July 2008

Here are a couple of medical factoids you might find interesting.

1. Where is the best place to have an out-of-hospital cardiac arrest? Your first thought is probably “No place!” I agree, but that isn’t one of the possible answers. Your choices are between different public facilities such as shopping malls, airports, and so on. Give up? The answer is a gambling casino, in which everyone is under continuous video surveillance, presumably to catch cheaters.Of all public facilities, gambling casinos have the highest resuscitation rates and rates of survival to hospital discharge. As soon as someone collapses, the person watching the monitor sends help. So relax, have a few free mixed drinks, and get some more chips. “We’ll leave the defibrillator on for you.”
    
   
2. Have you ever seen a map of the US with cancer death rates (click to view map) shown for each state? There are large differences between the rates for different states. While Utah is in the group of states with the lowest cancer death rates (dark blue states), Utah has the lowest death rate from all types of cancer of any state. This result is probably due to the fact that most Utah residents are Mormons, and Mormons smoke and drink less than most Americans. It’s part of their religion. Both alcohol and tobacco cause a variety of cancers. In fact, about 30% of all cancer deaths are due to tobacco alone.

Depressed patients suffer greatly during the weeks or even months required for antidepressants to provide relief.

When I was a resident - a physician-in-training, I was once called to help with a resuscitation from a cardiac arrest. A patient from the psychiatry unit had hanged himself in the bathroom with a bed sheet. By the time I arrived, the doctors and nurses had cut him down and were doing CPR. Unfortunately, they were too late. They resuscitated him, but he later died in the ICU. This certainly brought home the point about depression being a potentially fatal illness. Even before this happened, something one of my medical school professors once said had stuck permanently in my head: “Depressed patients may kill themselves, even in the hospital.”

Antidepressants take weeks or even months to work

One of the most important limitations of the current treatment of depression is the long delay, usually two weeks or more, between beginning treatment and improvement in mood. Since the first or even second antidepressant given may not be effective, depressed patients often suffer tremendously while waiting for treatment to make them feel better. An article in the June 2008 Journal of Clinical Psychiatry reviews this problem of the need for a more rapid response to depression treatment.

Suicide risk increases in the month after a patient starts antidepressants

Although the long-term risk of suicide in depression is decreased by drug treatment, there is an increased risk of suicide during the first month after a patient starts an antidepressant. The reason for this is unclear. It may be that energy and motivation improve first, while improvement in depression and suicidal tendency occurs more gradually. Thus, the patient may still be suicidal when he or she has more energy and motivation to act on self-destructive impulses. A more rapid response would hopefully allow a faster return to health and a decreased chance of suicide.

Ketamine can relieve even treatment-resistant depression within hours

Recently, the anesthetic drug ketamine, when given intravenously, has been shown to produce a rapid (within 2 hours) and sustained (1-2 weeks) antidepressant effect in patients with previously treatment-resistant depression (depression which is not relieved after multiple different antidepressant drugs have been tried). This is a remarkable result, since no other depression treatment has ever produced such a rapid response. Interestingly, ketamine is closely related to phencyclidine (PCP, “angel dust”). Ketamine is thought to affect the metabolism of the brain transmitter glutamate, and further research is ongoing.

Another treatment, intravenous thyroid-stimulating hormone (TRH) may produce an antidepressant response in hours in some patients, but larger, well-controlled studies are necessary to confirm these results.

Electroconvulsive therapy (ECT) is a very humane and effective treatment

Electroconvulsive therapy (ECT, “shock therapy”) produces faster relief of depression than medication. Half of patients improve after one week of treatment, and many studies report improvement after one treatment. Although the public perception of ECT is often negative, ECT has long been considered the most effective and the most rapidly effective treatment for depression.

The future will likely bring better, faster-acting depression treatments

Treatments which produce an antidepressant response within hours to days are not available now but would prevent much suffering. Hopefully, such treatments will be available soon.

