Oct 21, 2016

Clotting factor

The story

When your friends fainted in med school, it's because they saw or smelled something gnarly in the OR. But for everyone else, finding a cause for syncope can be tough. New evidence suggests that pulmonary embolism (PE) plays a larger role than previously thought.

The basics

It's easy to get familiar with syncope in the ED, where about 1% of visits are prompted by a syncopal event. Vasovagal syncope is the most common cause, followed by cardiac syncope and several others. Yet even after expensive work-ups as many as 50% of episodes remain undiagnosed despite an annual Medicare price tag of about $2.5 billion.

The blood clot

Investigators in Italy, citing a lack of consideration for PE in European and American syncope evaluation guidelines, studied 560 patients who presented with a first episode of syncope. All patients were evaluated with D-dimer testing and were assessed for PE with the Wells criteria. If either test was positive, patients were imaged for PE with CT angiogram or V/Q scan. PE was found in over 40% of patients who screened positive, or about 17% of all patients in the study. A 2-minute cartoon video can tell you more.

The takeaway

Given the huge number of emboli found in this study of primarily elderly patients (average age 80), PE could very well be the largest cause of unexplained syncope. Make sure to put it on the differential for your syncope admissions, and consider ordering a D-dimer if in the ED.

Say it on rounds

When you get prank paged, and you can't figure out the culprit

Think of H. pylori as a similarly elusive villain. The bacteria thrives in the stomach lining, where the acidic environment inactivates antibiotics. And while triple therapy has been the standard-of-care for over 20 years, H. pylori resistance to clarithomycin is increasingly common. A 1,600 patient RCT in Taiwan found that 10-day treatment with bismuth-based quadruple therapy produced a higher eradication rate than 14-day treatment with triple therapy or concomitant therapy, adding to a growing body of evidence supporting quadruple therapy as the best choice for initial treatment. 

When your favorite horror movie makes your skin crawl

This Halloween, be thankful that it's just your imagination. A large cohort study in Tanzania found that infection with the parasite worm Wuchereria bancrofti was associated with a two-fold increase in the incidence of new HIV infection after controlling for sexual behaviors and other variables. Investigators think that systemic infection, termed lymphatic filariasis, downregulates host anti-viral T-cell response. Since up to 44% of Tanzanians are infected in coastal regions, the study raises the possibility that eradicating helminth infection may decrease the spread of HIV.

Get meta

With rapid response teams (RRTs) and hospital mortality. In 2004 the Institute of Healthcare Improvement recommended that hospitals establish RRTs to respond urgently to predictable signs of impending cardiac arrest, and over 50% of hospitals had done so by 2010. A meta-analysis of 30 studies and over 3 million hospital admissions concluded that the implentation of RRTs was associated with a significant reduction in hospital mortality and non-ICU cardiopulmonary arrests.
J Hosp Med

Brush up

Red blood cell tranfusion

Like residency, anemia can make you tired and unpleasant. When do you transfuse? Per recently released AABA guidelines, use a hemoglobin threshold of 7 g / dL with a target range of 7 to 9 g / dL for patients without major hemorrhage or acute coronary syndrome (ACS). For ACS patients, use a threshold of 8 g / dL with a target range of 8 to 10 g / dL. Transfuse one unit at a time if the patient isn't actively bleeding and re-check a CBC before giving more. Chronically anemic patients should have individualized thresholds and targets.

What's the evidence

For transfusion thresholds in critically ill patients? 1999's TRICC trial showed that a restrictive transfusion strategy (hemoglobin  < 7 g / dL) was associated with lower in-hospital mortality compared to a liberal strategy (hemoglobin < 10 g / dL) in critically ill patients without ACS, hypoxemia or hemorrhage. The more recent TRISS study (2014) evaluated patients with septic shock and found similar 90-day mortality rates for patients transfused at a threshold of 7 g / dL vs. 9 g / dL, but the conservative transfusion group used half as much blood. 

What your public health friends are talking about

STDs have reached unprecedented highs in the US, says a new report from the CDC. Some have chalked up the rise to budget cuts for public health programs, while others believe there is a Tinder effect.

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