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Friday, November 18, 2011

Bedside ultrasound--what a great way to improve medical care and potentially reduce costs

I just completed a 2 day course in "point of care ultrasound" at Harvard Medical School.  It was great. I am completely sold, a convert, a true believer.

Ultrasound is by no means a new technology. Bats use it. Bugs use it. Whales use it. A very high frequency sound wave is produced and when it hits an object it bounces back and is sensed by the creature that produced it. Submarines have used it since the first world war to locate objects, since other detection methods based on light were not useful. Doctors have used rudimentary forms of ultrasound since the 1940s to detect abnormalities in the body. In the last 30 years the machines used in ultrasound imaging have become smaller and more accurate, and the number of conditions that can be detected by ultrasound has increased vastly.  

Medical imaging studies of all kinds have become better since I emerged from medical school, and the pictures of the body that they produce are beautiful.  We have x-rays, an old technology, which look at the body by projecting radiation produced by electrons through flesh and detecting the emerging rays on the other side, initially being recorded on a kind of photographic film, and now more often by a silicon detection screen which converts the image into a digital file. X-rays impart ionizing energy to tissue and can cause healthy cells to develop DNA abnormalities which can turn them into cancer cells. CT scans use x-rays in larger numbers to produce more accurate images which a computer can use to create images that look like slices through the body. CT scans impart even more radiation to tissue than standard x-rays. They are also very expensive (at our hospital a CT scan can be billed at two to three thousand dollars.) In order to get more accurate pictures, a contrast material is often injected into a vein, which can cause fatal allergies and kidney failure.  MRI scanning produces even prettier pictures, using the fact that powerful magnets can tweak protons (present in water) in such a way that they produce a signal which can be recorded digitally. MRI scans are not particularly dangerous, except that contrast material used for MRI can cause a horrible scarring condition of the skin in patients with kidney problems, and they are even more expensive than CT scans.  All of these imaging procedures have probably saved countless lives while contributing to the development of iatrogenic disease and billions of dollars of health care related economic mischief.

Ultrasound imaging is very different than x-ray, CT or MRI scans. Safety is one of the greatest differences. Sound waves impart very little energy to tissue at the wavelengths and amplitudes used in medical machines.  Although ultrasound can be used to clean your jewelry or your teeth, imaging ultrasound is much more gentle and does no appreciable harm.

Cost is another issue: ultrasound machines, unless treated roughly, are durable and can take many pictures without using resources beyond the initial cost of the machine.

Immediacy is the difference that has impressed me most. If I have a patient in my office who I suspect has something wrong inside their body, somewhere I can't see or feel adequately (and the body has lots of those places) I often recommend that they have some sort of imaging test. If it is an x-ray or a CT or an MRI, I order that test, send the patient to the radiology suite where the technician takes the pictures after administering the contrast material if that is required. Those pictures go to the radiologist, a physician who I know but usually don't actually see very often, who interprets what I think is wrong with the patient from a brief sentence I write on my order, looks at the picture, dictates an interpretation (or sometimes calls me, but not often) and I later read that interpretation. Sometimes I look at the picture too, but I am not as good at looking at those pictures as the radiologist, so often I don't. Traditionally, I only order an ultrasound to look for specific things that ultrasounds are very good at seeing: gallstones, blood clots in the legs, function of the heart or blockage of the kidneys. If I do, the technician performs the ultrasound and the radiologist then reads the moving picture of the ultrasound images after they are performed, because ultrasound is a very dynamic procedure, looking at the body's inner workings in real time and from many different angles, since every body is a little different. Still shots from an ultrasound are blurry and hard to read like a glimpse out of the window of a fast moving car. I rarely look at ultrasound images, because only the still shots are available to me and they are of limited use.

Enter "point of care" ultrasound, that is to say ultrasound performed by the examining physician when the patient is seen. When a person gets an ultrasound, a smooth plastic transducer, shaped a bit like the handle of a paintbrush, liberally coated with ultrasound gel is applied to the skin and images appear on a screen. If I am doing the ultrasound, I slide the transducer around, looking at the structures underneath the skin and adjusting my angles and the pictures on the screen until I have seen all that I need to see. If I see something interesting, I can look at it from another angle, can look at structures near it and generally investigate until I am satisfied. There is no sending the patient to a technician, no radiologist being unsure of exactly what I am interested in, no delay. The examination is simply an extension of my history and physical exam. Nice for the patient, because I can tell them more, nice for me because looking inside the human body is unimaginably cool. In the setting of an emergency room, where belly pain could be gas or something life threatening, ultrasound can make a huge difference in survival. Right now, many people with problems that are  trivial get CT scans of everything, just to make sure. Costs are huge and radiation exposure considerable. Routine use of ultrasound by the physician at the bedside could be game changing.

There are drawbacks. Ultrasound can't see everything. There are lung conditions that can be identified, but many that can't be. Certain tumors are too small to be seen, certain other conditions just don't register on ultrasound. MDs who aren't radiologists may miss subtle abnormalities, and if they don't recognize their limits, could reassure a patient in error. Patients may assume that when a doctor has a look with an ultrasound, they will find everything that is wrong inside. Much like the standard history and physical, bedside ultrasound is limited. Doctors worry that if they are not great at ultrasound, they will be sued by patients who discover that something was missed. Still, after the experience that I have had (combined with medical knowledge and 25 years of looking at images) I think that I could help people considerably more with an exam that included ultrasound. And it doesn't really take that long, which is pretty amazing.

Here is an example of how bedside ultrasound might change my practice:

Scenario 1--appointment without ultrasound. A 35 year old woman comes in and tells me that she has been really fatigued lately and has had some belly pain. I ask her the usual questions, do a physical exam which is normal and decide that I need some blood tests and see her back in a week to discuss them. We talk about stress and irritable bowel syndrome and getting more fiber and more exercise.

Scenario 2--appointment with ultrasound. Same patient, same issues. I do a quick ultrasound. I am able to look at her liver, spleen, kidneys, and see nothing of concern. I quickly check her heart, and it is pumping normally, with no obvious problems of the valves or muscle. I then take a quick peak at her uterus and find out that she is pregnant. We can still discuss exercise, stress and fiber, but she and I have learned a great deal more with just a touch of technology thrown in. Blood tests? maybe not necessary. Followup? If needed, and more likely with an obstetrician.

There are certifications for certain physicians who do point of care ultrasound, which involve taking courses and doing a certain number of procedures which are corroborated by radiologists. Really only emergency medicine has standardized requirements like that, and the rest of us docs are left to invent the standards ourselves. These standards should allow us to use this technology and keep us from doing stupid things like saying or implying that we know things we don't know. Most physicians don't know how to do ultrasound, but many medical residents are now learning it as a matter of course during their training. It seems likely that it will become part of what we do, and that when it does, many of our routines will be streamlined.

The course that I took was excellent, but there are many other ultrasound courses throughout the US which are also excellent, at least that's what some of the other participants told me. The American Institute of Ultrasound in Medicine publishes a list of some of the practical ultrasound courses that are available at this website:

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