Book Review: ECGs for the Emergency Physician 1

ECGs for the Emergency Physician 1 is basically an ECG teaching file with a good mix of clear-cut and more abstruse cases. Interpretations are provided by Dr. Amal Mattu who probably needs no introduction from me as one of the most influential ECG teachers of this generation.

ecgs-for-emergency-physician-1-mattu-paperback-cover-art

The clear typeface and crisp images are striking. The index is also outstanding. Why can’t all ECG books be this well-designed?

Almost all the information in the book, published in 2003, has stood the test of time. Still, a decade is a long time, even for a field like electrocardiography. It would therefore be interesting to see an updated edition, which combined the best of volumes 1 and 2 and had some of Dr. Mattu’s new material thrown in for good measure. It should not be too difficult or costly to put together a book like that. For now, one should refer to Dr. Mattu’s free ECG video lecture series for his most recent teachings.

This book is ideal, more like necessary, for anyone who want to become an expert at reading 12-lead electrocardiograms. I recommend it very highly.

[Please read important Disclaimer.]

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Teach Yourself Dermatology!

You can become good to excellent at dermatology with the aid of no more than three books:

  1. Andrews’ Diseases of the Skin: Clinical Dermatology, 11e (2011): this book is king when it comes to a profoundly medicine-based understanding of dermatology. I seldom, if ever, recommend textbooks – and this one is more than 1210 pages long. You don’t have to read all of it, though. I would recommend, however, reading important topics in great depth. What are the important topics in dermatology? All of infectious diseases pretty much.
  2. Skin Disease: Diagnosis and Treatment, 3e (2011, reviewed here). This is a good general and introductory dermatology book. You won’t be wowed by the coolest pictures (for that you will need to see Fitzpatrick’s). The text is solid, however, without gimmicks and full of clinical pearls. It covers most of the important skin conditions that primary care doctors need to know. In some respects, the book is very much the “opposite” of Andrew’s, which is much more detailed and in-depth.
  3. Dermatology: Illustrated Study Guide and Comprehensive Board Review (2012): this is the finest dermatology review book around. It’s really rare for an individual author to display such an amazing depth and breadth of knowledge. This is the book that I would use to prepare for standardized testing in dermatology.

Now the proviso: no book can accurately depict what subtle skin lesions look like in real life, in patients with varied skin tones, stages, ages and lighting. Dermatology is not radiology. Pneumonia is always in the lung, but almost everything in dermatology can be made to look like something else when the lighting is off and the lesion is someplace else.  Therefore, to become good at dermatology diagnosis, you will need to see a lot of skin pathology in real life. Unfortunately, I cannot help you with that (at the moment!). You need good clinical exposure and good mentorship. There’s no way around that.

[Please read important Disclaimer.]

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Book Review: Rapid Interpretation of ECGs in Emergency Medicine

I don’t have any electrocardiography books on my list of best medical books of all time. There are a few contenders for that spot.  One of them is Rapid Interpretation of ECGs in Emergency Medicine: A Visual Guide (2012) by Drs. Jennifer Martindale and David Brown.

The book is basically a marked-up atlas of important, must-be-able-to-interpret-correctly electrocardiograms. Almost every important ECG that you can think of can be found here: hyperkalemia, Brugada pattern, Wolff-Parkinson-White pattern, Wellens sign,  arrhythmogenic right ventricular cardiomyopathy, and many more. These findings are shown both as unkowns and as fully marked-up versions with highlights arrows and text. That way, the reader can first look at the unknown, guess the interpretation, and then look at the marked-up version for confirmation and explanation. There are sometimes several variations of important ECG patterns, which helps improve the reader’s ability to identify and diagnose important ECG abnormalities. Also, there is an excellent introductory essay at the beginning of each chapter: they tell you what they are going to show you, then they show it to you, and then they explain to you what they just showed you. Well done!

 

Rapid Interpretation of ECGs in Emergency Medicine

The titling of the book as an emergency medicine work is a bit unfortunate because, as the authors correctly point out in the preface, the intended audience “is not only emergency physicians, but also physicians from other specialties; residents in emergency medicine, internal medicine, and family practice; physician assistants; nurse practitioners; and advanced medical students who want to become more competent in ECG interpretation.” The title, as it stands, artificially limits the market potential of this book in a very substantial way. Further, one shouldn’t have to wait for the third line of the title to learn that we are dealing with “a visual guide.” The book is first and foremost a visual guide to ECGs. Therefore, the next edition should probably be titled more simply: A Visual Guide to ECG Interpretation. Done! People who want to get better at ECG interpretation, whether emergency medicine-oriented or not, will know what it is, how to find it, and what to do with it.

In any event, and regardless of what one wants to call it, this is plainly one of the best electrocardiography books in existence.

