FDA approval, doctors should be able to use
it for patients in the emergency room, intensive care unit and operating
room.

Previously, doctors have used pulmonary artery catheters to measure the
heart's output, but studies have shown that these catheters can lead to
serious complications due to damage to the cardiovascular system. Other
devices have attempted to measure cardiac output through electrodes on
the patient's chest, but were less accurate because of interference from
the lungs and other organs.

Testosterone Aids Older Men's Brains, SFVAMC Study Shows

Older men with higher testosterone levels performed better on tests of
cognition in a new study from VA researchers. The study suggests that
older men who are prescribed testosterone supplements may reduce their
risk of cognitive decline, a pre-cursor state to Alzheimer's disease,
the researchers said.

Men's bodies tend to produce less testosterone as they age, and some
doctors have begun prescribing supplements of the hormone to increase
libido and treat other age-related problems in men.

> "The men in the study with higher levels of bioavailable testosterone,
> the testosterone that can reach the brain, did significantly better on
> these cognitive tests than men with lower levels," said lead author
> Kristine Yaffe, MD, chief of geriatric psychiatry at SFVAMC and UCSF
> assistant professor of psychiatry, neurology and epidemiology and
> biostatistics.

However, Dr. Yaffe does not recommend that men begin taking testosterone
to improve cognition. "Our study only looked at natural testosterone
levels and so it doesn't prove that testosterone supplements can prevent
cognitive decline. We will need results of large randomized clinical
trials in older men before we can confidently say that testosterone
supplements are beneficial and safe," she said.

Taking testosterone, or over-the-counter supplements that boost levels
of the hormone, can have side effects including increased risk of
prostate cancer, increased cholesterol levels, acne and male pattern
baldness. Although some previous studies have suggested that
testosterone might benefit the brain, most of these studies were of
younger men.

The study, which was published in the April issue of the Journal of the
American Geriatrics Society, looked at 300 older men enrolled in a
larger study of risk factors for osteoporosis in men that included
cognitive testing.

The cognitive tests measured concentration, memory, attention, language,
and other cognitive skills. When scores on these tests decline
significantly, or are well below average, this serves as a warning of a
high risk of Alzheimer's disease, Dr. Yaffe said.

In addition to testosterone, the researchers measured estrogen and sex
hormone binding globulin, a protein that binds these two hormones.
Although testosterone was linked to better scores on the tests, estrogen
had essentially no effect on performance. Previous studies of women have
shown that higher estrogen levels can reduce their risk of cognitive
decline.

Other research has shown that men have higher levels of both estrogen
and testosterone than women, and that women have a 30 percent greater
risk of developing Alzheimer's Disease, Yaffe said. Some researchers
hypothesize that women's increased Alzheimer's risk is related to lower
hormone levels.

This study doesn't explain how testosterone acts on the brain, Dr. Yaffe
said, but other studies of mice have shown that the parts of the brain
that handle learning and memory tasks are replete with receptors for
testosterone.

In comparing scores, the researchers focused on bioavailable
testosterone, which is not bound to the proteins, because when the
hormone is bound to protein it has essentially no effect on the brain.

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