Posts Tagged ‘CT’

We’re still doing too many head CTs on children with headaches

August 19, 2013  |  General  |  No Comments

Many, myself included, have written about the overuse of head computed tomography (CT) scanning in children. This concern has become more focused now that we have some data on the radiation risk of those scans. The bottom line is not that we should stop doing head CTs in children, but that we should always balance the risk against the benefit, just as we should do with all medical testing. In the case of CT, the risk is tiny, but it is not zero. That risk is worth taking if the benefit is substantially more than the risk; that is, if getting the information that the CT yields is a good exchange for the risk. Put another way, is the risk of not getting the information the scan gives us greater than the risk of doing the scan itself? As a PICU doctor I order a lot of head CT scans, and I think about this trade-off with each one.

A very common reason doctors order a head CT is to evaluate a headache, even when they know the chances of finding a serious cause for the headache, such as a brain tumor, are very small. In many situations those chances of finding something bad are near zero. So how should we analyze the risk/benefit ratio between doing the CT or not? Various experts have formulated recommendations for when a head CT is indicated to help guide us in our decision-making. These include any items in the following list. The key thing to keep in mind is that serious brain problems, especially a tumor, only very rarely appear without some other abnormality accompanying the headache.

  • Age less than 3 years
  • Sudden, explosive and severe headaches
  • Associated changes in mental status or performance
  • Headaches that awaken a child from sleep
  • Associated nausea and vomiting
  • A steadily worsening pattern of headache

A recent study in Pediatrics, the journal of the American Academy of Pediatrics, assessed how well doctors (and families, too — parents often urge doctors to do CTs) are doing. The answer is not so well.

The authors of the study examined the claims records of over 15,000 children who had had at least two visits to a doctor with the complaint of headache — 25% of them received at least one head CT scan as part of the evaluation of their symptoms. Interestingly, children seen by a neurologist, a brain specialist, were only half as likely to get a CT scan. Children seen in an emergency department were four times more likely to get a CT scan than were children evaluated in a doctor’s office.

Some of these results are easily explained. It makes sense that a neurologist is more skilled in evaluating headaches and is therefore more comfortable not doing a CT than is a doctor who only occasionally treats headache. Children being seen in an emergency department are usually there because of some acute problem, so if they are there for a headache it is more likely to be new and sudden. Emergency department doctors rarely know the child, so they are probably more swayed to rule out a serious problem while they have the child there. Also, emergency room doctors order a lot of head CT scans anyway, probably too many, for minor head injuries. So they are already primed to order scans for headaches.

What is the ideal number of CT scans for headaches in children? Certainly we don’t want every scan to show an abnormality; if that were the case, it would mean we are not ordering enough of them. We want most of them to be negative to make sure we are catching all the serious problems. But the finding that a quarter of all children going to the doctor for a headache are getting a CT scan is disturbing — it’s too many.

Parents have a key role in this, especially since at least one study indicates that a major reason for doctors ordering all those scans is that parents are anxious enough not to trust either the doctor’s judgement or the standard list of indications for a scan, whether that’s for a headache or a bonk on the head. I have encountered that myself. Remember that the recommendations for head CT have been validated by research; if your child with a headache doesn’t fit any of them, it is best to wait and see how things go.

 

New information about radiation from CT scans and cancer risk

June 8, 2013  |  General  |  3 Comments

I’ve written before about the increased risk for future cancer, if any, of diagnostic radiation (here , here, and here). These posts have generated a large number of comments and questions from parents. Most take the form of fear they have needlessly increased their child’s future cancer risk by agreeing to a CT scan. A new research study give us some important new information about that issue.

There are a couple of important things to keep in mind. First, none of us can avoid radiation. It is all around us. It comes from the ground beneath us, in the form of radioactive elements in the earth and radon gas, and from outer space, in the form of cosmic radiation. Where we live affects the amount of this background radiation we receive. For example, higher altitude brings us closer to space (and to cosmic rays) and ground radiation varies from place to place. The result is that someone like me, who lives at over 7,000 feet elevation in the Rocky Mountain region, gets around 50% more background radiation than someone living on the East Coast.

