seeking perfection

Tuesday, December 1, 2015

Another week of NFL football is in the books, as well as another week of referee controversy. The Monday morning quarterback mantra from fans has always been “just get it right” and that led to the use of coaches’ challenge, referee review and the frustration of the home viewer having better angles on replay than what was available to the people actually at the game. Not so long ago, missed calls were part of the game experience and allowed players, coaches and fans to know that referees would miss calls. Seeking perfection led to the realization that perfection may not be attainable even with all the technology in the world. Welcome to the world of medicine where perfection is expected regardless of the price and the use and abuse of technology is an expected consequence.

Let’s talk about what happens with a patient complaining of chest pain or shortness of breath happen. Everybody worries about a heart attack, but there are other potentially life threatening diagnosis options that need to be considered. Pulmonary embolism, a blood clot to the lung, may be tough a diagnosis to make and it is hammered into every medical student, intern and resident that a PE needs to be considered in any chest pain patient. Their mantra: do NOT miss this diagnosis. Historically, the diagnosis was tough to make and relied on tests that would indirectly help find the lung blood clot. Ultrasound of the legs would look for a clot that might have travelled to the lung. A lung ventilation perfusion scan might show a lack of blood flow to part of the lung and presume that a blood clot was stopping blood circulation. The gold standard was an angiogram where catheters were threaded into the pulmonary arteries and dye injected.

Technology changes and gets better over time. CT scan is now the test of choice to look at the blood vessels in the chest and find blood clots. CT is readily available in even the smallest hospitals and with the marvels of the internet and virtual radiology; a specialist sitting at a monitor thousands of miles away can interpret the images immediately. But technology has spawned a new problem; the mantra of perfection to never miss a pulmonary embolus has led to a spike in chest CT scans to look for the elusive diagnosis.

But there may be a flaw in technology. Unlike the images, the result of the CT scan may not black and white. There is no controversy when a large pulmonary embolus is present in the large lung arteries, but as the arteries branch and get smaller, the ability to see the clot on CT gets more difficult. Radiologists can disagree as to whether a blood clot exists and whether the scan is positive or negative. Adding to the confusion is the idea that a tiny PE may be no big deal and people may have always had small clots that were never appreciated in the past, because old technology couldn’t find them.

The quest to find every last clot has led to doctors in North America to perhaps order too many CTS. With the fear of missing a diagnosis and perhaps being named in a lawsuit, only 1 in 8 CTs performed for a pulmonary embolus is positive for a clot. In Europe, where risk tolerance might be higher, that number is 1 in 4. More than 85% of scans in North America are normal!

So who cares if more CTs are done? Aside from the price, (technology does not come cheap), there is the risk of excess radiation exposure, the potential kidney damage from the intravenous dye injection, and the long-term risks of anticoagulation. Blood thinners will be prescribed even for the tiniest of clot, regardless if the clot was responsible for the patient’s symptoms. Patients with pulmonary embolus are prescribed six months of blood thinning medications with all the potential bleeding complications.

NFL officiating perfection is a potential. Enough camera angles combined with unlimited time to review each video clip would make certain that every referee call as correct but that would deliver an unwatchable game. There is big cost to achieve perfection in medical diagnosis, both financial and with medical compilations. Perhaps it may be that not being perfect may be perfectly reasonable.

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pulmonary embolus

Monday, February 23, 2015

If only patients would read the textbook and always have the same complaints and physical findings for an illness or disease. That would make diagnosis much easier. But real life is never easy when it comes to diagnosis and treatment. Consider the sad stories of Chris Bosh and Jerome Kersey.

Mr. Bosh, in the prime of his career as an NBA superstar notices some pain in his chest and for a few days doesn’t feel quite right. He sees his doctor and after a few tests, the diagnosis is made of pulmonary embolus, blood clots in his lungs. Mr. Kersey, at age 52 a retired basketball star, has one of the common presenting complaints for pulmonary embolus (PE). He dies suddenly with no warning and the diagnosis is made by the coroner. Mr. Kersey is not alone. Pulmonary embolus is the second only to cardiac arrest as the most common cause of sudden death.