Are you a mugger looking for an easy mark? If an old person with a cane is what you have in mind, Centerville, Ohio might not be the best place to look. The elderly at Centreville’s St. Leonard retirement village are taking cane-fighting classes, according to a 6/12/08 Wall Street Journal article.

The class provides the health benefits of exercise and also teaches the elderly to defend themselves with something they may already own and can carry almost anywhere.

Practiced with regard to physical limitations, martial arts can have significant health benefits for the elderly. Any aerobic exercise is beneficial. Another martial art, Tai chi, which involves slow, graceful movements, develops strength and balance and has been shown to help prevent falls in the elderly.

The cane has many advantages as a weapon. A cane is a weapon which can be carried anywhere legally, unconcealed. No one will tell you can’t carry a cane on an airplane. With training, the cane is an extremely effective, even lethal weapon. When I worked as a prison physician, I always refused to write prescriptions for canes. Aluminum crutches, yes. Wooden canes, never.

An important safety precaution to observe when learning cane or stick fighting, unless you are practicing alone, is to always wear safety glasses.

A rifle-sized laser weapon system - click image to enlarge

Laser attack

US naval intelligence officer Lt. Jack Daley and his Canadian pilot made a third pass over the Russian ship. April 4, 1997 was a bright, cloudless day over the Strait of Juan de Fuca, north of Seattle, Washington. Daley and the pilot were flying a helicopter and photographing a Russian cargo ship, the Kapitan Man, which was suspected of spying on US submarines. As Daley photographed the ship’s antenna array he saw a blinding flash. He turned his head and rubbed his eyes.

After returning from the mission, Lt. Daley and the pilot began to have headaches and visual problems. One of the photographs of the ship showed a laser light shining from the bridge of the Kapitan Man. Both men suffered permanent eye damage, and medical examination of the men was consistent with laser-induced retinal damage.

Lasers are widely used for modern warfighting

The energy of the laser light is confined to a very narrow beam. There are many types of lasers which differ in wavelength, energy, and other characteristics. Lasers have many uses on the modern battlefield. High energy lasers (HEL) can potentially damage or destroy structural targets such as ships, aircraft, and missiles. However, HELs are not thought to be widely available or practical at present, are not primarily intended for use against personnel, and will not be discussed further in this article. Of course, much of the information on military lasers is classified, so our understanding of laser weapons must be considered incomplete.

Low energy lasers (LEL) are widely used in the armed forces of all countries to guide and control conventional weapons. They can be small, portable, hand-held, and battery operated. LELs can also be directly used as weapons. LELs can destroy or blind many of the battlefield sensors used in fire control systems.

However, the most important use of LELs is against the human eye, the organ most sensitive to laser light. Nonweapon LELs in range finders and targeting system are dangerous to the eye at a range of several miles. The hazardous range may be tens of miles if magnifying optics such as binoculars are in use. Magnifying optics placed in front of the eye increase the susceptibility of the eye to laser-induced damage.

Retinal photograph: retinal hole and preretinal hemorrhage after exposure to a Nd:YAG laser. Photo: US Army.	Retinal photograph made after multiple acute retinal burns from a Nd:YAG laser rangefinder. Photo: US Army.

When used against the eye, LELs can cause temporary visual impairment such as flash blindness, discomfort, or disabling glare. Such lasers can cause permanent visual impairment by destroying part of the retina, the inner coating of the back of the eyes, or by causing bleeding in the eye.

Protection – optical filters

One method of protecting the eyes from a laser is the use of glass or plastic optical filters which block the laser beam. Optical filters can be defeated by using a more powerful laser or a laser with a light frequency not blocked by the filter.

Some lasers can be tuned to change the frequency of the emitted laser light (frequency-agile laser). A filter which would protect against all of the light frequencies which can be emitted by frequency-agile lasers would make it impossible for the soldier to see well enough to fight.

Examples of US Army laser eye protection. Photo: US Army.