Another thing to keep in mind is that simple x-rays, like chest x-rays and those of arms and legs, carry very little radiation above background. A good way to think of it is that a typical chest x-ray has the same radiation as a couple of days of ordinary living at sea level, a bit more at the altitude where I live. A typical plane flight half-way across the country also has about the same excess radiation exposure as a chest x-ray. So these amounts are really trivial unless your child gets hundreds of x-rays. It is computed tomography studies — CT scans — that really matter when we consider this issue. There are many charts you can find comparing the radiation dose of various x-ray studies: here is a good one from the FDA.

We have always assumed that CT scans, which deliver much more radiation than simple x-rays, likely increase cancer risk by some amount, although that amount was presumed to be tiny. A recent study from Australia, published in the prestigious British Medical Journal, gives us some specific information about that. The actual article is here, with a useful accompanying editorial discussing its importance here. The article is tough going for those not used to this sort of thing, but the editorial is quite readable for nonphysicians.

What did the researchers find? They found there was indeed a measurable increase in cancer risk following CT scans of the head. BUT — and this is an important but — the absolute number of increased cancers was extremely small.

What does that mean for a parent whose child needs a CT scan? To decide that you need to consider the difference between population risk and personal risk. The researchers studied 10.9 million people who got 680,211 CT scans. Over a nearly 10 year follow-up period, about 60,000 cases of cancer occurred in the total group; the group with the CT scans had 25% more cancers. The overall estimate was that CT caused one excess cancer for every 4,000 cancer cases. So that is a measurable increase in population risk. The increased risk for an individual patient, though, was miniscule. Still, the risk was not zero.

What this means for parents is what it has always meant: be reasonable and sensible. Everything we do in medicine carries risk, and this includes not doing something. If your child has a problem that a CT scan will help figure out, the question is this: what is the risk of doing the scan (which is not zero, but is exceedingly small) balanced against the risk of not getting the information the scan gives (which typically is significant).

My bottom line is that this research gives us important information about population risk for CT scanning. But it really just reinforces what we have always known about every medical test: always balance risk against benefit, and never do a test for trivial reasons, such as curiosity.

Be sensible, and be reasonable. Respect diagnostic radiation, but don’t have an irrational fear of it.

Acute sinusitis in children: causes and treatment

October 5, 2012  |  General  |  No Comments

The sinuses are air-filled cavities in our skulls. They are important for a couple of reasons. For one thing, they help warm and humidify the air we breathe in through our nose. For another thing, they make our skulls lighter; if those sinus cavities were solid bone we would have a much heavier weight to carry around on our shoulders. There are several sinus cavities in the skull, as you can see in the figure below. The image is from a CT (computed tomography) scan of a person’s skull. The CT is a kind of x-ray, in which bone is white, air is black, and solid tissues are shades of gray. CT images come in “cuts,” which show sequential slices through the skull. Each cut is about a quarter inch wide. This one is through the skull just behind the nose, with the person looking right at you. The blackness shows that the sinuses are filled with air as they should be.

The sinuses don’t all develop at the same time. A baby is born with ethmoid and small maxillary sinuses, with the frontal sinuses over the eyebrows developing by age eight or so.

The sinuses have tiny openings into the nasal passages. They represent one of the areas in the body (the entrance to the lung is another example) where a sterile area, one free of bacteria, is in very close proximity to an area heavily colonized by bacteria. In this case the normally sterile sinuses are connected via a passageway to the nasal passages, which are loaded with bacteria. When bacteria manage to invade a sinus, they cause a condition called acute bacterial sinusitis, or just sinusitis for short. The CT image below shows what that looks like: the arrows show fluid layered in the sinuses, which should be completely black with only air. The scan also shows the nasal tissues in the middle to be quite swollen compared to the normal image above.

