Oct 28, 2016

Fresh air

The story

Like whether or not the printer is working in the medicine lounge, sorting out who benefits from oxygen in chronic obstructive pulmonary disease (COPD) is anyone's guess. New trial results help clarify the role of the home oxygen tank.

The background

The 70's were notable for more than just funny photos of your parents: two modest trials (Annals / Lancet) found that long-term supplemental oxygen therapy reduced mortality in COPD patients with severe hypoxemia, defined as partial pressure of arterial oxygen (PaO2) < 55 mm Hg or pulse oximetry (SpO2) < 89%. The results quickly found their way into COPD guidelines, but the role of supplemental oxygen in moderate COPD (SpO2 89 - 93%) remained poorly studied.

The breeze

The 740 patient LOTT trial looked at COPD patients with mild-to-moderate hypoxemia over an 18-month period. No differences in death rate or time to first hospitalization were found between patients with and without supplemental oxygen. Mortality, COPD exacerbations, quality of life, and functional status were similar between groups, as were symptoms of anxiety and depression. A quick study cartoon can tell you more.

The takeaway

It usually takes just one prescription to start COPD'ers on an indefinite supply of home oxygen, along with all of the associated expenses, equipment, and awkward interactions with supply company reps. LOTT helps answer who really needs oxygen therapy, and will help keep patients with moderate COPD away from supplemental O2.

Say it on rounds

When you turn the lights on in the overnight call room, and everyone wakes up

Sometimes it helps to get some context before barging in. Or at least so says Germany's single-center CAD-man study, which compared CT imaging to invasive coronary angiography (cardiac cath) in patients with atypical angina or chest pain. CT screening before cath increased the diagnostic yield for angiography to 75% relative to a 15% yield when cath was done upfront. Rates of cardiac events and complications were similar between groups, but patients preferred non-invasive testing.

When you can't see it, but you can smell it

Time on the wards will teach you that the nose is a superb tool. Orthopedists agree, and in a first-in-man trial, scientists found that nasal cartilage grafts were safe and effective when used to repair cartilage tears in the knee. There were no adverse reactions among the trial's ten patients, and participants reported improved pain, function and quality of life up to 2 years after the procedure. The nasal grafts are an intriguing source for cartilage repair because they form tissue easily and adapt well to new environments.

When your supervising resident is a bit OCD

Comes with the territory, but what's his / her pulse? A Swedish cohort of over 1 million enlisted men (age 18) found that those with resting heart rates > 82 beats per minute were more likely to develop mental illness later in life, including obsessive compulsive disorder, schizophrenia, and anxiety. Since similar results were seen in patients with high blood pressure, some think that autonomic nervous system dysfunction may be an early marker of psychiatric disease.
JAMA Psychiatry

Brush up


Like a lot of diseases, gout plays well with others. The most common comorbidities are hypertension (74% of patients), chronic kidney disease (71%), and obesity (53%). Patients often present for the first time with an acute flare of the foot or ankle. If you suspect new gout in your primary care clinic, look to tap the affected joint. The gold standard for diagnosis is microscopic confirmation of negatively birefringent needle-shaped crystals in synovial fluid.

What's the evidence

For diet recommendations in gout? Tell your patients to avoid alcohol and purine-rich foods like red meats and fish, since both have been linked to gout flares through case control studies. Fructose and sugar sweetened beverages were linked to new cases of gout through a 2008 prospective cohort study, while a 2014 review found little evidence that dietary supplements like vitamin C and skim milk powder reduce gout flares.

What your mathematics friends are talking about

Researchers used Bayesian phylogenetic analyses to pin the US HIV epidemic origin to the year 1970 in New York City, clearing Patient Zero from blame as the progenitor of the 1980's AIDS epidemic.

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