There may be close to a million people each year in the US who suffer from PE, but it’s a hard diagnosis to make and the frequency may be even higher. Consider that autopsy studies of people who die in the hospital found that up to 60% had PEs and the diagnosis was missed 70% of the time. And for that reasons, doctors have a high worry factor when it comes to making the diagnosis. Patients show up complaining to their doctor about chest pain, worrying about their hearts, but as it turns out, lots more things cause chest pain that just heart disease.

Modern medicine hasn’t yet figured out how to help patients like Mr. Kersey who die without warning, but Mr. Bosh is a different story. His diagnosis is made and his doctors can high five themselves for not missing the potentially lethal disease. Now comes the tough decisions about treatment options. They all have to do with anticoagulation or thinning the blood. The blood clots in the lung, and there may be one or many, are actually located in the pulmonary arteries. Those are the large blood vessels where blood is pumped from the heart to the lungs, so that oxygen can be attached to red blood cells and then circulated to the rest of the body. Clots in the artery act like a dam and it makes it tough for the heart to pump against resistance. This can strain the heart muscle. If that isn’t enough of a problem, if enough clot is present, blood can’t get into the lung tissue and get loaded with oxygen. The potential exists for shock, hypotension (low blood pressure) and death.

pulmonary artery

The diagnosis is often made by CT and the amount of blood clot can be seen. The patient’s vital signs are monitored and their stability is assessed. The treatment for pulmonary embolus is anticoagulation or thinning the blood with medications. The first questions is whether the patient is so unstable that clotting busting drugs need to be used to dissolve the emboli that are already there. Usually, the answer is no and routine anticoagulation medication can be used. The second question to be answered is whether the patient can be treated at home. Many patients with PEs are stable and will need to be on blood thinning medication for a prolonged period of time. There are different medications available to use as an outpatient and the decision needs to be made whether to use a combination of enoxaparin (Lovenox) and warfarin (Coumadin) or the newer anticoagulants like apixaban (Eliquis) or rivaroxiban (Xarelto).

So how does one decide stability? It’s all about the vital signs. If the patient is tachycardic (rapid heart rate), tachypneic (rapid respiratory rate) and/or hypoxic (low blood oxygen), hospitalization and observation may be appropriate, even if the patient would get the same medications as they would if they were an outpatient. Abnormal vital signs presume that the heart and lungs are not working as well as they should and cannot deliver an adequate oxygen load to the body. Blood tests may be able to quantify how sick. Arterial blood gasses can measure how much oxygen is getting loaded into the blood stream and whether, the lungs are able to remove waste products from the blood. Troponin levels, normally a marker used to check for heart attack, can also help decide whether the heart muscle is being strained because it has to squeeze harder to push blood past the pulmonary artery clots. An echocardiogram, or ultrasound of the heart can also help assess heart strain.

Medications are also evolving and treatment strategies depend upon patient situation and physician comfort in using the newer anticoagulation medications like Eliquis and Xarelto. Classically, warfarin is used and blood levels have to be measured routinely to make certain the blood is adequately thinned. Warfarin dosing is adjusted based on those blood test results. That means patients have to go to the lab routinely, the doctors and nurses have to follow up on the tests and adjust medications. Studies suggest that patient blood is inadequately thinned more that 30% of the time. The new drugs do not need adjustment, blood tests or much follow up. Their downside: price is much more expensive than warfarin (but there is no need for blood tests or office visits) and…the anticoagulation cannot be emergently reversed in a bleeding emergency or if emergency surgery is required. Warfarin can be.

Finally, the question most basketball fans were asking: how long does a patient have to be anticoagulated, because on blood thinners, contact sports are out of the question because of the risk of fatal bleeding from trauma, especially to the head. The easy answer is at least three months. The real answer is…it depends. Questions that need to be asked have to do with the reason for the clot, the patients’ underlying risk of bleeding, if it is a recurrent clot and what other medical issues are present. The American College of Chest Physicians publishes guidelines for the diagnosis and treatment of blood clots and the summary is 47 pages long.

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