How does it happen? Virtually all cases of bacterial sinusitis begin with a viral upper respiratory infection — a common cold. The effects of a viral infection on the lining of the nose, which is what we term respiratory epithelium, is to stun the normal function of the tissue. The respiratory epithelium normally does a good job keeping debris, including microorganisms, out of the sinuses. It does this in a couple of ways. It secretes mucous in modest amounts, which entraps invaders. It then moves this mucous out by an ingenious mechanism. Respiratory epithelium is covered with a fine blanket of what are called cilia,  microscopic structures that look like long fronds of kelp rising from the ocean floor. The cilia wave back in forth in unison, which moves the mucous along out of the sinuses and down the nose like a conveyer belt. A cold increases mucous production dramatically and also interferes with cilia function.

So with nearly every cold the sinuses get gummed up and inflamed. Most of the time the system recovers in time to keep bacteria in the nasal passages from crawling into the sinuses, reproducing, and causing infection. When the bacteria win the race, bacterial sinusitis results. In children the symptoms are pain and persistent nasal drainage, sometimes with fever. Note that cloudy, nasty-looking nasal drainage does not necessarily mean bacterial sinusitis is there, because that often happens with a simple viral cold. So how do doctors decide if sinusitis is present? There are three common patterns to look for:

  1. Persistent symptoms, meaning significant nasal drainage for more than 10 days
  2. Severe symptoms — fever over 101 degrees and cloudy, nasty nasal drainage, both for three to four days
  3. Worsening symptoms — return of nasty, cloudy nasal drainage after initial resolution, often accompanied by fever that was not initially present

The key thing is that virtually all colds cause inflammation of the sinuses. But that inflammation should be gone by ten days. If it isn’t, bacterial sinusitis is usually present. Most experts recommend antibiotic treatment at this point. Although x-rays or CT scans are often done, the current consensus is that they aren’t needed unless treatment fails to resolve the symptoms. For children, the current recommendation for the best antibiotic is amoxicillin or amoxicillin/clavulonate (brand name Augmentin), usually for ten to fourteen days. The choice depends upon local patterns in antibiotic resistance among bacteria. Of note, decongestants, such as antihistamines like diphenhydramine (brand name Benadryl), don’t help.

These are the most current expert recommendations. You can read more about acute sinusitis and its treatment here, a summary paper published by the Infectious Diseases Society of America. It has a nice flow chart on page two.

Malpractice: how likely are doctors to get sued in their careers?

August 22, 2011  |  General  |  3 Comments

Nearly everyone has heard about the medical malpractice controversy. Most doctors call it a crisis, saying, among other things, that physicians are retiring early because of it or altering their practice — not taking on what they might see as patients more likely to sue. Nonphysicians aren’t so sure about that.

What is clear is that malpractice insurance premiums, what a doctor pays every year to an insurance company and which is required by all states I know to practice, are also climbing inexorably. This seems to be happening even some states that have enacted various kinds of limits on malpractice awards, even though these measures were intended, among other things, to halt these rises in premiums. In other states, notably Mississippi, this may not be the case.

It’s also clear that the entire system we have of malpractice also does a terrible job with the two things it’s supposed to do: sanction doctors who practice bad medicine, and thereby protect the public, and compensate patients who have been injured by bad medical practice. In fact, neither of these things happen.

Meanwhile doctors fear malpractice lawsuits. This has both psychological and practical effects on physicians. There is the general perception that doctors practice a lot of what is called “defensive medicine,” doing things we otherwise would not do if we did not fear getting sued if we didn’t do them. So emergency departments get a whole lot of head CT scans, even when the probability of finding anything significant is remote. It only takes one scan you didn’t do, even though best practice guidelines say you shouldn’t, to land you in court. It’s unknown how much defensive medicine affects healthcare, but it certainly is a real thing — I’ve seen it in action, and I’m sure I’ve done it myself now and then. You can read a good article about it’s magnitude here, but it clearly costs billions. It’s also inherently unsafe: unnecessary testing can lead to unnecessary procedures, and thus unnecessary risk to patients.

