Cyanosis

Descriptions of cyanopathia or Morbus caeruleus (cyanosis) have populated medical literature since the time of Hippocrates, although the actual pathophysiology behind its development eluded physicians until the advent of objective anatomy and physiology. Morgagni, “accurate anatomist,” philosopher, and one of the fathers of contemporary medicine, is often credited with having first described cyanosis (in association with stasis due to pulmonic stenosis [1761]),(1) however, it was actually deSenac, personal physician to King Louis XV (and the first to elucidate the relationship between atrial fibrillation and mitral stenosis), who first described the pathophysiology of cyanosis (albeit not entirely correctly!) in 1749.(2) It was not until over 2 centuries later, however, that Christen Lundsgaard actually quantified the amount of deoxygenated hemoglobin that was required to produce that bluish discoloration that produces the clinical finding of cyanosis.(2)

Features of Cyanosis
Cyanosis is an abnormal bluish discoloration of the skin and mucous membranes; it is caused by high levels of deoxygenated (reduced) hemoglobin (or its derivatives) circulating within the superficial dermal capillaries and subpapillary venous plexus (not, as commonly taught, the deeper arteries and veins).(1) Hypoxemia, not to be confused with hypoxia (which reflects tissue oxygenation), is the deficient oxygenation of blood that leads to cyanosis.(3)

Whether or not cyanosis is apparent to the human eye depends on dermal thickness, cutaneous pigmentation, and state of the cutaneous capillaries.(4) In light of this, cyanosis is best appreciated in areas of the body where the overlying epidermis is thin and the blood vessel supply abundant, such as the lips, malar prominences (nose and cheeks), ears, and oral mucous membranes (buccal, sublingual); it is better appreciated in fluorescent lighting.(1)

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-- Sarah M. McMullen, MD, Ward Patrick, MD

This article originally appeared in the March 2013 issue of The American Journal of Medicine.

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March 2013: Lyme Disease

The March 2013 issue of The American Journal of Medicine includes a thorough review of acute and chronic Lyme disease diagnosis and treatment, in addition to explaining some common misconceptions about Lyme disease. In this video, Editor-in-chief Dr. Joseph S. Alpert discusses some of the high points of the article.

The Fallen Soldier

Remembering the Fallen Soldier: John McCrae on Flanders Fields

The name John McCrae is not one instantly recognized in the annals of medical history. Although a friend and colleague of such giants as William Osler and Harvey Cushing, McCrae's contribution to history is the mournful poem In Flanders Field, which he wrote on a World War I battlefield during a brief respite from caring for his wounded and dying comrades.

Born on November 30, 1872, in the town of Guelph, Canada, John Alexander McCrae was destined to serve in the military. Descending from Highland Scots, the McCrae family had a proud tradition of serving in the army. He joined a corps of cadets during high school and by age 15 years served as the bugler for his father's artillery unit in the Canadian militia. After high school, McCrae obtained a scholarship to the University of Toronto and graduated with a biology degree in 1894. Although plagued by severe asthma attacks throughout his life, McCrae served as an officer in the Canadian militia while in college and subsequently received a commission in the field artillery.(1)

Deciding on a career in medicine, McCrae graduated first in his class at the University of Toronto Medical School in 1898. He completed internship at Toronto General Hospital and then left Canada to serve as a Resident House Officer under William Osler at Johns Hopkins. Although awarded a pathology fellowship at McGill University in 1900, he instead left training to serve his native Canada in the intervening Boer War. McCrae finished his military service in 1901 and returned to Canada, where he completed fellowship and was named Pathologist for Montreal General Hospital.

McCrae's driving interests in military service and science were tempered by a fondness for writing poetry.

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-- Mathew W. Lively, DO, Richard D. Layne, MD

This article originally appeared in the January 2013 issue of The American Journal of Medicine.

Adherence to PIOPED II Investigators' Recommendations for Computed Tomography Pulmonary Angiography

Non-adherence to recommendations for CT pulmonary angiography is common and exposes patients to increased risks, including potential false positive diagnoses of pulmonary embolism.

Abstract 
Background 
Computed tomography (CT) pulmonary angiography use has increased dramatically, raising concerns for patient safety. Adherence to recommendations and guidelines may protect patients. We measured adherence to the recommendations of Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED II) investigators for evaluation of suspected pulmonary embolism and the rate of potential false-positive pulmonary embolism diagnoses when recommendations of PIOPED II investigators were not followed.

Methods
We used a structured record review to identify 3500 consecutive CT pulmonary angiograms performed to investigate suspected pulmonary embolism in 2 urban emergency departments, calculating the revised Geneva score (RGS) to classify patients as “pulmonary embolism unlikely” (RGS≤10) or “pulmonary embolism likely” (RGS>10). CT pulmonary angiograms were concordant with PIOPED II investigator recommendations if pulmonary embolism was likely or pulmonary embolism was unlikely and a highly sensitive D-dimer test result was positive. We independently reviewed 482 CT pulmonary angiograms to measure the rate of potential false-positive pulmonary embolism diagnoses.

Results 
A total of 1592 of 3500 CT pulmonary angiograms (45.5%) followed the recommendations of PIOPED II investigators. The remaining 1908 CT pulmonary angiograms were performed on patients with an RGS≤10 without a D-dimer test (n=1588) or after a negative D-dimer test result (n=320). The overall rate of pulmonary embolism was 9.7%. Potential false-positive diagnoses of pulmonary embolism occurred in 2 of 3 patients with an RGS≤10 and a negative D-dimer test result.

Conclusions 
Nonadherence to recommendations for CT pulmonary angiography is common and exposes patients to increased risks, including potential false-positive diagnoses of pulmonary embolism.

