Friday, October 19, 2012

Normal Procalcitonin Rules-Out Line Sepsis

The use of procalcitonin in sepsis has been evolving rapidly in the recent literature.  The theory behind procalcitonin is that, typically, it is rapidly converted to calcitonin.  However, in the presence of gram-positive and gram-negative sepsis, circulating endotoxin results in a rapid rise in procalcitonin levels not seen during viral infection.  There's a nice study showing use of procalcitonin levels allows for reductions in antibiotic use in the ICU, without a corresponding increase in mortality – which makes it a promising test to assist in antibiotic stewardship.

This is a little bit different spin on the question addressing the use of procalcitonin levels in a population that is febrile all the time – pediatrics.  Most of the time, when children are febrile, the infectious etiology is either readily identifiable as bacterial or presumed to be viral.  However, in the subset of children with indwelling central venous catheters – they're treated presumptively as line sepsis until proven otherwise, despite the preponderance of viral etiologies.

This is a small case series of 62 children with indwelling lines, 14 of whom eventually grew positive blood cultures.  Using procalcitonin levels drawn in the Emergency Department to rule out bacteremia gave an AUC of 0.82 (0.70 to 0.93) with the "optimal" cutoff at 0.3 ng/mL giving a sensitivity of 93% and specificity of 63%.  I'm not sure I'd settle for anything less than 100% sensitivity for line sepsis, but there is a point at which the risks associated with healthcare delivery are equivalent to the risks of bloodstream infection.  This is a nice idea I wasn't previously familiar with that hopefully will be confirmed in subsequent evaluation.

"Procalcitonin as a Marker of Bacteremia in Children With Fever and a Central Venous Catheter Presenting to the Emergency Department"

Wednesday, October 17, 2012

New & Improved Glasgow Blatchford Score

Clinical decision instruments that predict short-term interventions and outcomes are fabulous things – precisely the sort of instruments that help Emergency Department physicians decide who will benefit from hospitalization.

This is the Glasgow Blatchford Score, a decision instrument applicable to presentations for upper gastrointestinal bleeding.  It has been "improved" by physicians from Kaiser, who have performed addition by subtraction – eliminating variables without a significant change in performance.  The original score has eight clinical features – the "improved" version has five, dropping chronic disease, melena, and syncope from the criteria.  Despite this, the AUC for therapeutic endpoints as well as for rebleeding and mortality is no different than the original score – at 0.85 and 0.83, respectively.

It is only a 200 patient cohort, and they don't break down exactly how many patients were in each quartile of possible modified GBS, but essentially, a score of 0 or 1 means <5% chance of needing a clinical intervention, scores of 2-6 about 20% need an intervention, and anything above that is 70% chance of intervention.  The incremental improvement over regular physician judgement is not examined, but, more objective evidence is always better.

"A modified Glasgow Blatchford Score improves risk stratification in upper gastrointestinal bleed: a prospective comparison of scoring systems"

Monday, October 15, 2012

A Month's Supply of Ketamine

This is a highly entertaining, short, qualitative survey of ketamine use in April 2011 at U.C. Davis.  Ketamine is quite popular outside the United States – but hasn't reached widespread, routine use here.

Specifically, this study looks at "low-dose ketamine" a supplementary analgesia in the Emergency Department.  Usually defined in the range of 0.1mg/kg to 0.3mg/kg, the authors use 0.2mg/kg.  Ketamine was generally efficacious, and adverse events were mild – highly limited by the size of their cohort, a mere 24 patients.  But the entertaining bit are the qualitative patient comments, including:

“I was in a science fiction movie.” 
“I was on TV.”
“I was a hippie.”
“It was pure euphoria.”
“I was scared.”
“I was hot.”

“It made me sleepy.”
“I was itchy.”

 ...and many others.

"Low-dose ketamine analgesia: patient and physician experience in the ED"