But how justified are doctors’ fears of getting sued? How likely in a lifetime of practice is a doctor to face a malpractice claim? That’s really the bottom line. If I’m lecturing to a medical school class, I’d like to be able to tell them what their chances are over a lifetime of practice. I’m nearly 60 years old and have not (yet) been sued — is that a fluke, or am I the norm? A recent study in the prestigious New England Journal of Medicine finally gives us some answers to these questions.

Not surprisingly, the risk of getting sued varies with the specialty. Neurosurgeons and anesthesiologists are high risk. So are obstetricians, since complications of childbirth leading to injury are frequent causes for lawsuits. Pediatricians get sued for those cases, too, because there often is a pediatrician involved in the care of the infant. Neurosurgeons, on average (it does vary from place to place), have a nearly 20% chance each year of getting sued. For pediatricians, it’s about 3%, although the rate for my own subspecialty of pediatric critical care is much higher than it is for general pediatricians.

There is an important caveat in these data, one that you can’t tease out of the article: not every doctor in a given specialty is equally likely to get sued. That is, some doctors, one would think the worst ones, are more likely to get sued. The problem is that this is not the case. Research has shown that overall competency is not correlated with getting sued. To doctors, it seems almost random, driven by luck. This is what can drive them crazy, as well as lead to more defensive medicine.

The nub of the article, though, is lifetime risk: how likely is a doctor to get sued in a lifetime of practice? The answer is — very, very likely. For those in high risk specialties, the chances are virtually 100%. So, if you become an obstetrician, you will be sued at least once. Even if you practice a low-risk specialty, like pediatrics, you have a 70-80% lifetime risk of getting sued.

More than anything else, those numbers emphasize that our current malpractice system is unsatisfactory. Think about it — it’s saying that every single neurosurgeon in America, and three-quarters of all pediatricians, are accused of malpractice at least once in their career. Malpractice is not the same thing as making a mistake; we all make mistakes, large or small. Malpractice is clear negligence leading to patient injury.

As it turns out, physicians accused of malpractice, if the case goes to trial, are far more likely to win than are the plaintiffs — the doctors win about 85% of the time. Clear-cut cases, in which the doctor very likely was negligent, tend to be settled without trial. But not always, and this is another aspect that upsets doctors; it is typically the insurance company, not the doctor, who decides to settle the case, even though the doctor may want to fight it out in court. So a financial decision by an insurance company creates a blot on a doctor’s record that lasts for the rest of his or her career. And it is a blot. Every time I renew my medical license or hospital privileges I have to answer, not only if there are any malpractice judgements against me, but also if there are any pending claims that haven’t even gotten to court yet. To be accused is to have the stain already.

Again, the system we’ve got is both a bad way to discipline and even remove from practice bad doctors, and an unfair and inefficient way to compensate patients who really have been injured by malpractice. We’ve got to do better. My own opinion is that some sort of medical injury board, sort of like a workman’s compensation board, should handle most of these. Both experts and members of the public would be represented. But if people can bypass such an arrangement, or sue anyway if they don’t get what they want, such boards would simply add another layer to the already slow and complicated process.

Reducing radiation exposure in x-rays for children: the Image Gently program

October 2, 2010  |  General

I’ve been doing this blog for three years, and by far the post that has provoked the most interest is this one, about the safety of x-rays. The comments, now at 102, keep steadily coming. Google tells me that the most common search string that brings folks here is some variant of the question: “how safe are x-rays?” Recent studies, such as this one, have highlighted the issue of CT scans.

The important thing to understand is that nobody wants to stop doing x-rays and CT scans. The latter in particular represent a quantum leap in our diagnostic ability, and appropriate x-ray studies improve and even save children’s lives. What we want is to strike a balance between doing too few and too many. The question always to consider is this: what is the risk of doing the x-ray or CT (still very, very tiny) versus the risk of not doing the study, of not getting the information the study provides. If the study is needed to rule out the possibility of a serious condition, then the risk/benefit calculation virtually always favors doing the test.

There is another consideration, one highlighted recently by the Alliance for Radiation Safety in Pediatric Imaging, an initiative led by pediatric radiologists — the Image Gently initiative. The concept is simple: use only as much radiation as you need to get a good picture. In the past, CT scanners in particular often used radiation doses more appropriate for adults than children. Using that dose causes risk without adding benefit.