To read this article in its entirety, please visit our website.

-- Daniel M. Adams, MD, Scott M. Stevens, MD, Scott C. Woller, MD, R. Scott Evans, PhD, James F. Lloyd, BS, Gregory L. Snow, PhD, Todd L. Allen, MD, Joseph R. Bledsoe, MD, Lynette M. Brown, MD, PhD, Denitza P. Blagev, MD, Todd D. Lovelace, MD, Talmage L. Shill, MD, Karen E. Conner, MD, MBA, Valerie T. Aston, RRT, C. Gregory Elliott, MD

This article originally appeared in the January 2013 issue of The American Journal of Medicine.

Related Article: Chasing Pulmonary Emboli: Let's Agree on One Big Thing

Skepticism: What Is True?

Skepticism or 'Things I Was Taught that Weren't True

"The philosophies of one age have become the absurdities of the next, and the foolishness of yesterday has become the wisdom of tomorrow.” 
Sir William Osler

“The altar cloth of one aeon is the doormat of the next.”
 Mark Twain

“The most erroneous stories are those we think we know best—and therefore never scrutinize or question.”
Stephen Jay Gould

“In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.” 
Galileo Galilei

“So many centuries after the Creation, it is unlikely that anyone could find hitherto unknown lands of any value.” 
Spanish Royal Commission, rejecting Christopher Columbus' proposal to sail west.

“What is allegedly true and useful today may be shown to be worthless tomorrow … remember Socrates and remain skeptical!”(1)
 J.S.A.

What was once true but have been disproven? To find out, read this article in its entirety on our website.

-- Joseph S. Alpert

This article originally appeared in the February 2013 issue of The American Journal of Medicine.

Mortality Rates for Black Males

United States Counties with Low Black Male Mortality Rates

In only 66 out of 1307 US counties, black men have a lower mortality than white men. What makes these counties different?

Abstract
Objective
In the United States, young and middle-aged black men have significantly higher total mortality than any other racial or ethnic group. We describe the characteristics of US counties with low non–Hispanic Black or African American male mortality (ages 25-64 years, 1999-2007).

Methods
Information was accessed through public data, the US Census, the US Compressed Mortality File, and the Native American Graves Repatriation Act military database.

Results
Of 1307 counties with black mortality rates classified as reliable by the National Center for Health Statistics (at least 20 deaths), 66 recorded lower mortality among black men than corresponding US whites. Most notable, 97% of the 66 counties were home to or adjacent a military installation versus 37% of comparable US counties (P<.001). Blacks in these counties had less poverty, higher percentages of elderly civilian veterans, and higher per capita income. Within these counties, national black:white disparities in mortality were eliminated for ischemic heart disease, accidents, diseases of the liver, chronic lower respiratory diseases, and mental disorder from psychoactive substance use. Application of age-, race-, ethnicity-, gender-, and urbanization-specific mortality rates from counties with relatively low mortality would reduce the black:white mortality rate ratio for black men aged 25 to 64 years from 1.67 to 1.20 nationally and to 1.00 in areas outside large central metropolitan areas.

Conclusions
These descriptive data demonstrate a small number of communities with low mortality rates among young and middle-aged black/African American men. Their characteristics may provide clinical and public health insights to reduce these higher mortality rates in the US population. Analytic epidemiologic studies are necessary to test these hypotheses.


To read this article in its entirety, please visit our website.

-- Robert S. Levine, MD, George Rust, MD, Muktar Aliyu, MD, PhD, Maria Pisu, PhD, Roger Zoorob, MD, MPH, Irwin Goldzweig, MS, Paul Juarez, PhD, Baqar Husaini, PhD, Charles H. Hennekens, MD, DrPH

 This article originally appeared in the January 2013 issue of The American Journal of Medicine.

Feb 2013: Statin Dosing

Is alternate day statin dosing a good idea? In this video, Editor-in-chief Dr. Joseph S. Alpert reviews new research into statin dosing in the February 2013 issue of The American Journal of Medicine.

Chasing Pulmonary Emboli

Chasing Pulmonary Emboli: Let's Agree on One Big Thing

Clinical practice guidelines can be great. It's nice to have guidelines for the diagnosis, management, and long-term care objectives for basically every condition known to medicine. Clinical practice guidelines are supposed to be the foundation of 21st century evidence-based medicine. But clinicians frequently do not follow clinical practice guidelines. Just Google “clinical practice guidelines”: after you note 7,100,000 citations on clinical practice guidelines in less than 0.5 seconds, you begin to understand why. First, which clinical practice guideline do you follow? Various professional organizations fight over the same meta-analyses and come to different conclusions—notoriously in regard to mammography recommendations, for example. There are differences in the United States among different organizations regarding when to start mammography, how often to screen, and when to stop. Other advanced medical systems in Europe look at the same data and choose very different intervals and start-up and ending ages. There are distinguished researchers who maintain that screening mammography in low-risk patients is entirely without merit and may do more harm than good.1 Which clinical practice guideline do you follow and how did you choose it? Or choose to ignore it?

Clinicians do not follow clinical practice guidelines for many reasons: lack of knowledge, disagreement (whether due to thoughtful analysis or simple egocentricity), distaste for cookbook approaches, inconvenience, inertia, patient unwillingness, and the like. There is an entire literature not only on clinical practice guidelines but also on why clinical practice guidelines are fabulous or awful, and even on why many clinicians refuse to follow them. But enough about this mess.

To read this article in its entirety, please visit our website.

-- Robert G. Stern

This article originally appeared in the January 2013 issue of The American Journal of Medicine.

Related Article:  Adherence to PIOPED II Investigators' Recommendations for Computed Tomography Pulmonary Angiography