Mark Yoffe MD

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Hypoxia: Critical but Often Poorly Understood Concepts

Hypoxemic Hypoxia
Arterial hypoxemia almost always points to either a reduction of the inspired oxygen tension or to a lung problem. When troubleshooting a hypoxemic patient, it sometimes helps to investigate the problem by breaking it down in an organized and stepwise fashion:
  1. Hardware and access issues: these are more or less obvious plumbing problems which can be fixed with straightforward mechanical means such as endotracheal intubation, repositioning of the endotracheal tube, cricothyroidotomy, or cranking up the inspired oxygen pressure (FiO2). Hardware issues are, in a sense, nonbiological: you need to get oxygen to flow from point “A,” which is either the atmosphere or an oxygen tank, to Point “B,” which is the alveoli. Broadly speaking, this is airway management and it comes before everything else.
  2. Shunting: shunting occurs when deoxygenated blood from the pulmonary circulation enters the systemic circulation without first abutting against functioning alveolocapillary membranes.  A chest radiograph is usually the first test done here because it is fast and cheap and reveals many of the more common causes of shunting such as pulmonary edema, pneumonia, and atelectasis. You fix shunting by increasing the PEEP and by getting rid of whatever substance or condition is causing the shunt: diuretics, antibiotics, pulmonary hygiene – whatever.
  3. Pulmonary embolism. If the hardware is in place and functioning well and the chest radiograph is clear, then PE is the next thing to think about in a hypoxemic patient. The test of choice here is, of course, a CT angiogram. This test has the added benefit of being able to pick up other more subtle forms of shunting which cannot be seen well on a chest radiograph, specifically interstitial lung disease, arteriovenous malformations, and milder forms of pulmonary edema. (When ordering a PE study, don’t write “rule out PE.” Rather, write “hypoxemia.” That way, you will get a lot more useful information from your friendly radiologist.)
  4. Arterial hypercarbia: the sum of all partial pressures of gasses in a closed system is constant, so a high PCO2 will “crowd out” oxygen and cause an automatic drop in PaO2 (Dalton’s law). If you are inclined to prove this diagnosis, the best way to do so is with an arterial blood gas. A normal venous PCO2 rules out arterial hypercarbia.

The above approach will enable you to figure out, in almost every instance, why your patient is hypoxemic.

While the PaO2 is the most accurate test and the reference standard for hypoxemia, it is a relatively invasive, painful and time-consuming test because it requires skilled puncture of an artery.  Instead, the percent oxygen saturation of hemoglobin  (SaO2) can serve as good surrogate test because it can be determined noninvasively with a pulse oximeter.

There are, however, situations where a patient can have a falsely low SaO2, despite a normal PaO2. These include:

  • Shocky patients with poor peripheral circulation
  • The presence of barriers (e.g., nail polish)
  • Tricuspid regurgitation, and
  • Mechanical failure of the pulse oximeter device itself.

Conversely, a falsely high SaO2 is also possible in patients with carbon monoxide poisoning and methemoglobinemia (see below).

 

Anemic Hypoxia

The critical concept here is that when the PaO2 is well within normal limits, small drops in PaO2 will cause only tiny drops in the blood’s total oxygen content. This is due to hemoglobin’s incredible oxygen-carrying capacity and the sigmoidal shape of the oxygen-hemoglobin dissociation curve.  A transfusion of packed red blood cells will add oxygen carrying capacity to an anemic patient and will improve total oxygen content, but it will not improve a poor PO2. Again, a low PO2 points squarely to a reduction of the inspired oxygen tension (FiO2) or to a lung problem. The PO2 needs to be fixed separately but concomitantly.

 

Circulatory Hypoxia

Poor systemic or local circulation. The PaO2 and hemoglobin may be normal, but oxygen is still not getting where it needs to go because of poor cardiac output or vascular supply.

 

Toxic Hypoxia

The most important causes of toxic hypoxia are carbon monoxide, methemoglobin, and cyanide. Carbon monoxide binds to hemoglobin, while methemoglobin is a hemoglobin derivative. They both prevent normal oxygen delivery to cells and cause a falsely-normal pulse oximeter reading. Therefore, if carbon monoxide poisoning or methemoglobinemia are suspected, ditch your regular pulse oximeter and get an arterial blood gas with cooximetry or perform a pulse cooximetry. A cooximeter will measure the relative concentrations of various forms of hemoglobin, including oxyhemoglobin, carboxyhemoglobin, and methemoglobin.

Cyanide poisoning is called histotoxic hypoxia because cyanide does not bind hemoglobin to a significant degree. Rather, it poisons tissues (mitochondria) directly and thereby prevents them from utilizing oxygen. Thus, in patients with cyanide poisoning, oxygen will float right past the capillaries and enters the venous circulation, instead of getting dropped off at the capillary level for cellular respiration. Cells are then forced to undergo anaerobic respiration and produce lactic acid in the process.

As with carbon monoxide poisoning and methemoglobinemia, the pulse oximeter will often be normal in cyanide poisoning. However, unlike patients with carbon monoxide poisoning and methemoglobinemia, patients with cyanide poisoning will frequently have a normal cooximetry reading as well. The key to clinching the diagnosis is to look for red (hyperoxic) venous blood, either on venipuncture or on funduscopic examination, especially in the presence of an otherwise unexplained profound lactic acidosis.

By

Please read important Disclaimer.