If my child needed a CT scan, I would ask the doctor to lay out the risk/benefit ratio — the risk of doing versus not doing the scan. If the scan is needed, I’d then ask if the radiologist will use the minimum dose required to get a good picture.

This site, from the International Atomic Energy Agency, has lots of useful information about protecting patients from unnecessary radiation.

Here’s a useful short post by a pediatric radiologist about all this.

Concussions in children

September 25, 2010  |  General  |  No Comments

Football season is upon us again, so it’s time to think about sports injuries. We frequently have children admitted to the PICU (or to what we call the intermediate or step-down unit) for observation, typically overnight, who have struck their head. They have had concussions. What is a concussion, and what does it mean for the child?

The term itself is centuries old, but even thirty-five years ago, when I was in training, the actual definition of concussion was a bit vague. What was usually meant was that the patient got hit on the head and either lost consciousness briefly or at least wasn’t quite himself for some period of time afterward. These days we’re more precise than that, but concussion is still a somewhat inexact term. This is mainly because of our ignorance of the subtleties of how the brain works.

The formal definition of concussion is a transient interruption in brain function. By implication, various scans of the brain, such as CT scans or MRI scans, show no abnormalities. Since all the imaging studies are normal, defining concussion is necessarily inexact. I’m sure one day we’ll have some kind of machine that detects the reason for the symptoms of concussion, but right now we don’t have such a thing — concussion is an entirely clinical diagnosis, meaning there’s specific no test for it.

There are several systems for grading concussions. Here’s how the American Academy of Neurology grades their severity:

Grade I: confusion, no loss of consciousness, symptoms last for < 15 minutes, has memory of the event Grade II: confusion, may lose memory of the event but no loss of consciousness, symptoms last for > 15 minutes
Grade III: loss of consciousness and no memory of the event

The list of symptoms that can come from a concussion is a long one. Headache, dizziness, vomiting, and ringing in the ears are common. Various behavioral changes are also common, such as lethargy, difficulty concentrating, and irritability.

What are the effects of concussion on a child? Years ago we pooh-poohed the idea that mild concussions cause brain problems. For example, football players were sent right back into the game after experiencing a concussion. We now know that is dangerous. As a general rule, we don’t recommend any contact sports for at least a week (some authorities say longer) after all symptoms have cleared. This is because a repeat blow to the head, even a very mild one, can cause severe injury to a brain that has not fully recovered from the last injury.

What about long term effects of concussions? The overwhelming majority of children who suffer a concussion, especially a mild one, recover completely. But around a fifth or so of children who have had severe concussions continue to have problems many months afterward.

You can read much more about concussions at this site, from the federal Centers for Disease Control, this one, from the Mayo Clinic, and this one, from the respected Brain Trauma Foundation.

Why we doctors order far too many scans

July 23, 2010  |  General  |  6 Comments

There’s a provocative editorial in a recent New England Journal of Medicine about the explosive rise in high-tech medical imaging. Everyone knows doctors order a lot of CT scans, MRI scans, and ultrasound studies, and that the number of these has been steadily increasing. And the cost is enormous. From the article: ” . . . these costs were the fastest-growing physician-directed expenditures in the Medicare program, far outstripping general medical inflation.”

To be fair, rising use of new medical technology is expected because, well, it’s new. What is unclear is that how much of this increased use has led to improved health to justify the cost. Clearly much of it doesn’t, and unnecessary scans, particularly CT scans, lead to risk with no benefit.

The practice of “defensive medicine,” of doctors ordering tests out of a fear of being sued for missing rare conditions, is often given as a cause for overuse of scans. There is some truth to that: the article cites a Massachusetts study showing that 28% of scans are done for that reason. Lawsuits over failing to diagnose things are common; lawsuits about overuse of tests are vanishingly rare.