Protection - indirect viewing

Another means of protection is indirect viewing: avoiding the use of one’s own eyes to look directly at the battlefield. Instead, one looks through a sensor, such as a low light television camera which will not transmit laser light to the eye. Of course, the sensor will be destroyed or inactivated after it is hit by a laser, but the sensor can then be replaced or repaired, and vision will be preserved.

Protection - the black eye patch

Another seemingly odd method of protection is to wear a black eye patch on one eye. After a laser attack at least one eye is preserved. However, after removal of the eye patch, the remaining eye will be vulnerable, but protective or evasive measures can then be taken.

The future

Laser weapons have not been widely used so far. In addition to the Kapitan Man incident described above, the British downed several Argentine planes during the Falklands War by using anti-eye lasers. Recently, pilots of a number of commercial airliners have been targeted with lasers during landing and takeoff. Despite the existence of international agreements which attempt to restrict the use of laser weapons, more widespread military use of these devices seems inevitable.

Human victims of kuru, a disease similar to mad cow disease, Papua New Guinea, 1963.

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You can acquire the disease kuru by eating your dead relatives. Kuru was discovered in the Fore people of Papua New Guinea and was transmitted by ritual cannibalism when the brains and other tissues of deceased tribe members were eaten at funeral feasts. Kuru, mad cow disease (bovine spongiform encephalopathy, or BSE) and variant Creutzfeldt-Jacob disease (vCJD) of humans, are all caused by prions. Prion diseases are a group of transmissible, degenerative, uniformly fatal brain diseases with very long incubation periods (the amount of time between infection and the appearance of illness), usually measured in years.

The Same Agent Causes Mad Cow Disease (BSE) and a Human Disease (vCJD)

BSE and vCJD are among the most important prion diseases. Both BSE and vCJD are caused by the same transmissible agent. vCJD is a rare but important disease in humans. The infectious agent which causes BSE can occasionally be transmitted by contaminated beef to humans, causing vCJD. BSE infections in cattle have also caused significant economic damage to the beef industry.

Cows with BSE behave abnormally and may be aggressive, thus the name “mad cow disease.” vCJD usually begins with depression, anxiety, and withdrawal, and then causes problems with walking and speech, hallucinations, mental decline, and death.

Kuru

The first prion disease described in humans was kuru. Discovered in the Fore people of Papua New Guineau, kuru was more common in women and children because while men ate the flesh of the deceased, the women and children ate the brains, the tissue in which most of the infectious agent is concentrated.

Kuru begins with headache and joint pain, followed by incoordination, tremor, involuntary movements, and mental decline. Death occurs within 3 months to 2 years. No one born since this ritual cannibalism ended in the mid-1950s has developed kuru, but those exposed before the practice ended continue to develop the disease as long as 50 years after exposure.

BSE and vCJD Outbreaks in the UK

An outbreak of BSE in cattle began in the UK in the 1980s. Transmission of the BSE agent to humans in contaminated beef was discovered in the UK when human vCJD cases were reported there in 1996. There have been almost 200,000 cases of BSE in the UK. Cooking beef does not appear to prevent infection, but the number of BSE and vCJD infections in the UK has decreased greatly since control measures were adopted there.

So far, 3 BSE infected cows have been reported in the US. The US has adopted regulations to keep BSE contaminated material out of human and animal food. The US has also banned the importation of cattle and cattle products from countries with BSE or at risk for BSE. There have been 2 cases of vCJD in the US, both apparently acquired in the UK.

Stop Eating Beef?

Although the eventual number of people who will develop vCJD is unknown, the disease is extremely rare, even in the UK where almost all of the vCJD cases in the world have been reported. The US Centers for Disease Control calculated that the risk of getting vCJD in the UK is very low: 1 case per 10 billion servings of beef, and the risk in the US is almost certainly much lower.

Dr. John Bartlett, Chief, Infectious Diseases, Johns Hopkins University School of Medicine, estimated that the risk of getting vCJD from eating beef is “equivalent to the risk of crossing Wolf Street.” Johns Hopkins Hospital is on Wolf Street in Baltimore, Maryland.