Resources

  • Fishman, Alfred, Fishman’s Pulmonary Diseases and Disorders (2008)
  • Terry Des Jardins, Clinical Manifestations & Assessment of Respiratory Disease, 6e (2010)

[Updated October 9, 2013]

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Book Review: Surgical Recall, 6e

Surgical Recall, 6e (2012) by Lorne H. Blackbourne MD is an 800-page handbook that is packed with very high-yield clinical information that all primary care physicians should find relevant.

The book is obviously is surgery oriented, but I find its content to be extremely relevant to all major medical specialties. Solid tumors, relevant to almost every branch of medicine, are covered particularly well. This information can be hard to find, in a condensed fashion, in many other medical review books.

Open this book when  you are done preparing for your boards in almost any specialty. You will be amazed at the wealth of critical and highly-tested information that routinely gets missed in other sources.

 

Surgical Recall

On the downside, this is predominantly a medical student-level surgery review book. Users who apply the internal medicine-related content to real-life situations uncritically will get their patients into a lot of trouble. For example, the proposed treatment of hypercalcemic crisis is “volume expansion with normal saline, diuresis with furosemide.” However, severely hypercalcemic patients tend to be extremely dehydrated. Furosemide would only worsen the problem and harm the patient if used at the outset. The relevant sentence needs clarification. Also, the book, which has a copyright of 2012, recommends “Zygris” for the treatment of septic shock. However, in 2011 the manufacturer withdrew Xigris, or drotrecogin alfa, from worldwide markets because of failure to demonstrate a survival benefit and because of a “question [regarding] the benefit-risk profile” of the drug.

Despite the aforementioned limitations, I recommend this medical book very highly because of its excellent coverage of surgery and related content. It is one of the best medical books of all time.

By

[Please read important Disclaimer.]

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2013: The Best Medical Books of All Time

Here is my as-of-year-2013 list of the best medical books of all time, books which I consider to be great to spectacular.

Anonymous posts are allowed. Please let me know if you have any additional suggestions for inclusion. I would especially like to add to the list books on electrocardiography, sports medicine, oncology and autoimmune diseases, subjects which are not represented in this list at all.

The oldest book on the list is Dr. Hoppenfeld’s Physical Examination of the Spine and Extremities. I seriously doubt whether its place on the list will be granted to a different musculoskeletal medicine book in my lifetime–but I’d be happy to prove myself wrong. The most recently-published book is Dr. Gallagher’s Board Stiff TEE: Transesophageal Echocardiography, 2e (2013). It is a great book about echocardiography in particular and about valvular heart disease in general.

There is a slight tendency toward including books published in the United States, in part because many outstanding medical books have, in fact, been published here. Availability bias, however, could not be avoided. Also unavoidable–at least in the short term–is the fact that I don’t understand or speak French, German, or Japanese. A good chunk, if not most, of the world’s medical literature is inaccessible to me because of language barriers. Please let me know if you know of any non-English language books that deserve special consideration.

Without further ado, and in no definitive order, here they are:

  1. Dr. Gerald de Lacey, The Chest X-Ray: A Survival Guide by  (2008, reviewed here).
  2. Igbaseimokumo, Usiakimi, MD, Brain CT Scans in Clinical Practice (2009, reviewed here)
  3. Herring, William, MD, Learning Radiology, Recognizing the Basics, 2e (2011, reviewed here)
  4. Kurtz, Ira, MD, Acid Base Case Studies (2004, reviewed here)
  5. Desai, Samir P., MD, Clinician’s Guide to Laboratory Medicine: Pocket (2009, reviewed here)
  6. Peters, Wallace, MD, Atlas of Tropical Medicine and Parasitology (2007, reviewed here)
  7. Schlossberg, David, MD, Differential Diagnosis of Infectious Diseases (1996, reviewed here)
  8. Klatt, Edward C., MD, Robbins and Cotran Atlas of Pathology, 2e (2009, reviewed here)
  9. Howick, Jeremy H., Dr., The Philosophy of Evidence-based Medicine (2011, reviewed here)
  10. Hauser, Alan R., MD, PhD., Antibiotic Basics for Clinicians: The ABCs of Choosing the Right Antibacterial Agent, 2e (2012, reviewed here)
  11. Orient, Jane M., MD, Sapira’s Art and Science of Bedside Diagnosis (2009)
  12. Hoppenfeld, Stanley, MD, Physical Examination of the Spine and Extremities (1976, reviewed here)
  13. Buttaravoli, Philip, MD, Minor Emergencies (2007, reviewed here)
  14. Blackbourne, Lorne H., MD, Surgical Recall, 6e (2012, reviewed here)
  15. Jarrell, Bruce, MD, NMS Surgery Casebook (2003, reviewed here)
  16. Silen, William, MD, Cope’s Early Diagnosis of the Acute Abdomen  (2010, reviewed here)
  17. Ovalle, William K., PhD.,  Netter’s Essential Histology (2007)
  18. Gallagher, Christopher, MD, Board Stiff TEE: Transesophageal Echocardiography, 2e (2013)
  19. Bain, Barbara Jane, Prof. Haematology, A Core Curriculum (2010, reviewed here)

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[Updated September 12, 2013. Please read important Disclaimer.]

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