Physician conflict-of-interest also plays a part. Through a loophole in Medicare regulations, physicians are allowed to refer patients for scans from which the physician benefits financially. That is wrong and needs to be fixed.

But there are deeper reasons. The root cause may well be “the style and content of clinical education and their impact on medical practice.” In other words, how doctors are trained. We use scans unthinkingly, and, unthinkingly, can cause harm. Again from the editorial: “The greatest risk that patients face with unnecessary imaging is the needless exposure to downstream testing and inappropriate treatment related to misdiagnosis and the overdiagnosis of common but unimportant findings.” I’ve seen that happen more than a few times.

CT scans and cancer: thinking about the meaning of risk

April 3, 2010  |  General

I’ve written before about how to think about the risk of x-rays that we doctors do — here, here, and here. These posts, particularly the first one, are the most read and commented upon ones I’ve done since starting the blog over two years ago. Some recent articles in the medical literature have got me thinking about the subject again, because I order more than a few CT scans for children.

The first thing to understand is that nothing we do in medicine is without risk. All tests have risks. If the test itself is virtually risk free, there is always a risk of obtaining (and acting upon) wrong information, and sometimes that is not a trivial thing.

The next thing to understand is that ordinary x-rays, what doctors often call “plain films” cause a vanishingly small risk to the child. You should not worry about those unless your child has received hundreds of them. You can read a nice comparison of radiation exposure of the various kinds of x-rays, and what it means, here.

CT (computed tomography) scans are different, because their radiation doses are much higher than plain films. And the number of CT scans has risen dramatically: there were 62 million of them done in 2007, 4 million of which were performed on children. In comparison, there were about 2 million done on people of all ages in 1980. This thirty-fold increase has been enough to double the average radiation exposure of Americans. What do we know about the risks of that increase?

CT scans do increase the lifetime risk of cancer, especially in children. But by how much? The answer is — we don’t know for sure, although there are some studies underway to find out exactly. What we can do is calculate the radiation doses that CT scanners deliver to specific organs and combine that information with that we have from atom bomb survivors (who of course got massively greater radiation exposure) to estimate what the lifetime cancer risk is. But understand that is a sort of guesstimate. This graph, taken from this article, is a good summary of what we know.

The chart divides CT scans into the two most commonly done — head (left panel) and abdomen (right panel). It then looks at the increased risk, over a lifetime, of getting cancer that is attributable to the CT scan. For abdominal scans, that’s 0.14%, if the scan happened before the age of one. What this means is that, for all kids who get cancer at some time in their life, about one in a thousand of those cases could be attributable to a CT they had earlier in life. That’s not at all the same thing as saying the scan gives them a 0.14% chance of getting cancer — over a lifetime, all of us have a risk much, much higher than that. Rather, it says that, among the large number of us who will get cancer, as many as one in a thousand of those could be attributable to the CT scan.

How should a parent interpret all this if the doctor says their child needs a CT scan? The main thing to remember, as I’ve said in my other posts on this issue, is that several times a very, very small number is still a very, very small number. So the practical implication is that, although CT scans do increase risk, for an individual child that risk is still very small.

The practical thing for a parent to do is to ask the doctor is what the risk is of not doing the scan, of not getting the information the scan gives. If the risk of not doing the scan, which is often very large, is greater than the risk of doing the scan, which is very small, the calculation favors doing the scan.

There is no question that CT scanning has been an enormous weapon in our war against disease and injury. What we are doing now is finding out ways we can avoid doing them if possible. For example, in children the most common indication for an abdominal CT is to diagnose appendicitis, and CT does a good job at that. Some recent research has focused on determining which children need a CT for that and which don’t. The FDA also has a program to try to do what it can to reduce unnecessary scanning. Because that’s the real issue: if the increase in use of CT scanning continues at the same clip over the next couple of decades that it has over the past, then we will have a much larger problem to deal with.

If you’re interested, you can read several of the articles from the medical literature that I’ve summarized in this post — here, here, and here.

Thinking about risk

March 21, 2009  |  General  |  24 Comments

I’ve recently been looking over the statistics about this blog. The most popular posts are those which talk about common issues — croup and concussions, for example. But one of the most often read posts gets its popularity from people using search engines like Google to answer this question: how risky are x-rays, especially CT scans, to children? You can read my actual posts about that here and here, but what struck me most about the popularity of this topic is what it tells us regarding how we think about risk. In particular, how do we tend to think about the risk of events occurring which are very rare, but which carry grave consequences if they happen? Lawyers call these events “small probability — large loss events.” Economists have studied the subject quite a bit, too, especially as it relates to investment decisions people make.

We humans are not entirely rational when we think about risk. We tend to focus on low-probability but high seriousness events, particularly if we are thinking about them in the context of choosing to do or not do something. So, for example, if your child needs a CT scan, as a parent you many think about how the radiation in that test increases your child’s chances of getting cancer. What we don’t think about is that your child is far, far more likely to suffer harm in a car accident while you are driving to the CT scanner than he is to suffer harm from the scan. But since we drive our children around every day, we don’t think much about that risk.

According to the National Cancer Institute, a child’s overall risk of developing any form of cancer is 1-2/10,000 children, or 0.01-0.02%. Also according to the NCI, this number has changed very little, if at all, over the past 30 years. The use of diagnostic x-rays in children, especially CT scans, has increased enormously during that time, so we should be reassured by these statistics. Even so, radiologists are increasingly vigilant about how they can reduce radiation exposure when they use x-rays.

Bottom line — it is always worth asking if the risk of a test exceeds the value of the information the test will give. But for x-rays, the benefit virtually always outweighs the risk.

We are all of us — different

September 27, 2008  |  General  |  No Comments

I recently had an experience of the sort any experienced physician has now and then. One of the doctors in the emergency department asked me to come down and help evaluate a small boy with breathing difficulties. The child indeed was breathing hard, although he was holding his own for the moment with the help of some extra oxygen. What was striking about the boy’s examination was that when I put my stethoscope to the child’s chest I couldn’t hear any air at all going into his left lung — none at all.

This is a common scenario for having something blocking the bronchus, the breathing tube, that leads to one of the lungs. In toddlers, it usually means there is what we call a foreign body, such as a peanut, a bit of popcorn, or a plastic toy down there, because toddlers are famous for putting anything in their mouth. If they suddenly breathe in, the object can end up where it shouldn’t be. After listening to the child’s chest, I assumed this was what had happened. So had the emergency department physician.

The treatment for an inhaled foreign body is not trivial. It requires the child to be anesthetized and have an instrument called a bronchoscope pushed down into his lungs looking for the object. Once found, we have attachments to fish it out. Before he arranged that, the emergency physician wanted to be surer of the diagnosis, and there were a couple of things that didn’t fit.

For one thing, no one had seen the child put anything in his mouth and he hadn’t been around any of the likely culprits. For another, his breathing problems came on over a couple of hours or so, not suddenly as usually happens with an inhaled object. Finally, although these objects can end up in either lung, they usually go to the right one, not the left. For these reasons the emergency doctor had ordered a couple of tests: first a chest x-ray, and then a CT scan. Neither one of them suggested a foreign body. In fact, they showed some abnormalities in both lungs.

Meanwhile, the child was about the same. He still had moderate difficulty breathing and needed oxygen. When he got back from the CT scanner, however, his examination findings had changed — now you could hear some air getting into his left side. More importantly, now it was easy to hear wheezing throughout his lungs. He was having an asthma attack.

This was a simple case, and the child did fine after some breathing treatments. One reason this case was interesting is that it illustrates an old medical saying, one which warns us that if we see something odd, it’s much more likely to be an uncommon manifestation of a common thing than an uncommon thing. Asthma blocks airflow out of the lungs. Although it usually does this more or less equally throughout the lungs, in this case it didn’t, at least at first.

But another reason it was an interesting case is that it reminds us that each of us is unique, and diseases can affect each of us differently. Usually these differences are small, but sometimes they are large. It’s also why you often find that the more experienced the physician, the more unwilling he is to predict with absolute certainty what will happen.